UNITED STATES
 SECURITIES AND EXCHANGE COMMISSION
 Washington, DC 20549
 FORM 10-K
 (Mark One)

 ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

 For the fiscal year ended December 31, 2024
 OR

 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

 For the transition period from to
 Commission File Number: 001-35966
 (Exact Name of Registrant as Specified in Its Charter)
 Delaware
 13-3680878

 (State or Other Jurisdiction of
Incorporation or Organization)
 (IRS Employer
Identification No.)

 455 Grand Union Boulevard

 Somerville, Massachusetts

 02145

 (Address of Principal Executive Offices)
 (Zip Code)

 ( 339) 499-9300
 (Registrant's Telephone Number, Including Area Code)

 Securities registered pursuant to Section 12(b) of the Act:

 Title of each class
 Trading Symbol(s)
 Name of each exchange on which registered

 Common Stock, $0.01 par value per share
 BLUE
 The Nasdaq Stock Market LLC

 Securities registered pursuant to Section 12(g) of the Act: None
 Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes No
 Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes No
 Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes No
 Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes No
 Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of "large accelerated filer", "accelerated filer", "smaller reporting company", and "emerging growth company" in Rule 12b-2 of the Exchange Act.
 Large accelerated filer

 Accelerated filer

 Non-accelerated filer

 Smaller reporting company

 Emerging growth company

 If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.
 Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.
 If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.
 Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant's executive officers during the relevant recovery period pursuant to § 240.10D-1(b).
 Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). Yes No
 The aggregate market value of common stock held by non-affiliates of the registrant based on the closing price of the registrant's common stock as reported on the Nasdaq Global Select Market on June 28, 2024, the last business day of the registrant's most recently completed second quarter, was $ 189,220,530.
 As of March 25, 2025, there were 9,790,070 shares of the registrant's common stock, par value $0.01 per share, outstanding.
 DOCUMENTS INCORPORATED BY REFERENCE
 None.

 Page

 PART I.

 Item 1.

 Business

 Item 1A.

 Risk Factors

 Item 1B.

 Unresolved Staff Comments

 Item 1C.

 Cybersecurity

 Item 2.

 Properties

 Item 3.

 Legal Proceedings

 Item 4.

 Mine Safety Disclosures

 PART II.

 Item 5.

 Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

 Item 6.

 [Reserved]

 Item 7.

 Management's Discussion and Analysis of Financial Condition and Results of Operations

 Item 7A.

 Quantitative and Qualitative Disclosures About Market Risks

 Item 8.

 Financial Statements and Supplementary Data

 Item 9.

 Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

 Item 9A.

 Controls and Procedures

 Item 9B.

 Other Information

 Item 9C.

 Disclosures Regarding Foreign Jurisdictions that Prevent Inspections

 PART III.

 Item 10.

 Directors, Executive Officers and Corporate Governance

 Item 11.

 Executive Compensation

 Item 12.

 Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

 Item 13.

 Certain Relationships and Related Transactions and Director Independence

 Item 14.

 Principal Accountant Fees and Services

 PART IV.

 Item 15.

 Exhibits and Financial Statement Schedules

 Item 16.

 Form 10-K Summary

 Signatures

 FORWARD-LOOKING STATEMENTS
 This Annual Report on Form 10-K contains forward-looking statements that involve risks and uncertainties, as well as assumptions that, if they never materialize or prove incorrect, could cause our results to differ materially from those expressed or implied by such forward-looking statements. We make such forward-looking statements pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995 and other federal securities laws. All statements other than statements of historical facts contained in this Annual Report on Form 10-K are forward-looking statements. In some cases, you can identify forward-looking statements by words such as "anticipate," "believe," "contemplate," "continue," "could," "estimate," "expect," "intend," "may," "plan," "potential," "predict," "project," "seek," "should," "target," "would," or the negative of these words or other comparable terminology. These forward-looking statements include, but are not limited to, statements about:
 • our entrance into an Agreement and Plan of Merger (the "Merger Agreement") with Beacon Parent Holdings, L.P., a Delaware limited partnership ("Parent"), and Beacon Merger Sub, Inc., a Delaware corporation ("Merger Sub"), including our beliefs about the potential benefits of the transaction contemplated by the Merger Agreement; and the planned completion and timing of the transaction contemplated by the Merger Agreement (the "Merger Transaction");
 • our plans and expectations regarding our commercialization activities for SKYSONA, ZYNTEGLO, and LYFGENIA, as well as any future approved products and the timing or success thereof, including expectations regarding our network of qualified treatment centers;
 • the initiation, timing, progress and results of our preclinical and clinical studies, and our research and development programs;
 • our ability to advance product candidates into, and successfully complete, clinical studies;
 • our ability to obtain adequate financing to fund our operations and to execute on our strategy;
 • our expectations and projections regarding the sufficiency of our cash and cash equivalents to fund our operations through the consummation of the Merger Transaction;
 • the impact of our Restructuring initiated in September 2024 and the anticipated reduction in cash operating expense;
 • our ability to establish and scale commercial viral vector and drug product manufacturing capabilities, and to ensure adequate supply of our viral vectors and drug products, and our plans and expectations regarding our manufacturing activities;
 • the timing or likelihood of regulatory filings and marketing approvals for our product candidates and our plans and expectations relating thereto;
 • our ability to obtain adequate pricing and reimbursement of any approved products;
 • the implementation of our business model, strategic plans for our business, product candidates and technology;
 • the scope of protection we are able to establish and maintain for intellectual property rights covering our product candidates and technology;
 • estimates of our expenses, future revenues, capital requirements and our needs for additional financing;
 • the potential benefits of strategic collaboration agreements and our ability to enter into strategic arrangements;
 • our ability to maintain and establish collaborations and licenses;
 • developments relating to our competitors and our industry;
 • the impact of the general economic conditions and uncertainties;
 • our ability to mitigate the commercial, reputational and regulatory risks to our business that may arise as a consequence of the restatement of our financial statements;

 • our ability to remediate the material weakness in our internal control over financial reporting; and
 • other risks and uncertainties, including those listed under Part I, Item 1A. Risk Factors.
 Any forward-looking statements in this Annual Report on Form 10-K reflect our current views with respect to future events or to our future financial performance and involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by these forward-looking statements. Factors that may cause actual results to differ materially from current expectations include, among other things, those listed under Part I, Item 1A. Risk Factors and elsewhere in this Annual Report on Form 10-K. Given these uncertainties, you should not place undue reliance on these forward-looking statements. Except as required by law, we assume no obligation to update or revise these forward-looking statements for any reason, even if new information becomes available in the future.
 This Annual Report on Form 10-K also contains estimates, projections and other information concerning our industry, our business, and the markets for certain diseases, including data regarding the estimated size of those markets, and the incidence and prevalence of certain medical conditions. Information that is based on estimates, forecasts, projections, market research or similar methodologies is inherently subject to uncertainties and actual events or circumstances may differ materially from events and circumstances reflected in this information. Unless otherwise expressly stated, we obtained this industry, business, market and other data from reports, research surveys, studies and similar data prepared by market research firms and other third parties, industry, medical and general publications, government data and similar sources.
 Summary of the Material and Other Risks Associated with Our Business
 Below is a summary of the material risks to our business, operations and the investment in our common stock. This summary does not address all of the risks that we face. Risks and uncertainties not presently known to us or that we presently deem less significant may also impair our business operations. Additional discussion of the risks summarized in this risk factor summary, and other risks that we face, can be found below under the heading "Risk Factors" and should be carefully considered, together with other information in this Annual Report on Form 10-K in its entirety before making investment decisions regarding our common stock.
 • The conditions under the Merger Agreement to Parent's and Merger Sub's consummation of the Merger Transaction may not be satisfied at all or in the anticipated timeframe.
 • The announcement of, or a failure to consummate, the Merger Transaction could negatively impact our business, financial condition, results of operations or our stock price.
 • We have incurred significant losses since our inception and we may not achieve our goal of becoming profitable in the timeframe we expect, or at all.
 • There is substantial doubt regarding our ability to continue as a going concern. We will need to raise additional funding, which may not be available on acceptable terms, or at all. Failure to obtain this necessary capital when needed may force us to delay, limit or terminate our commercial programs, product development efforts or other operations.
 • Among other potential adverse events, insertional oncogenesis is a significant risk of gene therapies using viral vectors that can integrate into the genome. Any such adverse events may require us to halt or delay further clinical development of our products or any future product candidates or to suspend or cease commercialization, and the commercial potential of our products and any such future product candidates may be materially and negatively impacted.
 • We rely on complex, single-source supply chains for SKYSONA, ZYNTEGLO, and LYFGENIA, respectively. The manufacture, testing and delivery of LVV and drug products present significant challenges for us, and we may not be able to produce our vector and drug products at the quality, quantities, or timing needed to support our clinical programs and commercialization.
 • The marketing and sale of ZYNTEGLO, SKYSONA and LYFGENIA may be unsuccessful or less successful than anticipated, particularly due to uncertainty about our financial condition and ability to continue as a going concern.
 • The commercial success of ZYNTEGLO, SKYSONA and LYFGENIA will depend upon the degree of market acceptance by physicians, patients, payers and other stakeholders.

 • If the market opportunities for our commercial products or any future product candidates are smaller than we believe they are, and if we are not able to successfully identify patients and achieve significant market share, our revenues may be adversely affected and our business may suffer.
 • The insurance coverage and reimbursement status of newly-approved products in the United States is uncertain. Due to the novel nature of our technology and the potential for our products to offer lifetime therapeutic benefit in a single administration, we face unique and additional challenges in obtaining adequate coverage and reimbursement for our products. Failure to obtain or maintain adequate coverage and reimbursement for any new or current product, including to the extent that payers 'non-prefer' any or all of our therapies to our competitors, could limit our ability to market those products and decrease our ability to generate revenue.
 • We face intense competition and rapid technological change and the possibility that our competitors may develop therapies that are more advanced, safer or more effective than ours, which may adversely affect our financial condition and our ability to successfully develop and commercialize ZYNTEGLO, SKYSONA and LYFGENIA.
 • The restatement of our consolidated financial statements for the year ended December 31, 2022 and the quarterly periods in the years ended December 31, 2022 and 2023 has subjected us to a number of additional risks and uncertainties, including increased possibility of legal proceedings.
 • Our existing and any future indebtedness could adversely affect our ability to operate our business.
 • We have identified a material weakness in our internal control over financial reporting and may identify additional material weaknesses in the future or otherwise fail to maintain an effective system of internal controls.

 Item 1. Business
 Overview
 We are a biotechnology company committed to commercializing potentially curative gene therapies for severe genetic diseases based on our proprietary lentiviral vector ("LVV") gene addition platform. We currently market three gene therapies: ZYNTEGLO (betibeglogene autotemcel, also known as beti-cel), and SKYSONA (elivaldogene autotemcel, also known as eli-cel), both of which received approval from the U.S. Food and Drug Administration (the "FDA") in 2022, and LYFGENIA (lovotibeglogene autotemcel, also known as lovo-cel), which received approval from the FDA in December 2023.
 The FDA approved ZYNTEGLO for the treatment of adult and pediatric patients with -thalassemia who require regular red blood cell transfusions on August 17, 2022. The FDA granted accelerated approval for SKYSONA to slow the progression of neurologic dysfunction in boys 4-17 years of age with early, active cerebral adrenoleukodystrophy ("CALD") on September 16, 2022. On December 8, 2023, the FDA approved LYFGENIA for the treatment of patients 12 years of age or older with sickle cell disease ("SCD") and a history of vaso-occlusive events ("VOEs").
 We are one of the only standalone commercial gene therapy companies today. We estimate that there are approximately 22,000 individuals living with SCD, -thalassemia and CALD in the U.S. whose conditions may potentially be addressable with our gene therapies; of these, we estimate that approximately 20,000 individuals living with SCD could be addressed with LYFGENIA. We estimate that there are between 1,300-1,500 patients living with -thalassemia and 40 patients diagnosed with CALD each year.
 Our treatments are administered at qualified treatment centers ("QTCs") – a network of transplant centers that are selected based on their expertise in cell and gene therapy and trained to administer our products. The QTC network for both ZYNTEGLO and LYFGENIA is synergistic. As of March 25, 2025, we had activated more than 70 total QTCs (defined as having a signed master services agreement) for both therapies. Six of those QTCs were also activated to administer SKYSONA. Additionally, we have put in place outcomes-based agreements for both ZYNTEGLO and LYFGENIA that provide payers with risk sharing tied to clinical outcomes that can be tracked in claims data.

 On February 21, 2025, we announced our entry into an Agreement and Plan of Merger (the "Merger Agreement") with Beacon Parent Holdings, L.P., a Delaware limited partnership ("Parent"), and Beacon Merger Sub, Inc., a Delaware corporation ("Merger Sub"). Pursuant to the Merger Agreement, Merger Sub will conduct a cash tender offer to acquire any and all of the outstanding shares of our common stock, par value $0.01 per share (the "Shares"), for (i) $3.00 in cash per Share, plus (ii) one contingent value right (each, a "CVR") per Share, representing the right to receive a non-tradeable contingent payment of $6.84 in cash, in each case subject to any applicable withholding taxes and without interest thereon. The transaction is expected to close in the first half of 2025, subject to the tender of a majority of the Shares, receipt of applicable regulatory approvals, and other customary closing conditions. We have also entered into amendments to our loan agreement with Hercules Capital, Inc. to facilitate adequate liquidity to position us to maintain operations through the closing.
 Our Platform
 We have designed each of our products to address the underlying cause of disease by introducing a functional copy of a gene to patients' own enriched hematopoietic stem and progenitor cells ("HSCs"). Our LVV gene therapies are traceable, which allows us to identify and track LVV-modified cells after delivery to a patient. In a rapidly advancing field, we have developed in-depth analytical methods to understand the safety of our LVV technologies, which are designed to deliver a sustained, lifelong response from a one-time treatment and to improve upon allogeneic hematopoietic stem cell transplant ("HSCT"), which carries significant limitations, including difficulty in identifying matched donors, risk of transplant-related graft-vs-host disease ("GVHD") and death, as well as to improve upon current treatment approaches used with patients not currently eligible to receive allogeneic HSCT.

 Our Programs
 LYFGENIA (lovotibeglogene autotemcel)
 On December 8, 2023, the FDA approved LYFGENIA (lovotibeglogene autotemcel, also known as lovo-cel) for the treatment of patients 12 years of age and older with SCD and a history of VOEs.
 SCD is a complex and progressive genetic disease associated with debilitating and unpredictable pain crises, anemia, irreversible damage to vital organs, and early death. In SCD, high concentrations of sickle hemoglobin (HbS) in red blood cells (RBCs) cause RBCs to become sickled, sticky, and rigid with a shorter life span, which manifests acutely as hemolytic anemia, vasculopathy, and vaso-occlusion. Pain onset can be sudden and unpredictable, often requiring hospitalization and transfusions, intravenous fluids, pain medications, and antibiotic therapy. Repeated VOEs result in end organ damage in fifty to sixty percent of adults with SCD, with 24 percent experiencing damage in multiple organs, and one in four patients experiencing a stroke by the age of 45. The impact of SCD is pervasive and affects every aspect of life for patients and their families and caregivers – from missed work and school, decreased quality of life and mental health, and diminished ability to complete daily tasks. In the U.S., there are approximately 100,000 people living with SCD, and the median age of death is 45 years of age.
 LYFGENIA works by using an LVV to permanently add a functional beta-globin gene ( A-T87Q-globin gene) into the patient's own HSCs. Durable production of adult hemoglobin with anti-sickling properties (HbAT87Q) is expected following successful engraftment. HbAT87Q has a similar oxygen-binding affinity to wild-type HbA and is designed to limit sickling of RBCs and reduce VOEs. The functional beta-globin gene is added into a patient's cells outside of the body (ex-vivo), and the modified cells are then administered to the patient via infusion. The treatment process is comprised of several steps that take place over the course of several months.
 Clinical Development Program
 We believe we have the most deeply studied gene therapy program for SCD, with the longest follow up for any clinical program in the field. We are conducting, or have conducted, the following clinical studies to evaluate the safety and efficacy of lovo-cel in the treatment of patients with SCD:
 • HGB-206 was a single-dose, open-label, non-randomized, multi-site Phase 1/2 clinical study in the U.S. evaluating the safety and efficacy of lovo-cel. A total of 45 patients were treated with lovo-cel in this study across three treatment cohorts. Patients must have been at least twelve years of age at enrollment with a diagnosis of SCD, with S/ S, S/ + or S/ 0 genotype. Patients must have had recurrent severe VOEs despite treatment with hydroxyurea or must have had intolerance to hydroxyurea. Five patients with a history of stroke were treated in HGB-206 Group C. We refer to patients treated in the HGB-206 study under the amended study protocol utilizing HSCs from peripheral blood after mobilization with plerixafor as patients in "Group C" (n=36) rather than utilizing HSCs collected via bone marrow harvest, as in Groups A (n=7) and B (n=2). A refined manufacturing process designed to increase vector copy number and further protocol refinements made to improve engraftment potential of gene-modified stem cells were used for Group B and Group C. The primary efficacy endpoint for this study was the percentage of patients with complete resolution of all VOEs, between six- and 18-months post-treatment, and the secondary efficacy endpoints for this study included the percentage of patients with complete resolution of severe VOEs and globin response based on A-T87Q expression and total hemoglobin. Safety endpoints included monitoring for laboratory parameters and frequency and severity of adverse events; the success and kinetics of HSC engraftment; the incidence of treatment related mortality and overall survival; the detection of vector-derived replication-competent lentivirus in any patient; and the characterization of events of insertional mutagenesis leading to oligoclonality, or leukemia. Each patient remained on study for approximately 24 months post-treatment and was then invited to enroll in LTF-307, a long-term follow-up protocol that will assess safety and efficacy for an additional 13 years.
 • HGB-210 is an ongoing, fully enrolled, single-dose, open-label, non-randomized, multi-site, Phase 3 clinical study in the U.S. designed to evaluate the efficacy and safety of lovo-cel in the treatment of patients with SCD, with a target enrollment of 35 pediatric and adult patients. The outstanding data to be collected in the study is intended to support the expansion of the LYFGENIA label to include pediatric patients under 12 years of age with SCD and a history of VOEs. Patients must be at least two years of age at enrollment with a diagnosis of sickle cell disease, with S/ S, S/ + or S/ 0 genotype. Patients must have recurrent VOEs despite treatment with hydroxyurea or must have had intolerance to hydroxyurea. The primary efficacy endpoint for this study is complete resolution of VOEs, between six- and 18-months post-treatment, and the secondary efficacy endpoint for this study includes the percentage of patients with complete resolution of severe VOEs and globin response based on A-T87Q expression and total hemoglobin. Safety endpoints include monitoring for laboratory parameters and frequency and severity of adverse events; the

 success and kinetics of HSC engraftment; the incidence of treatment related mortality and overall survival; the detection of vector-derived replication-competent lentivirus in any patient; and the characterization of events of insertional mutagenesis leading to oligoclonality or leukemia. Each patient remains on study for approximately 24 months post-treatment and is then invited to enroll in LTF-307, a long-term follow-up protocol that will assess safety and efficacy for an additional 13 years. Data from drug product manufactured at our commercial manufacturing facility for the HGB-210 study were included in the lovo-cel Biologics License Application ("BLA") submission to demonstrate analytical comparability and support validation of our commercial manufacturing process.
 • HGB-205 was a proof-of-concept, single-center Phase 1/2 study in France of three patients with SCD which also enrolled patients with transfusion-dependent -thalassemia ("TDT"). Those with SCD must have failed to achieve clinical benefit from treatment with hydroxyurea and have an additional poor prognostic risk factor (e.g., recurrent vaso-occlusive crises ("VOCs"), or acute chest syndrome). All patients must have been eligible for allogeneic HSCT, but without a matched sibling allogeneic HSCT donor. The primary objective of our HGB-205 study was to determine the safety, tolerability and success of engraftment of the drug product. The secondary objectives of the study were to quantify gene transfer efficiency and expression, and to measure the effects of treatment on disease-specific biological parameters and clinical events. In the case of patients with TDT and SCD, this meant the volume of RBC transfusions, and for patients with SCD, it also meant the number of VOCs and acute chest syndrome in each patient, compared with the two-year period prior to treatment. Safety evaluations performed during the study included success and kinetics of HSC engraftment, incidence of transplant-related mortality post-treatment, overall survival, detection of vector-derived replication-competent lentivirus in any patient and characterization of events of clonal predominance or leukemia/ lymphoma. Each patient remained on study for approximately 24 months post-treatment and then was invited to enroll in LTF-307, a long-term follow-up protocol that will assess safety and efficacy for an additional 13 years.
 • LTF-307 is the long-term follow-up study for patients with SCD from our HGB-205, HGB-206, or HGB-210 studies who were treated with lovo-cel. After each original study protocol's follow-up period of approximately two years, patients will be followed under LTF-307 for approximately an additional 13 years for a total of approximately 15 years post-treatment.
 Efficacy endpoints in the clinical studies focused on the resolution of VOEs and severe vaso-occlusive events ("sVOEs"), as well as globin response based on A-T87Q expression, total hemoglobin and health related quality of life measures. In the studies, VOEs are defined as episodes of acute pain with no medically determined cause other than a vaso-occlusion, lasting more than two hours and severe enough to require care at a medical facility. This includes acute chest syndrome requiring oxygen treatment and/or blood transfusion, acute hepatic sequestration, acute priapism lasting two hours and requiring care at a medical facility, and acute splenic sequestration. sVOEs require a 24-hour hospital stay or emergency room visit, or at least two visits to a hospital or emergency room over a 72-hour period, with both visits requiring intravenous treatment; all VOEs of priapism are also considered sVOEs.
 The FDA approved label for LYFGENIA is based on data from patients in the Phase 1/2 HGB-206 study, including safety data from 54 patients who initiated stem cell collection and efficacy data from 36 patients in Group C, following enhancements to the treatment and manufacturing processes made through the course of the clinical development program. 32 patients were evaluable for the endpoints of complete resolution of VOEs and sVOEs in the six -18 months post-infusion including eight adolescent patients.

 Data from the July 2024 data cut presented at the 66th American Society of Hematology (ASH) Annual Meeting & Exposition focused on 58 patients treated in Phase 1/2 HGB-206 Group C (n=36) and Phase 3 HGB-210 (n=22) studies. Median follow-up time was 47.7 months (4.0 years), with 15 study participants having 5 or more years of follow-up. The data showed that 36/38 (94.7%) of evaluable patients achieved complete resolution of sVOEs (sVOE-CR) in the 6-18 months post infusion, maintained for a median (min, max) of 42.3 (12.2, 70.5) months and 33/38 (86.8%) of evaluable patients achieved complete resolution of VOEs (VOE-CR), maintained for a median (min, max) of 42.4 (12.2, 70.5) months. 10/10 (100%) pediatric patients achieved complete resolution of VOEs and sVOEs. The first focused analysis of the clinical impact of lovo-cel on patients with SCD with a history of stroke, including overt stroke, was also presented and showed that patients with a history of overt stroke remained stable without recurrent stroke up to 9 years post-treatment (n=6), with median follow-up of 6.5 years. The analysis also included 21 patients who had evidence of silent stroke based on available MRI data at screening. In this cohort there were no reports of recurrent overt or silent stroke among patients with follow-up MRIs, with a median (min, max) 3.5 years follow-up (.48, 6.88 years). Other clinical outcomes in patients with a history of stroke—including expression of gene therapy derived anti-sickling hemoglobin (HBAT87Q), improvements in total hemoglobin, and impact on other hematologic markers—were consistent with those patients' respective study populations (HGB-206 Group A and HGB-206 Group C).

 Moreover, long-term follow up data support the durable, potentially curative benefits of LYFGENIA through stable production of anti-sickling adult hemoglobin and resolution of VOEs. Patients treated with LYFGENIA also experienced a sustained reduction in hemolysis markers, including total hemoglobin (Hb). Following engraftment, non transfused total Hb and %Hb fractions stabilized by approximately 6 months after lovo-cel infusion, and median percent of gene-therapy derived anti-sickling adult hemoglobin (HbAT87Q) was maintained generally at >40% of non-transfused total Hb throughout follow-up. Based on data from patient reported outcomes, treatment also resulted in decreased pain scores and improved quality of life for patients with SCD.

 The safety profile of the lovo-cel treatment regimen was generally consistent with underlying SCD and the known effects of myeloablative conditioning. There were no cases of graft failure or graft-versus-host disease (GVHD), no vector-related complications, and no insertional oncogenesis. For complete safety information please refer to the U.S. Prescribing Information. Safety findings for participants with a history of overt stroke did not differ from that in the overall treatment group. No increase in hypertension, bleeding issues, prolonged thrombocytopenia or catheter-related thromboses were observed. Serious adverse events related to LYFGENIA were reported in two patients with comorbid alpha-thalassemia trait and they included two serious adverse events each of anemia (4.3%) and 1 serious adverse event of myelodysplastic syndrome ("MDS") (2.1%). The diagnosis of MDS, made in January 2023, remains under evaluation. This patient is being followed by their physician, is not being treated for MDS, and remained clinically stable and free of VOEs as of March 3, 2025. One patient died due to sudden cardiac death which was deemed unrelated to LYFGENIA. As previously reported, cases of acute myeloid leukemia ("AML") were observed in two patients from the HGB-206 Group A cohort who were treated with an earlier version of the therapy prior to enhancements to the treatment and manufacturing processes. Both patients died due to AML. The LYFGENIA product label includes a boxed warning for the risk of hematologic malignancy.
 As part of the FDA approval, we are required to conduct a prospective, multi-center observational study (REG-503) which will evaluate the long-term safety of LYFGENIA, including the risk of secondary malignancies occurring after treatment with LYFGENIA in at least 250 patients.
 ZYNTEGLOTM (betibeglogene autotemcel)
 On August 17, 2022, the FDA approved ZYNTEGLO, the first gene therapy for people with -thalassemia who require regular red blood cell transfusions. ZYNTEGLO is approved for patients of all ages and genotypes and offers patients a potentially curative benefit through the achievement of durable transfusion independence and normal or near normal total hemoglobin levels.
 -thalassemia is a rare genetic blood disease caused by mutations in the beta-globin gene and characterized by significantly reduced or absent adult hemoglobin production. Patients with the most severe form, sometimes called transfusion-dependent -thalassemia or -thalassemia major, experience severe anemia and lifelong dependence on regular red blood cell transfusions, a lengthy process that patients typically undergo every 2-5 weeks. Despite advances in treatment and improved transfusion techniques, transfusions only temporarily address symptoms of anemia and people with -thalassemia who require regular transfusions have an increased risk for morbidity and mortality due to complications from treatment-related iron overload. Data from the Cooley's Anemia Foundation indicate that the median age of death of patients with transfusion-dependent -thalassemia in the U.S. who died during the last decade was just 37 years. We estimate that there are approximately 1,300-1,500 individuals with transfusion-dependent -thalassemia in the U.S.
 ZYNTEGLO works by using an LVV to add functional copies of a modified form of the beta-globin gene ( A-T87Q-globin gene) into a patient's own HSCs, allowing them to make normal to near normal levels of total hemoglobin without regular red blood cell ("RBC") transfusions. The functional beta-globin gene is added into a patient's cells outside of the body (ex-vivo), and the modified cells are then administered to the patient via infusion. The treatment process is comprised of several steps that take place over the course of several months.
 Clinical Development Program
 We are conducting, or have conducted, the following clinical studies to evaluate the safety and efficacy of beti-cel in the treatment of patients with -thalassemia:
 • HGB-207 was a single-dose, open-label, non-randomized, international, multi-site Phase 3 clinical study that evaluated the safety and efficacy of beti-cel to treat patients with transfusion-dependent -thalassemia ("TDT") and non- 0/ 0 genotypes. This study was completed in March 2022. Twenty-three patients were enrolled and completed dosing in the study, consisting of 15 adolescent and adult patients between 12 and 34 years of age at enrollment, and eight pediatric

 patients less than 12 years of age at enrollment. Age at enrollment ranged from four to 34 years old. To be enrolled, patients with TDT and non- 0/ 0 genotypes had to have received at least 100 mL/kg/year of RBCs or at least eight transfusions per year for the previous two years. All patients must have been eligible for HSCT, but without a known and available matched family HSCT donor. The primary endpoint of this study was the proportion of treated patients who achieved transfusion independence, defined as weighted average hemoglobin levels 9.0 g/dL without any RBC transfusions for a continuous period of at least 12 months at any time during the study after treatment. The secondary endpoints of this study were designed to quantify gene transfer efficiency and expression, and to measure the effects of treatment with beti-cel on transfusion requirements and clinical events. Safety evaluations performed during the study included monitoring of laboratory parameters, frequency and severity of clinical adverse events, incidence of acute and/or chronic graft versus host disease, success and kinetics of platelet and neutrophil engraftment, incidence of transplant-related mortality post-treatment, overall survival, detection of vector-derived replication-competent lentivirus in any patient and characterization of events of clonal predominance or leukemia. Each patient remained on study for approximately 24 months post-treatment and then was invited to enroll in LTF-303, a long-term follow-up protocol that is assessing safety and efficacy for an additional 13 years.
 • HGB-212 was a single-dose, open-label, non-randomized, international, multi-site Phase 3 clinical study that evaluated the efficacy and safety of beti-cel to treat patients with TDT who have either a 0/ 0, 0/IVS-I-110, or IVS-I-110/IVS-I-110 genotypes. This study was completed in November 2022. Eighteen patients were enrolled and completed dosing in the study, consisting of ten adolescent and adult patients between twelve and 34 years of age at enrollment, and eight patients less than twelve years of age at enrollment. To be eligible, patients must have received at least 100 mL/kg/year of RBCs or at least eight transfusions per year for the previous two years. All patients must have been clinically stable and eligible to undergo HSCT (but without a known and available matched family HSCT donor) and been treated and followed for at least the last two years in a specialized center that maintained detailed medical records, including transfusion history. The primary endpoint of this study was the proportion of treated patients who met the definition of transfusion independence, which was identical to the definition in our HGB-207 study. The secondary endpoints of this study were designed to measure the proportion of patients who meet the definition of transfusion reduction, which was defined as the reduction in volume of RBC transfusion requirements (in mL/kg) in the post-treatment time period of months 12 to 24 compared to the average annual transfusion requirement in the 24 months prior to enrollment, to quantify gene transfer efficiency and expression, and to measure the effects of treatment with beti-cel on transfusion requirements post-treatment and clinical events. Safety evaluations performed during the study included monitoring of laboratory parameters, frequency and severity of clinical adverse events, incidence of acute and/or chronic graft versus host disease, success and kinetics of platelet and neutrophil engraftment, incidence of transplant-related mortality post-treatment, overall survival, detection of vector-derived replication-competent lentivirus in any patient and characterization of events of clonal predominance or leukemia. Each patient remained on study for approximately 24 months post-treatment and then was invited to enroll in LTF-303, a long-term follow-up protocol that is assessing safety and efficacy for an additional 13 years.
 • HGB-204 was a single-dose, open-label, non-randomized, international, multi-site Phase 1/2 clinical study designed to evaluate the safety and efficacy of beti-cel in increasing hemoglobin production and the proportion of treated patients who meet the definition of transfusion independence. This study was completed in February 2018, and patients in this study were enrolled in a long-term follow-up protocol to assess safety and efficacy beyond the study follow-up period. Eighteen adults and adolescents were treated in the study. To be eligible for enrollment in this study, patients were between 12 and 35 years of age with a diagnosis of TDT and received at least 100 mL/kg/year of RBCs or at least eight transfusions per year in each of the two years preceding enrollment. The patients were also medically eligible for allogeneic HSCT. Efficacy was evaluated primarily by the production of 2.0 g/dL of hemoglobin A containing A-T87Q-globin for the six-month period between 18- and 24-months post-treatment. Exploratory efficacy endpoints included RBC transfusion requirements per month and per year, post-treatment. Safety evaluations performed during the study included success and kinetics of HSC engraftment, incidence of transplant-related mortality post-treatment, overall survival, detection of vector-derived replication-competent lentivirus in any patient and characterization of events of insertional mutagenesis leading to clonal predominance or leukemia. Subjects were monitored by regular screening. Each patient remained on study for approximately 24 months from time of consent and then was invited to enroll in LTF-303, a long-term follow-up protocol that is assessing safety and efficacy for an additional 13 years.
 • HGB-205 was a proof-of-concept, single-dose, open-label, non-randomized, Phase 1/2 clinical study conducted at a single site in France in four patients with -thalassemia that also enrolled patients with SCD. The primary objective of the HGB-205 study was to determine the safety, tolerability and success of engraftment of the drug product. Each patient remained on study for approximately 24 months from time of consent and then was invited to enroll in LTF-303, a long-term follow-up protocol that is assessing safety and efficacy for an additional 13 years.

 • LTF-303 is the long-term follow-up study for patients with -thalassemia from our HGB-204, HGB-205, HGB-207, or HGB-212 studies. Patients were invited to enroll in the long-term follow-up study once they completed the original study protocol's follow-up period of approximately two years. Under LTF-303, patients will be followed for approximately an additional 13 years for a total of approximately 15 years post-treatment. Each of HGB-204, HGB-205, HGB-207 and HGB-212 are complete, and all patients have transitioned to LTF-303.
 The approval of ZYNTEGLO was based primarily on data from the Phase 3 HGB-207 and HGB-212 studies and the long-term follow-up study LTF-303.

 As of the February 2024 data cut presented at the American Society of Hematology (ASH) Annual Meeting in December 2024, 63 adult and pediatric patients had received beti-cel across four clinical studies. Two participants had 10 years of follow-up, and 51 (81.0%) participants had 5 or more years of follow-up. These include two Phase 3 studies (N=41) that led to the FDA approval of ZYNTEGLO in August 2022. Data from the Phase 3 studies demonstrated that 90.2% (37/41) of patients treated achieved transfusion independence. Transfusion independence is defined as no longer needing red blood cell transfusions for at least 12 months while maintaining a weighted average total hemoglobin of at least 9 g/dL. Patients who achieved transfusion independence produced normal or near normal levels of total hemoglobin and demonstrated improvements in markers of iron overload and markers of ineffective erythropoiesis. Study participants treated with beti-cel who achieved and maintained transfusion independence demonstrated effective restoration of iron homeostasis over time and reduced iron management burden. Among participants who achieved transfusion independence, improvements in serum ferritin and liver iron concentration were sustained through month 60. 28/37 (75.7%) study participants who achieved transfusion independence in Phase 3 studies are no longer undergoing iron chelation therapy. The safety profile was consistent with known side effects of hematopoietic stem cell collection and the busulfan conditioning regimen. None of the study participants had a fatal event. No beti-cel–related serious adverse events were reported more than 2 years after infusion through last follow-up. No malignancies, insertional oncogenesis or vector-derived replication-competent lentivirus were reported in any study participants.
 As part of the FDA approval, we are currently conducting a required prospective, multi-center observational study (REG-501) which will evaluate the long-term safety of ZYNTEGLO, including the risk of secondary malignancies occurring after treatment with ZYNTEGLO in at least 150 patients.
 SKYSONATM (elivaldogene autotemcel)
 On September 16, 2022, the FDA granted accelerated approval of SKYSONA (elivaldogene autotemcel), also known as eli-cel, to slow the progression of neurologic dysfunction in boys 4-17 years of age with early, active CALD. The SKYSONA product label includes a boxed warning for the risk of hematologic malignancy.
 CALD is the most severe form of adrenoleukodystrophy, a rare X-linked metabolic disorder caused by mutations in the ABCD1 gene, which results in accumulation of very long-chain fatty acids ("VLCFAs") in plasma and tissues. CALD involves a progressive destruction of myelin, the protective sheath of the nerve cells in the brain that are responsible for thinking and muscle control. The disease, which primarily affects young boys, is associated with irreversible neurologic decline, including major functional disabilities such as loss of communication, cortical blindness, requirement for tube feeding, total incontinence, wheelchair dependence, or complete loss of voluntary movement. Nearly half of patients who do not receive treatment die within five years of symptom onset. Prior to the approval of SKYSONA treatment, effective options were limited to allo-HSCT, which is associated with the risk of serious potential complications including GVHD and death, which can increase dramatically in patients without a human leukocyte antigen matched donor.
 Our approach involves the ex vivo insertion of a functional copy of the ABCD1 gene into the patient's own HSCs via LVV. Following engraftment, we expect the transduced HSCs to differentiate into other cell types, including macrophages and cerebral microglia, which produce functional adrenoleukodystrophy protein ("ALDP"). We believe that the functional ALDP can then enable the local degradation of VLCFAs in the brain, which in turn can stabilize the disease by preventing further cerebral inflammation and demyelination that are characteristics of CALD.
 We have agreed to provide confirmatory long-term clinical data to the FDA as a condition of the SKYSONA accelerated approval, and continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.

 Clinical Development Program
 The approval of SKYSONA was based on data from our Phase 2/3 study (ALD-102 (n=32)) and Phase 3 study (ALD-104 (n=35)).
 Both open-label, single-arm studies enrolled patients with early, active CALD who had elevated VLCFA levels, a Loes score between 0.5 and 9 (inclusive), and gadolinium enhancement on magnetic resonance imaging (MRI) of demyelinating lesions. Additionally, patients were required to have a neurologic function score ("NFS") of 1, indicating limited changes in neurologic function. The efficacy of SKYSONA was compared to a natural history population.
 Per protocol, patients treated with SKYSONA were assessed using the NFS and monitored for the emergence of six Major Functional Disabilities ("MFDs") associated with CALD progression including loss of communication, cortical blindness, requirement for tube feeding, total incontinence, wheelchair dependence, or complete loss of voluntary movement.
 The accelerated approval of SKYSONA was based on an intermediate clinical endpoint of MFD-free survival. A post-hoc enrichment analysis in symptomatic patients assessed MFD-free survival from onset of symptoms (NFS 1) in SKYSONA treated (N=11) and untreated patients (N=7). SKYSONA treated patients had an estimated 72 percent likelihood of MFD-free survival at 24 months from time of first NFS 1, compared to untreated patients who had an estimated 43 percent likelihood of MFD-free survival.
 The most common adverse events (incidence [ 20%]) were mucositis, nausea, vomiting, febrile neutropenia, alopecia, decreased appetite, abdominal pain, constipation, pyrexia, diarrhea, headache and rash. Hematologic malignancy has developed in patients treated with SKYSONA in clinical studies and, as of March 25, 2025, MDS, MDS relapse, or AML had been diagnosed in ten patients after administration of SKYSONA. One patient experienced relapse of MDS post-allogeneic transplant. The SKYSONA product label includes a boxed warning for the risk of hematologic malignancy. In April 2024, U.S. Prescribing Information for SKYSONA, including the boxed warning, was revised to include updated information on hematologic malignancies diagnosed in our clinical study patients, as well as other updates to monitoring procedures and alternative treatment options.
 Studies ALD-102 and ALD-104 have been completed. All patients who completed 24 months of follow-up in studies ALD-102 or ALD-104 were encouraged to participate in a long-term follow-up study (LTF-304) to continue monitoring safety and efficacy outcomes through 15 years post-treatment.
 As part of the accelerated approval process with the FDA, we have post-marketing requirements to follow patients who received SKYSONA in studies ALD-102 and ALD-104 for a minimum of ten years to assess event-free survival or need for hematopoietic stem cell transplant. In addition, as a post-marketing requirement, a long-term study is being conducted to assess the safety of SKYSONA and the risk of secondary malignancies occurring after treatment with SKYSONA. We plan to fulfill this latter post-marketing requirement through an observational study (REG-502) which will enroll at least 120 patients followed for 15 years who receive SKYSONA in the commercial setting, and will include studying the effectiveness and safety in 24 boys with more advanced early, active CALD for at least five years.
 Manufacturing activities

 We have entered into multi-year agreements with external manufacturing partners to support our programs in the United States. We have a multi-year agreement with Thermo Fisher Scientific, Inc. ("Thermo Fisher", previously Novasep) for the production of suspension LVV to support the LYFGENIA program. We currently use an adherent cell culture process at SAFC Carlsbad, Inc. ("SAFC", a subsidiary of MilliporeSigma) to manufacture LVV for ZYNTEGLO and SKYSONA. In August 2024, we provided notice to SAFC of our intention to wind down adherent LVV manufacturing for ZYNTEGLO and SKYSONA and SAFC will cease production in the second half of 2025. We are currently seeking FDA approval to transition LVV manufacturing for ZYNTEGLO to the suspension process at Thermo Fisher. We continue to evaluate alternative manufacturing methods and plans for LVV for SKYSONA. In addition, we have entered into multi-year agreements with Lonza Houston, Inc. ("Lonza") to produce commercial ZYNTEGLO and SKYSONA drug product and with Minaris Regenerative Medicine ("Minaris") to produce clinical and commercial LYFGENIA drug product. In 2024, we received FDA approval to expand our capacity at Lonza to manufacture additional lots of ZYNTEGLO and SKYSONA. We also rely on specialized third parties for quality control testing with respect to our LVV and drug product.
 We believe our team of technical personnel has extensive manufacturing, analytical and quality experience as well as strong project management discipline to oversee these contract manufacturing activities, and to compile manufacturing and quality information for our regulatory submissions and commercialization efforts. For the treatment of patients with our drug

 product in the commercial setting, we are collaborating with participating QTCs in the United States to be centers for collection of HSCs from the patient and for infusion of drug product to the patient.
 Commercial operations
 Our strategy for the commercialization of ZYNTEGLO, SKYSONA and LYFGENIA centers on three key components:
 • A robust and synergistic qualified treatment center network
 • Timely and equitable access and reimbursement
 • An optimized patient and provider experience
 In order to treat patients, transplant centers must become part of our QTC network and supply chain. As of March 25, 2025, we had activated more than 70 total QTCs (defined as having a signed master services agreement) for ZYNTEGLO and LYFGENIA. ZYNTEGLO commercial launch operations are synergistic with LYFGENIA – with the same treatment centers, treaters, and patient services – which has allowed for a simplified activation process for LYFGENIA QTCs. QTCs were selected based on their expertise in areas such as transplant, cell, and gene therapy, and are trained to administer our therapies.
 For ZYNTEGLO, we have set a wholesale acquisition cost of $2.8 million. To help enable timely and quality access for patients with beta-thalassemia, we have established outcomes-based agreements with both commercial and Medicaid payers, under which we will reimburse contracted commercial and government payers up to 80% of the cost of the therapy if a patient does not meet designated clinical outcomes. For ZYNTEGLO, we offer reimbursement to payers in the event that a patient fails to achieve and maintain transfusion independence up to two years following infusion. Since launch, more than 200 million U.S. lives are covered through contracts or favorable coverage policies for ZYNTEGLO and there have been zero ultimate denials across both Medicaid and commercial payers.
 For LYFGENIA, we have set a wholesale acquisition price of $3.1 million. Similar to ZYNTEGLO, we are offering outcomes-based agreements for LYFGENIA that provide government and commercial payers with risk sharing tied to clinical outcomes that can be tracked in claims data and offer payers reimbursement tied to VOE-related hospitalizations during a defined period of time (typically within three years of treatment). As of March 25, 2025, we have signed outcomes-based agreements for LYFGENIA with multiple national payer organizations representing dozens of downstream plans and covering approximately 200 million U.S. lives. These agreements are now being pulled through into favorable coverage policies, aligned to clinical trial criteria, and at parity to our closest competitor. We have secured favorable coverage policies or placement on the preferred drug list in over half of all states; and over half of Medicaid-insured individuals with SCD in the U.S. live in a state that has approved at least one prior authorization for LYFGENIA. We also reached an agreement with the Center for Medicare and Medicaid Innovation to offer an outcomes-based agreement for LYFGENIA under the Cell and Gene Therapy (CGT) Access Model. See also "Risk Factors - Healthcare legislative reform measures may have a material adverse effect on our business and results of operations".
 As of March 25, 2025, SKYSONA was available through a network of six activated QTCs. We believe payers recognize the value and urgency to treat these patients, and to date there have been no ultimate denials by payers for the therapy. We have set a wholesale acquisition cost of $3 million for SKYSONA.
 In 2024, we completed a total of 70 patient starts (which we define as unique first cell collection) across our gene therapy portfolio: 43 for ZYNTEGLO, 21 for LYFGENIA and six for SKYSONA. As of March 25, 2025, we have completed 14 patient starts for ZYNTEGLO and 11 patient starts for LYFGENIA, each since the beginning of 2025. No patients have completed cell collection for SKYSONA yet in 2025.
 For each of our products, following cell collection, the patient's cells are shipped to a manufacturing facility where they are transduced with the appropriate LVV and tested to ensure they meet stringent release specification criteria. They are then frozen and shipped back to the QTC where the patient receives treatment via IV infusion. Typically, patients receive their drug product infusion approximately two quarters after initial cell collection. Our supply chain for LYFGENIA is separate and distinct from our supply chain for SKYSONA and ZYNTEGLO.
 For each of our therapies, we have established mybluebirdsupport, a patient support program that provides education and support navigating insurance and treatment.

 Intellectual property
 We strive to protect and enhance the proprietary technology, inventions, and improvements that are commercially important to the development of our business, including seeking, maintaining, and defending patent rights, whether developed internally or licensed from third parties. We also rely on trade secrets relating to our proprietary technology platform and on know-how, continuing technological innovation and in-licensing opportunities to develop, strengthen and maintain our proprietary position in the field of gene therapy that may be important for the development of our business. We additionally may rely on regulatory protection afforded through orphan drug designations, data exclusivity, market exclusivity, and patent term extensions where available.
 Our commercial success may depend in part on our ability to obtain and maintain patent and other proprietary protection for commercially important technology, inventions and know-how related to our business; defend and enforce our patents; preserve the confidentiality of our trade secrets; and operate without infringing the valid enforceable patents and proprietary rights of third parties. Our ability to stop third parties from making, using, selling, offering to sell, or importing our products may depend on the extent to which we have rights under valid and enforceable patents or trade secrets that cover these activities. With respect to both in-licensed and company-owned intellectual property, we cannot be sure that patents will be granted with respect to any of our pending patent applications or with respect to any patent applications filed by us in the future, nor can we be sure that any of our existing patents or any patents that may be granted to us in the future will be commercially useful in protecting our commercial products and methods of manufacturing the same.
 We have developed or in-licensed numerous patents and patent applications and possess substantial know-how and trade secrets relating to the development and commercialization of gene therapy products. Our proprietary intellectual property, including patent and non-patent intellectual property, is generally directed to, for example, certain genes, transgenes, methods of transferring genetic material into cells, genetically modified cells, processes to manufacture our lentivirus-based products and other proprietary technologies and processes related to our products. In connection with the wind down of our operations in Europe, we have decided to let certain non-U.S. patents and patent applications that we own lapse by ceasing further prosecution of certain pending ex-U.S. patent applications and not paying future maintenance fees for certain ex-U.S. patents when due. As of March 25, 2025, our patent portfolio includes the following:
 • approximately 12 patents or patent applications that we own or have exclusively in-licensed from third parties related to LVVs and vector systems;
 • approximately 110 patents or patent applications that we own or have exclusively in-licensed from third parties related to LVV or drug product manufacturing and associated assays;
 • approximately 36 patents or patent applications that we have non-exclusively in-licensed from third parties related to LVV or drug product manufacturing; and
 • approximately 10 patents or patent applications that we own or have exclusively in-licensed from third parties related to therapeutic cellular product candidates and assays.
 Examples of the products and technology areas covered by our intellectual property portfolio are described below. See also "—License agreements." From time to time, we also evaluate opportunities to sublicense our portfolio of patents and patent applications that we own or exclusively license, and we may enter into such licenses from time to time.
 ZYNTEGLO and LYFGENIA
 The ZYNTEGLO and LYFGENIA programs include the following patent portfolios described below.
 • RDF. The in-licensed patent portfolio from Research Development Foundation ("RDF") in part, contains patents and patent applications directed to aspects of our LVV that may be utilized to produce ZYNTEGLO and LYFGENIA. As of March 25, 2025, we had an exclusive license (from RDF) to two issued U.S. patents related to our LVV platform. We expect the issued composition of matter patents to expire from 2025-2027 in the United States.
 • SIRION. The in-licensed patent portfolio from SIRION Biotech GmbH ("SIRION") contains patents and patent applications directed to methods of manufacturing ex vivo gene therapy products with LVV. As of March 25, 2025, we had an exclusive license to three issued U.S. patents, two pending U.S. patent applications, three corresponding foreign patent applications and 47 issued corresponding foreign patents. We expect the issued method patents to expire in 2033. We expect any other composition of matter and methods patents, if issued from the pending patent

 applications and if the appropriate maintenance, renewal, annuity or other governmental fees are paid, to expire in 2033. We expect any other patents and patent applications in this portfolio, if issued, and if the appropriate maintenance, renewal, annuity, or other governmental fees are paid, to expire in 2033 (worldwide).
 SKYSONA
 The SKYSONA program includes the following patent portfolios described below.
 • RDF. The in-licensed RDF patent portfolio contains the patents and patent applications described above directed towards aspects of LVV that may be utilized to produce SKYSONA.
 • bluebird bio. The bluebird bio patent portfolio contains patents and patent applications directed to compositions of matter for SKYSONA vectors and compositions and methods of using the vectors and compositions in cell-based gene therapy of adrenoleukodystrophy or adrenomyeloneuropathy. As of March 25, 2025, we owned three U.S. patents and 7 issued foreign patents. We expect the issued composition of matter patents for SKYSONA vectors to expire in 2032.
 Lentiviral platform (e.g., LVV, manufacturing, and cell therapy products)
 The lentiviral platform, which is potentially applicable across our programs in severe genetic disease, includes the following patent portfolios described below.
 • RDF. The in-licensed RDF patent portfolio contains the patents and patent applications described above.
 • SIRION. The in-licensed SIRION patent portfolio contains the patents and patent applications described above.
 • bluebird bio. Another component of the bluebird bio patent portfolio includes LVV and drug product manufacturing platforms and is potentially applicable across our programs. This portion of the portfolio contains patents and patent applications directed to improved methods for transfection and transduction of therapeutic cells. As of March 25, 2025, we owned six issued U.S. patents, two pending U.S. patent applications and six corresponding foreign patent applications and 23 issued corresponding foreign patents. We expect the issued method patents to expire from 2032-2037. We expect composition of matter and method patents, if issued from the pending patent applications and if the appropriate maintenance, renewal, annuity or other governmental fees are paid, to expire from 2032-2037. We expect any other patents and patent applications in this portfolio, if issued, and if the appropriate maintenance, renewal, annuity, or other governmental fees are paid, to expire from 2032-2037 (worldwide).
 •2seventy bio. The 2seventy bio patent portfolios include LVV manufacturing platforms and improvements and are potentially applicable across our programs. As of March 25, 2025, we had a non-exclusive license to four patent families that include four pending U.S. patent applications and 32 corresponding foreign patent applications. We expect any composition of matter or methods patents, if issued from the pending patent applications, and if the appropriate maintenance, renewal, annuity or other governmental fees are paid, to expire from 2040-2042 (worldwide). We expect any other patents and patent applications in this portfolio, if issued, and if the appropriate maintenance, renewal, annuity, or other governmental fees are paid, to expire from 2040-2042 (worldwide).
 The term of individual patents depends upon the legal term of the patents in the countries in which they are obtained. In most countries in which we file, the patent term is 20 years from the date of filing the non-provisional application. In the United States, a patent's term may be lengthened by patent term adjustment, which compensates a patentee for administrative delays by the U.S. Patent and Trademark Office in granting a patent, or may be shortened if a patent is terminally disclaimed over an earlier-filed patent. A patent may be enforced during its term and/or up to six years after the patent has expired against past acts of infringement that occurred during the patent term.
 We may rely, in some circumstances, on trade secrets to protect our technology. However, trade secrets can be difficult to protect. We seek to protect our proprietary technology and processes, in part, by entering into confidentiality agreements with our employees, consultants, scientific advisors and third parties. We also seek to preserve the integrity and confidentiality of our data and trade secrets by maintaining physical security of our premises and physical and electronic security of our information technology systems. While we have confidence in these individuals, organizations and systems, agreements or security measures may be breached, and we may not have adequate remedies for any breach. In addition, our trade secrets may otherwise become known or be independently discovered by competitors. To the extent that our consultants or collaborators use intellectual property owned by others in their work for us, disputes may arise as to the rights in related or resulting know-how and inventions.

 License agreements
 Inserm-Transfert
 In May 2009, we entered into an exclusive license with Inserm-Transfert SA, referred to hereafter as Inserm, which is a wholly-owned subsidiary of Institut national de la sant et de la recherche m dicale, for use of certain patents and know-how related to the ABCD1 gene and corresponding protein, for use in the field of human ALD therapy. The agreement was amended in 2012, 2013, 2014 and 2015. The last patent in the Inserm licensed patent portfolio expired in February of 2016.
 We are obligated to pay Inserm a percentage of net sales as a royalty on any of our products that use the in-licensed intellectual property for the longer of the life of any in-licensed patents covering the product or 10 years from first commercial sale. Any net sales of SKYSONA are subject to this royalty which is in the low single digits.
 We are required to use all commercially reasonable efforts to develop products covered by in-licensed intellectual property and introduce them into the commercial market as soon as practical, consistent with our reasonable business practices and judgment in compliance with an agreed upon development plan. We have assumed certain development, regulatory and commercial milestone obligations and must report on our progress in achieving these milestones on an annual basis.
 We may unilaterally terminate the license agreement at any time. Either party may terminate the agreement in the event of the other party's material breach which remains uncured after 60 days of receiving written notice of such breach or in the event the other party becomes the subject of a voluntary or involuntary petition in bankruptcy and such petition is not dismissed with prejudice within 120 days after filing. In addition, Inserm may terminate the license agreement in the event that we cannot prove within 60 days of written notice from Inserm that we have been diligent in developing products covered by in-licensed intellectual property and introducing them into the commercial market.
 Absent early termination, the agreement will automatically terminate upon the expiration of all issued patents and filed patent applications within the patent rights covered by the agreement or 10 years from the date of first commercial sale of a product covered by in-licensed intellectual property, whichever is later. The license grant ceases in connection with any such termination. The longest-lived patent rights licensed to us under the agreement expired in 2016.
 Institut Pasteur
 In September 2011, we entered into a license with Institut Pasteur for certain patents relating to the use of DNA sequences, LVV and recombinant cells in the field of ex vivo gene therapy and CAR T cell-based therapy in a range of indications, excluding vaccinations. This agreement was amended twice in 2012, again in 2013 and most recently in 2015. The last patent in the Institut Pasteur licensed patent portfolio expired in 2023. The license is exclusive for products containing human and non-human LVV. Institut Pasteur retains the right, on behalf of itself, its licensees and research partners, to conduct research using the licensed intellectual property.
 We have the right to grant sublicenses outright to third parties under the agreement. For the first sublicense including a product targeting -hemoglobinopathies (including -thalassemia and SCD) or ALD (including CALD and adrenomyeloneuropathy), we must pay Institut Pasteur an additional payment of 3.0 million. If we receive any income (cash or non-cash) in connection with sublicenses for products targeting indications other than -hemoglobinopathies (including -thalassemia and SCD) or ALD (including CALD and adrenomyeloneuropathy), we must pay Institut Pasteur a percentage of such income varying from low single digits if the sublicense also includes licenses to intellectual property controlled by us, and a percentage of sublicense income in the mid-range double digits if the sublicense does not include licenses to intellectual property controlled by us.
 We are obligated to pay Institut Pasteur a percentage of net sales as a royalty on any of our commercialized products covered by the in-licensed intellectual property, which include ZYNTEGLO, SKYSONA and LYFGENIA. This royalty varies depending on the indication of the product but in any event is in the low single digits. The royalty is reduced if, during the five years following the first market authorization of a product covered by the in-licensed intellectual property, the last licensed patent expires. In addition, starting in 2016, we have been required to make an annual maintenance payment, offset by royalty payments on a year-by-year basis.
 We are required to use all reasonable commercial efforts (as compared to a company of similar size and scope) to develop and commercialize one or more products in the license field and to obtain any necessary governmental approvals in respect of, and market the products in the license field, if any. Additionally, we have assumed certain development and regulatory milestone obligations. We must report on our progress towards achieving these milestones on an annual basis. We may

 unilaterally terminate the license agreement at any time by sending Institut Pasteur 90 days prior written notice. Either party may terminate the license in the event of the other party's substantial breach which remains uncured after 60 days of receiving written notice of such breach. Institut Pasteur may also terminate the agreement in the event bankruptcy proceedings are opened against us and not dismissed within 60 days.
 Absent early termination, the agreement will automatically terminate upon the expiration of the last licensed patents or five years after first market authorization of the first product, whichever occurs later. In the event the agreement is terminated, while the license grant would cease, we would retain the right to manufacture, import, use and sell licensed products for a certain period of time post-termination. In addition, our ownership stake in certain jointly made improvements covered by the licensed patents would survive termination of the agreement. The longest-lived patent rights licensed to us under the agreement expired in 2023.
 Stanford University
 In July 2002, we entered into a non-exclusive license agreement with the Board of Trustees of the Leland Stanford Junior University, referred to herein as Stanford, which we amended and restated in April 2012. Under this agreement, we are granted a license to use the HEK293T cell line for any commercial or non-commercial use for research, nonclinical and clinical development purposes and for human and animal gene therapy products.
 We have the right to grant sublicenses outright to third parties under the agreement. For each such sublicense we grant, we must pay Stanford a fee (unless the sublicense is to a collaborating partner, contract manufacturer or contract research organization).
 We are obligated to pay Stanford a percentage of net sales as a royalty on any of our commercialized products covered by the in-licensed intellectual property, which include ZYNTEGLO, SKYSONA and LYFGENIA. This royalty varies with net sales but in any event is in the low single digits and is reduced for each third-party license that requires payments by us with respect to a licensed product, provided that the royalty to Stanford is not less than a specified percentage which is less than one percent. Since April 2013, we have been paying Stanford an annual maintenance fee, which is creditable against our royalty payments on a year-by-year basis.
 We may unilaterally terminate the agreement by giving Stanford 30 days' written notice. Stanford may also terminate the license agreement if after 30 days of providing notice we are delinquent on any report or payment, are not using commercially reasonable efforts to develop, manufacture and/or commercialize one or more products covered by the in-licensed intellectual property, are in material breach of any provision or provide any false report. Termination of this agreement may require us to utilize different cell types for vector manufacturing, which could lead to delays.
 Absent early termination, the license will expire in April 2037. We may elect to extend the term for an additional 25 years so long as we have a commercial product on the market at that time and we are in material compliance with the license agreement.
 Research Development Foundation
 In December 2011, we entered into an exclusive license with Research Development Foundation, which we refer to as RDF, to use certain patents that involve LVV. Any patents within this portfolio that have issued or may yet issue would have an expected statutory expiration date between 2021 and 2027. RDF retains the right, on behalf of itself and other nonprofit academic research institutions, to practice and use the licensed patents for any academic, non-clinical research and educational purposes. We have the right to grant sublicenses outright to third parties under the agreement.
 We are obligated to pay RDF a percentage of net sales as a royalty on any of our commercialized products covered by the in-licensed intellectual property, which include ZYNTEGLO, SKYSONA and LYFGENIA. This royalty is in the low single digits and is reduced by half if during the following ten years from the first marketing approval the last valid claim within the licensed patent that covers the licensed product expires or ends.
 We are required to use commercially reasonable and diligent efforts for a company of our size and resources to develop or commercialize products covered by the in-licensed intellectual property. We have also assumed certain regulatory milestone obligations and must report on our progress in achieving these milestones on an annual basis.
 RDF may terminate the agreement in the event of our material breach which remains uncured after 90 days of receiving written notice of such breach (30 days in the case of nonpayment) or in the event we become bankrupt, our business or assets or

 property are placed in the hands of a receiver, assignee or trustee, we institute or suffer to be instituted any procedure in bankruptcy court for reorganization or rearrangement of our financial affairs, make a general assignment for the benefit of creditors, or if we or an affiliate or a sublicensee institutes any procedure challenging the validity or patentability of any patent or patent application within the licensed patents, the agreement will immediately terminate.
 Absent early termination, the agreement will continue until its expiration upon the later of there being no more valid claims within the licensed patents or the expiration of our royalty obligations on licensed products that are subject to an earned royalty, if such earned royalty is based on the minimum 10-year royalty period described above. In the event the agreement is terminated, while the license grant would cease, RDF will grant our sublicensees a direct license. The longest-lived patent rights licensed to us under the agreement are in one U.S. patent currently expected to expire in 2027.
 SIRION
 In December 2015, we entered into a license agreement with SIRION Biotech Gmbh, which we refer to as SIRION, pursuant to which we exclusively licensed certain patents and patent applications directed towards aspects of manufacturing gene therapy products. Any patents within this portfolio that have issued or may yet issue would have an expected statutory expiration date in 2033. We have the right to grant sublicenses to third parties, subject to certain conditions.
 We are obligated to pay SIRION a percentage of net sales as a royalty on any of our commercialized products covered by the in-licensed intellectual property, which includes ZYNTEGLO and LYFGENIA. These royalties are in the low single digits and are reduced for royalties payable to third parties, up to a cap.
 We have also assumed certain development and regulatory milestones, and we must report on our progress in achieving those milestones on a periodic basis.
 We may unilaterally terminate the license agreement at any time with prior written notice to SIRION. Either party may terminate the agreement in the event of a material breach that remains uncured following a notice period. Either party may also terminate the agreement in the event bankruptcy proceedings are opened against the other and are not dismissed within a specified period of time. Absent early termination, the agreement will automatically terminate upon the expiration of the patent rights covered by the agreement. The longest-lived patent rights licensed to us under the Agreement are currently expected to expire in 2033.
 Competition
 The biotechnology and pharmaceutical industries are characterized by intense and rapidly changing competition to develop new technologies and proprietary products. Not only must we compete with other companies that are focused on gene therapy products, but any products that we commercialize will compete with existing therapies and new therapies that may become available in the future. Many of our competitors, either alone or with their strategic partners, have substantially greater financial, technical, and human resources than we do and significantly greater experience obtaining FDA and other regulatory approvals of therapies and commercializing those therapies. Accordingly, our competitors may be more successful than us in achieving widespread market acceptance in the U.S. and global markets. Our competitors' therapies may be more effective, or more effectively marketed and sold, than any therapy we may commercialize and may render our treatments obsolete or non-competitive before we can recover the expenses of developing and commercializing any of our therapies.
 These competitors also compete with us in recruiting and retaining qualified commercial, scientific and management personnel, establishing clinical study sites, and registering patients for clinical studies, as well as in acquiring technologies complementary to, or necessary for, our programs. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies.
 We anticipate that we will face intense and increasing competition as new therapies enter the market and advanced technologies become available. We expect any therapies that we develop and commercialize to compete on the basis of, among other things, efficacy, safety, convenience of administration and delivery, price, the level of generic competition, and the availability of reimbursement from government and other third-party payers.
 Our commercial opportunity could be reduced or eliminated if our competitors develop and commercialize therapies or conditioning regimens that are safer, more effective, have fewer or less severe side effects, are more convenient or are less expensive than any therapies that we may develop. Depending on how successful these competitive efforts are, it is possible they may increase the barriers to adoption and success for our therapies or result in greater access and reimbursement for

 competing products. In addition, our ability to compete may be affected in many cases by insurers or other third-party payers seeking to encourage the use of generic products or other lower-priced options. Competitors include the following:
 Sickle cell disease — LYFGENIA's primary competitor is CASGEVY (exa-cel, marketed by Vertex Pharmaceuticals), which leverages the CRISPR/Cas9 gene editing platform to disrupt the BCL11A erythroid enhancer. Similar to LYFGENIA, CASGEVY is administered via autologous HSCT treatment. CASGEVY and LYFGENIA were both approved by the FDA on December 8, 2023.
 The current standard of care for the treatment of SCD in the developed world is chronic blood transfusions or hydroxyurea (a generic drug). In addition, patients treated with chronic blood transfusions often receive iron chelation therapy to help manage the iron overload. We are aware of ongoing studies that continue to evaluate the efficacy and safety of hydroxyurea in various populations. In addition, a limited number of patients with SCD receive allogeneic HSCT treatment, particularly if a sufficiently well-matched source of donor cells is identified. There are a number of academic and industry-sponsored research and development programs to improve the tolerability and safety of allogeneic HSCT with less well-matched sources of donor cells, while increasing the availability of suitable donors. There are also a number of other FDA approved therapies for SCD, including Endari (L-glutamine, marketed by Emmaus Life Sciences, Inc.), and Adakveo (crizanlizumab, a p-selectin antibody marketed by Novartis). A number of different therapeutic approaches for the chronic treatment of SCD are under investigation targeting the various aspects of SCD pathophysiology, including: a pyruvate kinase receptor activator, mitapivat, in a Phase 2/3 trial supported by Agios Pharmaceuticals, Inc.; and a selective small molecule inhibitor of ectoderm development protein designed to increase the expression of fetal hemoglobin, pociredir, in a Phase 1 study supported by Fulcrum Therapeutics, Inc. There are additional gene therapy programs in development for SCD including programs from Beam Therapeutics. Beam Therapeutics uses base editing to target the HGB1/2 promoter and upregulate HgF, and they continue to enroll patients in their Phase 1/2 trial.
 -thalassemia — ZYNTEGLO was the first FDA approved gene therapy for the treatment of adult and pediatric beta-thalassemia patients who require regular RBC transfusions in August 2022, and we initiated treatment of the first ZYNTEGLO patient in the commercial setting in December 2022. ZYNTEGLO's primary competitor is CASGEVY, which was approved by the FDA for the treatment of patients 12 and older with transfusion-dependent -thalassemia in January 2024.
 The current standard of care for the treatment of -thalassemia in the developed world is chronic blood transfusions to address the patient's anemia. In addition, such patients often receive iron chelation therapy to help manage the iron overload associated with their chronic blood transfusions. Novartis and Chiesi, who provide the leading iron chelation therapies, are seeking to develop improvements to their product profile and accessibility. A number of different approaches are under investigation that seek to improve the current standard of care treatment options. Reblozyl (luspatercept), a subcutaneously-delivered protein therapeutic marketed by Merck and Bristol Myers Squibb that targets molecules in the TGF- superfamily, has been approved in the United States for the treatment of anemia in adult patients with -thalassemia who require regular red blood cell transfusions, and was approved in the European Union for the treatment of adult patients with transfusion-dependent anemia associated with -thalassemia. Additionally, Agios is developing mitapivat for both transfusion-dependent and non-transfusion-dependent -thalassemia, and has reported positive clinical data from two Phase 3 studies. Some patients with -thalassemia receive HSCT treatment, particularly if a sufficiently well-matched source of donor cells is identified. In addition, there are a number of academic and industry-sponsored research and development programs to improve the outcomes of allogeneic HSCT, or the tolerability and safety of haploidentical HSCT, while increasing the availability of suitable donors.
 CALD — The current standard of care for the treatment of CALD is allogeneic HSCT. Various academic centers around the world are seeking to develop improvements to allogeneic HSCT. Other possible treatments being investigated include Minoryx Therapeutics' MIN-102 (leriglitazone), and Viking Therapeutics' VK0214.
 Government regulation
 In the United States, biological products, including gene therapy products, are subject to regulation under the Federal Food, Drug, and Cosmetic Act ("FD&C Act") and the Public Health Service Act ("PHS Act") and other federal, state, local and foreign statutes and regulations. Both the FD&C Act and the PHS Act and their corresponding regulations govern, among other things, the testing, manufacturing, safety, efficacy, purity, potency, labeling, packaging, storage, record keeping, distribution, import, export, reporting, record keeping, post-approval monitoring, advertising and other promotional practices involving biological products. FDA approval must be obtained before marketing certain biological products, including our products and any future product candidates. The process of obtaining regulatory approvals for lifecycle management, including post-approval changes associated with our approved products, and the subsequent compliance with appropriate federal, state, local and foreign statutes and regulations require the expenditure of substantial time and financial resources and we may not be able to obtain the

 required regulatory approvals. Further, we have ongoing clinical studies requiring health authorities to oversee and approve ongoing clinical activities.
 U.S. biological products development process
 The process required by the FDA before a biological product may be marketed in the United States generally involves the following:
 • completion of nonclinical laboratory tests and animal studies according to good laboratory practices ("GLPs"), and other applicable regulations;
 • submission to the FDA of an investigational new drug application ("IND"), which must become effective before human clinical studies may begin;
 • approval by an institutional review board ("IRB"), or ethics committee at each clinical site before the trial commences;
 • performance of adequate and well-controlled human clinical studies according to the FDA's regulations commonly referred to as good clinical practices ("GCPs") and any additional requirements for the protection of human research subjects and their health information, to establish the safety, purity and potency or efficacy of the proposed biological product for its intended use;
 • preparation and submission to the FDA of a BLA for marketing approval that includes substantial evidence of safety, and efficacy from results of nonclinical testing and clinical studies;
 • satisfactory completion of an FDA inspection of the manufacturing facility or facilities where the biological product is produced to assess compliance with GMP, to assure that the facilities, methods and controls are adequate to preserve the biological product's safety, identity, strength, quality, purity and potency, and, if applicable, the FDA's good tissue practices ("GTPs") for the human cellular and tissue products;
 • potential FDA audit of the nonclinical and clinical study sites that generated the data in support of the BLA; and
 • FDA review and approval, or licensure, of the BLA.
 Before testing any biological product candidate, including a gene therapy product, in humans, the product candidate enters the preclinical testing stage. Preclinical tests, also referred to as nonclinical studies, include laboratory evaluations of product chemistry, toxicity and formulation, as well as animal studies to assess the potential safety and activity of the product candidate. The conduct of the preclinical tests must comply with federal regulations and requirements including GLPs, where applicable.
 The clinical study sponsor must submit the results of the preclinical tests, together with manufacturing information, analytical data, any available clinical data or literature, a proposed clinical protocol and investigator information, to the FDA as part of the IND. Some preclinical testing may continue even after the IND is submitted. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA places the clinical study on a clinical hold within that 30-day time period. In such a case, the IND sponsor and the FDA must resolve any outstanding concerns before the clinical study can begin. The FDA may also impose clinical holds on a biological product candidate at any time before or during clinical studies due to safety concerns or non-compliance. If the FDA imposes a clinical hold, studies may not recommence without FDA authorization and then only under terms authorized by the FDA. Accordingly, the submission of an IND may not result in the FDA allowing clinical studies to begin, or that, once begun, that such studies will be allowed to continue.
 In addition to the IND submission process, under the National Institutes of Health ("NIH"), Guidelines for Research Involving Recombinant DNA Molecules ("NIH Guidelines"), supervision of human gene transfer trials includes evaluation and assessment by an institutional biosafety committee ("IBC"), a local institutional committee that reviews and oversees research utilizing recombinant or synthetic nucleic acid molecules at that institution. The IBC assesses the safety of the research and identifies any potential risk to public health or the environment, and such review may result in some delay before initiation of a clinical trial. While the NIH Guidelines are not mandatory unless the research in question is being conducted at or sponsored by institutions receiving NIH funding of recombinant or synthetic nucleic acid molecule research, many companies and other institutions not otherwise subject to the NIH Guidelines voluntarily follow them.
 Clinical studies involve the administration of the biological product candidate to patients under the supervision of qualified investigators, generally physicians not employed by or under the study sponsor's control and studies must be conducted and

 monitored in accordance with the FDA's regulations comprising the GCP requirements, including, among other things, the requirement that all research subjects provide informed consent. Clinical studies are conducted under protocols detailing, among other things, the objectives of the clinical study, dosing procedures, subject selection and exclusion criteria, and the parameters to be used to monitor subject safety, including stopping rules that assure a clinical study will be stopped if certain adverse events should occur. Each protocol and any amendments to the protocol must be submitted to the FDA as part of the IND. While the IND is active, annual progress reports detailing the results of the clinical trials and nonclinical studies performed since the last progress report, among other information, must be submitted to the FDA, and written IND safety reports must be promptly submitted to the FDA and the investigators for serious and unexpected adverse events, any findings from other studies, tests in laboratory animals or in vitro testing that suggest a significant risk for human subjects, or any clinically important increase in the rate of a serious suspected adverse reaction over that listed in the protocol or investigator brochure.
 Further, each clinical study must be reviewed and approved by an IRB at or servicing each institution at which the clinical study will be conducted. An IRB is charged with protecting the welfare and rights of study participants and considers such items as whether the risks to individuals participating in the clinical studies are minimized and are reasonable in relation to anticipated benefits. The IRB also approves the form and content of the informed consent that must be signed by each clinical study subject or his or her legal representative and must monitor the clinical study until completed. The FDA or the sponsor may suspend, or its data safety monitoring board may recommend suspension of a clinical study at any time on various grounds, including a finding that the research subjects or patients are being exposed to an unacceptable health risk. Similarly, an IRB can suspend or terminate approval of a clinical study at its institution if the clinical study is not being conducted in accordance with the IRB's requirements or if the biological product candidate has been associated with unexpected serious harm to patients.
 Human clinical studies are typically conducted in three sequential phases that may overlap or be combined:
 • Phase 1. The biological product is initially introduced into healthy human subjects or patients with the target disease or condition. These studies are designed to test, among other things, the safety, dosage tolerance, absorption, metabolism and distribution, of the investigational product in humans, the side effects associated with increasing doses, and if possible, to gain early evidence on effectiveness.
 • Phase 2. The biological product is evaluated in a limited patient population with the specified disease or condition to identify possible adverse effects and safety risks, to preliminarily evaluate the efficacy of the product for specific targeted diseases and to determine dosage tolerance, optimal dosage and dosing schedule.
 • Phase 3. The biological product is administered to an expanded patient population to further evaluate dosage, to provide statistically significant evidence of clinical efficacy, and to further test for safety, generally at geographically dispersed clinical study sites. These clinical studies are intended to establish the overall risk/benefit ratio of the product and provide an adequate basis for product labeling.
 Post-approval clinical studies, sometimes referred to as Phase 4 clinical studies, may be conducted after initial marketing approval. These clinical studies are used to gain additional experience from the treatment of patients in the intended therapeutic indication, particularly for long-term safety follow-up. The FDA may also require, or sponsors may voluntarily decide, to continue evaluating patients in ongoing clinical trials to gather additional information regarding the long-term effects of any approved products. For example, the FDA recommends that sponsors of certain gene therapy clinical trials observe subjects for potential gene therapy-related delayed adverse events for a 15-year period, including a minimum of five years of annual examinations followed by ten years of annual queries, either in person or by questionnaire, of study subjects.
 Concurrent with clinical studies, companies usually complete additional animal studies and must also develop additional information about the physical characteristics of the biological product as well as finalize a process for manufacturing the product in commercial quantities in accordance with GMP requirements. To help reduce the risk of the introduction of adventitious agents with use of biological products, the PHS Act emphasizes the importance of manufacturing control for products whose attributes cannot be precisely defined. The manufacturing process must be capable of consistently producing quality batches of the product candidate and, among other things, the sponsor must develop methods for testing the safety, identity, strength, quality, potency and purity of the final biological product. Additionally, appropriate packaging must be selected and tested and stability studies must be conducted to demonstrate that biological product quality is maintained over its defined shelf life.

 U.S. review and approval processes
 FDA approval of a BLA must be obtained before commercial marketing of the biological product candidate. The BLA must include results of product development, including results from laboratory and animal studies, human studies, information on the manufacture and composition of the product, proposed labeling and other relevant information. Data can come from company-sponsored clinical studies intended to test the safety and effectiveness of a use of the product, or from a number of alternative sources, including studies initiated by independent investigators. In addition, under the Pediatric Research Equity Act ("PREA") as amended, a BLA or supplement to a BLA must contain data to assess the safety and effectiveness of the biological product for the claimed indications in all relevant pediatric subpopulations and to support dosing and administration for each pediatric subpopulation for which the product is safe and effective. The FDA may grant deferrals for submission of data or full or partial waivers of the PREA requirements. Unless otherwise required by regulation, PREA does not apply to any biological product for an indication for which orphan designation has been granted.
 Within 60 days following submission of the application, the FDA reviews a BLA submitted to determine if it is substantially complete before the agency accepts it for filing. The FDA may refuse to file any BLA that it deems incomplete or not properly reviewable at the time of submission and may request additional information. In this event, the BLA must be resubmitted with the additional information. The resubmitted application also is subject to review before the FDA accepts it for filing. Once the submission is accepted for filing, the FDA begins an in-depth substantive review of the BLA. The FDA reviews the BLA to determine, among other things, whether the proposed product is safe, pure and potent, or effective, for its intended use, and has an acceptable purity profile, and whether the product is being manufactured in accordance with GMP to assure and preserve the product's identity, safety, strength, quality, potency and purity. The FDA's goal is to review standard applications within ten months after the filing date, or, if the application qualifies for priority review, six months after the FDA accepts the application for filing. In both standard and priority reviews, the review process may also be extended by FDA to review additional information deemed a "major amendment" to the application.
 The FDA may refer applications for novel biological products or biological products that present difficult questions of safety or efficacy to an advisory committee, typically a panel that includes clinicians and other experts, for review and evaluation, potentially including a recommendation as to whether the application should be approved and under what conditions. The FDA is not bound by the recommendations of an advisory committee, but it considers such recommendations carefully when making decisions.
 During the biological product approval process, the FDA also will determine whether a Risk Evaluation and Mitigation Strategy ("REMS") is necessary to assure the safe use of the biological product. If the FDA concludes a REMS is needed, the sponsor of the BLA must submit a proposed REMS; the FDA will not approve the BLA without a REMS, if required.
 Before approving a BLA, the FDA will inspect the facilities at which the product is manufactured. The FDA will not approve the product unless it determines that the manufacturing processes and facilities are in compliance with GMP requirements and adequate to assure consistent production of the product within required specifications. For a gene therapy product, the FDA also will not approve the product if the manufacturer is not in compliance with GTP regulations applicable to the operations that it performs. These are FDA regulations that govern the methods used in, and the facilities and controls used for, the manufacture of human cells, tissues, and cellular and tissue-based products ("HCT/Ps") which are human cells or tissue intended for implantation, transplant, infusion, or transfer into a human recipient. The primary intent of the GTP requirements is to ensure that cell and tissue-based products are manufactured in a manner designed to prevent the introduction, transmission and spread of communicable disease. FDA regulations also require tissue establishments to register and list their HCT/Ps with the FDA and, when applicable, to evaluate donors through screening and testing. Additionally, before approving a BLA, the FDA will typically inspect one or more clinical sites, as well as the applicant, to assure that the clinical studies were conducted in compliance with IND study requirements and GCP requirements.
 After the FDA evaluates a BLA and conducts inspections, the FDA may issue an approval letter or a Complete Response Letter ("CRL"). An approval letter authorizes commercial marketing of the product with specific prescribing information for specific indications. A CRL will describe all deficiencies that the FDA has identified in the BLA, except that where the FDA determines that the data supporting the application are inadequate to support approval, the FDA may issue the CRL without first conducting required inspections, testing submitted product lots, and/or reviewing proposed labeling. In issuing the CRL, the FDA may recommend actions that the applicant might take to place a resubmitted BLA in condition for approval, including requests for additional information or clarification, or requirements for additional clinical or nonclinical testing. The FDA may delay or refuse to approve a BLA if applicable regulatory criteria are not satisfied.
 If a product receives regulatory approval, the approval may be significantly limited to specific diseases and dosages or the indications for use may otherwise be limited, which could restrict the commercial value of the product. Further, the FDA may

 require that certain contraindications, warnings or precautions be included in the product labeling. The FDA may impose restrictions and conditions on product distribution, prescribing, or dispensing in the form of a REMS, or otherwise limit the scope of any approval. In addition, the FDA may require post marketing clinical studies, sometimes referred to as Phase 4 clinical studies, designed to further assess a biological product's safety and effectiveness, and testing and surveillance programs to monitor the safety of approved products that have been commercialized.
 Orphan drug designation
 Under the Orphan Drug Act, the FDA may grant orphan designation to a drug or biological product intended to treat a rare disease or condition, which is generally a disease or condition that affects fewer than 200,000 individuals in the United States, or more than 200,000 individuals in the United States and for which there is no reasonable expectation that the cost of developing and making a drug or biological product available in the United States for this type of disease or condition will be recovered from sales of the product. Orphan product designation must be requested before submitting a BLA. After the FDA grants orphan product designation, the identity of the therapeutic agent and its potential orphan use are disclosed publicly by the FDA. Orphan product designation does not convey any advantage in or shorten the duration of the regulatory review and approval process.
 If a product that has orphan designation subsequently receives the first FDA approval for the disease or condition for which it has such designation, the product is entitled to orphan product exclusivity, which means that the FDA may not approve any other applications to market the same drug or biological product for the same disease or condition for seven years, except in limited circumstances, such as a showing of clinical superiority to the product with orphan exclusivity. The designation of such drug also entitles a party to financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages, exemptions from PREA requirements and BLA user-fee waivers. Competitors, however, may receive approval of different products for the disease or condition for which the orphan product has exclusivity or obtain approval for the same product but for a different disease or condition for which the orphan product has exclusivity. Orphan product exclusivity also could block the approval of a product for seven years if a competitor obtains approval of the same biological product as defined by the FDA or if the product candidate is determined to be contained within the competitor's product for the same condition or disease. If a drug or biological product designated as an orphan product receives marketing approval for a disease or condition broader than what is designated, it may not be entitled to orphan product exclusivity.
 Expedited development and review programs
 The FDA has a Fast Track program that is intended to expedite or facilitate the process for reviewing drugs and biological products that meet certain criteria. Specifically, drugs and biological product candidates are eligible for Fast Track designation if they are intended to treat a serious or life-threatening condition and demonstrate the potential to address unmet medical needs for the condition. Fast Track designation applies to the combination of the product candidate and the specific indication for which it is being studied. The product candidate sponsor may request the FDA to designate the drug or biologic as a Fast Track product at any time during the clinical development of the product candidate. Fast Track designation provides opportunities for more frequent interactions with the FDA, and with regard to a Fast Track product candidate, the FDA may consider for review sections of the marketing application on a rolling basis before the complete application is submitted, if the sponsor provides a schedule for the submission of the sections of the application, the FDA agrees to accept sections of the application and determines that the schedule is acceptable, and the sponsor pays any required user fees upon submission of the first section of the application.
 A biological product candidate intended to treat a serious or life-threatening disease or condition may also be eligible for Breakthrough Therapy designation to expedite its development and review. A product candidate can receive Breakthrough Therapy designation if preliminary clinical evidence indicates that the product candidate, alone or in combination with one or more other drugs or biologics, may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. The designation includes all Fast Track designation features, as well as more intensive FDA interaction and guidance beginning as early as Phase 1 and an organizational commitment to expedite the development and review of the product candidate, including involvement of senior managers. Moreover, an investigational drug or biologic is eligible for RMAT designation if: (1) it meets the definition of a regenerative medicine therapy, which is defined as a cell therapy, therapeutic tissue engineering product, human cell and tissue product, or any combination product using such therapies or products, with limited exceptions; (2) it is intended to treat, modify, reverse, or cure a serious disease or condition; and (3) preliminary clinical evidence indicates that the investigational drug has the potential to address unmet medical needs for such disease or condition. In a February 2019 final guidance, the FDA also stated that certain gene therapies that lead to a sustained effect on cells or tissues may meet the definition of a regenerative medicine therapy. RMAT designation provides potential benefits that include more frequent meetings with FDA to discuss the development plan for the product candidate, eligibility for rolling review and priority review of BLAs.

 Any product candidate submitted to the FDA for marketing, including those receiving Fast Track designation, Breakthrough Therapy designation or RMAT designation, may be eligible for other types of FDA programs intended to expedite development and review, such as priority review. A BLA is eligible for priority review if the product candidate is designed to treat a serious condition, and if approved would provide a significant improvement safety or effectiveness compared to marketed products. The FDA will attempt to direct additional resources to the evaluation of an application for designated for priority review in an effort to facilitate the review. Additionally, depending on the design of the applicable clinical studies, a product candidate may be eligible for accelerated approval. In particular, drug or biological products studied for their safety and effectiveness in treating serious or life-threatening illnesses and that provide meaningful therapeutic benefit over existing treatments may receive accelerated approval, which means that they may be approved on the basis of the FDA's determination that the product candidate has an effect on a surrogate endpoint that is reasonably likely to predict a clinical benefit, or on a clinical endpoint that can be measured earlier than irreversible morbidity or mortality, such as an intermediate endpoint, that is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefit, taking into account the severity, rarity, or prevalence of the condition and the availability or lack of alternative treatments.
 As a condition of approval, the FDA generally requires that a sponsor of a drug or biological product receiving accelerated approval perform adequate and well-controlled confirmatory clinical studies, and may require such confirmatory studies to be underway prior to granting any accelerated approval. Failure to conduct required confirmatory trials in a timely manner, or to verify a clinical benefit during such confirmatory trials, will allow the FDA to withdraw the approved biologic product from the market on an expedited basis. In addition, the FDA currently requires as a condition for accelerated approval pre-submission of promotional materials, which could adversely impact the timing of the commercial launch of the product.
 Fast Track designation, Breakthrough Therapy designation, RMAT designation priority review and accelerated approval do not change the standards for approval but may expedite the development or approval process. Even if a product candidate qualifies for one or more of these programs, the FDA may later decide that the product no longer meets the conditions for qualification or decide that the time period for FDA review or approval will not be shortened.
 Post-approval requirements
 Maintaining compliance with applicable federal, state, and local statutes and regulations requires the expenditure of substantial time and financial resources. Rigorous and extensive FDA regulation of biological products continues after approval, particularly with respect to GMP. Manufacturers of approved products are required to comply with applicable requirements in the GMP regulations, including quality control and quality assurance and maintenance of records and documentation. Other post-approval requirements applicable to biological products, include reporting of GMP deviations that may affect the identity, potency, purity and overall safety of a distributed product, record-keeping requirements, reporting of adverse effects, reporting updated safety and efficacy information, and complying with electronic record and signature requirements. After a BLA is approved, the product also may be subject to official lot release. As part of the manufacturing process, the manufacturer is required to perform certain tests on each lot of the product before it is released for distribution. If the product is subject to official release by the FDA, the manufacturer submits samples of each lot of product to the FDA together with a release protocol showing a summary of the history of manufacture of the lot and the results of all of the manufacturer's tests performed on the lot. The FDA also may perform certain confirmatory tests on lots of some products before releasing the lots for distribution by the manufacturer.
 Biological product manufacturers and other entities involved in the manufacture and distribution of approved biological products are required to register their establishments with the FDA and certain state agencies, and are subject to periodic unannounced inspections by the FDA and certain state agencies for compliance with GMPs and other laws. Accordingly, manufacturers must continue to expend time, money, and effort in the area of production and quality control to maintain GMP compliance. Discovery of problems with a product after approval may result in restrictions on a product, manufacturer, or holder of an approved BLA, including withdrawal of the product from the market. In addition, changes to the manufacturing process or facility generally require prior FDA approval before being implemented and other types of changes to the approved product, such as adding new indications and additional labeling claims, are also subject to further FDA review and approval. In addition, companies that manufacture or distribute drug or biological products or that hold approved BLAs must comply with other regulatory requirements, including submitting annual reports, reporting information about adverse drug experiences, and maintaining certain records. Newly discovered or developed safety or effectiveness data may require changes to a drug's approved labeling, including the addition of new warnings and contraindications, and also may require the implementation of other risk management measures, including a REMS or the conduct of post-marketing studies to assess a newly-discovered safety issue.
 Manufacturers must comply with the FDA's advertising and promotion requirements, such as those related to direct-to-consumer advertising and advertising to healthcare professionals, the prohibition on promoting products for uses or in patient

 populations that are not described in the product's approved labeling (known as "off-label use"), industry-sponsored scientific and educational activities, and promotional activities involving the internet. Discovery of previously unknown problems or the failure to comply with the applicable regulatory requirements may result in restrictions on the marketing of a product or withdrawal of the product from the market as well as possible civil or criminal sanctions. Failure to comply with the applicable U.S. requirements at any time during the product development process, approval process or after approval, may subject an applicant or manufacturer to administrative or judicial civil or criminal sanctions and adverse publicity. Consequences could include refusal to approve pending applications, withdrawal of an approval, clinical hold, warning or untitled letters, product recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines, refusals of government contracts, mandated corrective advertising or communications with healthcare professionals, debarment, restitution, disgorgement of profits, or civil or criminal penalties.
 U.S. patent term restoration
 Depending upon the timing, duration and specifics of the FDA approval of the use of our product candidates, some of our U.S. patents may be eligible for limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, commonly referred to as the Hatch-Waxman Amendments. The Hatch-Waxman Amendments permit a patent restoration term of up to five years as compensation for patent term lost during product development and the FDA regulatory review process. However, patent term restoration cannot extend the remaining term of a patent beyond a total of 14 years from the product's approval date. The patent term restoration period is generally one-half the time between the effective date of an IND and the submission date of a BLA plus the time between the submission date of a BLA and the approval of that application. Only one patent applicable to an approved biological product is eligible for the extension and the application for the extension must be submitted prior to the expiration of the patent. The U.S. PTO, in consultation with the FDA, reviews and approves the application for any patent term extension or restoration. In the future, we may intend to apply for restoration of patent term for one of our currently owned or licensed patents to add patent life beyond its current expiration date, depending on the expected length of the clinical studies and other factors involved in the filing of the relevant BLA.
 Biosimilars and Exclusivity
 A biological product can obtain pediatric market exclusivity in the United States. Pediatric exclusivity, if granted, adds six months to existing regulatory exclusivity periods and patent terms. This six-month exclusivity, which runs from the end of all existing exclusivity protections or patent term, may be granted based on the voluntary completion of a pediatric study in accordance with an FDA-issued "Written Request" for such a study.
 The Patient Protection and Affordable Care Act (the "ACA") signed into law on March 23, 2010, includes a subtitle called the Biologics Price Competition and Innovation Act of 2009 (the "BPCIA") which created an abbreviated approval pathway for biological products shown to be similar to, or interchangeable with, an FDA-licensed reference biological product. This amendment to the PHS Act attempts to minimize duplicative testing. Biosimilarity, which requires that there be no clinically meaningful differences between the biological product and the reference product in terms of safety, purity, and potency, can be shown through analytical studies, animal studies, and a clinical study or studies. Interchangeability requires that a product is biosimilar to the reference product and the product must demonstrate that it can be expected to produce the same clinical results as the reference product and, for products administered multiple times, the biologic and the reference biologic may be switched after one has been previously administered without increasing safety risks or risks of diminished efficacy relative to exclusive use of the reference biologic.
 Under the BPCIA, an application for a biosimilar product may not be submitted to the FDA until four years following the date that the reference product was first licensed by the FDA. In addition, the approval of a biosimilar product may not be made effective by the FDA until 12 years from the date on which the reference product was first licensed. During this 12-year period of exclusivity, another company may still market a competing version of the reference product if the FDA approves a full BLA for the competing product containing the sponsor's own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of their product. The BPCIA also created certain exclusivity periods for biosimilars approved as interchangeable products. At this juncture, it is unclear whether products deemed "interchangeable" by the FDA will, in fact, be readily substituted by pharmacies, which are governed by state pharmacy law. In addition, recent legislative and regulatory proposals have sought to reduce or altogether eliminate the distinctions between interchangeable products and conventional biosimilar products, making the long-term status of these products unclear.

 Healthcare Laws
 In addition to restrictions on marketing of pharmaceutical products, several other types of state/ federal laws and trade association membership codes of conduct have been applied to restrict certain marketing practices in the pharmaceutical industry in recent years. These laws include without limitation, state and federal anti-kickback, fraud and abuse, false claims, data privacy and security and transparency laws and regulations with respect to drug pricing and payments and other transfers of value made to healthcare professionals.
 The U.S. federal Anti-Kickback statute prohibits, among other things, knowingly and willfully offering, paying, soliciting or receiving remuneration, directly or indirectly, in cash or in kind, to induce or in return for purchasing, leasing, ordering or arranging for or recommending the purchase, lease or order of any healthcare item or service reimbursable, in whole or in part, under Medicare, Medicaid or other federally financed healthcare programs. This statute has been interpreted to apply to arrangements between pharmaceutical manufacturers on one hand and prescribers, purchasers, and formulary managers on the other. A person or entity need not have actual knowledge of the federal Anti-Kickback Statute or specific intent to violate it in order to have committed a violation. Although there are a number of statutory exemptions and regulatory safe harbors protecting certain common activities from prosecution, the exemptions and safe harbors are drawn narrowly and practices that involve remuneration to those who prescribe, purchase, or recommend pharmaceutical and biological products, including certain discounts, or engaging healthcare professionals or patients as speakers or consultants, may be subject to scrutiny if they do not fit squarely within the exemption or safe harbor.
 The U.S. federal civil False Claims Act prohibits, among other things, any person from knowingly presenting, or causing to be presented, a false or fraudulent claim for payment of government funds, or knowingly making, using, or causing to be made or used, a false record or statement material to an obligation to pay money to the government or knowingly concealing or knowingly and improperly avoiding, decreasing, or concealing an obligation to pay money to the federal government. Manufacturers can be held liable under the False Claims Act even when they do not submit claims directly to government payers if they are deemed to "cause" the submission of false or fraudulent claims. The False Claims Act also permits a private individual acting as a "whistleblower" to bring actions on behalf of the federal government alleging violations of the False Claims Act and to share in any monetary recovery. In recent years, several pharmaceutical and other healthcare companies have faced enforcement actions under the federal False Claims Act for, among other things, allegedly submitting false or misleading pricing information to government health care programs and providing free product to customers with the expectation that the customers would bill federal programs for the product. Other companies have faced enforcement actions for causing false claims to be submitted because of the company's marketing the product for unapproved, and thus non-reimbursable, uses. Federal enforcement agencies also have shown increased interest in pharmaceutical companies' product and patient assistance programs, including reimbursement and co-pay support services, and a number of investigations into these programs have resulted in significant civil and criminal settlements. In addition, the government may assert that a claim including items or services resulting from a violation of the federal Anti-Kickback statute constitutes a false or fraudulent claim for purposes of the federal civil False Claims Act. Criminal prosecution is possible for making or presenting a false or fictitious or fraudulent claim to the federal government.
 The federal Civil Monetary Penalties Law prohibits, among other things, the offering or transferring of remuneration to a Medicare or Medicaid beneficiary that the person knows or should know is likely to influence the beneficiary's selection of a particular supplier of Medicare or Medicaid payable items or services.
 The Health Insurance Portability and Accountability Act of 1996 ("HIPAA") also created several new federal crimes, including healthcare fraud and false statements relating to healthcare matters. The healthcare fraud statute prohibits knowingly and willfully executing a scheme to defraud any healthcare benefit program, including private third-party payers. The false statements statute prohibits knowingly and willfully falsifying, concealing or covering up a material fact or making any materially false, fictitious or fraudulent statement in connection with the delivery of or payment for healthcare benefits, items or services. Similar to the federal Anti-Kickback Statute, a person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation.
 The U.S. federal Physician Payment Sunshine Act, being implemented as the Open Payments Program, requires certain manufacturers of drugs, devices, biologics and medical supplies to engage in extensive tracking of payments and other transfers of value to physicians (defined to include doctors, dentists, optometrists, podiatrists, chiropractors, certain non-physician practitioners (physician assistants, nurse practitioners, clinical nurse specialists, certified registered nurse anesthetists, anesthesiologist assistants, and certified nurse midwives) and teaching hospitals, including physician ownership and investment interests, and public reporting of such data. Pharmaceutical and biological manufacturers with products for which payment is available under Medicare, Medicaid or the State Children's Health Insurance Program are required to track such payments, and must submit a report on or before the 90th day of each calendar year disclosing reportable payments made in the previous

 calendar year. A number of other countries, states and municipalities have also implemented additional payment tracking and reporting requirements, which if not done correctly may result in additional penalties.
 In addition, the U.S. Foreign Corrupt Practices Act ("FCPA") prohibits corporations and individuals from engaging in certain activities to obtain or retain business or to influence a person working in an official capacity. It is illegal to pay, offer to pay or authorize the payment of anything of value to any official of another country, government staff member, political party or political candidate in an attempt to obtain or retain business or to otherwise influence a person working in that capacity. In many other countries, healthcare professionals who prescribe pharmaceuticals are employed by government entities, and the purchasers of pharmaceuticals are government entities. Our dealings with these prescribers and purchasers may be subject to the FCPA.
 The majority of states also have statutes or regulations similar to the federal anti-kickback and false claims laws, which apply to items and services reimbursed under Medicaid and other state programs, or, in several states, apply regardless of the payer. Several states also require pharmaceutical companies to report expenses relating to the marketing and promotion of pharmaceutical products in those states and to report gifts and payments to individual health care providers in those states. Some of these states also prohibit certain marketing-related activities including the provision of gifts, meals, or other items to certain health care providers. In addition, some state laws require pharmaceutical companies to comply with the pharmaceutical industry's voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government in addition to requiring manufacturers to report information related to payments to physicians and other healthcare providers, marketing expenditures, and drug pricing information. Certain state and local laws require the registration of pharmaceutical sales representatives.
 Violations of any of these laws or other applicable governmental regulations may result in significant penalties, including civil monetary penalties, damages, exclusion of an entity or individual from participation in government healthcare programs, additional reporting obligations and oversight if the government requires a corporate integrity agreement or other agreement to resolve allegations of non-compliance with these laws, criminal fines and imprisonment, as well as the potential curtailment or restructuring of our operations. Even if we are not determined to have violated these laws, government investigations into these issues typically require the expenditure of significant resources and generate negative publicity, which could harm our financial condition and divert the attention of our management from operating our business.
 Data Privacy and Security Laws
 Numerous state, federal and foreign laws, regulations and standards govern the collection, use, access to, confidentiality and security of health-related and other personal information, and could apply now or in the future to our operations or the operations of our partners. In the United States, numerous federal and state laws and regulations, including data breach notification laws, health information privacy and security laws and consumer protection laws and regulations govern the collection, use, disclosure, and protection of health-related and other personal information. In addition, certain foreign laws govern the privacy and security of personal data, including health-related data. Privacy and security laws, regulations, and other obligations are constantly evolving, may conflict with each other to complicate compliance efforts, and can result in investigations, proceedings, or actions that lead to significant civil and/or criminal penalties and restrictions on data processing.
 Pricing, Coverage and Reimbursement
 Uncertainty exists as to the coverage and reimbursement status of any drug products for which we obtain regulatory approval. In the United States, sales of any products for which we may receive regulatory approval for commercial sale will depend in part on the availability of reimbursement from third-party payers, including governments. In the United States, no uniform policy of coverage and reimbursement for drug products exists among third-party payers. Therefore, coverage and reimbursement for drug products can differ significantly from payer to payer. Third-party payers can include government healthcare systems, managed care providers, private health insurers and other organizations. The process for determining whether a payer will provide coverage for a drug product may be separate from the process for setting the price or reimbursement rate that the payer will pay for the drug product. Moreover, these processes vary in length and may take several weeks, months, or longer to conclude depending on the individual payer. Third-party payers may limit coverage to specific drug products on an approved list, or formulary, which might not include all FDA-approved drugs for a particular indication. Third-party payers may provide coverage, but place stringent limitations on such coverage, such as requiring alternative treatments to be tried first. These third-party payers are increasingly challenging the price and examining the medical necessity and cost-effectiveness of medical products and services, in addition to their safety, efficacy, and overall value. In addition, significant uncertainty exists as to the reimbursement status of newly approved healthcare products. We may need to conduct expensive pharmacoeconomic studies in order to demonstrate the medical necessity and cost-effectiveness of our products, in addition to incurring the costs required to obtain FDA approvals. Our product candidates may not be considered medically reasonable or

 necessary or cost-effective. Even if a drug product is covered, a payer's decision to provide coverage for a drug product does not imply that an adequate reimbursement rate will be approved. For products administered under the supervision of a physician, obtaining coverage and adequate reimbursement may be particularly difficult because of the higher prices often associated with such drugs. Additionally, separate reimbursement for the product itself or the treatment or procedure in which the product is used may not be available, which may impact physician utilization. Adequate third-party reimbursement may not be available to enable us to maintain price levels sufficient to realize an appropriate return on our investment in product development.
 The marketability of any products for which we receive regulatory approval for commercial sale may suffer if the government and third-party payers fail to provide adequate coverage and reimbursement. In addition, the emphasis on managed care in the United States has increased, and we expect will continue to exert downward pressure on pricing. Moreover, the policies of traditional insurance marketplace entities, like reinsurers and stop-loss carriers, toward gene therapies in general or our gene therapies in particular, can negatively impact payer decisions about coverage and reimbursement. Similarly, the policies of self-insured employers toward gene therapies in general or our gene therapies in particular, including the potential to exclude coverage, can negatively impact our ability to market our therapies. Coverage policies, third-party reimbursement rates and pharmaceutical pricing regulations may change at any time. Even if favorable coverage and reimbursement status is attained for one or more products for which we receive regulatory approval, less favorable coverage policies and reimbursement rates may be implemented in the future.
 We have proposed novel payment models, including outcomes-based contracts to assist with realizing the value and sharing the risk of a potential one-time treatment, such as for ZYNTEGLO and LYFGENIA. While we have signed outcomes-based contracts with several State Medicaid Agencies and with pharmacy benefit managers (PBMs) representing dozens of downstream insurance plans and are engaged in discussions with additional PBMs and national payers, there is no assurance that these payment models will be widely adopted. Even with these payment models, there may be substantial resistance to the cost of our products by payers and the public generally. These payment models may not be sufficient for payers to grant coverage and/or cover our therapy at parity with our competitors, and if we are unable to obtain adequate coverage for our products, the adoption of our products and access for patients may be limited. In addition, to the extent reimbursement for our products is subject to outcomes-based arrangements, our future revenues from product sales will be more at risk (though based on the structure of our contracts, this risk is quantifiable and relatively predictable). These factors could affect our ability to successfully commercialize our products and adversely impact our business, financial condition, results of operations and prospects.
 Government Price Reporting
 Medicaid is a joint federal and state program administered by the states for low income and disabled beneficiaries. Medicare is a federal program that is administered by the federal government covering individuals aged 65 and over as well as those with certain disabilities. We are enrolled in the Medicaid Drug Rebate Program ("MDRP"). Under the MDRP, as a condition of federal funds being made available for our covered outpatient drugs under Medicaid and for certain drugs or biologicals under Medicare Part B, we pay a rebate to state Medicaid programs for each unit of our covered outpatient drugs dispensed to a Medicaid beneficiary and paid for by the state Medicaid program. Medicaid rebates are based on pricing data that we report on a monthly and quarterly basis to the U.S. Centers for Medicare & Medicaid Services ("CMS"), the federal agency that administers the MDRP and Medicare programs. For the MDRP, these data include the average manufacturer price ("AMP") for each drug and, in the case of innovator products, best price. In connection with Medicare Part B, a pharmaceutical manufacturer must provide CMS with average sales price ("ASP") information for certain drugs or biologicals on a quarterly basis. ASP is calculated based on a statutorily defined formula, as well as regulations and interpretations of the statute by CMS. This information is used to compute Medicare Part B payment rates, which consist of ASP plus a specified percentage. If we become aware that our MDRP price reporting submission for a prior period was incorrect or has changed based on recalculation of the pricing data, we must resubmit the revised data for up to three years after the original due date. We may request to resubmit pricing data outside the three-year period if the change is a result of an outcomes-based agreement, when the outcome must be evaluated outside of the three-year period. If we fail to provide information timely or are found to have knowingly submitted false information to the government, we may be subject to civil monetary penalties and other sanctions, including termination from the MDRP, in which case payment would not be available for our covered outpatient drugs under Medicaid or, if applicable, Medicare Part B.
 Federal law requires that a manufacturer that participates in the MDRP also participate in the Public Health Service's 340B drug pricing program (the "340B program") in order for federal funds to be available for the manufacturer's drugs under Medicaid and Medicare Part B. The 340B program is administered by the Health Resources and Services Administration ("HRSA") and requires us, as a participating manufacturer, to agree to charge statutorily defined covered entities no more than the 340B "ceiling price" for our covered outpatient drugs when used in an outpatient setting. To date, bluebird's therapies have

 been administered in the inpatient setting exclusively, and we anticipate that most patients will continue to receive bluebird's therapies in an inpatient setting. However, in the event that patients are treated in an outpatient setting, the 340B "ceiling price" requirement may apply to these transactions if otherwise eligible under 340B legal standards. These 340B covered entities include a variety of community health clinics and other entities that receive health services grants from the Public Health Service, as well as hospitals that serve a disproportionate share of low income patients. A drug that is designated for a rare disease or condition by the Secretary of Health and Human Services is not subject to the 340B ceiling price requirement with regard to the following types of covered entities: rural referral centers, sole community hospitals, critical access hospitals, and free standing cancer hospitals. The 340B ceiling price is calculated using a statutory formula, which is based on the AMP and rebate amount for the covered outpatient drug as calculated under the MDRP. In general, products subject to Medicaid price reporting and rebate liability are also subject to the 340B ceiling price calculation and discount requirement. We must report 340B ceiling prices to HRSA on a quarterly basis, and HRSA publishes them to 340B covered entities. HRSA has finalized regulations regarding the calculation of the 340B ceiling price and the imposition of civil monetary penalties on manufacturers that knowingly and intentionally overcharge covered entities for 340B eligible drugs. HRSA has also finalized a revised administrative dispute resolution process through which 340B covered entities may pursue claims against participating manufacturers for overcharges, and through which manufacturers may pursue claims against 340B covered entities for engaging in unlawful diversion or duplicate discounting of 340B drugs. In addition, legislation may be introduced that, if enacted, would further expand the 340B program, such as adding further covered entities or requiring participating manufacturers to agree to provide 340B discounted pricing on drugs used in an inpatient setting.
 In order to be eligible to have drug products paid for with federal funds under Medicaid and Medicare Part B and purchased by certain federal agencies and grantees, we must also participate in the U.S. Department of Veterans Affairs ("VA") Federal Supply Schedule ("FSS") pricing program. Under the VA/FSS program, we must report the Non-Federal Average Manufacturer Price ("Non-FAMP") for our covered drugs to the VA and charge certain federal agencies no more than the Federal Ceiling Price, which is calculated based on Non-FAMP using a statutory formula. These four agencies are the VA, the U.S. Department of Defense, the U.S. Coast Guard, and the U.S. Public Health Service (including the Indian Health Service). We must also pay rebates on products purchased by military personnel and dependents through the TRICARE retail pharmacy program. If we fail to provide timely information or are found to have knowingly submitted false information, we may be subject to civil monetary penalties.
 Individual states continue to consider and have enacted legislation to limit the growth of healthcare costs, including the cost of prescription drugs and combination products. A number of states have either implemented or are considering implementation of drug price transparency legislation. Requirements under such laws include advance notice of planned price increases, reporting price increase amounts and factors considered in taking such increases, wholesale acquisition cost information disclosure to prescribers, purchasers, and state agencies, and new product notice and reporting. Such legislation could limit the price or payment for certain drugs, and a number of states may impose civil monetary penalties or pursue other enforcement mechanisms against manufacturers who fail to comply with drug price transparency requirements.
 Healthcare Reform and Potential Changes to Healthcare Laws
 A primary trend in the U.S. healthcare industry and elsewhere is cost containment. Government authorities and other third party payers have attempted to control costs by limiting coverage and the level of reimbursement for particular medical products and services, implementing reductions in Medicare and other healthcare funding and applying new payment methodologies. For example, in March 2010, the ACA was enacted, which, among other things, increased the minimum Medicaid rebates owed by most manufacturers under the Medicaid Drug Rebate Program; introduced a new methodology by which rebates owed by manufacturers under the Medicaid Drug Rebate Program are calculated for drugs that are inhaled, infused, instilled, implanted or injected; extended manufacturer Medicaid rebate obligations to utilization by individuals enrolled in Medicaid managed care plans; established a new Medicare Part D coverage gap discount program; subjected drug manufacturers to new annual fees based on pharmaceutical companies' share of sales to federal healthcare programs; imposed a new federal excise tax on the sale of certain medical devices; created a new Patient Centered Outcomes Research Institute to oversee, identify priorities in, and conduct comparative clinical effectiveness research, along with funding for such research; and established a Center for Medicare and Medicaid Innovation at the CMS to test innovative payment and service delivery models to lower Medicare and Medicaid spending.
 Since its enactment, there have been judicial, executive and Congressional challenges to certain aspects of the ACA. On June 17, 2021, the U.S. Supreme Court dismissed a recent judicial challenge to the ACA brought by several states without specifically ruling on the constitutionality of the ACA. In addition, other legislative changes have been proposed and adopted in the United States since the ACA was enacted. The Budget Control Act of 2011, among other things, led to reductions of Medicare payments to providers, which will remain in effect through 2032 unless additional Congressional action is taken. More recently, in March 2021, President Biden signed into law the American Rescue Plan Act of 2021, which eliminated the

 statutory cap on the Medicaid drug rebate, beginning January 1, 2024. The rebate was previously capped at 100% of a drug's AMP.

 Most significantly, in August 2022, President Biden signed the Inflation Reduction Act of 2022 (IRA) into law. This statute marks the most significant action by Congress with respect to the pharmaceutical industry since adoption of the ACA in 2010. Among other things, the IRA requires manufacturers of certain drugs to engage in price negotiations with Medicare, with prices that can be negotiated subject to a cap (with resulting prices for the initial ten drugs first effective in 2026); imposes rebates under Medicare Part B and Medicare Part D to penalize price increases that outpace inflation (first due in 2023); redesigns the Medicare Part D benefit (beginning in 2024); and replaces the Part D coverage gap discount program with a new discounting program (beginning in 2025). CMS has published the negotiated prices for the initial ten drugs, which will first be effective in 2026, and has published the list of the subsequent 15 drugs that will be subject to negotiation. The IRA permits the Secretary of the Department of Health and Human Services (HHS) to implement many of these provisions through guidance, as opposed to regulation, for the initial years. HHS has and will continue to issue and update guidance as these programs are implemented, although the Medicare drug price negotiation program is currently subject to legal challenges. While the direct impact of the IRA on the pharmaceutical industry and the indirect impact on our business cannot yet be fully determined, it is likely to be significant.
 Additionally, there has been increasing legislative and enforcement interest in the United States with respect to specialty drug pricing practices. Specifically, there have been several recent Congressional inquiries and proposed and enacted federal and state legislation designed to, among other things, bring more transparency to drug and biologic pricing, reduce the cost of prescription drugs and biologics under Medicare, review the relationship between pricing and manufacturer patient programs and reform government program reimbursement methodologies for drugs and biologics.
 Individual states in the United States have also become increasingly active in passing legislation and implementing regulations designed to control pharmaceutical and biological product pricing, including price or provider reimbursement constraints, patient out-of-pocket cost caps for certain classes of therapy, discounts, restrictions on certain product access, marketing cost disclosure and other transparency measures, and, in some cases, measures designed to encourage importation from other countries and bulk purchasing. Some states have enacted legislation creating so-called prescription drug affordability boards, which ultimately may attempt to impose price limits on certain drugs in these states.
 We cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative or executive action, either in the United States or abroad. We expect that additional state and federal healthcare reform measures will be adopted in the future, any of which could limit the amounts that governments and third-party payers will pay for healthcare products and services.
 Human capital
 As of January 31, 2025, we had 248 full-time employees, 34 of whom have Ph. D., M.D. or Pharm. D. degrees. Of these full-time employees, 154 employees are engaged in research and development activities and 94 employees are engaged in commercial, finance, legal, business development, human resources, information technology, facilities and other general administrative functions. We have no collective bargaining agreements with our employees, and we have not experienced any work stoppages. We are an organization committed to creating an inclusive and engaged culture that meets the needs of the whole employee, through competitive total rewards and retention efforts and commitment to Diversity, Equity, Inclusion and Belonging.
 Compensation and benefits programs
 Our compensation programs are designed to align our employees' interests with the drivers of growth and stockholder returns by supporting the Company's achievement of its primary business goals. Our goal is to attract and retain employees whose talents, expertise, leadership, and contributions are expected to sustain growth and drive long-term stockholder value. Consequently, we provide employee wages and benefits that are competitive within our industry, and we engage a nationally recognized outside compensation and benefits consulting firm to independently evaluate the effectiveness of our compensation and benefit programs and to provide benchmarking against our peers within the industry. Through our pay-for-performance culture, we seek to align our employees' interests with those of stockholders by linking annual changes in compensation to overall Company performance, as well as each individual's contribution to the results achieved. The emphasis on overall Company performance is intended to align the employee's financial interests with the interests of stockholders. We are also committed to providing comprehensive benefit options and it is our intention to offer benefits that will allow our employees and their families to live healthier and more secure lives. All employees are eligible for medical, dental, and vision insurance, paid and unpaid leaves, employee stock purchase plan, 401(k) plan, and group life and disability coverage.

 Corporate Information
 We were incorporated in Delaware in April 1992 under the name Genetix Pharmaceuticals Inc., and subsequently changed our name to bluebird bio, Inc. in September 2010. Our mailing address and executive offices are at 455 Grand Union Boulevard, Somerville, Massachusetts, and our telephone number at that address is (339) 499-9300. We maintain an Internet website at the following address: www.bluebirdbio.com. The information on our website is not incorporated by reference in this annual report on Form 10-K or in any other filings we make with the Securities and Exchange Commission ("SEC").
 We make available on or through our website certain reports and amendments to those reports that we file with or furnish to the SEC in accordance with the Securities Exchange Act of 1934, as amended. These include our annual reports on Form 10-K, our quarterly reports on Form 10-Q, and our current reports on Form 8-K, and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Exchange Act. We make this information available on or through our website free of charge as soon as reasonably practicable after we electronically file the information with, or furnish it to, the SEC.

 Item 1A. Risk Factors
 An investment in shares of our common stock involves a high degree of risk. You should carefully consider the following information about these risks, together with the other information appearing elsewhere in this Annual Report on Form 10-K, including our financial statements and related notes hereto, before deciding to invest in our common stock. The occurrence of any of the following risks could have a material adverse effect on our business, financial condition, results of operations and future growth prospects. In these circumstances, the market price of our common stock could decline, and you may lose all or part of your investment.
 Risks related to the Merger Transaction
 The conditions under the Merger Agreement to Parent's and Merger Sub's consummation of the Merger Transaction may not be satisfied at all or in the anticipated timeframe.
 On February 21, 2025, we entered into an Agreement and Plan of Merger (the "Merger Agreement") with Beacon Parent Holdings, L.P., a Delaware limited partnership ("Parent"), and Beacon Merger Sub, Inc., a Delaware corporation ("Merger Sub"), pursuant to which Merger Sub will conduct a cash tender offer (the "Offer") to acquire any and all of the outstanding shares of our common stock, par value $0.01 per share (the "Shares"), for (i) $3.00 in cash per Share, plus (ii) one contingent value right (each, a "CVR") per Share, representing the right to receive a non-tradeable contingent payment of $6.84 in cash, in each case subject to any applicable withholding taxes and without interest thereon. The Offer will initially remain open for a minimum of 20 business days, subject to certain possible extensions on the terms set forth in the Merger Agreement (as such date and time may be so extended, the "Expiration Time"). Upon the terms and subject to the conditions set forth in the Merger Agreement and in accordance with the DGCL, at the Effective Time (as defined in the Merger Agreement), Merger Sub will merge with and into the Company (the "Merger Transaction") pursuant to Section 251(h) of the DGCL with the Company as the surviving corporation (the "Surviving Corporation").
 Merger Sub's obligation to purchase the Shares validly tendered and not validly withdrawn pursuant to the Offer is subject to the satisfaction or waiver of customary conditions, including, among others, (i) there being validly tendered and not validly withdrawn immediately prior to the Expiration Time a number of Shares that, together with any Shares held by Parent, Merger Sub or any of their direct or indirect wholly owned subsidiaries, represents at least one more Share than 50% of the total number of all then outstanding Shares at the Expiration Time (the "Minimum Condition"), (ii) the absence of any law or order that prohibits consummation of the Offer or the Merger Transaction or that has the effect of making the Offer or Merger Transaction illegal, (iii) the accuracy of the representations and warranties of the Company contained in the Merger Agreement, subject to certain materiality standards, (iv) the Company's compliance and performance in all material respects with its covenants and agreements contained in the Merger Agreement, (v) the receipt of certain foreign regulatory approvals and (vi) the absence of any event, development or circumstance that has occurred since the date of the Merger Agreement that has had or would reasonably be expected to have a material adverse effect on the Company, as well as other customary conditions set forth in Annex A to the Merger Agreement. As a result, there can be no assurance that the Merger Transaction will be consummated. These conditions are described in more detail in the Merger Agreement, which is filed as an exhibit to the Current Report on Form 8-K, filed with the SEC on February 21, 2025, and incorporated herein by reference.

 The Company intends to pursue all required approvals in accordance with the Merger Agreement. However, no assurance can be given that the required approvals will be obtained and, even if all such approvals are obtained, no assurance can be given to the terms, conditions and timing of the approvals or that they will satisfy the terms of the Merger Agreement.
 The announcement of, or a failure to consummate, the Merger Transaction could negatively impact our business, financial condition, results of operations or our stock price.
 Our announcement of having entered into the Merger Agreement could cause a material disruption to our business and there can be no assurance that the conditions to the consummation of the Merger Transaction will be satisfied. The Merger Agreement may also be terminated by us and/or Parent in certain specified circumstances, as described below. We are subject to several risks as a result of the announcement of the Merger Agreement, including, but not limited to, the following:
 • if the Merger Transaction is not completed within the expected timeframe, or at all, the share price of our common stock will change to the extent that the current market price of our common stock reflects an assumption that the Merger Transaction will be consummated;
 • certain costs related to the Merger Transaction, including the fees and/or expenses of our legal, accounting and financial advisors must be paid even if the Merger Transaction is not completed;
 • pursuant to the Merger Agreement, we are subject to certain restrictions on the conduct of our business prior to the completion of the Merger Transaction, which restrictions could adversely affect our ability to realize certain of our business strategies or take advantage of certain business opportunities;
 • the attention of our management may be directed towards the consummation of the Merger Transaction and related matters, and their focus may be diverted from the day-to-day business operations of our company, including from other opportunities that might otherwise be beneficial to us;
 • our inability to retain existing key employees or hire new capable employees, given the uncertainty regarding our future, in order to execute on our continuing business operations;
 • a failure to complete the Merger Transaction within the proposed timeframe, or at all, may result in negative publicity and/or a negative impression of us in the investment community or business community generally;
 • difficulties maintaining relationships with collaborators, vendors, and other business partners;
 • third parties may determine to terminate and/or attempt to renegotiate their relationship with us as a result of the Merger Transaction, whether pursuant to the terms of their existing agreements with us or otherwise;
 • upon termination of the Merger Agreement by us or Parent under specified circumstances, we would be required to pay a termination fee of $1.5 million or an expense reimbursement of $300,000, depending on the circumstances surrounding such termination;
 • we could be subject to litigation related to any failure to complete the Merger Transaction; and
 • if the Merger Transaction is not completed, we will have depleted capital resources and will require additional financing to continue to operate; such financing may not be available within the necessary timeframe, on acceptable terms, or at all.
 In addition, our executive officers and directors may have interests in the Merger Transaction that are different from, or are in addition to, those of our stockholders generally. These interests include without limitation the following:
 • each member of the Board and each of our executive officers holds outstanding bluebird equity awards; and
 • each of our executive officers is party to an employment agreement that provides for severance payments and benefits upon a qualifying termination in connection with a change in control, which includes the Merger Transaction.

 The Merger Agreement contains provisions that could make it difficult for a third party to acquire us prior to the completion of the Merger Transaction.
 The Merger Agreement contains restrictions on our ability to obtain a third-party proposal for an acquisition of our company. These provisions include our agreement not to solicit or initiate any additional discussions with third parties regarding other proposals to acquire us, as well as restrictions on our ability to respond to such proposals, subject to fulfillment of certain fiduciary requirements of our board of directors. The Merger Agreement also contains certain termination rights, including, under certain circumstances, a requirement for us to pay to Parent a termination fee of approximately $1.5 million or an expense reimbursement of $300,000, depending on the circumstances surrounding such termination.
 These provisions might discourage an otherwise-interested third-party from considering or proposing an acquisition of our company, even one that may be deemed of greater value to our stockholders than the Merger Transaction. Furthermore, even if a third-party elects to propose an acquisition, the concept of a termination fee may result in that third-party offering a lower value to our stockholders than such third-party might otherwise have offered.
 Securities class action and derivative lawsuits in connection with the Merger Transaction could result in substantial costs and prevent or delay the consummation of the Merger Transaction.
 Securities class action lawsuits and derivative lawsuits are often brought against public companies that have entered into acquisition or merger agreements. Defending against and settling or otherwise resolving these types of claims can result in substantial costs, including costs associated with indemnification of directors and officers, and divert management time and resources. An adverse judgment in any such litigation relating to the Merger Transaction could result in monetary damages, which could have a negative impact on our financial condition. If a plaintiff is successful in obtaining an injunction prohibiting completion of the Merger Transaction, that injunction could delay or prevent the Merger Transaction from being completed, which could negatively impact our business, financial condition, results of operations or our stock price. As of March 25, 2025, four lawsuits challenging the Merger Transaction had been filed on behalf of purported stockholders of the Company.
 Risks related to our business

 We have incurred significant losses since our inception and we may not achieve our goal of becoming profitable in the timeframe we expect, or at all.
 We have incurred significant net losses since our inception in 1992, including net losses from continuing operations of $240.7 million for the year ended December 31, 2024. As of December 31, 2024, we had an accumulated deficit of $4.5 billion. To date, we have devoted significant financial resources to building our commercial infrastructure and research and development, including our clinical and preclinical development activities.
 If the Merger Transaction does not close, we will have incurred significant additional expenses and will continue to incur net losses for the foreseeable future and we may not become profitable on the timeline we anticipate, or at all. To date, we have financed our operations primarily through our loan agreement with Hercules Capital, Inc., the sale of equity securities and priority review vouchers, and, to a lesser extent, through collaboration agreements and grants from governmental agencies and charitable foundations. We did not generate material revenues from the sale of ZYNTEGLO in the European Union and are just beginning to recognize revenue from our approved products in the U.S. given the treatment cycle time, in which revenue is recognized upon infusion. Our future revenues will depend upon the size of any markets in which our products have received approval, and our ability to achieve sufficient market acceptance, reimbursement from third-party payers and adequate market share for our products in those markets.
 If the Merger Transaction does not close, we anticipate that our expenses may increase substantially, we may continue to incur operating losses, and we may not generate profit if and as we:
 • continue to explore strategic alternatives for our business;
 • grow our capabilities to support our commercialization efforts for ZYNTEGLO, SKYSONA and LYFGENIA, including continuing to establish a sales, marketing and distribution infrastructure in the United States;
 • obtain, build and expand manufacturing capacity, including capacity at third-party manufacturers;
 • attract and retain skilled personnel;

 • initiate additional research, preclinical, clinical or other programs as we seek to identify and validate additional product candidates;
 • continue our ongoing clinical development of ZYNTEGLO, SKYSONA and LYFGENIA, including completion of the HGB-210 clinical trial and long-term follow-up studies;
 • acquire or in-license other product candidates and technologies;
 • maintain, protect and expand our intellectual property portfolio;
 • incur expenses for legal, accounting, and other professional services in connection with the restatement of our consolidated financial statements;
 • defend against lawsuits, including patent or stockholder litigation; and
 • experience any delays or encounter issues with any of the above.
 The net losses we incur may fluctuate significantly from quarter to quarter and year to year, such that a period-to-period comparison of our results of operations may not be a good indication of our future performance. Further, there is no assurance that we will ever achieve profitability. In addition, in any particular quarter or quarters, our operating results could be below the expectations of securities analysts or investors, which could cause our stock price to decline.
 There is substantial doubt regarding our ability to continue as a going concern. We will need to raise additional funding, which may not be available on acceptable terms, or at all. Failure to obtain this necessary capital when needed may force us to delay, limit or terminate our commercial programs, product development efforts or other operations.
 Based on our current business plan as of the date hereof, management has concluded that there is substantial doubt regarding our ability to continue as a going concern. See Part II, Item 7 "Management's Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources" of this Annual Report on Form 10-K for a discussion of our expected cash runway. Accordingly, if the Merger Transaction does not close, we may be in immediate default under the terms of our loan agreement with Hercules Capital, Inc., and will be at substantial risk of defaulting on our cash covenants thereunder and will need to raise additional funding in order to continue as a going concern.
 We cannot guarantee that financing will be available in sufficient amounts or on terms acceptable to us, if at all. Moreover, the terms of any financing may adversely affect the holdings or the rights of our stockholders and the issuance of additional securities, whether equity, traditional debt or other debt-like arrangements, by us, or the possibility of such issuance, may cause the market price of our shares to decline. The sale of additional equity or convertible securities would dilute all of our stockholders. The incurrence of indebtedness would result in increased fixed payment obligations and we may be required to agree to certain restrictive covenants, such as limitations on our ability to incur additional debt, limitations on our ability to acquire, sell or license intellectual property rights and other operating restrictions that could adversely impact our ability to conduct our business. See also "Risk Factors – "Our existing and any future indebtedness could adversely affect our ability to operate our business". We could also be required to seek funds through arrangements with collaborative partners or otherwise, which may require us to relinquish rights to some of our technologies or products or otherwise agree to terms unfavorable to us, any of which may have a material adverse effect on our business, operating results and prospects. In addition, our efforts to raise additional funding may divert our management from their day-to-day activities, which may adversely affect our ability to develop and commercialize our products.
 Furthermore, as a result of the restatement of our consolidated financial statements for the year ended December 31, 2022 and the quarterly periods in the years ended December 31, 2022 and 2023, we were delayed in filing our Annual Report on Form 10-K for the year ended December 31, 2023 and our Quarterly Reports on Form 10-Q for each of the periods ended March 31, 2024 and June 30, 2024. As a result, we will not be eligible to sell securities under our existing shelf registration statement on Form S-3 or file a new Form S-3 until we have regained compliance with the requirements of Form S-3. See "Risk Factor — The restatement of our consolidated financial statements for the year ended December 31, 2022 and the quarterly periods in the years ended December 31, 2022 and 2023 has subjected us to a number of additional risks and uncertainties, including increased possibility of legal proceedings". Our inability to use Form S-3 could make it more difficult and costly for us to obtain funding through a sale of securities.
 Moreover, as a result of volatile market conditions, the cost and availability of capital has been and may continue to be adversely affected. Lenders and institutional investors may reduce, and in some cases, cease to provide credit to businesses and

 consumers. Continued turbulence in the U.S. market and economy may adversely affect our liquidity and financial condition, including our ability to access the capital markets to meet liquidity needs. In addition, we maintain the majority of our cash and cash equivalents in accounts with major financial institutions, and our deposits at these institutions exceed insured limits. Market conditions can impact the viability of these institutions. In the event of failure of any of the financial institutions where we maintain our cash and cash equivalents, there can be no assurance that we would be able to access uninsured funds in a timely manner or at all. Any inability to access or delay in accessing these funds could adversely affect our business and financial position.
 If the Merger Transaction does not close and we are then unable to obtain funding on a timely basis, or if revenues from product sales are less than we have projected, we will be at risk of further revising our business plan and strategy, which may result in us significantly curtailing, delaying or discontinuing the commercialization of any current or future products or may result in our being unable to continue or expand our operations or otherwise capitalize on our business opportunities or continue as a going concern. As a result, our business, financial condition and results of operations could be materially affected.
 In order to manage cash flow needs, we have delayed certain ordinary course payments to our vendors and suppliers. These delays could damage our relationships with key partners, which could result in cessation of services, legal disputes, or other interruptions that may negatively impact our operations. Additionally, delayed payments could impact the attractiveness of the Company to investors or financing partners.
 In order to manage cash flow needs, we have deferred the payment of amounts due to certain of our vendors and suppliers beyond our typical payment cycle. For instance, as of March 14, 2025, we owed approximately $50 million in third-party payables in excess of amounts typically due in recent prior quarters, which includes amounts owed to manufacturing and release testing vendors. These delays may have a negative impact on our relationships with affected vendors and suppliers, who may discontinue work, seek to renegotiate terms of our agreements, or pursue legal action against us. For example, certain of our vendors and suppliers have indicated that without timely payment, they will cease work. As a result, our business, financial condition and results of operations could be materially affected. Furthermore, if the Merger Transaction does not close, the quantity of overdue payables on our balance sheet could negatively impact our ability to raise additional funding.
 Our existing and any future indebtedness could adversely affect our ability to operate our business.
 On March 15, 2024, we entered into a Loan and Security Agreement, by and among the Company, the several banks and other financial institutions or entities party thereto, as lenders (the "Lender"), and Hercules Capital, Inc., as administrative agent and collateral agent, which we amended on April 30, 2024, July 9, 2024, August 13, 2024, August 29, 2024 and February 21, 2025 (as amended, the "LSA"). The LSA provides a secured term loan facility of up to $175.0 million (collectively, the "Term Loans"), consisting of: (a) an initial tranche of term loans in an aggregate amount of $75.0 million, which was funded at closing (the "Initial Loan"); (b) an additional tranche of term loans in an aggregate amount of $25.0 million, which will be available, subject to customary terms and conditions, during the period commencing on the date the Company has (x) received at least $75.0 million in gross cash proceeds from qualified financing transactions by December 20, 2024 (which milestone we did not achieve) and (y) completed patient starts (cell collections) for at least 50 LYFGENIA patients by March 31, 2025 or 70 LYFGENIA patients by June 30, 2025 (the "Tranche 2 Milestone") and ending on the earlier of (i) the date that is 30 days immediately following achievement of the Tranche 2 Milestone and (ii) July 31, 2025; (c) an additional tranche of term loans in an aggregate amount of $25.0 million, which will be available, subject to customary terms and conditions, during the period commencing on the date the Company has (x) received at least $100.0 million in gross cash proceeds from qualified financing transactions by December 20, 2024 or at least $125.0 million by June 30, 2025 and (y) completed 70 drug product deliveries within a given six-month period ending no later than December 31, 2025, at least 40 of which are for LYFGENIA (the "Tranche 3 Milestone") and ending on the earlier of (i) the date that is 30 days immediately following the date the Company achieves the Tranche 3 Milestone and (ii) December 31, 2025; and (d) an additional tranche of term loans of $50.0 million, available in the sole discretion of the lenders, and subject to customary terms and conditions, until December 15, 2026. Although our entry into the LSA and receipt of funds thereunder extended our cash runway, our outstanding indebtedness, including any additional indebtedness beyond our borrowings under the LSA, combined with our other financial obligations and contractual commitments (including commitments with respect to deferred payments as described in "Risk Factors - In order to manage cash flow needs, we have delayed certain ordinary course payments to our vendors and suppliers"), could have significant adverse consequences, including:
 • requiring us to dedicate a portion of our cash resources to the payment of interest and principal, reducing money available to fund working capital, capital expenditures, product candidate development and other general corporate purposes;

 • increasing our vulnerability to adverse changes in general economic, industry and market conditions;
 • subjecting us to restrictive covenants that may reduce our ability to take certain corporate actions or obtain further debt or equity financing;
 • limiting our flexibility in planning for, or reacting to, changes in our business and the industry in which we compete; and
 • placing us at a competitive disadvantage compared to our competitors that have less debt or better debt servicing options.
 The Term Loans are secured by a lien on substantially all of our assets. We intend to satisfy our current and future debt service obligations with our then-existing cash and cash equivalents. However, we may not have sufficient funds, and may be unable to arrange for additional financing, to pay the amounts due under the LSA or any other debt instruments. Failure to make payments or comply with other covenants under the LSA or such other debt instruments could result in an event of default and acceleration of amounts due. Other events of default under the LSA include, among others: (i) the occurrence of any event that the Lender interprets as a material adverse effect (including potentially with respect to our declining cash position or negative data results), (ii) a change in control as delineated under the Loan Agreement, (iii) failure of the Merger Transaction to close on or before April 25, 2025, which may be extended to May 23, 2025 and further extended to June 20, 2025, subject to certain conditions, and (iv) breaches of covenants in the LSA, including, among others, a minimum cash coverage requirement and a covenant that requires us to meet certain revenue levels; if we do not meet our projections, we may be unable to satisfy these covenants. For example, if the Merger Transaction does not close, we project that we may not maintain the minimum cash coverage requirement within the next 12 months. Upon the occurrence and continuance of an event of default, the Lender has the right to require us to repay the Term Loans immediately, which we would be unable to do given our current cash position. Accordingly, if the Merger Transaction does not close, we may be in immediate default under the terms of the LSA and will be at substantial risk of defaulting on our cash covenants thereunder. Any declaration by the Lender of an event of default would significantly harm our business and prospects and could cause the price of our common stock to decline or force us to discontinue our operations immediately and seek bankruptcy protection. If we raise any additional debt financing, the terms of such additional debt could further restrict our operating and financial flexibility.
 Among other potential adverse events, insertional oncogenesis is a significant risk of gene therapies using viral vectors that can integrate into the genome. Any such adverse events may require us to halt or delay further clinical development of our products or any future product candidates or to suspend or cease commercialization, and the commercial potential of our products and any such future product candidates may be materially and negatively impacted.
 Adverse events or other undesirable side effects caused by our products or any future product candidates could cause us or regulatory authorities to interrupt, delay or halt clinical trials and could result in a more restrictive label or the delay, denial or withdrawal of regulatory approval by the FDA or other comparable foreign regulatory authorities. A potentially significant risk in any gene therapy product using viral vectors that can integrate into the genome is that the vector will insert in or near cancer-causing genes, leading to the proliferation of certain cellular clones that could cause cancer in the patient, known as insertional oncogenesis. For instance, multiple patients with CALD treated with eli-cel (now SKYSONA) in our clinical studies have been diagnosed with myelodysplastic syndrome ("MDS"), or acute myeloid leukemia ("AML"), likely mediated by Lenti-D LVV insertion. SKYSONA's label includes a boxed warning for the known risk of hematologic malignancy and, accordingly, we expect additional cases to arise over time. In April 2024, the boxed warning was revised to include updated information on hematologic malignancies diagnosed in our clinical study patients, as well as other updates to monitoring procedures and alternative treatment options. We continue to closely monitor potential cases of hematologic malignancy in patients treated with SKYSONA and we are communicating regularly with treating physicians and regulatory authorities. In November 2024, the FDA published a notice to healthcare providers indicating that it was investigating SKYSONA with respect to serious risks of hematologic malignancies, based on cases of MDS and AML observed in patients previously enrolled in our clinical trials for eli-cel. No cases of insertional oncogenesis have been identified in patients treated with ZYNTEGLO or LYFGENIA.
 Separately, in December 2021, the FDA placed the lovo-cel clinical development program under a partial clinical hold for patients under the age of 18. The hold related to a case of persistent anemia in an adolescent patient with two -globin gene deletions (- 3.7/- 3.7), also known as alpha-thalassemia trait, who was treated with lovo-cel. In December 2022, the FDA lifted its partial clinical hold for patients under the age of 18 in studies evaluating lovo-cel for SCD. Notwithstanding the lifting of this partial clinical hold, additional adverse events or new data or analyses regarding previously reported events may indicate significant safety issues, and the FDA could potentially impose or reimpose a clinical hold in the future on studies evaluating

 lovo-cel. Moreover, laboratory results following gene therapy can be difficult to interpret, resulting in different or changing diagnoses by treating physicians. For instance, on January 31, 2023, we received a physician diagnosis of MDS in a patient treated with lovo-cel, in response to lab results obtained through routine monitoring of the same adolescent patient with two -globin gene deletions subject to the partial clinical hold noted above. Consistent with established safety protocols, the information was reviewed by an independent Data Monitoring Committee which concluded that available evidence did not support a diagnosis of MDS and additional data would be needed to confirm such diagnosis, and that lovo-cel clinical studies should continue. Test results received since the investigator's initial report (including integration site analysis) demonstrated no evidence of insertional oncogenesis and as of March 3, 2025, the patient remained clinically stable with stable laboratory results and was not undergoing treatment for an MDS diagnosis. Study investigators and the FDA were informed and we will continue to monitor additional analyses as further test results are received.
 Furthermore, treatment with our products and any future product candidates involves or may involve chemotherapy or myeloablative treatments, which can cause side effects or adverse events that may impact the perception of the potential benefits of our products and any future product candidates. For instance, MDS leading to AML is a known risk of certain myeloablative regimens. Accordingly, it is possible that the events of MDS and AML previously reported in our HGB-206 clinical study of lovo-cel in SCD were caused by underlying SCD, transplant procedure, and stress on the bone marrow following drug product infusion in connection with the lovo-cel treatment. The product label for LYFGENIA includes a boxed warning for the known risk of hematologic malignancy. We cannot make assurances that additional patients treated with SKYSONA, ZYNTEGLO or LYFGENIA in the clinical or commercial setting will not be diagnosed with hematologic malignancy. Additionally, the procedures associated with the administration or collection of cells for ZYNTEGLO, SKYSONA, or LYFGENIA, could potentially cause other adverse events that have not yet been predicted. The inclusion of patients with significant underlying medical problems in our clinical studies may result in deaths, or other adverse medical events, due to other therapies or medications that such patients may be using, or the progression of their disease.
 Moreover, patients treated with our therapies, including lovo-cel, have exhibited persistent oligoclonality, which we define as two consecutive instances of (i) any LVV insertion site observed at >=10% relative frequency, or (ii) two or more insertion sites observed at >= to 5% relative frequency, as measured by integration site analysis. Based on our clinical protocols, we increase monitoring of patients who exhibit persistent oligoclonality. It is not clear at this time whether persistent oligoclonality represents an increased risk of developing hematologic malignancy in the future, but it is a criterion used by the FDA to evaluate the safety of gene therapies over time.
 Additionally, there is the potential risk of other delayed adverse events following exposure to gene therapy products due to persistent biological activity of the genetic material or other components of products used to carry the genetic material. The FDA has stated that LVVs possess characteristics that may pose high risks of delayed adverse events.
 If any such adverse events occur, including insertional oncogenesis, further advancement of our ongoing and future clinical studies and other development efforts could be halted or delayed, and we may be unable to commercialize our approved products in the manner we expect, or at all. It is possible that upon occurrence or recurrence of any of these events, the FDA may place one or more of our programs on hold, impose requirements that result in delays for regulatory approvals for our products or any future product candidates, require the implementation of risk evaluation or mitigation strategies, or may cause us to cease commercialization of our approved products. If any of these were to occur, the commercial potential of our programs may be materially and negatively impacted.
 Although ZYNTEGLO, SKYSONA and LYFGENIA have been approved by the FDA, serious safety events may result in an approved product being removed from the market or its market opportunity being significantly reduced. For instance, it is possible that as we commercialize our products, conduct long-term follow-up, or test any future product candidates in larger, longer and more extensive clinical trials, or as use of these products or any future products becomes more widespread, illnesses, injuries, discomforts and other adverse events that were observed in previous trials, as well as conditions that did not occur or went undetected in previous trials, will be reported by patients. Many times, side effects (that may or may not be related to our products or any future product candidate) are only detectable after investigational products are tested in large-scale clinical trials or, in some cases, after they are made available to patients on a commercial scale following approval. Other patients receiving our products may develop hematologic malignancies in the future, which may negatively impact the commercial prospects of our products and any future product candidates. We or others may later identify undesirable side effects or adverse events caused by such products, or side effects or adverse events could accumulate over time, and a number of potentially significant negative consequences could result, including but not limited to:
 • regulatory authorities may suspend, limit or withdraw approvals of such product, or seek an injunction against its manufacture or distribution;

 • regulatory authorities may require additional warnings on the label, including "boxed" warnings, or issue safety alerts, "Dear Healthcare Provider" or "Dear Doctor" letters, press releases or other communications containing warnings or other safety information about the product;
 • we may be required to change the way the product is administered or conduct additional clinical trials or post-marketing studies;
 • we may be required to create a risk evaluation and mitigation strategy, or REMS which could include elements to assure safe use, or a medication guide outlining the risks of such side effects for distribution to patients;
 • we may be subject to fines, injunctions or the imposition of criminal penalties;
 • patients and/or treating physicians could perceive the risk of undesirable side effects or adverse events caused by the product to exceed its potential benefit and choose not to use the product;
 • we could choose to remove such product from the market;
 • we could be sued and held liable for harm caused to patients; and
 • our reputation may suffer.
 Any of these events could impair our ability to develop or commercialize our products or any future product candidates, and their commercial potential may be materially and negatively impacted.
 We rely on complex, single-source supply chains for SKYSONA, ZYNTEGLO, and LYFGENIA, respectively. The manufacture, testing and delivery of LVV and drug products present significant challenges for us, and we may not be able to produce our vector and drug products at the quality, quantities, or timing needed to support our clinical programs and commercialization.
 We rely on third parties to manufacture the LVV and the drug product for ZYNTEGLO, SKYSONA and LYFGENIA. The manufacture of LVV and drug products is complex and requires significant expertise. Even with the relevant experience and expertise, manufacturers of cell therapy products often encounter difficulties in production, particularly in scaling out and validating initial production, managing the transition from clinical manufacturing to manufacturing in the commercial setting, and ensuring that the product meets required specifications. These problems include difficulties with production costs and yields, quality control, quality assurance testing, operator error, scarcity of qualified manufacturing and quality control testing personnel, shortages of any production raw materials as well as compliance with strictly enforced federal, state and foreign regulations. Further, the transition from clinical to commercial manufacturing is complex and has resulted in, and may continue to result in, lower operational success rates due to, among other things, tighter specifications and higher regulatory standards associated with commercial products. We cannot make any assurances that these problems will not occur in the future, or that we will be able to resolve or address in a timely manner or with available funds problems that occur. Because of this complexity, transitioning production of either LVV or drug products to backup or second source manufacturing requires a lengthy technology transfer process and regulatory review and approval, which often takes significant time and may require additional significant financial expenditures.
 We currently have only one manufacturer of final drug product and one manufacturer of LVV for both ZYNTEGLO and SKYSONA and, separately, one manufacturer of final drug product and one manufacturer of LVV for LYFGENIA; accordingly, any significant disruption or change in our supplier relationships could harm our business. For instance, in August 2024 we provided notice to our manufacturer of adherent LVV for ZYNTEGLO and SKYSONA that we intend to wind down production of adherent LVV, which will cease in the second half of 2025. We are currently seeking FDA approval to transition LVV manufacturing for ZYNTEGLO to the suspension process used for LYFGENIA, and we continue to evaluate alternative manufacturing methods and plans for LVV for SKYSONA. Since any change to manufacturing methods requires FDA approval, we may be delayed in transitioning to such alternatives. Additionally, we have experienced challenges in manufacturing adherent LVV, which is currently used in ZYNTEGLO and SKYSONA. As a result of these events or delays, or other difficulties related to our manufacturing relationships and processes, we may be unable to meet our manufacturing forecasts in the future. Any inability to meet our manufacturing forecasts could impact the ongoing commercialization of these drug products, and hinder our ability to meet our financial goals.

 Further, we source key materials from third parties, either directly through agreements with suppliers or indirectly through our manufacturers who have agreements with suppliers. There are a small number of suppliers for certain key materials that are used to manufacture SKYSONA, ZYNTEGLO, and LYFGENIA. Such suppliers may not sell these key materials to us or to our manufacturers at the times we need them or on commercially reasonable terms. We do not control the process for acquisition of all key materials and shortages may occur for reasons beyond our control.
 To date, we have secured adequate commercial-scale drug product manufacturing capacity in order to meet our near-term sales forecasts for ZYNTEGLO, SKYSONA and LYFGENIA, including recent approval to double our manufacturing capacity for ZYNTEGLO and SKYSONA. However, our manufacturing rate for ZYNTEGLO is currently limited by capacity constraints and to meet demand we would need to expand further; any expansion of manufacturing capacity is subject to FDA approval, which we may not receive. If we fail to secure adequate capacity to manufacture our drug products or LVV used in the manufacture of our drug products in accordance with our forecasts we may be unable to execute on our commercialization plans on the timing that we expect, or at all.
 The actual cost to manufacture our LVV and drug products could be greater than we expect and could materially and adversely affect the commercial viability of SKYSONA, ZYNTEGLO, or LYFGENIA. If we or our third-party manufacturers are unable to produce the necessary quantities of LVV and drug product, or in compliance with GMP or other pertinent regulatory requirements, and within our planned time frame and cost parameters, including due to reduced operational success rates as a result of the transition to commercial manufacturing, the development and commercialization of our products and future product candidates may be materially harmed, result in delays in our plans or increased capital expenditures.
 Additionally, since the hematopoietic stem cells ("HSCs") used as starting material for our products have a limited window of stability following procurement from a patient, we have initially established transduction facilities in areas that we believe can adequately service patients from regions where we are commercializing SKYSONA, ZYNTEGLO, and LYFGENIA. However, we cannot ensure that such facilities will enable us to produce and deliver drug product in a timely manner; any issues with production and delivery of drug product could have a material adverse effect on our successful commercialization or further development of our products or any future product candidates. Moreover, establishing additional facilities in appropriate regions may be financially impractical or impeded by technical, quality, or regulatory issues related to these new sites and we may also run into technical or scientific issues related to transfer of our transduction process or other developmental issues that we may be unable to resolve in a timely manner or with available funds.
 Changes in our manufacturing processes may cause delays in our clinical development and commercialization plans.
 The manufacturing processes for our LVV and our drug products are complex. We explore improvements to our manufacturing processes on a continual basis, as we evaluate clinical and manufacturing data and based on discussions with regulatory authorities. In some circumstances, changes in the manufacturing process may require us to perform additional comparability studies, collect additional data from patients, submit additional regulatory filings, or comply with additional requirements, which may lead to delays in our clinical development and commercialization plans. Such changes may require regulatory review and approval including reaching agreement with the FDA on an acceptable comparability data package. The FDA may require us to conduct additional clinical studies, collect additional data, develop additional assays, or modify product specifications relating to such comparability analysis and, therefore, the proposed change may not be approved in a timely manner, if at all. Any such requests or delays may impact our commercialization plans and may require substantial additional funds.
 Risks related to commercialization
 The marketing and sale of ZYNTEGLO, SKYSONA and LYFGENIA may be unsuccessful or less successful than anticipated, particularly due to uncertainty about our financial condition and ability to continue as a going concern.
 We have limited experience as a commercial company as we recently launched our three FDA-approved products, ZYNTEGLO, SKYSONA and LYFGENIA. Consequently, there is limited information about our ability to overcome many of the risks and uncertainties encountered by companies commercializing products in the biopharmaceutical industry in the U.S. To execute our business plan, we will need to successfully:
 • sustain adequate pricing and reimbursement for ZYNTEGLO, SKYSONA and LYFGENIA across all U.S. payer segments;
 • establish and maintain, in the regions where we hope to treat patients, relationships with qualified treatment centers who will be treating the patients who receive ZYNTEGLO, SKYSONA, and LYFGENIA;

 • manage our manufacturing capabilities and supply chain operations in the coordination and delivery of drug product to patients at qualified treatment centers;
 • manage our spending as we engage in commercialization efforts;
 • manage the patient uptake process for each of our products, including with respect to overall timing and potential barriers such as clinical assessment periods and payer approval processes;
 • attract and retain employees with relevant commercial, sales and marketing expertise; and
 • initiate, develop and maintain successful strategic alliances.
 If we are not successful in accomplishing these objectives, we may not be able to effectively commercialize ZYNTEGLO, SKYSONA or LYFGENIA, raise capital, or continue our operations. For instance, uncertainty about our financial condition has impacted the rate of patient starts as providers have expressed concern regarding our financial condition, and accordingly has affected the timing of our revenue expectations. If we are unable to meet our forecasts, our business may suffer. Additionally, due to our financial instability, we have experienced a high degree of turnover in our employee base, particularly with respect to our commercial field-based team, which may impact our ability to successfully commercialize our products. If the Merger Transaction does not close as planned, these factors could be exacerbated.
 The commercial success of ZYNTEGLO, SKYSONA and LYFGENIA will depend upon the degree of market acceptance by physicians, patients, payers and other stakeholders.
 The commercial success of ZYNTEGLO, SKYSONA, and LYFGENIA will depend in part on the medical community, patients, and third-party or governmental payers accepting gene therapy products in general, and ZYNTEGLO, SKYSONA, and LYFGENIA, in particular, as medically useful, cost effective, and safe. ZYNTEGLO, SKYSONA, and LYFGENIA may not gain market acceptance by physicians, patients, payers and other stakeholders. If these products do not achieve an adequate level of acceptance, we may not generate significant product revenue and may not become profitable and our future business prospects will be adversely impacted. The degree of market acceptance of ZYNTEGLO, SKYSONA, and LYFGENIA will depend on a number of factors, including:
 • our ability to compete with alternative treatments, including other approved gene therapies for similar indications, including with respect to potential and perceived efficacy and other potential advantages;
 • the prevalence and severity of any side effects, including any limitations or warnings contained in a product's approved labeling; for instance, each of the LYFGENIA and SKYSONA product labels includes a boxed warning for the risk of hematologic malignancy;
 • the prevalence and severity of any side effects resulting from the chemotherapy and myeloablative treatments associated with the procedure by which our products are administered, including the possible prejudicial effects that chemotherapy can have on fertility;
 • relative convenience and ease of administration, including patients' willingness and ability to travel to qualified treatment centers within our network;
 • given the complexity of manufacturing product and the reduced operational success rates in connection with the transition to commercial manufacturing, the perception or possibility that issues may continue to arise in the supply of product which could delay treatment;
 • the willingness of the target patient population to try new therapies and of physicians to prescribe these therapies, which may be lower with respect to our therapies that treat non-acute conditions;
 • the strength of marketing and distribution support and timing of market introduction of competitive products;
 • the pricing of our products, including in comparison to competitors;
 • publicity concerning our products, or competing products and treatments;

 • publicity regarding our company, including uncertainty surrounding the Merger Transaction and our financial condition, which may influence decision making of patients and physicians;
 • sufficient insurance coverage or reimbursement;
 • the possible occurrence of adverse clinical findings or decreased effectiveness of a product or product candidate over time identified during continued monitoring and evaluation of patients; and
 • the mix of private and governmental payer coverage, which can impact both the total reimbursement for the drug and the time-to-reimbursement, and the conditions to coverage imposed by the various payers, including non-preferred or exclusion decisions in favor of our competitor.
 Even if a product displays a favorable efficacy and safety profile in clinical studies, market acceptance of the product will not be known until some period after it is launched. Our efforts to educate the medical community and payers on the benefits of our products may require significant resources and may never be successful. Our efforts to educate the marketplace may require more resources than are required by the conventional technologies marketed by our competitors. Any of these factors may cause ZYNTEGLO, SKYSONA, or LYFGENIA to be unsuccessful or less successful than anticipated.
 If the market opportunities for our commercial products or any future product candidates are smaller than we believe they are, and if we are not able to successfully identify patients and achieve significant market share, our revenues may be adversely affected and our business may suffer.
 Our platform focuses on treatments for severe genetic diseases. Our projections of both the number of people who have these diseases, as well as the subset of people with these diseases who have the potential to benefit from treatment with our products or any future product candidates we may develop, are based on estimates. These estimates have been derived from a variety of sources, including scientific literature, surveys of clinics, patient foundations, or market research, and may prove to be incorrect. Further, new studies may change the estimated incidence or prevalence of these diseases. The number of patients may turn out to be lower or more difficult to identify than expected. Additionally, the potentially addressable patient populations for our products or any future product candidates may be limited or may not be amenable to treatment with such products or product candidates. For instance, each of the SKYSONA and LYFGENIA product labels includes a boxed warning for the risk of hematologic malignancy, which may impact market opportunity.
 Any of these factors may negatively affect our ability to generate revenues from sales of our products as forecasted and our ability to achieve and maintain profitability and, as a consequence, our business may suffer.
 We have limited sales and distribution experience and limited capabilities for marketing and market access. If we are unable to establish and maintain these commercial capabilities and infrastructure, or to enter into agreements with third parties to market and sell our products, we may be unable to generate sufficient revenue to sustain our business.
 We have limited prior sales or distribution experience and limited capabilities for marketing and market access, and we did not generate meaningful product sales following the commercial launch of ZYNTEGLO in Europe. To successfully commercialize ZYNTEGLO, SKYSONA, and LYFGENIA, we will need to further develop these capabilities. We may need to expand our infrastructure to further support commercial operations in the United States, either on our own or with others. Commercializing an autologous gene therapy is resource-intensive and has required, and will continue to require, substantial investment in commercial capabilities. Additionally, due to our financial instability, we have experienced a high degree of turnover in our employee base, particularly with respect to our commercial field-based team, which may impact our ability to successfully commercialize our products and require additional investment in the recruitment and retention of personnel. We are competing with companies that currently have extensive and well-funded marketing and sales operations. Without significant commercial experience as a company or the support of a third party to perform these functions, including marketing and sales functions, we may be unable to compete successfully against these more established companies.
 Furthermore, a significant proportion of the patient populations for ZYNTEGLO, SKYSONA, and LYFGENIA lies outside of the United States. We currently expect to focus our operations and efforts on markets in the United States and will need to rely heavily on third parties for commercializing any products in geographies outside of the United States, if at all. We may enter into collaborations with third parties to utilize their mature marketing and distribution capabilities, but we may be unable to enter into agreements on favorable terms, if at all. If we do not enter into collaboration arrangements with third parties to pursue regulatory authorization or commercialization of our programs for markets outside of the United States, or if our future collaborative partners do not commit sufficient resources to such efforts, we may be unable to generate sufficient revenue to sustain our business.

 We may encounter challenges with engaging or coordinating with qualified treatment centers needed for the ongoing commercialization of ZYNTEGLO, SKYSONA and LYFGENIA.
 Our commercial strategy is to engage apheresis and transplant centers as qualified treatment centers for the collection of patient HSCs and infusion of the drug product once manufactured. To ensure that the qualified treatment centers are prepared to collect patient HSCs and to ship them to our transduction facilities in accordance with our specifications and regulatory requirements, we train and conduct quality assessments of each center as part of engagement. These qualified treatment centers are the first and last points on our complex supply chain to reach patients in the commercial setting. We may encounter challenges or delays in engaging and interacting with our qualified treatment centers, and such challenges could impact a qualified treatment center's willingness and ability to administer our products. For instance, providers at certain qualified treatment centers have expressed concern regarding our financial condition, which has delayed patient starts.
 Furthermore, we may fail to manage the logistics of collecting and shipping patient material to the manufacturing site and shipping the drug product back to the patient. Logistical and shipment delays and problems caused by us, our third-party vendors, and other factors not in our control, such as weather, could prevent or delay the manufacture of or delivery of drug product to patients. If our qualified treatment centers fail to perform satisfactorily, we may suffer reputational, operational, and business harm. Additionally, delays with infusion at the qualified treatment centers, due to, for instance, the patient's schedule or health condition or such center's capacity or the availability of manufacturing slots at our CMOs, or due to the need for multiple cell collections, could result in a patient becoming medically ineligible for our treatment or selecting an alternative treatment, the drug product becoming unusable and loss of medical coverage, which would have a material adverse effect on commercial sales. These delays may also impact our relationship with our qualified treatment center network. Any failure in our engagement or interaction with our qualified treatment centers due to delays in treatment or complications related to manufacturing, among other things, may limit patient access to our therapies and, accordingly, have a material adverse effect on our commercial forecasts and business.
 We are required to maintain a complex chain of identity and chain of custody with respect to patient material as it moves through the manufacturing process, from the qualified treatment center to the transduction facility, and back to the patient. Failure to maintain chain of identity and chain of custody could result in adverse patient outcomes, loss of product or regulatory action.
 The insurance coverage and reimbursement status of newly-approved products in the United States is uncertain. Due to the novel nature of our technology and the potential for our products to offer lifetime therapeutic benefit in a single administration, we face unique and additional challenges in obtaining adequate coverage and reimbursement for our products. Failure to obtain or maintain adequate coverage and reimbursement for any new or current product, including to the extent that payers 'non-prefer' any or all of our therapies to our competitors, could limit our ability to market those products and decrease our ability to generate revenue.
 The availability and extent of reimbursement by governmental and private payers is essential for most patients to be able to afford healthcare, and especially expensive medicines, such as gene therapy products. Sales of our products depend substantially on the extent to which our products are covered by health maintenance, managed care, pharmacy benefit and similar healthcare management organizations, or are reimbursed by government health administration authorities, private health coverage insurers and other payers. There is no assurance that payers will be willing to, or continue to, reimburse providers at the company-established list price or that reimbursement levels that payers will be willing to pay will be sufficient. Moreover, given that our therapies are generally administered in the inpatient care setting, it is important that our products are either reimbursed as a separate item from the underlying services incurred during the patient's hospitalization or that, if reimbursement for our therapies is "bundled" with reimbursement for the hospital stay, the bundled payment rate adequately reflects the price of our therapy. We cannot assure you that payers will agree to either "separate reimbursement" or an appropriate bundled payment rate. Accordingly, the estimation of potential revenues is complex and it is difficult to predict what payers will decide with respect to reimbursement for fundamentally novel products such as ours, as there is no body of established practices and precedents for these new products.
 In the U.S., regional Medicare Administrative Contractors ("MACs") are responsible for making a determination with regard to whether a new therapy meets the federal standard of "reasonable and necessary" such that it is covered and reimbursed by Medicare. For the Medicaid program, each State Medicaid Agency is responsible for establishing coverage criteria, billing policies, and reimbursement rates for FDA-approved drugs. Reimbursement methodologies in Medicare and Medicaid can vary based on the type of therapeutic agent and setting of care, and for Medicaid, the reimbursement methodologies also vary by state. There is uncertainty with this process both in terms of the timing of the decision-making process and the coverage decision itself. We anticipate that Medicaid coverage will be significant for the potential patient

 population for our products. On the other hand, we anticipate that Medicare coverage will be less significant, given that only a small percentage of our patient population may be Medicare eligible. We expect these patients may be dually eligible for Medicare and Medicaid based on meeting federally-established disability standards, in which case Medicare serves as the primary payer and Medicaid as the secondary payer for any service not otherwise covered by Medicare that is covered under a State's Medicaid program.
 Moreover, increasing efforts by governmental and third-party payers to cap or reduce healthcare costs may cause such payers to limit both coverage and level of reimbursement for new products approved and, as a result, they may not cover or provide adequate payment for ZYNTEGLO, SKYSONA, or LYFGENIA. The reimbursement policies of reinsurers, stop-loss carriers, and self-insured employers, including those that exclude coverage for gene therapies, could negatively impact our ability to market our therapies. We expect to experience pricing pressures in connection with the sale of our products due to greater scrutiny on list prices and total prescription drug spending across all payer channels as well as additional legislative changes at the state and federal level; moreover, public pressure from payers or negative public opinion regarding our list prices could affect the perception of our company and the value or cost-effectiveness of our therapies, which could impact our ability to successfully market our products. Further, net prices for drugs may be reduced by mandatory discounts or rebates required by government or private payers. As a result, increasingly high barriers are being erected to the entry of new products, often in the form of limiting the patient population for whom a new therapy is deemed "medically necessary." Even if coverage is provided, the amount payers are willing to reimburse may not be sufficient.
 Furthermore, because a provider is responsible for costs associated not just with obtaining our medicines but also with the underlying hospital stay in which the administration of our therapies occurs, the pricing and reimbursement dynamics that impact patient access are not entirely within our control as providers and payers negotiate separately for the cost of the associated items and services, decisions in which we cannot and do not play a role. These services include the collection of HSCs from the patient, followed by chemotherapy and myeloablative treatments, and inpatient hospital stay following drug product infusion. If our customers are unable to obtain adequate levels of reimbursement, our ability to successfully market and sell our products will be adversely affected.
 We have entered into and continue to engage with payers across all channels around outcomes-based contracts for ZYNTEGLO and LYFGENIA. In the event that a payer opts for the outcomes-based contract, we will need to reserve a certain portion of revenue from each sale to account for the potential that a rebate will be owed if the pre-established outcome metric is not achieved over a designated period of time, which differs depending on the product and the agreement, following drug product administration. The amount of revenue reserved for a potential rebate depends on the product and payer type; for instance, our outcomes-based contract for ZYNTEGLO could require us to remit up to 80% of the cost of the therapy to a payer based on patient outcomes achieved. In the event that rebates are due under these contracts, we may be required to adjust revenue previously recognized. Despite our efforts to engage with CMS and work with experts to ensure all of our payer contracting efforts comply with relevant federal and state regulations, including government price reporting obligations, given the complexity of these arrangements, it is not possible to completely mitigate the risk that our interpretation differs from that of the regulatory authorities such that we may not be able to satisfy the compliance requirements, which may result in significant fines and liability.
 Collectively, these factors could affect our ability to successfully commercialize our products and generate or recognize revenues, which would adversely impact our business, financial condition, results of operations and prospects.
 Risks related to the research and development of our products and any future product candidates
 We face intense competition and rapid technological change and the possibility that our competitors may develop therapies that are more advanced, safer or more effective than ours, which may adversely affect our financial condition and our ability to successfully develop and commercialize ZYNTEGLO, SKYSONA and LYFGENIA.
 We are engaged in the development and commercialization of gene therapies for severe genetic diseases, which is a competitive and rapidly changing field. We have competitors both in the United States and internationally, including major multinational pharmaceutical companies, biotechnology companies and universities and other research institutions. Many of our competitors have substantially greater financial, technical and other resources, such as larger research and development staff, more experienced manufacturing capabilities, or more established commercial infrastructure. For instance, the FDA has approved a gene therapy for the treatment of sickle cell disease and beta thalassemia from Vertex Pharmaceuticals, Inc., which does not have a boxed warning and has a lower wholesale acquisition cost in the United States than that of LYFGENIA and ZYNTEGLO. Competition may increase further as a result of advances in the commercial applicability of technologies and greater availability of capital for investment in these industries. Our competitors may succeed in developing, acquiring or licensing on an exclusive basis, products that are more effective, safer, or less costly than any products that we may develop, or

 achieve patent protection, marketing approval, product commercialization and market penetration earlier than us. Additionally, technologies developed by our competitors may render our products or any future product candidates uneconomical or obsolete. As a result of any of these factors, we may not be successful in marketing our products against competitors.
 Finally, as a result of the expiration or successful challenge of our patent rights, we could face more litigation with respect to the validity and/or scope of patents relating to our competitors' products. The availability of our competitors' products could limit the demand, and the price we are able to charge, for any products that we may develop and commercialize.
 Clinical drug development involves a lengthy and expensive process, with an uncertain outcome. We may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development and commercialization of our products and any future product candidates.
 In order to obtain and maintain marketing approval from regulatory authorities for the commercialization of our products and future product candidates, we must conduct extensive clinical studies to demonstrate the safety, purity and potency, and/or efficacy, of the product candidates in humans. Clinical testing is expensive, time-consuming and uncertain as to outcome. There is a high failure rate for therapies proceeding through clinical studies. A number of companies in the pharmaceutical and biotechnology industries have suffered significant setbacks in later stage clinical studies even after achieving promising results in earlier stage clinical studies. We cannot guarantee that any clinical studies will be conducted as planned or completed on schedule, if at all. A failure of one or more clinical studies can occur at any stage of testing. Events that may prevent successful or timely completion of clinical development of our products and product candidates include:
 • inability to generate sufficient preclinical, toxicology, or other in vivo or in vitro data to support the initiation or continuation of clinical trials;
 • delays or failure in obtaining regulatory authorization to commence a trial;
 • delays in reaching agreement on acceptable terms with prospective contract research organizations ("CROs"), and clinical trial sites, and QTCs participating in post-approval registry studies, the terms of which can be subject to extensive negotiation and may vary significantly among different CROs and clinical trial sites;
 • delays in identifying, recruiting and training suitable clinical investigators;
 • delays in obtaining required IRB or ethics committee approvals at each clinical trial and/or QTC registry site;
 • delays in manufacturing, testing, releasing, validating or importing/exporting sufficient stable quantities of our future product candidates for use in clinical trials or the inability to do any of the foregoing;
 • insufficient or inadequate supply or quality of drug product or other materials necessary for use in clinical trials, or delays in sufficiently developing, characterizing or controlling a manufacturing process suitable for clinical trials;
 • imposition of a clinical hold by regulatory agencies, including after review of an IND or amendment or equivalent foreign application or amendment, as a result of a new safety finding that presents unreasonable risk to clinical trial participants or after an inspection of our clinical study operations or study sites or due to unforeseen safety issues;
 • failure by our CROs, other third parties or us to adhere to clinical trial protocols or failure to perform in accordance with the FDA's or any other regulatory authority's good clinical practice requirements ("GCPs") or applicable regulatory guidelines in other countries;
 • occurrence of adverse events associated with the product or product candidate that are viewed to outweigh its potential benefits, or occurrence of adverse events in trial of the same class of agents conducted by other companies, particularly due to the fact that we are required to follow patients in our clinical and registry studies for an extended period of time (up to 15 years);
 • changes to the clinical trial protocols;

 • clinical sites deviating from trial protocol or dropping out of a trial;
 • changes in the standard of care on which a clinical development plan was based, which may require new or additional trials;
 • selection of clinical endpoints that require prolonged periods of observation or analyses of resulting data;
 • the cost of clinical trials of our products or future product candidates being greater than we anticipate;
 • clinical trials of our products or future product candidates producing negative or inconclusive results, which may result in our deciding, or regulators requiring us, to conduct additional clinical trials or abandon development of such product candidates;
 • transfer of manufacturing processes to larger-scale facilities operated by a CMO and delays or failure by our CMOs or us to make any necessary changes to such manufacturing process; or
 • changes in regulatory requirements and guidance that require amending or submitting new clinical protocols.
 Clinical trials must be conducted in accordance with the FDA and other applicable regulatory authorities' legal requirements, regulations or guidelines, and are subject to oversight by these governmental agencies and ethics committees or IRBs at the medical institutions where the clinical trials are conducted.
 Further, conducting clinical trials in foreign countries, as we may do for our products or any future product candidates, presents additional risks that may delay completion of clinical trials. These risks include the failure of enrolled patients in foreign countries to adhere to clinical protocol as a result of differences in healthcare services or cultural customs, managing additional administrative burdens associated with foreign regulatory schemes, as well as political and economic risks relevant to such foreign countries.
 Moreover, principal investigators for our clinical trials may serve as scientific advisors or consultants to us from time to time and receive compensation in connection with such services. Under certain circumstances, we may be required to report some of these relationships to the FDA or comparable foreign regulatory authorities. The FDA or comparable foreign regulatory authority may conclude that a financial relationship between us and a principal investigator has created a conflict of interest or otherwise affected interpretation of the study. The FDA or comparable foreign regulatory authority may therefore question the integrity of the data generated at the applicable clinical trial site and the utility of the clinical trial itself may be jeopardized. This could result in a delay in approval, or rejection, of our marketing applications by the FDA or comparable foreign regulatory authority, as the case may be, and may ultimately lead to the denial of marketing approval of one or more of our products or product candidates.
 Delays in the completion of any clinical trial of our products or product candidates will increase our costs, slow down our product candidate development and approval process and delay or potentially jeopardize our ability to commence or continue product sales and generate product revenue. In addition, many of the factors that cause, or lead to, a delay in the commencement or completion of clinical trials may also ultimately lead to the denial of regulatory approval of our product candidates. Any delays to our clinical trials that occur as a result could shorten any period during which we may have the exclusive right to commercialize our product candidates and our competitors may be able to bring products to market before we do, and the commercial viability of our product candidates could be significantly reduced. Any of these occurrences may harm our business, financial condition and prospects significantly.
 We depend on enrollment of patients in our registry studies to complete required post marketing studies for our products, and on enrollment of patients in any future clinical trials we may conduct. If we experience delays or difficulties enrolling in our registry studies, including due to our financial condition or reputation, our research and development efforts, business, financial condition, and results of operations could be materially adversely affected.
 Successful and timely completion of clinical trials, including additional trials that the FDA may require we complete prior to or as part of approval of our products or future product candidates, will require that we enroll a sufficient number of patient candidates. For instance, we are required to conduct long-term observational registry studies evaluating the safety of ZYNTEGLO, SKYSONA and LYFGENIA. These registry studies and other trials we may decide to conduct may be subject to delays for a variety of reasons, including as a result of patient enrollment taking longer than anticipated, patient withdrawal or

 adverse events. These types of developments could cause us to delay the study or halt further development. If we are unable to complete required registry studies or any other post-marketing requirements under the terms specified by the FDA, we could be subject to FDA enforcement action, including restrictions on our ability to sell our products, misbranding charges and civil monetary penalties.
 Additionally, any future clinical trials we may conduct could compete with other clinical trials that are in the same therapeutic areas as any future product candidates, and this competition could reduce the number and types of patients available to us, as some patients who might have opted to enroll in our trials or to receive our commercial therapies may instead opt to enroll in a trial being conducted by one of our competitors. Because the number of qualified clinical investigators and clinical trial sites for the patient populations we pursue may be limited, we may conduct one or more future clinical trials at the same clinical trial sites that some of our competitors use, which will reduce the number of patients who are available for our clinical trials at such clinical trial sites. In addition, there may be limited patient pools from which to draw for clinical studies. In addition to the rarity of some diseases, the eligibility criteria of future clinical studies may further limit the pool of available study participants as we may require that patients have specific characteristics that we can measure or to assure their disease is either severe enough or not too advanced to include them in a study.
 Patient enrollment depends on many factors, including:
 • the size and nature of the patient population;
 • the severity of the disease under investigation;
 • eligibility criteria for the trial;
 • the proximity of patients to clinical sites;
 • the design of the clinical protocol, including long-term follow-up requirements;
 • the ability to obtain and maintain patient consents;
 • the ability to recruit clinical trial investigators with the appropriate competencies and experience;
 • the risk that patients enrolled in clinical trials will drop out of the trials before the administration of our product candidates or trial completion;
 • the availability of competing clinical trials;
 • the availability of new drugs approved for the indication the clinical trial is investigating; and
 • clinicians' and patients' perceptions as to the potential advantages of the drug being studied in relation to other available therapies, as well as publicity regarding our company, including uncertainty surrounding our financial condition, which may influence decision making of patients and physicians.
 These factors may make it difficult for us to enroll enough patients to complete our registry studies or any future clinical trials in a timely and cost-effective manner. Delays in the completion of any clinical trial may increase our costs, slow down our development process and could delay, or potentially jeopardize, our ability to obtain and maintain required regulatory approvals, commercialize our products or any future product candidates and generate revenue.
 Data from our clinical trials that we announce or publish from time to time may change as more patient data become available either through long-term patient follow-up and/or as such data are audited and verified, which could result in material changes to clinical and safety profiles for our products.
 From time to time, we may disclose top-line, interim or preliminary data from our clinical trials. Such data from clinical trials that we may complete are subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data become available or as patients from our clinical trials continue other treatments for their disease. In addition, the clinical trials evaluating our products, and likely those evaluating any future product candidates,

 generally require that we continue to monitor and evaluate safety and efficacy in patients over an extended period of time following treatment, including for up to fifteen years for some studies, which may result in changes to the safety or efficacy profile over time. Changes in the efficacy and safety profile of our products or any future product candidates over time could significantly harm our business prospects including resulting in volatility in the price of our common stock.
 Additionally, preliminary or top-line data are based on a preliminary analysis of then-available data, and the results and related findings and conclusions are subject to change following a more comprehensive review of the data related to the particular study or trial. We also make assumptions, estimations, calculations and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully and carefully evaluate all data. Interim data from clinical trials that we may conduct are further subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data become available. As a result, the top-line, interim or preliminary results that we report may differ from future results of the same studies, or different conclusions or considerations may qualify such results, once additional data have been received and fully evaluated. Further, disclosure of such data by us or by our competitors could also result in volatility in the price of our common stock. Further, others, including regulatory agencies, may not accept or agree with our assumptions, estimates, calculations, conclusions or analyses or may interpret or weigh the importance of data differently, which could impact the value of the particular program, the approvability or commercialization of the particular product candidate or product and our Company in general. In addition, the information we choose to publicly disclose regarding a particular study or clinical trial is based on what is typically extensive information, and you or others may not agree with what we determine is material or otherwise appropriate information to include in our disclosure. If others, including regulatory authorities, disagree with the conclusions reached with respect to such information and assessments, our ability to obtain approval for, and commercialize, our products and any future product candidates may be harmed, which could harm our business, operating results, prospects or financial condition.
 Although we have received accelerated approval from the FDA for SKYSONA, if our confirmatory trials do not verify clinical benefit, or if we do not comply with rigorous post-marketing requirements, the FDA may seek to withdraw any accelerated approval we have obtained.
 In September 2022, SKYSONA received accelerated approval from the FDA and we may in the future seek accelerated approval for one or more future product candidates. Under the accelerated approval program, the FDA may grant accelerated approval to a product candidate designed to treat a serious or life-threatening condition that provides meaningful therapeutic benefit over available therapies upon a determination that the product candidate has an effect on a surrogate endpoint or intermediate clinical endpoint that is reasonably likely to predict clinical benefit. The FDA considers a clinical benefit to be a positive therapeutic effect that is clinically meaningful in the context of a given disease, such as irreversible morbidity or mortality. For the purposes of accelerated approval, a surrogate endpoint is a marker, such as a laboratory measurement, radiographic image, physical sign, or other measure that is thought to predict clinical benefit, but is not itself a measure of clinical benefit. An intermediate clinical endpoint is a clinical endpoint that can be measured earlier than an effect on irreversible morbidity or mortality that is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefit.
 The accelerated approval pathway may be used in cases in which the advantage of a new drug over available therapy may not be a direct therapeutic advantage, but is a clinically important improvement from a patient and public health perspective. If granted, accelerated approval is usually contingent on the sponsor's agreement to conduct, in a diligent manner, one or more additional confirmatory studies to verify and describe the drug's clinical benefit. If such post-approval studies fail to confirm the drug's clinical benefit or are not completed in a timely manner, the FDA may withdraw its approval of the drug on an expedited basis. For example, we agreed to provide confirmatory long-term clinical data to the FDA as a condition of the SKYSONA accelerated approval, and continued approval for the approved indication will be contingent upon verification of clinical benefit with confirmatory clinical data. Moreover, certain payers, including state Medicaid agencies, may scrutinize therapies that reach the market through accelerated approval, which can lead to delays in broader access after approval and require additional company resources to address any concerns.
 In addition, in December 2022, President Biden signed an omnibus appropriations bill to fund the U.S. government through fiscal year 2023. Included in the omnibus bill is the Food and Drug Omnibus Reform Act of 2022, which among other things, provided FDA new statutory authority to mitigate potential risks to patients from continued marketing of ineffective drugs previously granted accelerated approval. Under these provisions, the FDA may require a sponsor of a product seeking accelerated approval to have a confirmatory trial underway prior to such approval being granted.

 Our biological products may face competition sooner than anticipated.
 The Affordable Care Act includes a subtitle called the Biologics Price Competition and Innovation Act of 2009 ("BPCIA"), which created an abbreviated approval pathway for biological products that are biosimilar to or interchangeable with an FDA-licensed reference biological product. Under the BPCIA, an application for a highly similar or "biosimilar" product may not be submitted to the FDA until four years following the date that the reference product was first licensed by the FDA. In addition, the approval of a biosimilar product may not be made effective by the FDA until 12 years from the date on which the reference product was first licensed. The 12-year exclusivity blocks the submission and approval of biosimilars under the abbreviated pathway only. During this 12-year period of exclusivity, another company may still market a competing version of the reference product if the FDA approves a full BLA for the competing product containing the sponsor's own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of their product. This exclusivity is only available to the "first licensure" of the reference biological product. If a biological product has a related structure to a previously licensed product from the same sponsor, it may not qualify as a first licensure. If LYFGENIA and ZYNTEGLO are considered to have a related structure, it is possible that LYFGENIA will not be granted its own 12-year exclusivity period and accordingly would be protected under ZYNTEGLO's 12-year exclusivity period.
 Moreover, the extent to which a biosimilar, once approved, will be substituted for any one of our reference products in a way that is similar to traditional generic substitution for non-biological products is not yet clear, and will depend on a number of marketplace factors that are still developing. This may further incentivize the development of competing versions or our products under the full BLA pathway rather than the biosimilars pathway.
 Negative public opinion and increased regulatory scrutiny of gene therapy and genetic research may damage public perception of our products and any future product candidates or adversely affect our ability to conduct our business or obtain and maintain marketing approvals for our products and any future product candidates.
 Public perception may be influenced by claims that gene therapy, including gene editing technologies, is unsafe or unethical, and research activities and adverse events in the field, even if not ultimately attributable to us or our products or any future product candidates, could result in increased governmental regulation, unfavorable public perception, challenges in recruiting patients to participate in our clinical studies, potential regulatory delays in the testing or approval of our products or any future product candidates, stricter labeling requirements for our approved products, and a decrease in demand for any such product. More restrictive government regulations or negative public opinion would have a negative effect on our business or financial condition and may delay or impair the development and commercialization of our products or any future product candidates or reduce demand for any approved products.
 Disruptions at the FDA and other government agencies caused by changing presidential administrations and related priorities, funding shortages or global health concerns could hinder their ability to hire, retain or deploy key leadership and other personnel, prevent new or modified products from being developed, reviewed, approved or commercialized in a timely manner or at all, which could negatively impact our business.
 The ability of the FDA and foreign regulatory authorities to review and approve new products can be affected by a variety of factors, including reductions in force or hiring freezes, government budget and funding levels, statutory, regulatory, and policy changes, the FDA's or foreign regulatory authorities' ability to hire and retain key personnel and accept the payment of user fees, and other events that may otherwise affect the FDA's or foreign regulatory authorities' ability to perform routine functions, including uncertainty associated with the new presidential administration in the United States. Average review times at the FDA and foreign regulatory authorities have fluctuated in recent years as a result. In addition, government funding of other government agencies that fund research and development activities is subject to the political process, which is inherently fluid and unpredictable. Disruptions at the FDA may also slow the time necessary for new drugs, medical devices and biologics or modifications to approved drugs and biologics to be reviewed and/or approved by necessary government agencies, which would adversely affect our business. For example, over the last several years, the U.S. government has shut down several times and certain regulatory agencies, such as the FDA, have had to furlough critical FDA employees and stop critical activities.
 Separately, in response to the global COVID-19 pandemic, the FDA postponed most inspections of domestic and foreign manufacturing facilities at various points. Even though the FDA has since resumed standard inspection operations any resurgence of the virus or emergence of new variants may lead to inspectional or administrative delays. If a prolonged government shutdown occurs, or if global health concerns prevent the FDA or other regulatory authorities from conducting their regular inspections, reviews, or other regulatory activities, it could significantly impact the ability of the FDA or other regulatory authorities to timely review and process our regulatory submissions, which could have a material adverse effect on our business.

 A Regenerative Medicine Advanced Therapy designation by the FDA, even if granted for any future product candidate, may not lead to a faster development or regulatory review or approval process and does not increase the likelihood that such future product candidate will receive marketing approval.
 We have obtained Regenerative Medicine Advanced Therapy ("RMAT") designation for LYFGENIA for the treatment of SCD, and we may seek additional RMAT designations for our future product candidates. A biological product candidate is eligible for RMAT designation if: (1) it meets the definition of a regenerative medicine therapy, which the FDA defines as a cell therapy, therapeutic tissue engineering product, human cell and tissue product, or any combination product using such therapies or products, with limited exceptions; (2) the candidate is intended to treat, modify, reverse, or cure a serious disease or condition; and (3) preliminary clinical evidence indicates that the candidate has the potential to address unmet medical needs for such disease or condition. RMAT designation provides potential benefits that include more frequent meetings with FDA to discuss the development plan for the product candidate, and eligibility for rolling review and priority review of BLAs. Product candidates granted RMAT designation may also be eligible for accelerated approval on the basis of a surrogate or intermediate endpoint reasonably likely to predict long-term clinical benefit, or through reliance upon data obtained from a meaningful number of sites, including through expansion to a sufficient number of sites, as appropriate. RMAT-designated product candidates that receive accelerated approval may, as appropriate, be able to fulfill their post-approval requirements through the submission of clinical evidence, clinical studies, patient registries, or other sources of real-world evidence (such as electronic health records); through the collection of larger confirmatory data sets; or via post-approval monitoring of all patients treated with such therapy prior to approval of the therapy.
 RMAT designation is within the sole discretion of the FDA. Accordingly, even if we believe one of our future product candidates meets the criteria for RMAT designation, the FDA may disagree and instead determine not to make such designation. RMAT designation does not change the standards for product approval, and there is no assurance that such designation or eligibility for such designation will result in expedited review or approval or that the approved indication will not be narrower than the indication covered by the RMAT designation. Additionally, RMAT designation can be revoked if the product candidate fails to meet the qualifications as clinical data continue to emerge.
 We have obtained orphan drug designation for our products, but we may be unable to maintain the benefits associated with orphan drug designation, including market exclusivity, which may cause our product revenue, if any, to be reduced.
 We have obtained orphan drug exclusivity for certain diseases or conditions for LYFGENIA, ZYNTEGLO and SKYSONA. Under the Orphan Drug Act, the FDA may designate a biological product as an orphan drug if it is intended to treat a rare disease or condition, defined as a patient population of fewer than 200,000 in the United States, or a patient population greater than 200,000 in the United States where there is no reasonable expectation that the cost of developing the drug will be recovered from sales in the United States. Orphan drug designation must be requested before submitting a BLA. In the United States, orphan drug designation entitles a party to financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages, waivers from certain pediatric clinical trial requirements, and application fee waivers. After the FDA grants orphan drug designation, the generic identity of the therapeutic agent and its potential orphan use are disclosed publicly by the FDA.
 In addition, if a product candidate receives the first FDA approval for the disease or condition for which it has orphan designation, the product is entitled to orphan drug exclusivity, which means the FDA may not approve any other application to market the same drug for the same disease or condition for a period of seven years, except in limited circumstances, such as a showing of clinical superiority over the product with orphan exclusivity or where the manufacturer is unable to assure sufficient product quantity for the orphan patient population. Exclusive marketing rights in the United States may also be unavailable if we or our collaborators seek approval for a disease or condition broader than the orphan designated disease or condition and may be lost if the FDA later determines that the request for designation was materially defective.
 Even if we obtain orphan drug designation for a future product candidate, we may not be the first to obtain marketing approval for any particular orphan disease or condition due to the uncertainties associated with developing pharmaceutical products. Further, we have received orphan drug exclusivity from the FDA for ZYNTEGLO for the treatment of adult and pediatric patients with beta-thalassemia who require regular red blood cell (RBC) transfusions; for SKYSONA for the slowing of progression of neurologic dysfunction in boys 4-17 years of age with early, active cerebral adrenoleukodystrophy; and for LYFGENIA for the treatment of patients 12 years of age or older with sickle cell disease and a history of vaso-occlusive events. These orphan drug exclusivities, and any exclusivities we may obtain in the future may not effectively protect the product from competition because different drugs can be approved for the same disease or condition. Even after an orphan drug is approved, the FDA can subsequently approve the same drug for the same condition if the FDA concludes that the later drug is clinically superior in that it is safer, more effective, or makes a major contribution to patient care. Orphan drug designation neither

 shortens the development time or regulatory review time of a drug nor gives the drug any advantage in the regulatory review or approval process.
 Risks related to our reliance on third parties
 We rely on third parties to conduct some or all aspects of our LVV production, drug product manufacturing, and testing, and these third parties may not perform satisfactorily.
 We do not independently conduct all aspects of our LVV production, drug product manufacturing, and testing. We currently rely, and expect to continue to rely, on third parties with respect to these items, including manufacturing and testing in the commercial context.
 Our reliance on these third parties for manufacturing, testing, research and development activities reduces our control over these activities but will not relieve us of our responsibility to ensure compliance with all required regulations and study protocols. For example, for products that we develop and commercialize on our own, we will remain responsible for ensuring that each of our IND-enabling studies and clinical studies are conducted in accordance with the study plan and protocols, and that our LVV and drug products are manufactured in accordance with GMP as applied in the relevant jurisdictions.
 If these third parties do not successfully carry out their contractual duties, including as a result of insolvency, meet expected deadlines, conduct our studies in accordance with regulatory requirements or our stated study plans and protocols, or manufacture our LVV and drug products in accordance with GMP, we will not be able to support commercialization of SKYSONA, ZYNTEGLO and LYFGENIA. Many of our agreements with these third parties contain termination provisions that allow these third parties to terminate their relationships with us at any time. Furthermore, we have delayed payments to certain of these third parties, which could impact their performance. See also "Risk Factors - In order to manage cash flow needs, we have delayed certain ordinary course payments to our vendors and suppliers". If we need to enter into alternative arrangements, our product development and commercialization activities could be delayed.
 Reliance on third-party manufacturers entails risks to which we would not be subject if we manufactured the products ourselves, including:
 • the inability to negotiate manufacturing agreements with third parties under commercially reasonable terms, including the inability to negotiate favorable terms to increase capacity to meet future forecasted demand;
 • reduced control as a result of using third-party manufacturers for all aspects of manufacturing activities;
 • the risk that these activities are not conducted in accordance with our study plans and protocols, including the potential for failed product batches that have resulted, and may in the future result, in delays in treatment of patients;
 • termination or nonrenewal of manufacturing agreements with third parties in a manner or at a time that is costly or damaging to us; and
 • disruptions to the operations of our third-party manufacturers or suppliers caused by conditions unrelated to our business or operations, including, for example, the bankruptcy or financial condition of the manufacturer or supplier.
 We may be forced to manufacture LVV and drug product ourselves, for which we may not have the capabilities or resources, or enter into an agreement with a different manufacturer, which we may not be able to do on reasonable terms, if at all. In some cases, the technical skills required to manufacture our LVV or future product candidates may be unique or proprietary to the original manufacturer, and we may have difficulty or there may be contractual restrictions prohibiting us from, transferring such skills to a back-up or alternate supplier, or we may be unable to transfer such skills at all. Any of these events could lead to clinical study delays or impact our ability to obtain required regulatory approvals or successfully commercialize our products or any future product candidates. Some of these events could be the basis for FDA action, including injunction, recall, seizure or total or partial suspension of production.
 We and our contract manufacturers are subject to significant regulation with respect to manufacturing our products. The manufacturing facilities on which we rely may not continue to meet regulatory requirements and have limited capacity.
 All entities involved in the preparation of therapeutics for clinical studies or commercial sale, including our existing contract manufacturers for our products, or those we may use for any future product candidates, are subject to extensive regulation. Some components of a finished therapeutic product approved for commercial sale or used in late-stage clinical

 studies must be manufactured in accordance with GMP. These regulations govern manufacturing processes and procedures (including record keeping) and the implementation and operation of quality systems to control and assure the quality of investigational products and products approved for sale. Poor control of production processes can lead to the introduction of adventitious agents or other contaminants, or to inadvertent changes in the properties or stability of our products or any future product candidates that may not be detectable in final product testing. We or our contract manufacturers must adhere to the FDA's or other regulator's good laboratory practices ("GLP"), and GMP regulations enforced by the FDA or other regulator through facilities inspection programs. Our facilities and quality systems and the facilities and quality systems of some or all of our third-party contractors may be required to successfully complete a pre-approval inspection for compliance with GMPs and other applicable regulations as a condition of certain regulatory approvals. In addition, the regulatory authorities may, at any time, audit or inspect a manufacturing facility involved with the preparation of our products or the associated quality systems for compliance with the regulations applicable to the activities being conducted. If these facilities do not successfully complete any required inspections, it is possible FDA or other marketing approvals may be delayed, prevented or otherwise adversely affected.
 The regulatory authorities also may, at any time following approval of a product for sale, audit the manufacturing facilities of our third-party contractors. If any such inspection or audit identifies a failure to comply with applicable regulations or if a violation of our product specifications or applicable regulations occurs independent of such an inspection or audit, we or the relevant regulatory authority may require remedial measures that may be costly and/or time-consuming for us or a third-party to implement and that may include the temporary or permanent suspension of a clinical study or commercial sales or the temporary or permanent closure of a facility. Any such remedial measures imposed upon us or third parties with whom we contract could materially harm our business.
 Further, any plans to expand our manufacturing capacity are subject to the review and approval of regulatory authorities and there is no guarantee that we will receive such approval on the timelines we anticipate. Delays in our expansion of manufacturing capacity could affect our ability to meet demand and could materially harm our business.
 If we or any of our third-party manufacturers fail to maintain regulatory compliance, the FDA or other regulators can impose regulatory sanctions including, among other things, refusal to approve a pending application for a biologic product, or revocation of a pre-existing approval. As a result, our business, financial condition and results of operations may be materially harmed.
 Additionally, if supply from one approved manufacturer is interrupted, there could be a significant disruption in commercial supply. The number of manufacturers with the necessary manufacturing capabilities is limited. In addition, an alternative manufacturer would need to be qualified through a BLA supplement or similar regulatory submission which could result in further delay. The regulatory agencies may also require additional studies if a new manufacturer is relied upon for commercial production. Switching manufacturers may involve substantial costs and is likely to result in a delay in our desired clinical and commercial timelines.
 These factors could cause the delay of clinical studies, regulatory submissions, required approvals or commercialization of our products or any future product candidates, cause us to incur higher costs and prevent us from successfully commercializing our products or any future product candidates. Furthermore, if our suppliers fail to meet contractual requirements, and we are unable to secure one or more replacement suppliers capable of production at a substantially equivalent cost, our clinical studies or commercial production may be delayed and we could lose potential revenues.
 We rely on third parties to conduct, supervise and monitor our clinical studies, and if these third parties perform in an unsatisfactory manner, it may harm our business.
 We rely on CROs and clinical study sites to ensure our clinical studies are conducted properly and on time. While we will have agreements governing their activities, we will have limited influence over their actual performance. We will control only certain aspects of our CROs' activities. Nevertheless, we will be responsible for ensuring that each of our clinical studies is conducted in accordance with the applicable protocol and in accordance with applicable GCPs, GLPs and other legal, regulatory and scientific standards, and our reliance on the CROs does not relieve us of our regulatory responsibilities.
 We and our CROs are required to comply with the FDA's and other regulatory authorities' GCPs for conducting, recording and reporting the results of clinical studies to assure that the data and reported results are credible and accurate and that the rights, integrity and confidentiality of clinical study participants are protected. Regulatory authorities enforce these GCPs through periodic inspections of trial sponsors, principal investigators and trial sites. We cannot assure you that upon inspection by a given regulatory authority, such regulatory authority will determine that any of our clinical trials complies with GCP regulations. If we or our CROs fail to comply with applicable GCPs, the clinical data generated in our future clinical studies

 may be deemed unreliable and the FDA and other regulatory authorities may require us to perform additional clinical studies before approving any marketing applications.
 If our CROs do not successfully carry out their contractual duties or obligations, fail to meet expected deadlines, or if the quality or accuracy of the clinical data they obtain is compromised due to the failure to adhere to our clinical protocols or regulatory requirements, or for any other reasons, our clinical studies may be extended, delayed or terminated, and we may not be able to successfully commercialize our products or any future product candidates. Furthermore, we have delayed payments to certain of these third parties, which could impact their performance. See also "Risk Factors - In order to manage cash flow needs, we have delayed certain ordinary course payments to our vendors and suppliers". As a result, our financial results and the commercial prospects for our products or any future product candidates would be harmed, our costs could increase, and our ability to generate revenues could be delayed.
 Our reliance on third parties requires us to share our trade secrets, which increases the possibility that a competitor will discover them or that our trade secrets will be misappropriated or disclosed.
 Because we rely on third parties to manufacture our vectors and our drug products, and because we collaborate with various organizations and academic institutions on the advancement of our gene therapy platform, we must, at times, share trade secrets with them. We seek to protect our proprietary technology in part by entering into confidentiality agreements and, if applicable, material transfer agreements, collaborative research agreements, consulting agreements or other similar agreements with our collaborators, advisors, employees and consultants prior to beginning research or disclosing proprietary information. These agreements typically limit the rights of the third parties to use or disclose our confidential information, such as trade secrets. Despite the contractual provisions employed when working with third parties, the need to share trade secrets and other confidential information increases the risk that such trade secrets become known by our competitors, are inadvertently incorporated into the technology of others, or are disclosed or used in violation of these agreements. Given that our proprietary position is based, in part, on our know-how and trade secrets, a competitor's discovery of our trade secrets or other unauthorized use or disclosure would impair our competitive position and may have a material adverse effect on our business.
 In addition, these agreements typically restrict the ability of our collaborators, advisors, employees and consultants to publish data potentially relating to our trade secrets. Our academic collaborators typically have rights to publish data, provided that we are notified in advance and may delay publication for a specified time in order to secure our intellectual property rights arising from the collaboration. In other cases, publication rights are controlled exclusively by us, although in some cases we may share these rights with other parties. We also conduct joint research and development programs that may require us to share trade secrets under the terms of our research and development partnerships or similar agreements. Despite our efforts to protect our trade secrets, our competitors may discover our trade secrets, either through breach of these agreements, independent development or publication of information including our trade secrets in cases where we do not have proprietary or otherwise protected rights at the time of publication. A competitor's discovery of our trade secrets would impair our competitive position and have an adverse impact on our business.
 Risks related to our financial condition and capital requirements
 We have not generated material revenue from product sales and may never be profitable.
 Our ability to generate revenues and achieve profitability depends on our ability, alone or with strategic collaboration partners, to successfully commercialize ZYNTEGLO, SKYSONA and LYFGENIA and other potential future product candidates (if and when approved). Our ability to generate revenues from product sales depends heavily on our success in:
 • developing a sustainable, commercial-scale, reproducible, and transferable manufacturing process for our vectors and drug products;
 • establishing and maintaining supply and manufacturing relationships with third parties that can provide adequate (in amount and quality) products and services to support clinical development for our product candidates and commercial demand for our approved products;
 • launching and commercializing our approved products with a sustainable field-based team and marketing and distribution infrastructure; for instance, due to our financial instability, we have experienced a high degree of turnover in our employee base, particularly with respect to our commercial field-based team;
 • obtaining sufficient pricing and reimbursement for our approved products from private and governmental payers;

 • obtaining market acceptance and adoption of our approved products and gene therapy as a viable treatment option, including among patients and providers, some of whom have recently expressed concern regarding our financial condition;
 • addressing any competing technological and market developments;
 • completing research and preclinical and clinical development of future product candidates;
 • seeking and obtaining regulatory and marketing approvals for future product candidates for which we complete clinical studies;
 • negotiating favorable terms in any collaboration, licensing or other arrangements into which we may enter; and
 • maintaining, protecting and expanding our portfolio of intellectual property rights, including patents, trade secrets and know-how.
 If the Merger Transaction does not close, we expect to continue to incur significant expenditures for the foreseeable future, and we expect these expenditures to increase, which costs may increase further as competitors enter the market. Even if we are able to generate material product revenues, we may not become profitable and may need to obtain additional funding to continue operations.
 If the estimates we make, or the assumptions on which we rely, in preparing our consolidated financial statements are incorrect, our actual results may vary from those reflected in our projections and accruals.
 Our consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP"). The preparation of these consolidated financial statements requires us to make estimates and judgments that affect the reported amounts of our assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities. We base our estimates on historical experience and on various other assumptions that we believe to be reasonable under the circumstances. We cannot assure you, however, that our estimates, or the assumptions underlying them, will be correct. We may be incorrect in our assumptions regarding the applicability of drug pricing programs and rebates that may be applicable to our products and future product candidates, which may result in our under- or over-estimating our anticipated product revenues especially as applicable laws and regulations governing pricing evolve over time. In addition, to the extent payment for our products and future product candidates is subject to outcomes-based arrangements over time, as it is for ZYNTEGLO and LYFGENIA, the total payments received from product sales may vary, our cash collection of future payments and revenue assumptions from product sales will be at risk, and the timing of revenue recognition will not correspond to the timing of cash collection.
 Further, from time to time we issue financial guidance relating to our expectations for our cash, cash equivalents, and marketable securities available for operations, which guidance is based on estimates and the judgment of management. Moreover, our future net product revenues will depend upon the size of the markets in which the products have received approval, the ability to manufacture and deliver drug product to patients, the ability of such products to achieve sufficient market acceptance, reimbursement from third-party payers, adequate market share in those markets and performance of the drug product subject to outcome-based programs. If, for any reason, our expenses differ materially from our guidance or we utilize our cash more quickly than anticipated, we may have to adjust our publicly announced financial guidance. If we fail to meet, or if we are required to change or update any element of, our publicly disclosed financial guidance or other expectations about our business, including with respect to revenue generation, our stock price could decline.
 Our operating results may fluctuate significantly, which makes our future operating results difficult to predict and could cause our operating results to fall below expectations or our guidance.
 Our operating results are difficult to predict and will likely fluctuate from quarter to quarter and year to year. We expect that revenues from product sales will be difficult to predict from period to period, given the absence of significant historical sales data for ZYNTEGLO, SKYSONA, and LYFGENIA.
 Further, changes in our operations, such as undertaking of additional programs, or business activities, or entry into strategic transactions, including potential future acquisitions of products, technologies or businesses may also cause significant fluctuations in our expenses.

 The cumulative effects of these factors, further exacerbated by the impact of the ongoing volatility in macro-economic conditions, will likely result in large fluctuations and unpredictability in our quarterly and annual operating results. As a result, comparing our operating results on a period-to-period basis may not be meaningful. Investors should not rely on our past results as an indication of our future performance. This variability and unpredictability could also result in our failing to meet the expectations of industry or financial analysts or investors for any period. If our revenue or operating results fall below the expectations of analysts or investors or below any forecasts we may provide to the market, or if the forecasts we provide to the market are below the expectations of analysts or investors, the price of our common stock could decline substantially. Such a stock price decline could occur even when we have met any previously publicly stated revenue or earnings guidance we may provide.
 Amounts under our factoring arrangement are subject to terms that may adversely affect our operations and financial condition.
 We entered into an accounts receivable factoring agreement in December 2023. The factoring agreement provides for us to have access to up to $100.0 million on a revolving basis, measured by the outstanding balance of purchased accounts from time to time. Upon receipt of the upfront purchase price for any purchased accounts, we will have sold and assigned all of our rights in such purchased accounts and all proceeds thereof. The buyer has the right to require that we repurchase any purchased account that was ineligible as of the date of purchase or with respect to which any account debtor asserts a dispute that is not resolved by the related due date. The buyer does not have recourse to us for the insolvency or other credit risk of the account debtors. We have granted the buyer a security interest in the purchased accounts, and proceeds thereof, as more fully described in the agreement, in order to perfect the buyer's ownership interest in the purchased accounts and secure the payment and performance of all our obligations to the buyer under the agreement. If the buyer demands repurchase and we fail to do so, or if we cause or permit any other event of default as defined in the agreement, or fail to comply with covenants set forth in the agreement, we would be subject to additional expenses and lose access to this agreement to fund further accounts receivable. Such results could have a material adverse effect on our operations and financial condition.
 Risks related to our business operations
 Our future success depends on our ability to retain key employees and to attract, retain and motivate qualified personnel.
 We are highly dependent on our executive team and key employees, the loss of whose services may adversely impact the achievement of our objectives. While we have entered into employment agreements with each of our executive officers, any of them could leave our employment at any time, as all of our employees are "at will" employees. Recruiting and retaining other qualified employees, consultants and advisors for our business, including scientific and technical personnel, as well as sales and marketing staff, will also be critical to our success, and our financial condition has made it more challenging to recruit and retain qualified personnel. For example, we have experienced high rates of attrition recently due, in part, to uncertainty about our financial condition, and the Merger Transaction may exacerbate this issue given uncertainty about whether or when the transaction will close and the impact of the Merger Transaction on our employees. In addition, there is currently a shortage of skilled executives in our industry, which is likely to continue. As a result, competition for skilled personnel is intense and our turnover rate has been high. We may not be able to attract and retain personnel on acceptable terms given the competition among numerous pharmaceutical and biotechnology companies for individuals with similar skill sets. The inability to recruit or loss of the services of any executive, key employee, consultant or advisor may impede the progress of our research, development and commercialization objectives.
 Our restructuring and reductions in force undertaken to optimize our cost structure may not achieve our intended outcome.
 In September 2024, we implemented a restructuring plan designed to support our commercial focus and reduce our cash operating expenses. This restructuring plan included a reduction of our workforce by approximately 25% of our headcount. Additionally, in the ordinary course of business and in light of our limited financial resources, we regularly review our headcount and have eliminated, and may continue to eliminate, additional roles in an effort to optimize our cost structure. These reductions in force have resulted in and may continue to result in unintended consequences and costs, such as the loss of institutional knowledge and expertise, attrition beyond the intended number of employees, decreased morale among our remaining employees, and the risk that we may not achieve the anticipated benefits of the reduction in force. In addition, while positions have been eliminated, certain functions necessary to our operations remain, and we may be unsuccessful in distributing the duties and obligations of departed employees among our remaining employees. Reductions in our workforce could also make it difficult for us to pursue, or prevent us from pursuing, new opportunities and initiatives due to insufficient personnel, or require us to incur additional and unanticipated costs to hire new personnel to pursue such opportunities or initiatives. If we are unable to realize the anticipated benefits from the reductions in force, or if we experience significant adverse consequences from the reductions in force, our business, financial condition, and results of operations may be

 materially adversely affected. We may undertake further similar cost-saving initiatives, which may include additional restructuring or workforce reductions. These types of cost-reduction activities can be complex and result in unintended consequences and costs, including further attrition beyond the intended number of employees due to decreased employee morale, loss of institutional knowledge and expertise and adversely impact our business.
 Our products remain subject to regulatory scrutiny.
 For any regulatory approvals that we have or may receive, the manufacturing processes, labeling, packaging, distribution, adverse event reporting, storage, advertising, promotion, import, export and recordkeeping for our products and/or any future product candidates will be subject to extensive and ongoing regulatory requirements. These requirements include submissions of safety and other post-marketing information and reports, registration, as well as ongoing compliance with cGMPs and GCPs for any clinical trials that we may conduct. In addition, manufacturers of drug products and their facilities are subject to continual review and periodic, unannounced inspections by the FDA and other regulatory authorities for compliance with cGMP regulations and standards. Even though we have obtained regulatory approval in the U.S. for ZYNTEGLO, SKYSONA and LYFGENIA, any regulatory approvals we receive will require the submission of reports to regulatory authorities and surveillance to monitor the safety and efficacy of such product, and such approvals may contain significant limitations related to use restrictions for specified age groups, warnings, precautions or contraindications, and may include burdensome post-approval study or risk management requirements. For example, the FDA typically advises that patients treated with integrating gene therapy undergo follow-up observations for potential adverse events for a 15-year period. Furthermore, we have agreed to provide confirmatory long-term clinical data to the FDA as a condition of the SKYSONA accelerated approval, and continued approval for the approved indication will be contingent upon verification and description of clinical benefit in a confirmatory trial. If our confirmatory trials fail to adequately verify or describe the anticipated clinical benefit of SKYSONA, or if we fail to conduct such trials in a timely manner, the FDA could withdraw its approval for SKYSONA on an expedited basis. In addition to our ongoing process of monitoring and reporting safety results to the FDA, the FDA reported in November 2024 that it was investigating SKYSONA with respect to serious risks of hematologic malignancies, based on cases of MDS and AML observed in patients previously enrolled in our clinical trials.
 Additionally, the holder of an approved BLA is obligated to monitor and report adverse events. The holder of an approved BLA must also submit new or supplemental applications and obtain FDA approval for certain changes to the approved product, product labeling or manufacturing process. Advertising and promotional materials must comply with FDA rules and are subject to FDA review, in addition to other potentially applicable federal and state laws. We have experienced interruptions in clinical programs due to safety concerns arising from our SKYSONA and LYFGENIA programs, and we can make no assurance that we will not experience interruptions in any clinical studies, marketing or other commercialization activities in the future, whether due to safety concerns in any approved or investigational products, or due to events arising from programs that utilize technologies similar to or related to ours.
 In addition, product manufacturers and their facilities are subject to payment of user fees and continual review and periodic inspections by the FDA and other regulatory authorities for compliance with good manufacturing practices ("GMP") and adherence to commitments made in the BLA. If we or a regulatory agency discovers previously unknown problems with a product such as adverse events of unanticipated severity or frequency, or problems with the facility where the product is manufactured, a regulatory agency may impose restrictions relative to that product or the manufacturing facility, including requiring recall or withdrawal of the product from the market or suspension of manufacturing.
 If we fail to comply with applicable regulatory requirements following marketing approval for a product, a regulatory agency may:
 • issue a warning letter asserting that we are in violation of the law;
 • seek an injunction or impose civil or criminal penalties or monetary fines;
 • suspend or withdraw marketing approval;
 • suspend any ongoing clinical studies;
 • refuse to approve a pending marketing application, such as a BLA or supplements to a BLA submitted by us;
 • seize product; or
 • refuse to allow us to enter into supply contracts, including government contracts.

 Any government investigation of alleged violations of law could require us to expend significant time and resources in response and could generate negative publicity. The occurrence of any event or penalty described above may inhibit our ability to commercialize any approved product and generate revenues.
 The FDA's and other regulatory authorities' policies may change and additional government regulations may be promulgated that could prevent, limit or delay marketing authorization of any future product candidates we develop. We also cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative action, either in the United States or abroad. If we are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we are not able to maintain regulatory compliance, we may be subject to enforcement action and we may not achieve or sustain profitability.
 The FDA and other regulatory agencies actively enforce the laws and regulations prohibiting the promotion of off-label uses.
 The FDA strictly regulates marketing, labeling, advertising and promotion of prescription drugs and biologics. These regulations include standards and restrictions for direct-to-consumer advertising, industry-sponsored scientific and educational activities, promotional activities involving the internet and off-label promotion. Any regulatory approval that the FDA grants is limited to those specific diseases and indications for which a product is deemed to be safe, pure and potent, or effective, by the FDA. For example, the current FDA-approved indication for ZYNTEGLO is limited to the treatment of adult and pediatric patients with -thalassemia who require regular red blood cell transfusions; the FDA-approved indication for SKYSONA is limited to slow the progression of neurologic dysfunction in boys 4-17 years of age with early, active CALD, which is defined to include to asymptomatic or mildly symptomatic (neurologic function score, NFS 1) boys who have gadolinium enhancement on brain magnetic resonance imaging and Loes scores of 0.5-9; and the FDA-approved indication for LYFGENIA is limited to the treatment of sickle cell disease in patients ages 12 and older who have a history of VOEs.
 While physicians in the United States may choose, and are generally permitted, to prescribe drugs for uses that are not described in the product's labeling and for uses that differ from those tested in clinical trials and approved by the regulatory authorities, our ability to manufacture and promote any products will be narrowly limited to those indications that are specifically approved by the FDA. If we are found to have manufactured and promoted such off-label uses, we may become subject to significant liability. The U.S. federal government has levied large civil and criminal fines against companies for alleged improper promotion of off-label use and has enjoined several companies from engaging in off-label promotion. The FDA has also requested that companies enter into consent decrees or permanent injunctions under which specified promotional conduct is changed or curtailed. If we cannot successfully manage the promotion of any of our products, we could become subject to significant liability, which would materially adversely affect our business and financial condition.
 We are subject, directly or indirectly, to federal and state healthcare fraud and abuse laws and false claims laws. If we are unable to comply, or have not fully complied, with such laws, we could face substantial penalties, reputational harm, and diminished profits and future earnings.
 In the United States, the research, manufacturing, distribution, sale, and promotion of drugs and biologic products are subject to regulation by various federal, state, and local authorities in addition to FDA, including CMS, other divisions of the HHS, (e.g., the Office of Inspector General), the United States Department of Justice offices of the United States Attorney, the Federal Trade Commission and state and local governments. Our operations are directly, or indirectly through our prescribers, customers and purchasers, subject to various federal and state fraud and abuse laws and regulations.
 These laws apply to, among other things, our sales, marketing, patient services and educational programs and include the following:
 • the federal Anti-Kickback Statute, which prohibits, among other things, knowingly and willfully soliciting, receiving, offering or paying any remuneration (including any kickback, bribe or rebate), directly or indirectly, overtly or covertly, in cash or in kind, to induce, or in return for, either the referral of an individual, or the purchase, lease, order or recommendation of any good, facility, item or service for which payment may be made, in whole or in part, under the Medicare and Medicaid programs or other federal healthcare programs. A person or entity can be found guilty of violating the statute without actual knowledge of the statute or specific intent to violate it. The Anti-Kickback Statute has been interpreted to apply to arrangements between pharmaceutical manufacturers on the one hand and prescribers, purchasers, and formulary managers on the other. There are a number of statutory exceptions and regulatory safe harbors protecting some common activities from prosecution;

 • the federal civil and criminal false claims laws, including the False Claims Act, or FCA, and civil monetary penalty laws, which prohibit any person or entity from, among other things, knowingly presenting, or causing to be presented, a false, fictitious or fraudulent claim for payment to, or approval by, the federal government or knowingly making, using or causing to be made or used a false record or statement material to a false or fraudulent claim to the federal government. In addition, the government may assert that a claim including items or services resulting from a violation of the federal Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the FCA;
 • HIPAA, which created federal criminal statutes that prohibit knowingly and willfully executing, or attempting to execute, a scheme to defraud any healthcare benefit program or obtain, by means of false or fraudulent pretenses, representations, or promises, any of the money or property owned by, or under the custody or control of, any healthcare benefit program, regardless of the payer (e.g., public or private) and knowingly and willfully falsifying, concealing or covering up by any trick or device a material fact or making any materially false statements in connection with the delivery of, or payment for, healthcare benefits, items or services relating to healthcare matters. Similar to the federal Anti-Kickback Statute, a person or entity can be found guilty of violating HIPAA without actual knowledge of the statutes or specific intent to violate them;
 • the Physician Payments Sunshine Act, created under the ACA, and its implementing regulations, which require manufacturers of drugs, devices, biologics and medical supplies for which payment is available under Medicare, Medicaid or the Children's Health Insurance Program (with certain exceptions) to report annually to CMS information related to payments or other transfers of value made to physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors), certain non-physician practitioners (physician assistants, nurse practitioners, clinical nurse specialists, certified nurse anesthetists, anesthesiologist assistants and certified nurse midwives), and teaching hospitals, as well as ownership and investment interests held by physicians and their immediate family members;
 • federal consumer protection and unfair competition laws, which broadly regulate marketplace activities and activities that potentially harm consumers; and
 • analogous or related foreign, state or local laws and regulations, including anti-kickback and false claims laws, which may apply to sales or marketing arrangements and claims involving healthcare items or services reimbursed by non-governmental third-party payers, including private insurers; state laws that require pharmaceutical companies to comply with the pharmaceutical industry's voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government or otherwise restrict payments that may be made to healthcare providers; and state laws that require drug manufacturers to report information related to payments and other transfers of value to physicians and other healthcare providers or marketing expenditures.
 State and federal regulatory and enforcement agencies continue actively to investigate violations of health care laws and regulations, and the United States Congress continues to strengthen the arsenal of enforcement tools. Most recently, the Bipartisan Budget Act of 2018 increased the criminal and civil penalties that can be imposed for violating certain federal health care laws, including the Anti-Kickback Statute. Enforcement agencies also continue to pursue novel theories of liability under these laws. In particular, government agencies have recently increased regulatory scrutiny and enforcement activity with respect to programs supported or sponsored by pharmaceutical companies, including reimbursement and co-pay support, funding of independent charitable foundations and other programs that offer benefits for patients. Several investigations into these programs have resulted in significant civil and criminal settlements. In addition, in July 2024, the Office of Inspector General (OIG) issued two negative opinions to pharmaceutical companies seeking to offer fertility support for gene therapy patients insured by Medicaid and other federal healthcare programs. OIG stated that it lacked data to conclude that the fertility support programs would pose a sufficiently low risk of fraud and abuse under the federal Anti-Kickback Statute to grant prospective immunity.
 Because of the breadth of these laws and the narrowness of the statutory exceptions and safe harbors available, it is possible that some of our business activities could be subject to challenge under one or more of such laws. If our operations are found to be in violation of any of the laws described above or any other government regulations that apply to us, we may be subject to penalties, including civil and criminal penalties, damages, fines, exclusion from participation in government health care programs, such as Medicare and Medicaid, imprisonment and the curtailment or restructuring of our operations, any of which could adversely affect our ability to operate our business and our results of operations. Even if we are not determined to have violated these laws, government investigations into these issues typically require the expenditure of significant resources and generate negative publicity, which could harm our financial condition and divert the attention of our management from operating our business.

 Actual or perceived failures to comply with applicable data protection, privacy and security laws, regulations, standards and other requirements could adversely affect our business, results of operations, and financial condition.
 The global data protection landscape is rapidly evolving, and we are or may become subject to numerous state, federal and foreign laws, requirements and regulations governing the collection, use, disclosure, retention, and security of personal information, such as information that we may collect in connection with clinical trials. Implementation standards and enforcement practices are likely to remain uncertain for the foreseeable future, and we cannot yet determine the impact future laws, regulations, standards, or perception of their requirements may have on our business. This evolution may create uncertainty in our business, affect our ability to operate in certain jurisdictions or to collect, store, transfer use and share personal information, necessitate the acceptance of more onerous obligations in our contracts, result in liability or impose additional costs on us. The cost of compliance with these laws, regulations and standards is high and is likely to increase in the future. Any failure or perceived failure by us to comply with federal, state or foreign laws or regulations, our internal policies and procedures or our contracts governing our processing of personal information could result in negative publicity, government investigations and enforcement actions, claims by third parties and damage to our reputation, any of which could have a material adverse effect on our business, results of operation, and financial condition.
 In the U.S., HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act of 2009 and their implementing regulations (collectively, "HIPAA"), imposes requirements on certain covered healthcare providers, health plans, and healthcare clearinghouses as well as their respective business associates that perform services for them that involve the use, or disclosure of, individually identifiable health information, relating to the privacy, security and transmission of individually identifiable health information. In addition, we may obtain health information from third parties (including research institutions from which we obtain clinical trial data), which are subject to privacy and security requirements under HIPAA. Depending on the facts and circumstances, we could be subject to significant penalties if we violate HIPAA. Certain states have also adopted comparable privacy and security laws and regulations, which govern the privacy, processing and protection of health-related and other personal information. For example, the California Consumer Privacy Act, as amended by the California Privacy Rights Act (collectively, the "CCPA") requires covered businesses that process the personal information of California residents to, among other things: (i) provide certain disclosures to California residents regarding the business's collection, use, and disclosure of their personal information; (ii) receive and respond to requests from California residents to access, delete, and correct their personal information, or to opt out of certain disclosures of their personal information; and (iii) enter into specific contractual provisions with service providers that process California resident personal information on the business's behalf. Additional compliance investment and potential business process changes may be required. Similar laws have passed in other states and are continuing to be proposed at the state and federal level, reflecting a trend toward more stringent privacy legislation in the United States. The enactment of such laws could have potentially conflicting requirements that would make compliance challenging. In the event that we are subject to or affected by HIPAA, the CCPA or other domestic privacy and data protection laws, any liability from failure to comply with the requirements of these laws could adversely affect our financial condition.
 Furthermore, the Federal Trade Commission ("FTC") has authority to initiate enforcement actions against entities that make deceptive statements about privacy and data sharing in privacy policies, fail to limit third-party use of personal health information, fail to implement policies to protect personal health information or engage in other unfair practices that harm customers or that may violate Section 5(a) of the FTC Act. For example, according to the FTC, failing to take appropriate steps to keep consumers' personal information secure can constitute unfair acts or practices in or affecting commerce in violation of Section 5(a) of the Federal Trade Commission Act. The FTC expects a company's data security measures to be reasonable and appropriate in light of the sensitivity and volume of consumer information it holds, the size and complexity of its business, and the cost of available tools to improve security and reduce vulnerabilities. The FTC and many state Attorneys General continue to enforce federal and state consumer protection laws against companies for online collection, use, dissemination and security practices that appear to be unfair or deceptive, including by. regulating the presentation of website content.
 We are also or may become subject to rapidly evolving data protection laws, rules and regulations in foreign jurisdictions. For example, in Europe, the European Union General Data Protection Regulation ("GDPR") went into effect in May 2018 and imposes strict requirements for processing the personal data of individuals within the European Economic Area ("EEA"). Companies that must comply with the GDPR face increased compliance obligations and risk, including more robust regulatory enforcement of data protection requirements and potential fines for noncompliance of up to 20 million or 4% of the annual global revenues of the noncompliant company, whichever is greater. Among other requirements, the GDPR regulates transfers of personal data subject to the GDPR to third countries that have not been found to provide adequate protection to such personal data, including the United States, and the efficacy and longevity of current transfer mechanisms between the EEA, and the United States remains uncertain. Case law from the Court of Justice of the European Union ("CJEU") states that reliance on the standard contractual clauses ("SCCs") - a standard form of contract approved by the European Commission as an adequate

 personal data transfer mechanism - alone may not necessarily be sufficient in all circumstances and that transfers must be assessed on a case-by-case basis. On July 10, 2023, the European Commission adopted its Adequacy Decision in relation to the new EU-US Data Privacy Framework ("DPF"), rendering the DPF effective as a GDPR transfer mechanism to U.S. entities self-certified under the DPF. We expect the existing legal complexity and uncertainty regarding international personal data transfers to continue. As supervisory authorities issue further guidance on personal data export mechanisms, including circumstances where the SCCs cannot be used, and/or start taking enforcement action, we could suffer additional costs, complaints and/or regulatory investigations or fines, and/or if we are otherwise unable to transfer personal data between and among countries and regions in which we operate, it could affect the manner in which we provide our services, the geographical location or segregation of our relevant systems and operations, and could adversely affect our financial results.
 Since the beginning of 2021, after the end of the transition period following the United Kingdom's departure from the European Union, we are also subject to the United Kingdom data protection regime, which imposes separate but similar obligations to those under the GDPR and comparable penalties, including fines of up to 17.5 million or 4% of a noncompliant company's global annual revenue for the preceding financial year, whichever is greater. On October 12, 2023, the United Kingdom Extension to the DPF came into effect (as approved by the United Kingdom Government), as a data transfer mechanism from the United Kingdom to U.S. entities self-certified under the DPF. As we continue to expand into other foreign countries and jurisdictions, we may be subject to additional laws and regulations that may affect how we conduct business.
 If we fail to comply with reporting and payment obligations under the Medicaid Drug Rebate Program or other governmental pricing programs, we could be subject to additional reimbursement requirements, penalties, sanctions and fines, which could have a material adverse effect on our business, financial condition, results of operations and growth prospects.
 We participate in governmental programs that impose extensive drug price reporting and payment obligations on pharmaceutical manufacturers. Medicaid is a joint federal and state program that is administered by the states for low income and disabled beneficiaries. Under the Medicaid Drug Rebate Program (the "MDRP"), as a condition of federal funds being made available for our covered outpatient drugs under Medicaid and certain drugs or biologicals under Medicare Part B, we pay a rebate to state Medicaid programs for each unit of our covered outpatient drugs dispensed to a Medicaid beneficiary and paid for by the state Medicaid program. Medicaid rebates are based on pricing data that we report on a monthly and quarterly basis to CMS, the federal agency that administers the MDRP and Medicare programs. For the MDRP, these data include the Average Manufacturer Price ("AMP") for each drug and, in the case of innovator products, best price. In connection with Medicare Part B, a pharmaceutical manufacturer must provide CMS with average sales price ("ASP") information for certain drugs or biologicals on a quarterly basis. ASP is calculated based on a statutorily defined formula, as well as regulations and interpretations of the statute by CMS. If we become aware that our MDRP price reporting submission for a prior period was incorrect or has changed as a result of recalculation of the pricing data, we must resubmit the corrected data for up to three years after those data originally were due. If we fail to provide information on a timely basis or are found to have knowingly submitted false information to the government, we may be subject to civil monetary penalties and other sanctions, including termination from the MDRP, in which case payment would not be available for our covered outpatient drugs under Medicaid or, if applicable, Medicare Part B.
 Federal law requires that any company that participates in the MDRP also participate in the 340B program in order for federal funds to be available for the manufacturer's drugs under Medicaid and Medicare Part B. The 340B program is administered by HRSA and requires us, as a participating manufacturer, to agree to charge statutorily defined covered entities no more than the 340B "ceiling price" for our covered outpatient drugs when used in an outpatient setting. To date, bluebird's therapies have been administered in the inpatient setting exclusively and we anticipate that most patients will continue to receive bluebird's therapies in an inpatient setting. However, in the event that patients are treated in an outpatient setting, the 340B "ceiling price" requirement may apply to these transactions if otherwise eligible under 340B legal standards. These 340B covered entities include a variety of community health clinics and other entities that receive health services grants from the Public Health Service, as well as hospitals that serve a disproportionate share of low income patients. A drug that is designated for a rare disease or condition by the Secretary of Health and Human Services is not subject to the 340B ceiling price requirement with regard to the following types of covered entities: rural referral centers, sole community hospitals, critical access hospitals, and free standing cancer hospitals. The 340B ceiling price is calculated using a statutory formula, which is based on the AMP and rebate amount for the covered outpatient drug as calculated under the MDRP. In general, products subject to Medicaid price reporting and rebate liability are also subject to the 340B ceiling price calculation and discount requirement. We must report 340B ceiling prices to HRSA on a quarterly basis, and HRSA publishes them to 340B covered entities. HRSA has finalized regulations regarding the calculation of the 340B ceiling price and the imposition of civil monetary penalties on manufacturers that knowingly and intentionally overcharge covered entities for 340B eligible drugs. HRSA has also finalized a revised administrative dispute resolution process through which 340B covered entities may pursue claims against participating manufacturers for overcharges, and through which manufacturers may pursue claims against 340B covered

 entities for engaging in unlawful diversion or duplicate discounting of 340B drugs. In addition, legislation may be introduced that, if enacted, would further expand the 340B program, such as adding further covered entities or requiring participating manufacturers to agree to provide 340B discounted pricing on drugs used in an inpatient setting.
 In order to be eligible to have drug products paid for with federal funds under Medicaid and Medicare Part B and purchased by certain federal agencies and grantees, we must also participate in the VA/FSS pricing program. Under the VA/FSS program, we must report the Non-FAMP for our covered drugs to the VA and charge certain federal agencies no more than the Federal Ceiling Price, which is calculated based on Non FAMP using a statutory formula. These four agencies are the VA, the U.S. Department of Defense, the U.S. Coast Guard, and the U.S. Public Health Service (including the Indian Health Service). We must also pay rebates on products purchased by military personnel and dependents through the TRICARE retail pharmacy program. If we fail to provide timely information or are found to have knowingly submitted false information, we may be subject to civil monetary penalties.
 Individual states continue to consider and have enacted legislation to limit the growth of healthcare costs, including the cost of prescription drugs and combination products. A number of states have either implemented or are considering implementation of drug price transparency legislation that may prevent or limit our ability to take price increases at certain rates or frequencies. Requirements under such laws include advance notice of planned price increases, reporting price increase amounts and factors considered in taking such increases, wholesale acquisition cost information disclosure to prescribers, purchasers, and state agencies, and new product notice and reporting. Such legislation could limit the price or payment for certain drugs, and states may impose civil monetary penalties or pursue other enforcement mechanisms against manufacturers who fail to comply with drug price transparency requirements. If we are found to have violated state law requirements, we may become subject to penalties or other enforcement mechanisms, which could have a material adverse effect on our business.
 Pricing and rebate calculations vary across products and programs, are complex, and are often subject to interpretation by us, governmental or regulatory agencies, and the courts, which can change and evolve over time. Such pricing calculations and reporting, along with any necessary restatements and recalculations, could increase our costs for complying with the laws and regulations governing the MDRP and other governmental programs, and under the MDRP could result in an overage or undercharge in Medicaid rebate liability for past quarters. Price recalculations under the MDRP also may affect the ceiling price at which we are required to offer products under the 340B program. Civil monetary penalties can be applied if we are found to have knowingly submitted any false price or product information to the government, if we fail to submit the required price data on a timely basis, or if we are found to have charged 340B covered entities more than the statutorily mandated ceiling price. CMS could also terminate our Medicaid drug rebate agreement, in which case federal payments may not be available under Medicaid or Medicare Part B, if applicable, for our covered outpatient drugs. Pursuant to the Inflation Reduction Act of 2022 (the "IRA"), the AMP figures we report will also be used to compute rebates under Medicare Part D triggered by price increases that outpace inflation. We cannot assure you that our submissions will not be found to be incomplete or incorrect.
 We face potential product liability, and, if successful claims are brought against us, we may incur substantial liability and costs. If the use of our products or product candidates harm patients, or is perceived to harm patients even when such harm is unrelated to our products or product candidates, our marketing approvals could be revoked or otherwise negatively impacted and we could be subject to costly and damaging product liability claims.
 The use of products and product candidates in clinical studies and the sale of products for which we have obtained marketing approval exposes us to the risk of product liability claims. Product liability claims might be brought against us by patients participating in clinical trials, consumers, healthcare providers, pharmaceutical companies or others selling or otherwise coming into contact with our products and any future product candidates. There is a risk that our products and any future product candidates may induce adverse events. For instance, each of the LYFGENIA and SKYSONA product labels includes a boxed warning for the risk of hematologic malignancy. If we cannot successfully defend against product liability claims, we could incur substantial liability and costs. In addition, regardless of merit or eventual outcome, product liability claims may result in:
 • impairment of our business reputation;
 • withdrawal of clinical study participants;
 • costs due to related litigation;
 • distraction of management's attention from our primary business;

 • substantial monetary awards to patients or other claimants;
 • the inability to develop our product candidates or commercialize any approved product; and
 • decreased demand for any approved product.
 We carry product liability insurance and we believe our product liability insurance coverage is sufficient in light of our current clinical programs and approved products; however, we may not be able to maintain insurance coverage at commercially reasonable cost or in sufficient amounts to protect us against losses due to liability. On occasion, large judgments have been awarded in class action lawsuits based on drugs or medical treatments that had unanticipated adverse effects. A successful product liability claim or series of claims brought against us could cause our stock price to decline and, if judgments exceed our insurance coverage, could adversely affect our results of operations and business.
 Patients with the diseases targeted by our products and product candidates are often already in severe and advanced stages of disease and have both known and unknown significant pre-existing and potentially life-threatening health risks. During the course of treatment, patients may suffer adverse events, including death, for reasons that may be related to our products and product candidates. Such events could subject us to costly litigation, require us to pay substantial amounts of money to injured patients, delay, negatively impact or end our opportunity to receive or maintain marketing approval for any approved product, or require us to suspend or abandon our commercialization efforts. Even in a circumstance in which we do not believe that an adverse event is related to our products and product candidates the investigation into the circumstance may be time-consuming or inconclusive. These investigations may interrupt our sales efforts, delay our marketing approval process in other countries, or impact and limit the type of marketing approval our product candidates may receive or our approved products maintain. As a result of these factors, a product liability claim, even if successfully defended, could have a material adverse effect on our business, financial condition or results of operations.
 The increasing focus on environmental sustainability and social initiatives could increase our costs, harm our reputation and adversely impact our financial results.
 There has been increasing public focus by investors, patients, environmental activists, the media and governmental and nongovernmental organizations on a variety of environmental, social and other sustainability matters. We may experience pressure to make commitments relating to sustainability matters that affect us, including the design and implementation of specific risk mitigation strategic initiatives relating to sustainability. If we are not effective in addressing environmental, social and other sustainability matters affecting our business, or setting and meeting relevant sustainability goals, our reputation and financial results may suffer. In addition, even if we are effective at addressing such concerns, we may experience increased costs as a result of executing upon our sustainability goals that may not be offset by any benefit to our reputation, which could have an adverse impact on our business and financial condition.
 In addition, this emphasis on environmental and social matters has resulted in the adoption of new laws and regulations, including new reporting requirements, and may result in the adoption of additional laws and regulations in the future. New reporting requirements may be particularly difficult or expensive to comply with and, if we fail to comply, we may be required to issue financial restatements, suffer harm to our reputation or otherwise have our business be adversely impacted. Such ESG matters may also impact our suppliers or patients, which may adversely impact our business, financial condition and results of operations.
 In addition, this emphasis on environmental, social and other sustainability matters has resulted and may result in the adoption of new laws and regulations, including new reporting requirements. If we fail to comply with new laws, regulations or reporting requirements, our reputation and business could be adversely impacted.
 Healthcare legislative reform measures may have a material adverse effect on our business and results of operations.
 The United States has enacted or proposed legislative and regulatory changes affecting the healthcare system that could prevent or delay marketing approval of any future product candidates, restrict or regulate post-approval activities and affect our ability to profitably sell products for which we have obtained marketing approval. Changes in regulations, statutes or the interpretation of existing regulations could impact our business in the future by requiring, for example: (i) changes to our manufacturing arrangements; (ii) additions or modifications to product labeling; (iii) the recall or discontinuation of our products; (iv) additional record-keeping requirements; or (v) directly or indirectly limit the net price of sales to federal healthcare programs that form a substantial portion of our business. If any such changes were to be imposed, they could adversely affect the operation of our business.

 A primary trend in the U.S. healthcare industry and elsewhere is cost containment. Government authorities and other third-party payers have attempted to control costs by limiting coverage and the level of reimbursement for particular medical products and services, implementing reductions in Medicare and other healthcare funding and applying new payment methodologies. For example, in March 2010, the Affordable Care Act ("ACA") was enacted, which, among other things, increased the minimum Medicaid rebates owed by most manufacturers under the Medicaid Drug Rebate Program; introduced a new methodology by which rebates owed by manufacturers under the Medicaid Drug Rebate Program are calculated for drugs that are inhaled, infused, instilled, implanted or injected; extended manufacturer Medicaid rebate obligations to utilization by individuals enrolled in Medicaid managed care plans; established a Medicare Part D coverage gap discount program (to be replaced by a new program in 2025, as discussed below); subjected drug manufacturers to new annual fees based on pharmaceutical companies' share of sales to federal healthcare programs; imposed a new federal excise tax on the sale of certain medical devices; created a new Patient Centered Outcomes Research Institute to oversee, identify priorities in, and conduct comparative clinical effectiveness research, along with funding for such research; and established a Center for Medicare and Medicaid Innovation ("CMMI") at the CMS to test innovative payment and service delivery models to lower Medicare and Medicaid spending.
 Since its enactment, there have been judicial, executive and Congressional challenges to certain aspects of the ACA. On June 17, 2021, the U.S. Supreme Court dismissed the most recent judicial challenge to the ACA brought by several states without specifically ruling on the constitutionality of the ACA. In addition, other legislative changes have been proposed and adopted in the United States since the ACA was enacted. The Budget Control Act of 2011, among other things, led to reductions of Medicare payments to providers, which will remain in effect through 2032 unless additional Congressional action is taken. More recently, in March 2021, President Biden signed into law the American Rescue Plan Act of 2021, which eliminated the statutory cap on the Medicaid drug rebate beginning January 1, 2024. The rebate was previously capped at 100% of a drug's AMP.
 Most significantly, in August 2022, President Biden signed the Inflation Reduction Act of 2022 ("IRA") into law. This statute marks the most significant action by Congress with respect to the pharmaceutical industry since adoption of the ACA in 2010. Among other things, the IRA requires manufacturers of certain drugs to engage in price negotiations with Medicare, with prices that can be negotiated subject to a cap (with resulting prices for the initial ten drugs first effective in 2026); imposes rebates under Medicare Part B and Medicare Part D to penalize price increases that outpace inflation (first due in 2023); redesigns the Medicare Part D benefit (beginning in 2024); and replaces the Part D coverage gap discount program with a new discounting program (beginning in 2025). CMS has published the negotiated prices for the initial ten drugs, which will first be effective in 2026, and has published the list of the subsequent 15 drugs that will be subject to negotiation. The IRA permits the Secretary of the Department of Health and Human Services (HHS) to implement many of these provisions through guidance, as opposed to regulation, for the initial years. HHS has and will continue to issue and update guidance as these programs are implemented, although the Medicare drug price negotiation program is currently subject to legal challenges. While the impact of the IRA on the pharmaceutical industry cannot yet be fully determined, it is likely to be significant.
 Established under the ACA, CMMI is tasked to develop and test health care payment and service delivery models to improve patient care, lower costs and better align payment systems to promote patient-centered practices. In general, CMMI conducts alternative payment models for a specified period of time, evaluates the results of the model, and then makes recommendations to Congress based on the outcome of the model. In 2023, CMMI initiated the Cell and Gene Therapy ("CGT") Access Model. This voluntary payment model is designed to test whether a CMS-led approach to developing and administering outcomes-based agreements ("OBAs") for cell and gene therapies would improve Medicaid beneficiaries' access to innovative treatments. The participants in this voluntary model are pharmaceutical manufacturers and states. In December 2024, we entered into an agreement with CMMI to offer an OBA for LYFGENIA under the model. The enrollment period for states that wish to participate in the CGT Access Model ended in March of 2025. It is unclear if the CGT Access Model will be conducted as originally envisioned or what actions the Trump administration may take with respect to the CGT Access Model.
 At the U.S. state level, legislatures have increasingly passed legislation and implemented regulations designed to control pharmaceutical and biological product pricing, including price or provider reimbursement constraints, patient out-of-pocket cost caps for certain classes of therapy, discounts, restrictions on certain product access, marketing cost disclosure and other transparency measures, and, in some cases, measures designed to encourage importation from other countries and bulk purchasing. Some states have enacted legislation creating so-called prescription drug affordability boards, which ultimately may attempt to impose price limits on certain drugs in these states.
 We expect that the healthcare reform measures that have been adopted and may be adopted in the future, may result in more rigorous coverage criteria and in additional downward pressure on the price that we receive for any approved product and could seriously harm our future revenues. Any reduction in reimbursement from Medicare or other government programs may result in a similar reduction in payments from private third-party payers.

 There have been, and likely will continue to be, legislative and regulatory proposals at the foreign, federal and state levels directed at broadening the availability of healthcare and containing or lowering the cost of healthcare. The implementation of cost containment measures or other healthcare reforms may prevent us from being able to generate revenue, attain profitability, or commercialize our products and any future product candidates. Such reforms could have an adverse effect on anticipated revenue from products and any future product candidates that we may successfully develop and for which we may obtain marketing approval and may affect our overall financial condition and ability to develop such future product candidates.
 Our information technology systems, or those of our third-party collaborators, service providers, contractors or consultants, may fail or suffer security breaches, which could result in a material disruption of any future product candidates' development programs and activities related to our approved products and have a material adverse effect on our reputation, business, financial condition or results of operations.
 We collect and maintain information in digital form that is necessary to conduct our business, and we are increasingly dependent on information technology systems and infrastructure to operate our business, including our mobile and web-based applications, our e-commerce platform and our enterprise software. In the ordinary course of our business, we collect, store and transmit large amounts of confidential information, including intellectual property, proprietary business information, clinical trial data, and personal information (collectively, "Confidential Information") of customers and our employees and contractors. It is critical that we do so in a secure manner to maintain the confidentiality and integrity of such Confidential Information.
 Our information technology systems and those of our current or future third-party collaborators, service providers, contractors and consultants may fail and are vulnerable to attack, damage and interruption from computer viruses and malware (e.g. ransomware), misconfigurations, "bugs" or other vulnerabilities, malicious code, natural disasters, terrorism, war, telecommunication and electrical failures, hacking, cyberattacks, phishing attacks and other social engineering schemes, employee theft or misuse, human error, fraud, denial or degradation of service attacks, sophisticated nation-state and nation-state-supported actors or unauthorized access or use by persons inside our organizations, or persons with access to systems inside our organization. Attacks on information technology systems are increasing in their frequency, levels of persistence, sophistication and intensity, and they are being conducted by increasingly sophisticated and organized groups and individuals with a wide range of motives and expertise. The prevalent use of mobile devices and unauthorized applications also increases the risk of data security incidents. As a result of the continued hybrid working environment, we may also face increased cybersecurity risks due to our reliance on internet technology and the number of our employees who are working remotely, which may create additional opportunities for cybercriminals to exploit vulnerabilities. Furthermore, because the techniques used to obtain unauthorized access to, or to sabotage, systems change frequently and often are not recognized until launched against a target, we may be unable to anticipate these techniques or implement adequate preventative measures. We may also experience security breaches that may remain undetected for an extended period. Even if identified, we may be unable to adequately investigate or remediate incidents or breaches due to attackers increasingly using tools and techniques that are designed to circumvent controls, to avoid detection, and to remove or obfuscate forensic evidence. There can also be no assurance that our and our current or future third-party collaborators', service providers', contractors' and consultants' cybersecurity risk management program and processes, including policies, controls or procedures, will be fully implemented, complied with or effective in protecting our systems, networks and Confidential Information.
 We and certain of our service providers are from time to time subject to cyberattacks and security incidents. While we do not believe that we have experienced any significant system failure, accident or security breach to date, if we were to experience a system failure, accident or security breach that causes interruptions in our operations or the operations of third-party collaborators, service providers, contractors and consultants, it could result in significant reputational, financial, legal, regulatory, business or operational harm. For example, the loss of clinical trial data for any future product candidates could result in delays in our marketing approval efforts and significantly increase our costs to recover or reproduce the data. To the extent that any disruption or security breach results in a loss of or damage to our data or applications or other data or applications relating to our technology or our products and any future product candidates, or inappropriate disclosure of Confidential Information, we could incur liabilities and the further development of any future product candidates could be delayed. In addition, we rely on third-party service providers for management of the manufacture and delivery of drug product to patients in the commercial context, including for chain of identity and chain of custody. We also rely on third-party service providers for aspects of our internal control over financial reporting and such service providers may experience a material system failure or fail to carry out their obligations in other respects, which may impact our ability to produce accurate and timely financial statements, thus harming our operating results, our ability to operate our business, and our investors' view of us. In addition, our liability insurance may not be sufficient in type or amount to cover us against claims related to material failures, security breaches, cyberattacks and other related breaches.
 Any failure or perceived failure by us or any third-party collaborators, service providers, contractors or consultants to comply with our privacy, confidentiality, data security or similar obligations to third parties, or any data security incidents or

 other security breaches that result in the unauthorized access, release or transfer of sensitive information, including personally identifiable information, may result in governmental investigations, enforcement actions, regulatory fines, litigation or public statements against us. These events could cause third parties to lose trust in us or could result in claims by third parties asserting that we have breached our privacy, confidentiality, data security or similar obligations, any of which could have a material adverse effect on our reputation, business, financial condition or results of operations. While we have implemented data security measures intended to protect our information technology systems and infrastructure, there can be no assurance that such measures will successfully prevent service interruptions or data security incidents. Further, our insurance coverage may not be sufficient to cover the financial, legal, business or reputational losses that may result from an interruption or breach of our systems.
 Risks related to the separation of our oncology programs and portfolio
 We may incur operational difficulties or be exposed to claims and liabilities as a result of the separation of 2seventy bio.
 On November 4, 2021, we distributed all of the outstanding shares of 2seventy bio, Inc. ("2seventy") common stock to our stockholders in connection with the separation of our oncology programs and portfolio. In connection with the distribution, we entered into a separation agreement and various other agreements (including a tax matters agreement, an employee matters agreement, transition services agreements and an intellectual property license agreement). These agreements govern the separation and distribution and the relationship between us and 2seventy going forward, including with respect to the assignment and assumption of assets and liabilities and potential tax-related losses associated with the separation and distribution. They also provide for the performance of services by each company for the benefit of the other for a period of time.
 As a result of the separation, we remain contractually liable in connection with certain agreements transferred to 2seventy; for instance, we may be liable in the event of a breach by 2seventy of an assigned lease agreement, which could result in material expenses. Although the separation agreement provides for indemnification obligations designed to make 2seventy financially responsible for many liabilities that may exist relating to its business activities, whether incurred prior to or after the distribution, including any pending or future litigation, we cannot guarantee that 2seventy will be able to satisfy its indemnification obligations, including as related to the lease agreement. It is also possible that a court would disregard the allocation agreed to between us and 2seventy and require us to assume responsibility for obligations allocated to 2seventy. Third parties could also seek to hold us responsible for any of these liabilities or obligations, and the indemnity rights we have under the separation agreement may not be sufficient to fully cover all of these liabilities and obligations. Even if we are successful in obtaining indemnification, we may have to bear costs temporarily. In addition, our indemnity obligations to 2seventy, including those related to assets or liabilities allocated to us, may be significant. These risks could negatively affect our business, financial condition or results of operations.
 If the distribution of shares of 2seventy, together with certain related transactions, does not qualify as a transaction that is generally tax-free for U.S. federal income tax purposes, we and our stockholders could be subject to significant tax liabilities.
 The completion of the distribution of shares of 2seventy was conditioned upon, among other things, our receipt of a private letter ruling from the U.S. Internal Revenue Service (the "IRS"), and an opinion from Goodwin Procter LLP, both satisfactory to our board of directors and both continuing to be valid, together confirming that the distribution, together with certain related transactions, generally is tax-free for U.S. federal income tax purposes under Sections 355 and 368(a)(1)(D) of the U.S. Internal Revenue Code of 1986, as amended (the "Code"). We have received a favorable private letter ruling from the IRS addressing one significant issue of the qualification of the distribution under Section 355 of the Code. However, the private letter ruling does not address the remaining issues that are relevant to determining whether the distribution, together with certain related transactions, qualifies as a transaction that is generally tax-free for U.S. federal income tax purposes. This can include events that occur following the distribution such as subsequent public offerings by us or 2seventy or share sales to persons that engaged in negotiations over share purchases prior to the distribution. Subsequent tax opinions have been obtained by us and 2seventy in connection with certain post-distribution sales of 2seventy's shares. The IRS private letter ruling, the opinion of Goodwin Procter LLP and tax opinions related to certain subsequent post-distribution sales of 2seventy shares were based, among other things, on various facts and assumptions, as well as certain representations, statements and undertakings from us and 2seventy (including those relating to the past and future conduct of us and 2seventy) and were subject to certain caveats. If any of these facts, assumptions, representations, statements or undertakings is, or becomes, inaccurate or incomplete, or if we or 2seventy breach any of our respective covenants relating to the separation, the IRS private letter ruling and tax opinion may be invalid. Moreover, the opinion is not binding on the IRS or any courts. Accordingly, notwithstanding receipt of the IRS private letter ruling and an opinion of Goodwin Procter LLP at the time of the distribution, the IRS could determine that the distribution and certain related transactions should be treated as taxable transactions for U.S. federal income tax purposes.

 If the distribution, together with certain related transactions, were to fail to qualify as a transaction that is generally tax-free under Sections 355 and 368(a)(1)(D) of the Code, in general, for U.S. federal income tax purposes, we would recognize taxable gain as if we have sold 2seventy's distributed common stock in a taxable sale for its fair market value and our stockholders who receive shares of 2seventy common stock in the distribution would be subject to tax as if they had received a taxable distribution equal to the fair market value of such shares.
 In connection with the distribution, we and 2seventy entered into a tax matters agreement pursuant to which each party is responsible for certain liabilities and obligations following the distribution. In general, under the terms of the tax matters agreement, if the distribution, together with certain related transactions, were to fail to qualify as a transaction that is generally tax-free for U.S. federal income tax purposes under Sections 355 and 368(a)(1)(D) of the Code, and if and to the extent that such failure results from a prohibited change of control in us under Section 355(e) of the Code, or an acquisition of our stock or assets or certain actions, omissions or failures to act, by us, then we will bear any resulting taxes, interest, penalties and other costs. If and to the extent that such failure results from a prohibited change of control in 2seventy under Section 355(e) of the Code or an acquisition of 2seventy stock or assets or certain actions by 2seventy, then 2seventy will be obligated to indemnify us for any resulting taxes, interest, penalties and other costs, including any reductions in our net operating loss carryforwards or other tax assets. If such failure does not result from a prohibited change of control in us or 2seventy under Section 355(e) of the Code and both we and 2seventy are responsible for such failure, liability will be shared according to relative fault. If neither we nor 2seventy is responsible for such failure, we will bear any resulting taxes, interest, penalties and other costs.
 Risks related to our intellectual property
 If we are unable to obtain or protect intellectual property rights related to our products, we may not be able to compete effectively in our markets.
 We rely upon a combination of patents, trade secret protection and confidentiality agreements to protect the intellectual property related to our products. The strength of patents in the biotechnology and pharmaceutical field involves complex legal and scientific questions and can be uncertain. The patent applications that we own or in-license may fail to result in issued patents with claims that cover our products in the United States or in other foreign countries. There is no assurance that all of the potentially relevant prior art relating to our patents and patent applications has been found, which can invalidate a patent or prevent a patent from issuing from a pending patent application. Even if patents do successfully issue and even if such patents cover our products, third parties may challenge their validity, enforceability or scope, which may result in such patents being narrowed or invalidated. Furthermore, even if they are unchallenged, our patents and patent applications may not adequately protect our intellectual property, provide exclusivity for our products or prevent others from designing around our claims. Any of these outcomes could impair our ability to prevent competition from third parties, which may have an adverse impact on our business.
 If the patent applications we hold or have in-licensed with respect to our programs or our products fail to issue, if their breadth or strength of protection is threatened, or if they fail to provide meaningful exclusivity for our products, it could dissuade companies from collaborating with us to develop product candidates, and threaten our ability to commercialize our current and future products. Several patent applications covering our products have been filed recently. We cannot offer any assurances about which, if any, patents will issue, the breadth of any such patent or whether any issued patents will be found invalid and unenforceable or will be threatened by third parties. Any successful opposition to these patents or any other patents owned by or licensed to us could deprive us of rights necessary for the successful commercialization of any future product candidates that we may develop. Further, if we encounter delays in regulatory approvals, the period of time during which we could market a product or product candidate under patent protection could be reduced. Since patent applications in the United States and most other countries are confidential for a period of time after filing, and some remain so until issued, we cannot be certain that we were the first to file any patent application related to a product candidate. Furthermore, if third parties have filed such patent applications, an interference proceeding in the United States can be initiated by a third party to determine who was the first to invent any of the subject matter covered by the patent claims of our applications. In addition, patents have a limited lifespan. In the United States, the natural expiration of a patent is generally 20 years after it is filed. Various extensions may be available however the life of a patent, and the protection it affords, is limited. Even if patents covering our products are obtained, once the patent life has expired for a product, we may be open to competition from generic medications.
 In addition to the protection afforded by patents, we rely on trade secret protection and confidentiality agreements to protect proprietary know-how that is not patentable or that we elect not to patent, processes for which patents are difficult to enforce and any other elements of our product candidate discovery and development processes that involve proprietary know-how, and information or technology that is not covered by patents. However, trade secrets can be difficult to protect. We seek to protect our proprietary technology and processes, in part, by entering into confidentiality agreements with our employees, consultants, scientific advisors and contractors. We also seek to preserve the integrity and confidentiality of our data and trade

 secrets by maintaining physical security of our premises and physical and electronic security of our information technology systems. While we have confidence in these individuals, organizations and systems, agreements or security measures may be breached, and we may not have adequate remedies for any breach. In addition, our trade secrets may otherwise become known or be independently discovered by competitors.
 Although we expect all of our employees and consultants to assign their inventions to us, and all of our employees, consultants, advisors and any third parties who have access to our proprietary know-how, information or technology to enter into confidentiality agreements, we cannot provide any assurances that all such agreements have been duly executed or that our trade secrets and other confidential proprietary information will not be disclosed or that competitors will not otherwise gain access to our trade secrets or independently develop substantially equivalent information and techniques. Misappropriation or unauthorized disclosure of our trade secrets could impair our competitive position and may have a material adverse effect on our business. Additionally, if the steps taken to maintain our trade secrets are deemed inadequate, we may have insufficient recourse against third parties for misappropriating the trade secret. In addition, others may independently discover our trade secrets and proprietary information. For example, the FDA, as part of its Transparency Initiative, is currently considering whether to make additional information publicly available on a routine basis, including information that we may consider to be trade secrets or other proprietary information, and it is not clear at the present time how the FDA's disclosure policies may change in the future, if at all.
 Further, the laws of some foreign countries do not protect proprietary rights to the same extent or in the same manner as the laws of the United States. As a result, we may encounter significant problems in protecting and defending our intellectual property both in the United States and abroad. If we are unable to prevent material disclosure of the non-patented intellectual property related to our technologies to third parties, and there is no guarantee that we will have any such enforceable trade secret protection, we may not be able to establish or maintain a competitive advantage in our market, which could materially adversely affect our business, results of operations and financial condition.
 Third-party claims of intellectual property infringement may prevent or delay our development and commercialization efforts.
 Our commercial success depends in part on our avoiding infringement of the patents and proprietary rights of third parties. There is a substantial amount of litigation, both within and outside the United States, involving patent and other intellectual property rights in the biotechnology and pharmaceutical industries, including patent infringement lawsuits, interferences, oppositions, ex parte reexaminations, post-grant review, and inter partes review proceedings before the U.S. Patent and Trademark Office ("U.S. PTO") and corresponding foreign patent offices. Numerous U.S. and foreign issued patents and pending patent applications, which are owned by third parties, exist in the fields in which we are pursuing development candidates. As the biotechnology and pharmaceutical industries expand and more patents are issued, the risk increases that our products may be subject to claims of infringement of the patent rights of third parties.
 Third parties have asserted and in the future may assert that we are employing their proprietary technology without authorization. For example, as discussed in Part I, Item 3, "Legal Proceedings", San Rocco Therapeutics, LLC, formerly known as Errant Gene Therapeutics, LLC has alleged that our use of the BB305 lentiviral vector, including in connection with the beti-cel program infringes U.S. Patent Nos. 7,541,179 and 8,058,061, and seeks equitable, injunctive and monetary relief, including royalties, treble damages, attorney fees and costs. There may be third-party patents or patent applications with claims to materials, formulations, methods of manufacture or methods for treatment related to the use or manufacture of our product candidates. Because patent applications can take many years to issue, there may be currently pending patent applications which may later result in issued patents that our product candidates may infringe.
 In addition, third parties may obtain patents in the future and claim that use of our technologies infringes upon these patents. If any third-party patents were held by a court of competent jurisdiction to cover the manufacturing process of any of our products, any molecules formed during the manufacturing process or any final product itself, the holders of any such patents may be able to block our ability to commercialize such product unless we obtained a license under the applicable patents, or until such patents expire. Similarly, if any third-party patents were held by a court of competent jurisdiction to cover aspects of our formulations, processes for manufacture or methods of use, including combination therapy, the holders of any such patents may be able to block our ability to develop and commercialize the applicable product unless we obtained a license or until such patent expires. In either case, such a license may not be available on commercially reasonable terms or at all.
 Parties making claims against us may obtain injunctive or other equitable relief, which could effectively block our ability to further commercialize one or more of our products. Defense of these claims, regardless of their merit, would involve substantial litigation expense and would be a substantial diversion of employee resources from our business. In the event of a successful claim of infringement against us, we may have to pay substantial damages, including treble damages and attorney's fees for

 willful infringement, pay royalties, redesign our infringing products or obtain one or more licenses from third parties, which may be impossible or require substantial time and monetary expenditure.
 We may not be successful in obtaining or maintaining necessary rights to gene therapy product components and processes for our programs through acquisitions and in-licenses.
 Presently we have rights to the intellectual property, through licenses from third parties and under patents that we own, to manufacture and commercialize our products. Because our programs may involve additional technologies that may require the use of proprietary rights held by third parties, the growth of our business may depend in part on our ability to acquire, in-license or use these proprietary rights. For instance, we may elect to leverage advancements in complementary technologies such as in reduced toxicity conditioning or in stem cell mobilization. We may be unable to acquire or in-license any compositions, methods of use, processes or other third-party intellectual property rights from third parties that we identify. The licensing and acquisition of third-party intellectual property rights is a competitive area, and a number of more established companies are also pursuing strategies to license or acquire third-party intellectual property rights that we may consider attractive. These established companies may have a competitive advantage over us due to their size, cash resources and greater clinical development and commercialization capabilities.
 For example, we sometimes collaborate with U.S. and foreign academic institutions to accelerate our preclinical research or clinical development under written agreements with these institutions. Typically, these institutions provide us with an option to negotiate a license to any of the institution's rights in technology resulting from the collaboration. Regardless of such right of first negotiation for intellectual property, we may be unable to negotiate a license within the specified time frame or under terms that are acceptable to us. If we are unable to do so, the institution may offer the intellectual property rights to other parties, potentially blocking our ability to pursue our program.
 In addition, companies that perceive us to be a competitor may be unwilling to assign or license rights to us. We also may be unable to license or acquire third-party intellectual property rights on terms that would allow us to make an appropriate return on our investment. If we are unable to successfully obtain rights to required third-party intellectual property rights, our business, financial condition and prospects for growth could suffer.
 If we fail to comply with our obligations in the agreements under which we license intellectual property rights from third parties or otherwise experience disruptions to our business relationships with our licensors, we could lose license rights that are important to our business.
 We are a party to a number of intellectual property license agreements that are important to our business and expect to enter into additional license agreements in the future. Our existing license agreements impose, and we expect that future license agreements will impose, various diligence, milestone payment, royalty and other obligations on us. Pursuant to an intellectual property license agreement with 2seventy, we granted sublicenses to 2seventy to certain existing license agreements. If we fail to comply with our obligations under these agreements, we or 2seventy materially breach these agreements, or we are subject to a bankruptcy, the licensor may have the right to terminate the license, in which event we would not be able to market products covered by the license.
 We may need to obtain licenses from third parties to advance the development of future product candidates or allow commercialization of our products, and we have done so from time to time. We may fail to obtain any of these licenses at a reasonable cost or on reasonable terms, if at all. In that event, we may be required to expend significant time and resources to develop or license replacement technology. If we are unable to do so, we may be unable to develop or commercialize the affected products or product candidates, which could harm our business significantly. We cannot provide any assurances that third-party patents do not exist which might be enforced against our approved products, or future products or product candidates, resulting in either an injunction prohibiting our sales, or, with respect to our sales, an obligation on our part to pay royalties and/or other forms of compensation to third parties.
 In many cases, patent prosecution of our licensed technology is controlled solely by the licensor. If our licensors fail to obtain and maintain patent or other protection for the proprietary intellectual property we license from them, we could lose our rights to the intellectual property or our exclusivity with respect to those rights, and our competitors could market competing products using the intellectual property. In certain cases, we control the prosecution of patents resulting from licensed technology. In the event we breach any of our obligations related to such prosecution, we may incur significant liability to our licensing partners. Licensing of intellectual property is of critical importance to our business and involves complex legal, business and scientific issues and is complicated by the rapid pace of scientific discovery in our industry. Disputes may arise regarding intellectual property subject to a licensing agreement, including:

 • the scope of rights granted under the license agreement and other interpretation-related issues;
 • the extent to which our technology and processes infringe on intellectual property of the licensor that is not subject to the licensing agreement;
 • the sublicensing of patent and other rights under our collaborative development relationships;
 • our diligence obligations under the license agreement and what activities satisfy those diligence obligations;
 • the ownership of inventions and know-how resulting from the joint creation or use of intellectual property by our licensors and us and our partners; and
 • the priority of invention of patented technology.
 If disputes over intellectual property that we have licensed prevent or impair our ability to maintain our current licensing arrangements on acceptable terms, we may be unable to successfully develop and commercialize the affected approved products or product candidates.
 We may be involved in lawsuits to protect or enforce our patents or the patents of our licensors, which could be expensive, time-consuming and unsuccessful.
 Competitors may infringe our patents or the patents of our licensors. To counter infringement or unauthorized use, we may be required to file infringement claims, which can be expensive and time consuming. In addition, in an infringement proceeding, a court may decide that a patent of ours or our licensors is not valid, is unenforceable and/or is not infringed, or may refuse to stop the other party from using the technology at issue on the grounds that our patents do not cover the technology in question. In patent litigation in the United States, defendant counterclaims alleging invalidity and/or unenforceability are commonplace. Grounds for a validity challenge could be an alleged failure to meet any of several statutory requirements, including patent eligible subject matter, lack of novelty, obviousness or non-enablement. Grounds for an unenforceability assertion could be an allegation that someone connected with prosecution of the patent withheld relevant information from the U.S. PTO, or made a misleading statement, during prosecution. Third parties may also raise similar claims before administrative bodies in the United States or abroad, even outside the context of litigation. Such mechanisms include re-examination, post grant review, and equivalent proceedings in foreign jurisdictions (e.g., opposition proceedings). Such proceedings could result in revocation or amendment to our patents in such a way that they no longer cover our product candidates. The outcome following legal assertions of invalidity and unenforceability is unpredictable. With respect to the validity question, for example, we cannot be certain that there is no invalidating prior art, of which we and the patent examiner were unaware during prosecution. If a defendant were to prevail on a legal assertion of invalidity and/or unenforceability, we would lose at least part, and perhaps all, of the patent protection on our products and product candidates. Such a loss of patent protection would have a material adverse impact on our business.
 Interference proceedings provoked by third parties or brought by us may be necessary to determine the priority of inventions with respect to our patents or patent applications or those of our licensors. An unfavorable outcome could require us to cease using the related technology or to attempt to license rights to it from the prevailing party. Our business could be harmed if the prevailing party does not offer us a license on commercially reasonable terms. Our defense of litigation or interference proceedings may fail and, even if successful, may result in substantial costs and distract our management and other employees. We may not be able to prevent, alone or with our licensors, misappropriation of our intellectual property rights, particularly in countries where the laws may not protect those rights as fully as in the United States.
 Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation. There could also be public announcements of the results of hearings, motions or other interim proceedings or developments. If securities analysts or investors perceive these results to be negative, it could have a material adverse effect on the price of our common stock.
 We may be subject to claims that our employees, consultants or independent contractors have wrongfully used or disclosed confidential information of third parties or that our employees have wrongfully used or disclosed alleged trade secrets of their former employers.
 We employ individuals who were previously employed at universities or other biotechnology or pharmaceutical companies, including our competitors or potential competitors. Although we try to ensure that our employees, consultants and

 independent contractors do not use the proprietary information or know-how of others in their work for us, we may be subject to claims that we or our employees, consultants or independent contractors have inadvertently or otherwise used or disclosed intellectual property, including trade secrets or other proprietary information, of any of our employee's former employer or other third parties. Litigation may be necessary to defend against these claims. If we fail in defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights or personnel, which could adversely impact our business. Even if we are successful in defending against such claims, litigation could result in substantial costs and be a distraction to management and other employees.
 We may be subject to claims challenging the inventorship or ownership of our patents and other intellectual property.
 We may also be subject to claims that former employees, collaborators or other third parties have an ownership interest in our patents or other intellectual property. We have had in the past, and we may also have in the future, ownership disputes arising, for example, from conflicting obligations of consultants or others who are involved in developing our products and product candidates. Litigation may be necessary to defend against these and other claims challenging inventorship or ownership. If we fail in defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights, such as exclusive ownership of, or right to use, valuable intellectual property. Such an outcome could have a material adverse effect on our business. Even if we are successful in defending against such claims, litigation could result in substantial costs and be a distraction to management and other employees.
 Obtaining and maintaining our patent protection depends on compliance with various procedural, document submission, fee payment and other requirements imposed by governmental patent agencies, and our patent protection could be reduced or eliminated for non-compliance with these requirements.
 Periodic maintenance fees, renewal fees, annuity fees and various other governmental fees on patents and/or applications will be due to be paid to the U.S. PTO and various governmental patent agencies outside of the United States in several stages over the lifetime of the patents and/or applications. We have systems in place to remind us to pay these fees, and we employ an outside firm and rely on our outside counsel to pay these fees due to non-U.S. patent agencies. The U.S. PTO and various non-U.S. governmental patent agencies require compliance with a number of procedural, documentary, fee payment and other similar provisions during the patent application process. We employ reputable law firms and other professionals to help us comply, and in many cases, an inadvertent lapse can be cured by payment of a late fee or by other means in accordance with the applicable rules. However, there are situations in which non-compliance can result in abandonment or lapse of the patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction. In such an event, our competitors might be able to enter the market and this circumstance would have a material adverse effect on our business.
 Changes in U.S. patent law could diminish the value of patents in general, thereby impairing our ability to protect our potential products.
 As is the case with other biotechnology companies, our success is heavily dependent on intellectual property, particularly patents. Obtaining and enforcing patents in the biotechnology industry involve both technological and legal complexity, and is therefore costly, time consuming and inherently uncertain. In addition, the United States has recently enacted and is currently implementing wide-ranging patent reform legislation. Recent U.S. Supreme Court rulings have narrowed the scope of patent protection available in certain circumstances and weakened the rights of patent owners in certain situations. In addition to increasing uncertainty with regard to our ability to obtain patents in the future, this combination of events has created uncertainty with respect to the value of patents, once obtained. Depending on decisions by the U.S. Congress, the federal courts, and the U.S. PTO, the laws and regulations governing patents could change in unpredictable ways that would weaken our ability to obtain new patents or to enforce our existing patents and patents that we might obtain in the future.
 We may not be able to protect our intellectual property rights throughout the world.
 Filing, prosecuting and defending patents on our products and any future product candidates in all countries throughout the world would be prohibitively expensive, and our intellectual property rights in some countries outside the United States can be less extensive than those in the United States. In addition, the laws of some foreign countries do not protect intellectual property rights to the same extent as federal and state laws in the United States. Consequently, we may not be able to prevent third parties from practicing our inventions in all countries outside the United States, or from selling or importing products made using our inventions in and into the United States or other jurisdictions. Competitors may use our technologies in jurisdictions where we have not obtained patent protection to develop their own products and further, may export otherwise infringing products to territories where we have patent protection, but enforcement is not as strong as that in the United States. These products may compete with our products and our patents or other intellectual property rights may not be effective or sufficient to prevent them from competing.

 Many companies have encountered significant problems in protecting and defending intellectual property rights in foreign jurisdictions. The legal systems of certain countries, particularly certain developing countries, do not favor the enforcement of patents, trade secrets and other intellectual property protection, particularly those relating to biotechnology products, which could make it difficult for us to stop the infringement of our patents or marketing of competing products in violation of our proprietary rights generally. Proceedings to enforce our patent rights in foreign jurisdictions could result in substantial costs and divert our efforts and attention from other aspects of our business, could put our patents at risk of being invalidated or interpreted narrowly and our patent applications at risk of not issuing and could provoke third parties to assert claims against us. We may not prevail in any lawsuits that we initiate and the damages or other remedies awarded, if any, may not be commercially meaningful. Accordingly, our efforts to enforce our intellectual property rights around the world may be inadequate to obtain a significant commercial advantage from the intellectual property that we develop or license.
 Risks related to ownership of our common stock
 The market price of our common stock may be highly volatile, and you may not be able to resell your shares at or above the price at which you purchase them.
 Companies trading in the stock market in general, and The Nasdaq Global Select Market in particular, have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of these companies. Broad market and biotechnology and pharmaceutical industry factors, such as the recent volatility and disruption experienced in the global economy and rising interest and inflation rates, may negatively affect the market price of our common stock, regardless of our actual operating performance.
 The market price of our common stock has been volatile in the past, and may continue to be volatile for the foreseeable future. Our stock price could be subject to wide fluctuations in response to a variety of factors, including the following:
 • adverse results or delays in preclinical or clinical studies;
 • reports of adverse events, either from patients participating in our clinical trials or in connection with sales of our commercial products or other gene therapy products in the market;
 • failure to consummate the Merger Transaction;
 • inability to obtain additional funding;
 • failure to successfully manage and sustain the commercial launch of ZYNTEGLO, SKYSONA or LYFGENIA, including failure to manage our supply chain operations in the coordination and delivery of drug product to patients at qualified treatment centers;
 • failure to obtain sufficient pricing and reimbursement for ZYNTEGLO, SKYSONA or LYFGENIA from private and governmental payers;
 • failure to obtain market acceptance and adoption of ZYNTEGLO, SKYSONA or LYFGENIA;
 • failure to maintain our existing strategic collaborations or enter into new collaborations;
 • failure by us or our licensors and strategic collaboration partners to prosecute, maintain or enforce our intellectual property rights;
 • changes in laws or regulations applicable to future products;
 • inability to obtain adequate product supply for ZYNTEGLO, SKYSONA or LYFGENIA, or the inability to do so at acceptable prices;
 • adverse regulatory decisions;
 • announcements of clinical trial results or progress in the development of programs by our competitors, and the introduction of new products, services or technologies by our competitors;
 • failure to meet or exceed financial projections we may provide to the public;

 • failure to meet or exceed the financial projections of the investment community;
 • the perception of the pharmaceutical industry by the public, legislatures, regulators and the investment community;
 • announcements of significant acquisitions, strategic partnerships, joint ventures or capital commitments by us, our strategic collaboration partner or our competitors;
 • disputes or other developments relating to proprietary rights, including patents, litigation matters and our ability to obtain patent protection for our technologies;
 • additions or departures of key scientific or management personnel;
 • significant lawsuits, including patent or stockholder litigation;
 • changes in the market valuations of similar companies;
 • global macroeconomic conditions, including as impacted by geopolitical conflicts and war;
 • sales of our common stock by us or our stockholders in the future; and
 • trading volume of our common stock.
 The restatement of our consolidated financial statements for the year ended December 31, 2022 and the quarterly periods in the years ended December 31, 2022 and 2023 has subjected us to a number of additional risks and uncertainties, including increased possibility of legal proceedings.
 As discussed elsewhere in this Annual Report, our management determined that our consolidated financial statements for the year ended December 31, 2022 and the quarterly periods in the years ended December 31, 2022 and 2023 should be restated due to errors relating to our accounting for lease arrangements, including embedded leases, and the application of our accounting policy for the treatment of non-lease components in lease arrangements, including embedded leases. The restatement of our consolidated financial statements caused us to incur substantial expenses for legal, accounting, and other professional services. As a result of the restatement, we were delayed in filing our Annual Report on Form 10-K for the year ended December 31, 2023, and our Quarterly Reports on Form 10-Q for each of the three-month periods ended March 31, 2024 and June 30, 2024. There can be no assurance that we will be able to timely file our required reports for future periods. In addition, as a result of the restatement, investors may lose confidence in our financial reporting, the price of our common stock could decline and we may be subject to litigation or regulatory enforcement actions.
 We have identified a material weakness in our internal control over financial reporting and may identify additional material weaknesses in the future or otherwise fail to maintain an effective system of internal controls.
 A material weakness is a deficiency, or a combination of deficiencies, in internal control over financial reporting, such that there is a reasonable possibility that a material misstatement of a company's annual or interim financial statements will not be prevented or detected on a timely basis. We identified a material weakness in our internal controls related to our accounting for lease arrangements, including embedded leases, and the application of our accounting policy for the treatment of non-lease components in lease agreements, including embedded leases. The material weakness resulted in the restatement of the Company's previously issued consolidated financial statements for the year ended December 31, 2022 and the quarterly periods in the years ended December 31, 2022 and 2023. As a result of the material weakness, our management concluded that our internal control over financial reporting was not effective as of December 31, 2023. Additionally, the material weakness in our internal control over financial reporting has resulted in our management concluding that our disclosure controls and procedures were not effective as of December 31, 2023.
 Our management, under the oversight of the Audit Committee of our Board of Directors and in consultation with outside advisors, has begun implementing measures designed to remediate the material weakness. Management has begun to implement enhancements to its internal control over financial reporting, which are expected to include refinements and enhancements to the complement of personnel, design and operation of its controls related to the accounting for, and identification of, leases. The Company began to implement these enhancements to the design of its controls during the fourth quarter of 2024. However, this material weakness will not be considered remediated until management designs and implements effective controls that operate for a sufficient period of time and management has concluded, through testing, that these controls are effective. The Company

 will monitor the effectiveness of the remediation plan and will refine the remediation plan, as needed. Until remediated, the material weakness could result in future errors to the Company's financial statements.
 In addition, we cannot assure you that the measures we are taking will be sufficient to remediate the material weakness or avoid the identification of additional material weaknesses in the future. Our failure to implement and maintain effective internal control over financial reporting could result in the identification of additional errors in our consolidated financial statements that could result in a further restatement of our financial statements and could cause us to fail to meet our periodic reporting obligations, any of which could diminish investor confidence in us, cause a decline in the price of our common stock and subject us to litigation or regulatory enforcement actions.
 Actual or potential sales of our common stock by our employees, including our executive officers, pursuant to pre-arranged stock trading plans could cause our stock price to fall or prevent it from increasing for numerous reasons, and actual or potential sales by such persons could be viewed negatively by other investors.
 In accordance with the guidelines specified under Rule 10b5-1 of the Securities Exchange Act of 1934, as amended, and our policies regarding stock transactions, a number of our employees, including executive officers and members of our board of directors, have adopted and may continue to adopt stock trading plans pursuant to which they have arranged to sell shares of our common stock from time to time in the future. Generally, sales under such plans by our executive officers and directors require public filings. Actual or potential sales of our common stock by such persons could cause the price of our common stock to fall or prevent it from increasing for numerous reasons.
 Future sales and issuances of our common stock or rights to purchase common stock, including pursuant to our equity incentive plans, could result in additional dilution of the percentage ownership of our stockholders and could cause our stock price to fall.
 Additional capital will be needed in the future to continue our planned operations. To the extent we raise additional capital by issuing equity securities, our stockholders may experience substantial dilution. We may sell common stock, convertible securities or other equity securities in one or more transactions at prices and in a manner we determine from time to time. If we sell common stock, convertible securities or other equity securities, investors may be materially diluted by subsequent sales. These sales may also result in material dilution to our existing stockholders, and new investors could gain rights superior to our existing stockholders.
 Pursuant to our 2023 Incentive Award Plan (as amended and restated, the "2023 Plan") we are authorized to grant stock options and other equity-based awards to our employees, directors and consultants. The 2023 Plan authorizes the issuance of up to 1.01 million shares. We also make equity grants to certain new employees joining the Company pursuant to an inducement plan, and our compensation committee may elect to increase the number of shares available for future grant under the inducement plan without stockholder approval. We also have an Employee Stock Purchase Plan and any shares of common stock purchased pursuant to that plan will also cause dilution.
 We may be subject to litigation, which may result in substantial costs and a diversion of management's attention and resources, which could harm our business.
 In the past, securities class action litigation has often been brought against a company following a decline in the market price of its securities. We are currently litigating, and have in the past litigated, class action complaints filed by purported stockholders against us and certain of our directors and officers. For instance, on March 28, 2024, a class action lawsuit captioned Garry Gill v. bluebird bio, Inc. et al., Case No. 1:24-cv-10803-PBS, was filed against us in the United States District Court for the District of Massachusetts and we may face additional securities class action litigation in the future. This risk is especially relevant for us because biotechnology and pharmaceutical companies have experienced significant stock price volatility in recent years, and we expect to experience continued stock price volatility. Separately, two purported bluebird shareholders, derivatively and purportedly on behalf of bluebird, have each filed a shareholder derivative action in the United States District Court for the District of Massachusetts against our directors and certain members of management alleging, among other things, breaches of their fiduciary duties. In addition, we are subject to certain litigation in connection with the Merger Transaction. See also "Risk Factors - Securities class action and derivative lawsuits in connection with the Merger Transaction could result in substantial costs and prevent or delay the consummation of the Merger Transaction". Defending against our current and any future litigation could result in substantial costs and a diversion of management's attention and resources, which could harm our business.
 We are also a party to litigation and subject to claims incident to the ordinary course of business. The outcome of litigation is inherently unpredictable and an adverse result in any litigation could materially harm our financial condition, reputation and

 business. Regardless of the outcome, litigation can have an adverse impact on us because of defense costs, diversion of management resources and other factors.
 Our ability to use our net operating loss carryforwards and certain other tax attributes may be limited.
 Under Sections 382 and 383 of the Code, if a corporation undergoes an "Ownership Change," generally defined as a cumulative change of greater than 50% (by value) in its equity ownership over a three-year period, the corporation's ability to use its pre-change net operating loss carryforwards ("NOLs") and other pre-change tax attributes (such as research and development tax credits) to offset its post-change income and taxes may be limited. We have completed several financings since our inception, which we believe have resulted in shifts in our equity ownership. We completed a study through December 2023 confirming no Ownership Changes have occurred since our initial public offering in 2013. We may have experienced Ownership Changes since December 2023, and we may also experience Ownership Changes in the future as a result of subsequent shifts in our equity ownership, some of which are outside our control. There is a significant likelihood that we will experience an Ownership Change as a result of future equity offerings, although whether we experience an Ownership Change will depend on the specific facts that apply at the time of any offering. If finalized, Treasury Regulations currently proposed under Section 382 of the Code may further limit our ability to utilize our pre-change NOLs or other pre-change tax attributes if we undergo a future Ownership Change. Accordingly, if we earn net taxable income, our ability to use our pre-change NOLs and other pre-change tax attributes to offset U.S. federal taxable income may be subject to limitations, which could potentially result in significant increased future tax liability to us, which could materially adversely affect our profitability and cash position. In addition, at the state level, there may be periods during which the use of NOLs and other pre-change tax attributes is suspended or otherwise limited, which could accelerate or permanently increase state taxes owed.
 We do not intend to pay cash dividends on our common stock so any returns will be limited to the value of our stock.
 We have never declared or paid any cash dividends on our common stock. We currently anticipate that we will retain future earnings for the development, operation and expansion of our business and do not anticipate declaring or paying any cash dividends for the foreseeable future. Any return to stockholders will therefore be limited to the appreciation of their stock. The Merger Agreement also generally restricts our ability to pay any dividends on our common stock during the interim period between the execution of the Merger Agreement and the effective time of the Merger Transaction (or the date on which the Merger Agreement is earlier terminated).
 Provisions in our amended and restated certificate of incorporation and by-laws, as well as provisions of Delaware law, could make it more difficult for a third-party to acquire us or increase the cost of acquiring us, even if doing so would benefit our stockholders or remove our current management.
 Our amended and restated certificate of incorporation, amended and restated by-laws and Delaware law contain provisions that may have the effect of delaying or preventing a change in control of us or changes in our management. Our amended and restated certificate of incorporation and by-laws, include provisions that:
 • authorize "blank check" preferred stock, which could be issued by our board of directors without stockholder approval and may contain voting, liquidation, dividend and other rights superior to our common stock;
 • create a classified board of directors whose members serve staggered three-year terms;
 • specify that special meetings of our stockholders can be called only by our board of directors, the chairperson of our board of directors, our chief executive officer or our president;
 • prohibit stockholder action by written consent;
 • establish an advance notice procedure for stockholder approvals to be brought before an annual meeting of our stockholders, including proposed nominations of persons for election to our board of directors;
 • provide that our directors may be removed only for cause;
 • provide that vacancies on our board of directors may be filled only by a majority of directors then in office, even though less than a quorum;
 • specify that no stockholder is permitted to cumulate votes at any election of directors;

 • expressly authorize our board of directors to modify, alter or repeal our amended and restated by-laws; and
 • require supermajority votes of the holders of our common stock to amend specified provisions of our amended and restated certificate of incorporation and amended and restated by-laws.
 These provisions, alone or together, could delay or prevent hostile takeovers and changes in control or changes in our management.
 In addition, because we are incorporated in Delaware, we are governed by the provisions of Section 203 of the Delaware General Corporation Law, which limits the ability of stockholders owning in excess of 15% of our outstanding voting stock to merge or combine with us.
 Any provision of our amended and restated certificate of incorporation or amended and restated by-laws or Delaware law that has the effect of delaying or deterring a change in control could limit the opportunity for our stockholders to receive a premium for their shares of our common stock, and could also affect the price that some investors are willing to pay for our common stock.
 Our amended and restated certificate of incorporation and amended and restated by-laws designate specific courts as the exclusive forum for certain litigation that may be initiated by our stockholders, which could limit our stockholders' ability to obtain a favorable judicial forum for disputes with us.
 Our amended and restated certificate of incorporation and amended and restated by-laws specify that, unless we consent in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware will be the sole and exclusive forum for most legal actions involving claims brought against us by stockholders, other than suits brought to enforce any liability or duty created by the Securities Exchange Act of 1934, as amended (the "Exchange Act") or any other claim for which the federal courts have exclusive jurisdiction and any action that the Court of Chancery of the State of Delaware has dismissed for lack of subject matter jurisdiction, which may be brought in another state or federal court sitting in the State of Delaware. Our amended and restated by-laws also specify that, unless we consent in writing to the selection of an alternate forum, the United States District Court for the District of Massachusetts shall be the sole and exclusive forum for the resolution of any complaint asserting a cause of action arising under the Securities Act of 1933, as amended (the "Securities Act"). Any person or entity purchasing or otherwise acquiring any interest in shares of our capital stock shall be deemed to have notice of and to have consented to the provisions of our amended and restated certificate of incorporation and amended and restated by-laws described above.
 We believe these provisions benefit us by providing increased consistency in the application of Delaware law by chancellors particularly experienced in resolving corporate disputes or federal judges experienced in resolving Securities Act disputes, efficient administration of cases on a more expedited schedule relative to other forums and protection against the burdens of multi-forum litigation. However, the provision may have the effect of discouraging lawsuits against our directors, officers, employees, and agents as it may limit any stockholder's ability to bring a claim in a judicial forum that such stockholder finds favorable for disputes with us or our directors, officers, employees, or agents and result in increased costs for stockholders to bring a claim. The enforceability of similar choice of forum provisions in other companies' certificates of incorporation and by-laws has been challenged in legal proceedings, and it is possible that, in connection with any applicable action brought against us, a court could find the choice of forum provisions contained in our amended and restated certificate of incorporation and amended and restated by-laws to be inapplicable or unenforceable in such action. If a court were to find the choice of forum provision contained in our amended and restated certificate of incorporation or amended and restated by-laws to be inapplicable or unenforceable in an action, we may incur additional costs associated with resolving such action in other jurisdictions, which could adversely affect our business, financial condition, or results of operations.
 Changes in tax law and regulations could adversely affect our business, financial condition and results of operations.
 New income, sales, use or other tax laws, statutes, rules, regulations or ordinances could be enacted at any time, which could affect the tax treatment of any of our future earnings. Further, existing tax laws, statutes, rules, regulations or ordinances could be interpreted, changed, modified or applied adversely to us. Generally, future changes in applicable tax laws and regulations, or their interpretation and application, potentially with retroactive effect, could have an adverse effect on our business, financial conditions and results of operations. We are unable to predict whether such changes will occur and, if so, the ultimate impact on our business. We urge investors to consult with their legal and tax advisers regarding the implications of potential changes in tax laws on an investment in our common stock.

 Unstable market and economic conditions may have serious adverse consequences on our business, financial condition and share price.
 The global economy, including credit and financial markets, has recently experienced extreme volatility and disruptions, including severely diminished liquidity and credit availability, fluctuating interest and inflation rates, declines in consumer confidence, declines in economic growth, increases in unemployment rates, geopolitical conflicts and war, and uncertainty about economic stability. If the equity and credit markets continue to deteriorate or the United States enters a recession, it may make any necessary debt or equity financing more difficult to obtain in a timely manner or on favorable terms, more costly or more dilutive. In addition, there is a risk that one or more of our CROs, suppliers or other third-party providers may not survive an economic downturn or recession. As a result, our business, results of operations and price of our common stock may be adversely affected.

 Item 1B. Unresolved Staff Comments
 Not applicable.

 Item 1C. Cybersecurity
 Cybersecurity Risk Management and Strategy
 We have developed and implemented a cybersecurity risk management program intended to protect the confidentiality, integrity, and availability of our critical systems and information. Our cybersecurity risk management program includes a cybersecurity incident response plan.
 We design and assess our program based on the National Institute of Standards and Technology Cybersecurity Framework (NIST CSF). This does not imply that we meet any particular technical standards, specifications, or requirements, only that we use the NIST CSF as a guide to help us identify, assess, and manage cybersecurity risks relevant to our business.
 We evaluate cybersecurity risk as part of our overall enterprise risk management program, using systematic methodologies, reporting channels and governance processes that apply across the broader enterprise risk management program.
 Our cybersecurity risk management program includes:
 • risk assessments designed to help identify material cybersecurity risks to our critical systems, information, products, services, and our broader enterprise information technology environment;
 • a security team principally responsible for managing (1) our cybersecurity risk assessment processes, (2) our security controls, and (3) our response to cybersecurity incidents;
 • the use of external service providers, where appropriate, to assess, test or otherwise assist with aspects of our security controls;
 • cybersecurity awareness training of our employees, incident response personnel, and senior management, including training on best practices for data privacy and security and safekeeping of patient information;
 • a cybersecurity incident response plan that includes procedures for responding to cybersecurity incidents; and
 • a third-party risk management process for information technology software service providers, suppliers, and vendors that have access to our critical systems and information.
 We have not identified risks from known cybersecurity threats, including as a result of any prior cybersecurity incidents, that have materially affected or are reasonably likely to materially affect us, including our operations, business strategy, results of operations, or financial condition. For more information, see the section titled "Risk Factor— Our information technology systems, or those of our third-party collaborators, service providers, contractors or consultants, may fail or suffer security breaches, which could result in a material disruption of our product candidates' development programs and activities related to our approved products and have a material adverse effect on our reputation, business, financial condition or results of operations."

 Cybersecurity Governance
 Our Board considers cybersecurity risk as part of its risk oversight function and has delegated to the Audit Committee oversight of cybersecurity and other information technology risks. The Audit Committee oversees management's implementation of our cybersecurity risk management program.
 The Audit Committee receives periodic reports from management on our cybersecurity risks. In addition, management updates the Audit Committee, as necessary, regarding any material cybersecurity incidents, as well as any incidents with lesser impact potential.
 The Audit Committee reports to the full Board regarding its activities, including those related to cybersecurity. The full Board also receives briefings from management on our cyber risk management program. Board members receive presentations on cybersecurity topics from our Head of Information Technology, internal security staff or external experts as part of the Board's continuing education on topics that impact public companies.
 Our Head of Information Technology and our Head of Information Security are responsible for assessing and managing our material risks from cybersecurity threats. The team has primary responsibility for our overall cybersecurity risk management program and supervises both our internal cybersecurity personnel and our retained external cybersecurity consultants. Our Head of Information Technology's experience includes 25 years in managing information technology departments, including four years specifically in cybersecurity and five years with the Company. Our Head of Information Security's experience includes 13 years in managing information technology departments, including 12 years specifically in cybersecurity and seven months with the Company.
 Our management team supervises efforts to prevent, detect, mitigate, and remediate cybersecurity risks and incidents through various means, which may include briefings from internal security personnel; threat intelligence and other information obtained from governmental, public or private sources, including external consultants engaged by us; and alerts and reports produced by security tools deployed in the information technology environment.

 Item 2. Properties
 Below is a summary of our material owned and leased properties as of December 31, 2024:
 Our current corporate headquarters encompasses approximately 61,180 square feet of office space and is located at 455 Grand Union Boulevard, Somerville, Massachusetts. The lease commenced in March 2022 and will continue until December 31, 2032.
 In October 2022, we entered into a sublease with Finch Therapeutics, Inc. ("Finch") for 42,162 square feet of office and laboratory space at Finch's corporate headquarters located at 100 Hood Park Drive, Charlestown, Massachusetts which Finch leases from Hood Park, LLC. This space is primarily used for our laboratory space. This sublease commenced December 15, 2022 and is expected to terminate on December 14, 2025.
 In April 2019, we entered into a sublease agreement for approximately 267,278 square feet of office space located at 50 Binney Street, Cambridge, Massachusetts. In December 2021, we entered into a sub-sublease agreement with Meta Platforms, Inc. to sublease the entirety of the 50 Binney Street premises which we have rights to under the sublease. The sub-sublease commenced April 1, 2022, and was terminated in February 2025. Refer to Note 21, Subsequent Events, for further information.
 We believe that our existing facilities are adequate for our current needs.

 Item 3. Legal Proceedings
 In the ordinary course of business, we are from time to time involved in lawsuits, claims, investigations, proceedings, and threats of litigation relating to intellectual property, commercial arrangements, employment and other matters. The outcome of these proceedings and claims cannot be predicted with certainty. We believe no governmental proceedings are pending or, to our knowledge, contemplated against us. We are not a party to any material proceedings in which any director, member of senior management or affiliate of ours is either a party adverse to us or our subsidiaries or has a material interest adverse to us or our subsidiaries.

 On October 21, 2021, San Rocco Therapeutics, LLC, formerly known as Errant Gene Therapeutics, LLC, filed a complaint against us in the United States District Court for the District of Delaware for alleged infringement of U.S. Patent Nos. 7,541,179 and 8,058,061. The term of U.S. Patent No. 8,058,061 already expired on November 25, 2022, and U.S. Patent No. 7,541,179 expired on May 13, 2024. The allegations relate to our use of the BB305 lentiviral vector, including in connection with the beti-cel program and seeks injunctive relief and money damages. On February 21, 2022, the parties stipulated to amend the case caption, in light of the plaintiff's name change, from Errant Gene Therapeutics, LLC to San Rocco Therapeutics, LLC ("SRT"). The Court granted this stipulation and, accordingly, the case is now captioned, San Rocco Therapeutics, LLC v. bluebird bio, Inc. and Third Rock Ventures, LLC, C.A. No. 21-1478-RGA. On April 6, 2022, we—along with Third Rock Ventures, LLC—filed a motion seeking various relief including to stay the proceedings and compel arbitration on two threshold issues, which we argued warranted complete dismissal of the action as a matter of law, regardless of the merits of SRT's underlying infringement claims. On July 26, 2022, the Court granted our request to stay the proceedings and issued an Order compelling the parties to arbitrate the threshold issues we raised. On February 7, 2023, the Arbitrator issued a final award finding in favor of SRT on both threshold issues, thereby enabling SRT to pursue its claims for alleged infringement. On March 1, 2023, the parties jointly stipulated, subject to the approval of the United States District Court for the District of Delaware, to lift the stay. The Court lifted the stay on March 2, 2023, and on March 31, 2023, we filed our answer to SRT's complaint with counterclaims asserting that we do not infringe the patents-in-suit and that the patents-in-suit are invalid. Also, on April 22, 2024, the Patent Trial & Appeal Board of the U.S. PTO found that our two petitions for inter partes review did not show by a preponderance of the evidence that the challenged claims of the patents-in-suit are unpatentable, and we filed notices of appeal with the U.S. Court of Appeals for the Federal Circuit on June 21, 2024. Our opening brief was filed on December 20, 2024, SRT's responsive brief is due March 28, 2025, and our reply brief is due May 19, 2025. On June 17, 2024, the Court entered a claim construction order in bluebird's favor. On July 17, 2024, the Court granted our request for leave to file a case-dispositive motion for summary judgment of noninfringement, and on July 25, 2024, the Court ordered a stay of discovery pending a decision on the summary judgment motion. On August 1, 2024, we filed our motion for summary judgment of noninfringement, SRT filed an opposition on September 3, 2024 and we filed our reply on September 17, 2024. Briefing is now complete, and oral argument is scheduled for April 23, 2025. We plan to vigorously defend against SRT's claims in this action.
 On March 28, 2024, a class action lawsuit captioned Garry Gill v. bluebird bio, Inc. et al., Case No. 1:24-cv-10803-PBS (the "Gill Action"), was filed against us in the United States District Court for the District of Massachusetts. An amended complaint was filed on August 15, 2024. The amended complaint purports to assert claims against us and certain of our current and former officers pursuant to Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and Rule 10b-5 promulgated thereunder, on behalf of a putative class of investors who purchased or otherwise acquired the Company's shares between April 24, 2023 and December 8, 2023 (the "class period"). Plaintiff seeks to recover damages allegedly caused by purported misstatements and omissions regarding (i) whether the Company could obtain FDA approval for the lovo-cel BLA without a black box warning for hematologic malignancies; and (ii) whether the Company would be granted a priority review voucher by the FDA in connection with the BLA, which it could sell in order to strengthen its financial position. The amended complaint claims these alleged statements and omissions operated to artificially inflate the price paid for our common stock during the class period. On September 2, 2024, the Court entered the parties' stipulated schedule for briefing a motion to dismiss the amended complaint. Our opening brief in support of a motion to dismiss was filed on October 11, 2024; Plaintiff filed an opposition on December 5, 2024; and we filed our reply brief on December 20, 2024. The Court held oral argument on our motion to dismiss on January 14, 2025 and took our motion under advisement. We intend to vigorously defend against the claims in this action.
 On June 27, 2024, a shareholder derivative lawsuit captioned imaitis v. Obenshain et al., Case No. 1:24-cv-11674-PBS, was filed nominally on our behalf against certain current and former members of Company management and the Board of Directors in the United States District Court for the District of Massachusetts. The complaint purports to assert derivative claims pursuant to Sections 10(b), 14(a), and 21D of the Securities Exchange Act of 1934, as well as for breach of fiduciary duties, unjust enrichment, waste of corporate assets, gross mismanagement, and abuse of control. Plaintiff seeks to recover damages on our behalf allegedly caused by purported materially false and misleading public statements and omissions, including in the April 28, 2023 proxy statement, regarding (i) whether the Company could obtain FDA approval for the lovo-cel BLA without a black box warning for hematologic malignancies; and (ii) whether the Company would be granted a priority review voucher by the FDA in connection with the BLA, which it could sell in order to strengthen its financial position. The complaint claims these allegedly misleading statements and omissions operated to artificially inflate the Company's common stock price during the relevant time period. To support its derivative claims, the complaint alleges that a legally required pre-suit demand on the Board would be futile and should be excused. On July 25, 2024, the case was consolidated with Syracuse v. Obenshain et al., Case No. 1:24-cv-11752 (D. Mass. July 8, 2024). The consolidated actions were recaptioned In re bluebird bio, Inc. Stockholder Derivative Litigation, Case No. 1:24-cv-11674-PBS. On September 19, 2024, the consolidated case was stayed pending resolution of the motion to dismiss filed in the Gill Action.

 On July 8, 2024, a shareholder derivative lawsuit captioned Syracuse v. Obenshain et al., Case No. 1:24-cv-11752-PBS, was filed nominally on our behalf against certain current and former members of Company management and the Board of Directors in the United States District Court for the District of Massachusetts. The complaint purports to assert derivative claims against pursuant to Section 14(a) of the Securities Exchange Act of 1934, as well as for breach of fiduciary duties, gross mismanagement, waste of corporate assets, and unjust enrichment. Plaintiff seeks to recover damages on our behalf allegedly caused by purported materially false and misleading public statements and omissions, including in the April 28, 2023 proxy statement, regarding (i) whether the Company could obtain FDA approval for the lovo-cel BLA without a black box warning for hematologic malignancies; and (ii) whether the Company would be granted a priority review voucher by the FDA in connection with the BLA, which it could sell in order to strengthen its financial position. The complaint claims these allegedly misleading statements and omissions operated to artificially inflate the Company's common stock price during the relevant time period. To support its derivative claims, the complaint alleges that a legally required pre-suit demand on the Board would be futile and should be excused. On July 25, 2024, the case was consolidated with imaitis v. Obenshain et al., Case No. 24-cv-11674 (D. Mass. July 27, 2024). The consolidated actions were recaptioned In re bluebird bio, Inc. Stockholder Derivative Litigation, Case No. 1:24-cv-11674-PBS. On September 19, 2024, the consolidated case was stayed pending resolution of the motion to dismiss filed in the Gill Action.
 As of the filing of this Annual Report on Form 10-K, four purported stockholders have filed lawsuits relating to the Merger Transaction (the "Lawsuits"): one on March 10, 2025, captioned Laughlin et al. v. bluebird bio, Inc., et al., No. 1:25-cv-02497 (N.D. Ill.); one on March 13, 2025, captioned Jones v. bluebird bio, Inc., et al., No. 651420/2025 (Sup. Ct. N.Y. Cnty.); two on March 17, 2025, captioned Kent v. bluebird bio, Inc., et al., No. 651424/2025 (Sup. Ct. N.Y. Cnty.), and Smith v. bluebird bio, Inc., et al., No. 1:25-cv-02802 (N.D. Ill.). Additionally, fifteen purported stockholders of bluebird have sent demand letters to the Company related to the Merger Transaction (the "Demand Letters"). Collectively, the Lawsuits and Demand Letters are referred to herein as the "Actions".
 The Lawsuits assert violations of Sections 14(d) and 14(e) of the Securities Exchange Act of 1934 and Rule 14d-9 promulgated thereunder, as well as claims under New York law for negligence and negligent misrepresentation and concealment. The Lawsuits seek injunctive relief to enjoin the merger, rescission or rescissory damages if the Merger Transaction is consummated, an order directing compliance with federal securities laws, and awards of attorneys' and experts' fees.
 The Actions additionally allege that the tender offer statement and recommendation statement filed by the Company with the U.S. Securities and Exchange Commission ("SEC") are materially incomplete and misleading due to alleged omissions relating to, among other things: (i) the Company's historical price data and stock trading history; (ii) the Company's financial projections, including net revenue forecasts and standalone business plans; (iii) financial analyses underlying the fairness opinion provided by the Company's financial advisor, Leerink Partners LLC ("Leerink Partners"); (iv) potential conflicts of interest involving Company insiders and Leerink Partners; (v) discussions regarding employment or retention of Company management; (vi) the sales process and background of the proposed transaction; and (vii) details concerning the Company's Transaction Committee.
 We believe that the disclosures contained in the tender offer statement and recommendation statement comply fully with all applicable laws. We deny the allegations in the Actions and intend to vigorously defend against them.

 Item 4. Mine Safety Disclosures
 Not applicable.

 Item 5. Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities
 Our common stock has been traded on the Nasdaq Global Select Market under the symbol "BLUE."
 Stock Performance Graph
 The graph set forth below compares the cumulative total stockholder return on our common stock between December 31, 2019 and December 31, 2024, with the cumulative total return of (a) the Nasdaq Biotechnology Index and (b) the Nasdaq Composite Index, over the same period. This graph assumes the investment of $100 on December 31, 2019 of our common stock, the Nasdaq Biotechnology Index and the Nasdaq Composite Index and assumes the reinvestment of dividends, if any.
 The comparisons shown in the graph below are based upon historical data. We caution that the stock price performance shown in the graph below is not necessarily indicative of, nor is it intended to forecast, the potential future performance of our common stock.

 Holders
 As of March 25, 2025, there were approximately 8 holders of record of our common stock. The actual number of stockholders is greater than this number of record holders, and includes stockholders who are beneficial owners, but whose shares are held in street name by brokers and other nominees. This number of holders of record also does not include stockholders whose shares may be held in trust by other entities.
 Dividends
 We have not paid any cash dividends on our common stock since inception and do not anticipate paying cash dividends in the foreseeable future.
 Securities Authorized for Issuance Under Equity Compensation Plans
 Information about our equity compensation plans is provided in Item 12 of Part III of this Annual Report on Form 10-K.

 Item 6. Reserved

 Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations
 The following is a discussion of the results of operations for our fiscal years ended December 31, 2024 and 2023, and changes in financial condition during those years. The following information should be read in conjunction with the consolidated financial statements and related notes thereto included in this Annual Report on Form 10-K.
 In addition to historical information, this report contains forward-looking statements that involve risks and uncertainties which may cause our actual results to differ materially from plans and results discussed in forward-looking statements. We encourage you to review the risks and uncertainties discussed in the sections entitled Item 1A. "Risk Factors" and "Forward-Looking Statements" included at the beginning of this Annual Report on Form 10-K. The risks and uncertainties can cause actual results to differ significantly from those forecast in forward-looking statements or implied in historical results and trends.
 We caution readers not to place undue reliance on any forward-looking statements made by us, which speak only as of the date they are made. We disclaim any obligation, except as specifically required by law and the rules of the SEC, to publicly update or revise any such statements to reflect any change in our expectations or in events, conditions or circumstances on which any such statements may be based, or that may affect the likelihood that actual results will differ from those set forth in the forward-looking statements.

 Overview
 We are a biotechnology company committed to commercializing potentially curative gene therapies for severe genetic diseases based on our proprietary lentiviral vector ("LVV") gene addition platform. We currently market three gene therapies: ZYNTEGLO (betibeglogene autotemcel, also known as beti-cel), SKYSONA (elivaldogene autotemcel, also known as eli-cel), both of which received approval from the U.S. Food and Drug Administration (the "FDA") in 2022, and LYFGENIA (lovotibeglogene autotemcel, also known as lovo-cel), which received approval from the FDA in December 2023.
 The FDA approved ZYNTEGLO for the treatment of adult and pediatric patients with -thalassemia who require regular red blood cell transfusions on August 17, 2022. The FDA granted accelerated approval of SKYSONA to slow the progression of neurologic dysfunction in boys 4-17 years of age with early, active cerebral adrenoleukodystrophy ("CALD") on September 16, 2022. On December 8, 2023, the FDA approved LYFGENIA for the treatment of patients 12 years of age or older with sickle cell disease ("SCD") and a history of vaso-occlusive-events.
 We are focusing our commercialization efforts in the U.S. market. We are continuing the long-term follow-up of patients previously enrolled within the clinical trial programs in Europe as planned but do not intend to initiate any new clinical trials in Europe for -thalassemia, CALD or SCD.
 Since our inception in 1992, we have devoted substantially all of our resources to our development and commercialization efforts relating to our products and product candidates, including activities to manufacture products and product candidates in compliance with good manufacturing practices ("GMP") to conduct clinical studies of our product candidates, to provide selling, general and administrative support for these operations, to market, commercially manufacture and distribute our approved products and to protect our intellectual property. We have funded our operations primarily through the sale of common stock in our public offerings, issuance of warrants, the sale of two Rare Pediatric Disease Priority Review Vouchers ("PRVs"), debt financing agreements, and through collaborations.
 In August 2022 and September 2022, we received the two PRVs under an FDA program intended to encourage the development of treatments for rare pediatric diseases. In the fourth quarter of 2022, we sold our first PRV for aggregate net proceeds of $102.0 million. In the first quarter of 2023, we sold our second PRV for aggregate net proceeds of $92.9 million, inclusive of additional legal costs incurred.
 In the first quarter of 2023, we sold 1.2 million shares of common stock (inclusive of shares sold pursuant to an option to the underwriters in connection with the offering) through an underwritten public offering at a price of $120.00 per share for aggregate net proceeds of $130.5 million, inclusive of additional offering costs incurred. In the fourth quarter of 2023, we sold 4.2 million shares of common stock through an underwritten public offering at a price of $30.00 per share for aggregate net proceeds of $118.1 million, after deducting for offering costs.
 In March 2024, we entered into a five-year term loan facility agreement with Hercules Capital, Inc. to secure debt financing for up to $175.0 million, available in four tranches. We amended this loan agreement on April 30, 2024, July 9, 2024, August 13, 2024, August 29, 2024 and February 21, 2025.

 In September 2024, we announced that we were initiating a restructuring action (the "Restructuring") following a comprehensive review of our operations. The Restructuring is anticipated to reduce our cash operating expenses by approximately 20% when fully realized in the third quarter of 2025, compared to the prior reporting period. The Restructuring included a reduction of our workforce by approximately 25% of employees during the fourth quarter of 2024. Refer to Note 19, Reduction in workforce to our condensed consolidated financial statements appearing elsewhere in this Annual Report on Form 10-K for more information on the Restructuring. Additionally, in the ordinary course of business and in light of our limited financial resources, we regularly review our headcount and have eliminated, and may continue to eliminate, additional roles in an effort to optimize our cost structure.
 As of December 31, 2024, we had cash and cash equivalents of approximately $62.3 million. Absent the sale of our PRVs, we have never been profitable and have incurred net losses in each year since inception. Our net loss was $240.7 million for the year ended December 31, 2024 and our accumulated deficit was $4.5 billion as of December 31, 2024. Substantially all of our net losses resulted from costs incurred in connection with our research and development programs, and from selling, general and administrative costs associated with our operations, and cost of product revenue. We expect to continue to incur significant expenses and operating losses for the foreseeable future, if and as we:
 • fund activities related to the commercialization of ZYNTEGLO, SKYSONA, and LYFGENIA in the United States;
 • scale our manufacturing capabilities in support of the commercialization of ZYNTEGLO, SKYSONA, and LYFGENIA;
 • conduct clinical studies; and
 • continue research and development-related activities for severe genetic diseases.
 Because of the numerous risks and uncertainties associated with product development and commercialization, we are unable to predict the timing or amount of increased expenses or when or if we will be able to achieve or maintain profitability. We may not be able to generate substantial revenue from the sale of our products, and we may not become profitable. If we fail to become profitable or are unable to sustain profitability on a continuing basis, then we may be unable to continue our operations at planned levels and be forced to reduce our operations. Until we reach profitability, if ever, we expect to continue to seek to fund our operations through public or private equity or debt financings, strategic collaborations, or other sources. However, we may be unable to raise additional funds or enter into such other arrangements when needed on favorable terms or at all. Our failure to raise capital or enter into such other arrangements as and when needed would have a negative impact on our financial condition and our business.
 Business update
 We had cash and cash equivalents of approximately $62.3 million as of December 31, 2024. If the Merger Transaction (as defined below) does not close, we will continue to generate operating losses and negative operating cash flows for the foreseeable future as we continue to commercialize ZYNTEGLO, SKYSONA, and LYFGENIA and we will require the need for additional funding to support our planned operations before becoming profitable.
 On February 21, 2025, we announced that we entered into an Agreement and Plan of Merger (the "Merger Agreement") with Beacon Parent Holdings, L.P., a Delaware limited partnership ("Parent"), and Beacon Merger Sub, Inc., a Delaware corporation ("Merger Sub"). Pursuant to the Merger Agreement, Merger Sub will conduct a cash a tender offer to acquire any and all of the outstanding shares of our common stock, for (i) $3.00 in cash per share, plus (ii) one contingent value right (each, a "CVR") per share, representing the right to receive a non-tradeable contingent payment of $6.84 in cash, in each case subject to any applicable withholding taxes and without interest thereon (the "Merger Transaction"). On March 7, 2025, Parent and Merger Sub commenced a cash tender offer to acquire any and all of the outstanding shares of our common stock. We expect the Merger Transaction will be completed in the first half of 2025, and as such, it is not included in our going concern assessment.
 We have also entered into amendments to our term loan facility with Hercules Capital, Inc. ("Hercules") to facilitate adequate liquidity to position us to maintain operations through the closing of the Merger Transaction.
 Based on current forecasts, which assume continued cost-saving initiatives, continued deferment of certain payments to vendors, and continued collaborative engagement from Hercules, we expect our existing cash and cash equivalents will enable us to fund our operations into the second quarter of 2025 and through the closing of the Merger Transaction. If we do not complete the Merger Transaction within the expected timeframe, or at all, we will be at risk of liquidation or bankruptcy.

 We have based our cash runway estimate on assumptions of revenues and operating costs that may prove to be wrong. Our cash runway estimate does not include use of our restricted cash, which as of December 31, 2024 was $43.6 million. In February 2025, $30.1 million of our restricted cash was released; the remaining $13.5 million of restricted cash is unlikely to be released in the near term. In addition, our future net product revenues will depend upon the demand for our products; the size of the markets for our products; our ability to achieve and maintain sufficient market acceptance and adequate market share in those markets; reimbursement from third-party payers; and the performance of drug product subject to outcome-based programs. As a result, we could deplete our capital resources sooner than we currently expect. If, for any reason, our revenues or our expenses differ materially from our assumptions or we utilize our cash more quickly than anticipated, we may be unable to maintain operations into the second quarter of 2025 and through the closing of the Merger Transaction.
 The accompanying financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of the uncertainties described above.
 Reverse stock split
 On December 12, 2024, we filed a Certificate of Amendment to our Amended and Restated Certificate of Incorporation, as amended, with the Secretary of State of the State of Delaware to effect a 1-for-20 reverse stock split of our common stock, effective December 12, 2024 at 5:00 p.m. All share and disclosure amounts in this Annual Report on Form 10-K have been updated to reflect this reverse stock split.
 Merger Agreement
 On February 21, 2025, we announced that we entered into the Merger Agreement with Parent and Merger Sub. On March 7, 2025, Parent and Merger Sub commenced a cash tender offer (the "Offer") to acquire any and all of the outstanding shares of our common stock, par value $0.01 per share (the "Shares"), for (i) $3.00 in cash per Share, plus (ii) one contingent value right per Share, representing the right to receive a non-tradeable contingent payment of up to $6.84 in cash, upon the achievement of the certain milestones. The transaction is expected to close in the first half of 2025, subject to the tender of a majority of the Shares, receipt of applicable regulatory approvals, and other customary closing conditions.

 Our Board of Directors unanimously determined that the Merger Agreement and the transactions contemplated by the Merger Agreement, including the Offer and the Merger Transaction, are advisable, fair to, and in our and our stockholders' best interests and declared it advisable for us to enter into the Merger Agreement.

 Financial operations overview
 Product revenue
 Our revenues were derived from product revenues associated with the sale of SKYSONA, LYFGENIA, and ZYNTEGLO for the year ended December 31, 2024. Our revenues were derived from product revenues associated with the sale of SKYSONA and ZYNTEGLO for the year ended December 31, 2023.
 Other revenue
 We have recognized an immaterial amount of revenue associated with grants.
 Cost of product revenue includes costs associated with the manufacture and sale of SKYSONA, LYFGENIA, and ZYNTEGLO for the year ended December 31, 2024. Cost of product revenue includes costs associated with the manufacture and sale of SKYSONA and ZYNTEGLO for the year ended December 31, 2023.
 Selling, general and administrative expenses
 Selling, general and administrative expenses consist primarily of salaries and related costs for personnel, including stock-based compensation and travel expenses for our employees in executive, operational, finance, legal, business development, commercial, information technology, and human resource functions. Other selling, general and administrative expenses include facility-related costs, professional fees for accounting, tax, legal and consulting services, directors' fees and expenses associated with obtaining and maintaining patents. These expenses include lease expense related to 50 Binney Street and 100 Binney Street; however, sublease income is presented in other income, net.

 Research and development expenses
 Research and development expenses consist primarily of costs incurred for the development of our product candidates, which include:
 • employee-related expenses, including salaries, benefits, travel and stock-based compensation expense;
 • expenses incurred under agreements with contract research organizations ("CROs") and clinical sites that conduct our clinical studies;
 • expenses, including amortization of right-of-use assets when used in research and development, incurred under agreements with contract manufacturing organizations ("CMOs") related to pre-commercial manufacturing activities;
 • facilities, depreciation, and other expenses, which include direct and allocated expenses for rent and maintenance of facilities, information technology, insurance, and other supplies in support of research and development activities;
 • costs associated with our research platform and preclinical activities;
 • milestones and upfront license payments; and
 • costs associated with our regulatory, quality assurance and quality control operations.
 Research and development costs including those under executory contracts and variable costs related to arrangements that contain a lease are expensed as incurred. Right-of-use assets related to arrangements with CMOs and contract testing organizations ("CTOs") that contain a lease under ASC 842 but have no alternative future use under ASC 730 are immediately expensed to research and development expense at commencement or upon a modification until commercialization is achieved. Costs for certain development activities are recognized based on an evaluation of the progress to completion of specific tasks using information and data provided to us by our vendors and our clinical sites. We cannot determine with certainty the duration and completion costs of the current clinical studies of our products or to what extent we will generate revenues from the commercialization and sale of our approved products. The duration, costs, and timing of clinical studies and development of our products will depend on a variety of factors, any of which could affect our research and development expenses, including:
 • the scope, rate of progress, and expense of our ongoing as well as any additional clinical studies and other research and development activities we undertake;
 • future clinical study results;
 • uncertainties in clinical study enrollment rates;
 • new manufacturing processes or protocols that we may choose to or be required to implement in the manufacture of our LVV or drug product;
 • regulatory feedback and changing standards for maintenance of regulatory approval;
 • the timing and receipt of any regulatory approvals.
 We plan to continue to incur research and development expenses for the foreseeable future as we continue to conduct research activities for our platform technology. We expect our research and development expenses to decrease in conjunction with an increase in commercial activities and selling, general and administrative expense due to the approvals of ZYNTEGLO, SKYSONA, and LYFGENIA. Our research and development expenses include expenses associated with the following activities:
 • the long-term follow-up protocol associated with the clinical studies of ZYNTEGLO, and a postmarketing study for the same;
 • the long-term follow-up protocol associated with the clinical studies of SKYSONA, and a postmarketing study for the same;
 • HGB-210, the long-term follow-up protocol associated with the clinical studies of LYFGENIA, and a postmarketing study for the same;
 • research and development activities for our platform technology; and
 • the manufacture of clinical study materials in support of our clinical studies.

 Our direct research and development expenses consist principally of external costs, such as fees paid to investigators, consultants, central laboratories and CROs in connection with our clinical studies, and costs related to acquiring and manufacturing clinical study materials. We allocate salary and benefit costs that are directly related to specific programs. We do not allocate personnel-related discretionary bonus or stock-based compensation costs, laboratory and related expenses, certain license and other collaboration costs, depreciation or other indirect costs that are deployed across multiple projects under development and, as such, the costs are separately classified as other research and development expenses in the table below:

 2024
 2023

 ZYNTEGLO (beti-cel)
 $
 4,303
 $
 10,767

 LYFGENIA (lovo-cel)

 21,112
 72,404

 SKYSONA (eli-cel)
 9,178
 13,671

 Preclinical programs
 1,254

 Total direct research and development expense
 34,750
 98,096

 Employee- and contractor-related expenses
 27,971
 29,413

 3,982
 9,000

 Laboratory and related expenses
 5,348
 3,859

 License and other collaboration expenses
 2,417

 Facility expenses
 22,177
 24,867

 Total other research and development expenses
 59,502
 69,556

 Total research and development expense
 $
 94,252
 $
 167,652

 Restructuring expenses
 Restructuring expenses consist of costs associated with postemployment nonretirement benefits in accordance with ASC 420, Exit or Disposal Cost Obligations. Such costs are based on the estimate of fair value in the period the expenses were incurred.
 Gain from sale of priority review voucher, net.
 Gain from sale of priority review voucher, net consists of gain from the sale of our priority review vouchers. In the first quarter of 2023, we sold a PRV for aggregate net proceeds of $92.9 million. We received the PRV in September 2022 under an FDA program intended to encourage the development of treatments for rare pediatric diseases.
 Interest income
 Interest income consists primarily of interest income earned on cash and cash equivalents and investments, if applicable.
 Interest expense consists primarily of interest expense associated with finance lease arrangements, term loan debt, and our factoring agreement.
 Other income, net
 Other income, net consists primarily of sublease income, gains and losses on the change in fair value of warrants, gains and losses on foreign currency transactions, and gains and losses on disposal of fixed assets.

 Critical accounting policies and significant judgments and estimates
 Our management's discussion and analysis of our financial condition and results of operations are based on our financial statements, which have been prepared in accordance with generally accepted accounting principles in the U.S. The preparation of these financial statements requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, and expenses and the disclosure of contingent assets and liabilities in our financial statements. On an ongoing basis, we evaluate our estimates and judgments, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future

 trends. We base our estimates on historical experience, known trends and events and various other factors that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions. In making estimates and judgments, management employs critical accounting policies.
 While our significant accounting policies are described in more detail in the notes to our financial statements appearing elsewhere in this annual report, we believe the following accounting policies to be most critical to the judgments and estimates used in the preparation of our financial statements.

 Revenue recognition
 Revenue recognition
 Under Topic 606, Revenue from Contracts with Customers, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. We only apply the five-step model to contracts when it is probable that the entity will collect the consideration to which it is entitled in exchange for the goods or services it transfers to the customer.
 Once a contract is determined to be within the scope of Topic 606, we assess the goods or services promised within each contract and determine those that are performance obligations. Arrangements that include rights to additional goods or services that are exercisable at a customer's discretion are generally considered options. We assess if these options provide a material right to the customer and if so, they are considered performance obligations.
 We assess whether each promised good or service is distinct for the purpose of identifying the performance obligations in the contract. This assessment involves subjective determinations and requires management to make judgments about the individual promised goods or services and whether such are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (that is, the good or service is capable of being distinct) and (ii) the entity's promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (that is, the promise to transfer the good or service is distinct within the context of the contract).
 The transaction price is then determined and allocated to the identified performance obligations in proportion to their standalone selling prices ("SSP") on a relative SSP basis. SSP is determined at contract inception and is not updated to reflect changes between contract inception and when the performance obligations are satisfied.
 If the consideration promised in a contract includes a variable amount, we estimate the amount of consideration to which we will be entitled in exchange for transferring the promised goods or services to a customer. We determine the amount of variable consideration by using the expected value method or the most likely amount method. We include the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, we re-evaluate the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjust our estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the period of adjustment.
 If an arrangement includes development and regulatory milestone payments, we evaluate whether the milestones are considered probable of being reached and estimate the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within our control or the licensee's control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received.
 We then recognize as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) each performance obligation is satisfied, either at a point in time or over time, and if over time recognition is based on the use of an output or input method.

 Product revenue
 We recognize product revenue in accordance with ASC 606, Revenue from Contracts with Customers. In 2024, product revenue represents sales of ZYNTEGLO, LYFGENIA, and SKYSONA in the United States. We recognize revenue from product sales at the point in time that we satisfy our performance obligation, which is upon patient infusion. Costs to manufacture and deliver the product are included in cost of product revenue.

 Leases
 Under ASU 2016-02, Leases (Topic 842), ("ASU 2016-02" or "ASC 842"), at the inception of an arrangement, we determine whether the arrangement is or contains a lease based on the unique facts and circumstances present in the arrangement. We lease real estate, principally office and lab space with administrative equipment, and have leases related to our third-party manufacturing and related operations.
 We determine if an arrangement is a lease at inception of the contract and we perform the lease classification test as of the lease commencement and subsequent modification date. Right-of-use assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease.
 Lease liabilities and their corresponding right-of-use assets are initially recorded based on the present value of lease payments over the expected remaining lease term. Certain adjustments to the right-of-use asset may be required for items such as incentives received. Our leases do not provide an implicit interest rate. We use our estimated incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. The incremental borrowing rate reflects the fixed rate at which we could borrow on a collateralized basis the amount of the lease payments in the same currency, for a similar term, in a similar economic environment. To estimate our incremental borrowing rate, a credit rating applicable to us is estimated using a synthetic credit rating analysis since we do not currently have a rating agency-based credit rating.
 For real estate leases deemed operating leases, lease amortization expense is primarily presented in selling, general and administrative expenses in operating expense in the income statement based on the nature of the lease. In cases when a real estate lease supports research and development or commercial production, we classify the amortization expense as research and development expense or assess the costs for capitalization to inventory, respectively. For financing leases which are principally related to our manufacturing operations, we present finance right-of-use assets in PP&E and recognize amortization expense associated with those assets on a straight-line basis over the shorter of the life of the leased asset or the related lease term and interest expense as a non-operating expense. When the finance lease right-of-use asset is used for research and development, we classify the amortization expense related to the finance lease right-of-use asset as research and development pursuant to the guidance in ASC 730, Research and Development Costs.
 We have elected not to recognize leases with an original term of one year or less on the balance sheet. We typically only include an initial lease term in our assessment of a lease arrangement. Options to renew a lease are not included in our assessment unless there is reasonable certainty that we will renew.
 Assumptions that we made at the commencement date are re-evaluated upon occurrence of certain events, including a lease modification. A lease modification results in a separate contract when the modification grants the lessee an additional right-of-use not included in the original lease and when lease payments increase commensurate with the standalone price for the additional right-of-use. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease. When a lease modification does not result in a separate contract, we reassess the classification of the existing lease at the effective date of the modification and remeasure the lease liability and adjust the carrying amount of the right-of-use asset by the amount of the remeasurement of the lease liability, including an update of the incremental borrowing rate used to measure the lease liability. Lease modifications associated with embedded leases in contract manufacturing arrangements may arise in greater frequency based on the complexity of gene therapy manufacturing processes and the related services provided by contract manufacturing organizations, which are combined with the lease components. We apply our judgment in determining whether the ongoing delivery of services to us by contract manufacturing organizations represent a change in the scope or consideration of the arrangement, which are accounted for as lease modifications, or are variable lease payments recognized as incurred.
 In accordance with ASC 842, components of a lease should be split into three categories: lease components, non-lease components, and non-components.

 Entities may elect not to separate lease and non-lease components. Rather, entities would account for each lease component and related non-lease component together as a single lease component. We have elected to account for lease and non-lease components together as a single lease component for both our real-estate leases as well as our embedded drug product and drug substance contract manufacturing leases. Accordingly, we allocate all of the contract consideration to the lease component only.
 ASC 842 allows for the use of judgment in determining whether the assumed lease term is for a major part of the remaining economic life of the underlying asset and whether the present value of lease payments represents substantially all of the fair value of the underlying asset. We apply the guidance referenced in ASC 842-10-55-2 to assist in determining leases classification across our portfolio of leases.

 Accrued research and development expenses
 As part of the process of preparing our financial statements, we are required to estimate our accrued expenses. This process involves reviewing open contracts and purchase orders, communicating with our personnel to identify services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of the actual cost. The majority of our service providers invoice us monthly in arrears for services performed or when contractual milestones are met. We make estimates of our accrued expenses as of each balance sheet date in our financial statements based on facts and circumstances known to us at that time.
 We recognize expenses related to clinical studies based on our estimates of the services received and efforts expended pursuant to contracts with multiple CROs and CMOs that conduct and manage clinical studies and clinical productions on our behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to our vendors will exceed the level of services provided and result in a prepayment of the clinical expense. Payments under some of these contracts depend on factors such as the successful enrollment of subjects and the completion of clinical study milestones. In accruing service fees, we estimate the time period over which services will be performed and the level of effort to be expended in each period and adjust accordingly.
 Other examples of estimated accrued research and development expenses include fees paid to:
 • investigative sites in connection with clinical studies;
 • vendors in connection with preclinical development activities; and
 • vendors related to the development, manufacturing, and distribution of clinical trial materials, where such fees are variable in nature and are not included in the measurement of embedded lase liabilities to CMOs.

 Stock-based compensation
 We issue stock-based awards to employees and non-employees, generally in the form of stock options and restricted stock units. We account for our stock-based awards in accordance with FASB ASC Topic 718, Compensation—Stock Compensation ("ASC 718"). ASC 718 requires all stock-based payments to employees, including grants of employee stock options and modifications to existing stock options, to be recognized in the consolidated statements of operations and comprehensive loss based on their fair values. Prior to the adoption of Accounting Standards Update ("ASU") No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting ("ASU 2018-07"), the measurement date for non-employee awards was generally the date the services are completed, resulting in financial reporting period adjustments to stock-based compensation during the vesting terms for changes in the fair value of the awards. After the adoption of ASU 2018-07, the measurement date for non-employee awards is the date of grant without changes in the fair value of the award. Stock-based compensation costs for non-employees are recognized as expense over the vesting period on a straight-line basis.
 Our stock-based awards are subject to either service or performance-based vesting conditions. Compensation expense related to awards to employees, non-employees, and directors, with service-based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated service period of the award, which is generally the vesting term. Compensation expense related to awards to employees and non-employees with performance-based vesting conditions is recognized based on the grant date fair value over the requisite service period using the accelerated attribution method to the extent achievement of the performance condition is probable. We estimate the probability that certain performance criteria will be met and do not recognize compensation expense until it is probable that the performance-based vesting condition will be achieved.

 We estimate the fair value of our stock-based awards to employees, non-employees, and directors, using the Black-Scholes option pricing model, which requires the input of subjective assumptions, including (i) the expected volatility of our stock, (ii) the expected term of the award, (iii) the risk-free interest rate, and (iv) expected dividends. Effective January 1, 2020, we eliminated the use of a representative peer group and use only our own historical volatility data in our estimate of expected volatility given that there is now a sufficient amount of historical information regarding the volatility of our own stock price. We estimate the expected life of our employee stock options using the "simplified" method, whereby, the expected life equals the average of the vesting term and the original contractual term of the option, unless there are more appropriate indicators of the expected life when measuring the fair value of a modified award. The risk-free interest rates for periods within the expected life of the option were based on the U.S. Treasury yield curve in effect during the period the options were granted.

 Recent accounting pronouncements
 See Note 2, Summary of significant accounting policies and basis of presentation, in the notes to consolidated financial statements for a description of recent accounting pronouncements applicable to our business.

 Results of Operations
 Comparison of the years ended December 31, 2024 and 2023:

 2024
 2023
 Change

 Revenue:

 Product revenue, net

 $
 83,795
 $
 29,065
 $
 54,730

 Other revenue
 (420)

 Total revenues
 83,807
 29,497
 54,310

 89,380
 33,527
 55,853

 Gross margin

 (5,573)
 (4,030)
 (1,543)

 Operating expenses:

 Selling, general and administrative
 167,874
 165,510
 2,364

 Research and development
 94,252
 167,652
 (73,400)

 Restructuring expense
 2,762
 —
 2,762

 Total operating expenses
 264,888
 333,162
 (68,274)

 Gain from sale of priority review voucher, net
 —
 92,930
 (92,930)

 Loss from operations
 (270,461)
 (244,262)
 (26,199)

 Interest income

 8,218
 9,869
 (1,651)

 (22,579)
 (16,353)
 (6,226)

 Other income, net

 44,177
 38,707
 5,470

 Loss before income taxes
 (240,645)
 (212,039)
 (28,606)

 Income tax benefit (expense)

 (70)
 (196)

 $
 (240,715)
 $
 (211,913)
 $
 (28,802)

 Revenue. Total revenue was $83.8 million for the year ended December 31, 2024, compared to $29.5 million for the year ended December 31, 2023. The increase of $54.3 million was primarily attributable to 37 infusions of our three commercial products in 2024 compared to 12 infusions in 2023 of ZYNTEGLO and SKYSONA only.
 Cost of product revenue. Cost of product revenue was $89.4 million for the year ended December 31, 2024, compared to $33.5 million for the year ended December 31, 2023. The increase is attributable to increased product sales during 2024.
 Selling, general and administrative expenses. Selling, general and administrative expenses were $167.9 million for the year ended December 31, 2024, compared to $165.5 million for the year ended December 31, 2023. The increase of $2.4 million was primarily due to the following:
 •$18.4 million of increased professional fees driven by increased audit, accounting advisory, and legal fees during 2024.
 These increased costs were partially offset by the following:
 •$8.1 million of decreased commercial readiness activity costs driven by an overall decrease to marketing expenses related to the commercial launch of LYFGENIA in 2023;
 •$4.7 million of decreased information technology and facility related costs primarily driven by decreased operating lease costs relating to a lease that terminated in 2023; and
 •$3.8 million of decreased net employee compensation, benefit, and other headcount related expenses, driven by an overall decrease in headcount and related bonus expense, which includes a reversal of accrued bonus expenses for employees included in the reduction in workforce, a decrease in vacation expense due to our change in vacation policy, and a decrease of $1.4 million in stock-based compensation expense.

 Research and development expenses. Research and development expenses were $94.3 million for the year ended December 31, 2024, compared to $167.7 million for the year ended December 31, 2023. The decrease of $73.4 million was primarily attributable to the following:
 •$32.7 million of decreased manufacturing costs primarily driven by material production being included in inventory and cost of product revenue for our commercial products;
 •$19.0 million of decreased net employee compensation, benefit, and other headcount related expenses, driven by related expenses being included in inventory and cost of product revenue for our commercial products, as well as an overall decrease in headcount and related bonus expense, which includes a reversal of accrued bonus expenses for employees included in the reduction in workforce, a decrease in vacation expense due to our change in vacation policy, and a decrease of $5.0 million in stock-based compensation expense;
 •$6.8 million of decrease clinical expenses due to reduced clinical spend as all of our drug candidates are commercial;
 •$5.3 million of decreased consulting fees, primarily driven by an overall decrease in consulting spend and fees relating to commercialized products being included in inventory and cost of product revenue;
 •$5.0 million of decreased information technology and facility-related costs primarily driven by information technology and facility-related expenses now being included in inventory and cost of product revenue;
 •$1.7 million of decreased professional service costs; and
 •$1.6 million of decreased non-clinical costs.
 Restructuring expenses. There were $2.8 million in restructuring expenses recorded for the year ended December 31, 2024, compared to $0.0 million for the year ended December 31, 2023.
 Gain from sale of priority review voucher, net. There was no gain from sale of priority review voucher for the year ended December 31, 2024 compared to $92.9 million for the year ended December 31, 2023.
 Interest income. The decrease in interest income was primarily due to an overall decrease in total cash balances in 2024 compared to 2023.
 Interest expense. The increase in interest expense is primarily due to interest expense associated with our term loan debt with Hercules that we entered into in March 2024 and our factoring agreement, partially offset by a decrease in the interest expense associated with finance lease arrangements.
 Other income, net. The increase in other income, net is primarily related to gains and losses on foreign currency transactions and gains on the change in fair value of warrants.

 Liquidity and Capital Resources
 As of December 31, 2024, we had cash and cash equivalents of approximately $62.3 million. Cash in excess of immediate requirements is invested in accordance with our investment policy, primarily with a view to liquidity and capital preservation. As of December 31, 2024, our funds are primarily held in U.S. government agency securities and treasuries, and money market accounts with maturities at date of purchase of 90 days or less.
 We have incurred losses and cumulative negative cash flows from operations since our inception in April 1992, and as of December 31, 2024, we had an accumulated deficit of $4.5 billion. We expect our research and development expenses to decrease in conjunction with an increase in commercial activities and selling, general and administrative expense due to the commercialization of ZYNTEGLO, SKYSONA, and LYFGENIA.
 On February 21, 2025, we announced that we entered into the Merger Agreement with Parent and Merger Sub, pursuant to which Merger Sub will conduct a cash tender offer to acquire any and all of the outstanding shares of our common stock. We expect the Merger Transaction will be completed in the first half of 2025, and as such, it is not included in our going concern assessment.
 Based on current forecasts, which assume continued cost-saving initiatives, continued deferment of certain payments to vendors, and continued collaborative engagement from Hercules, we expect our existing cash and cash equivalents will enable

 us to fund our operations into the second quarter of 2025 and through the closing of the Merger Transaction. If we do not complete the Merger Transaction within the expected timeframe, or at all, we will be at risk of liquidation or bankruptcy.
 We have based our cash runway estimate on assumptions of revenues and operating costs that may prove to be wrong. Our cash runway estimate does not include use of our restricted cash, which as of December 31, 2024 was $43.6 million. In February 2025, $30.1 million of our restricted cash was released; the remaining $13.5 million of restricted cash is unlikely to be released in the near term. In addition, our future net product revenues will depend upon the demand for our products; the size of the markets for our products; our ability to achieve and maintain sufficient market acceptance, and adequate market share in those markets; reimbursement from third-party payers; and the performance of drug product subject to outcome-based programs. As a result, we could deplete our capital resources sooner than we currently expect. If, for any reason, our revenues or our expenses differ materially from our assumptions or we utilize our cash more quickly than anticipated, we may be unable to maintain operations into the second quarter of 2025 and through the closing of the Merger Transaction.
 We have funded our operations principally from the sale of common stock in public offerings, the Loan Agreement, and the sale of the two PRVs. The following is a summary of recent financing transactions:
 • In January 2023, we sold our second PRV for aggregate net proceeds of $92.9 million.
 • In January 2023, we sold 1.2 million shares of common stock (inclusive of shares sold pursuant to an option to the underwriters in connection with the offering) in an underwritten public offering at a price of $120.00 per share for aggregate net proceeds of $130.5 million.
 • In August 2023, we entered into an Open Market Sales Agreement (the "Sales Agreement") with Jefferies LLC ("Jefferies") to sell shares of our common stock up to $125.0 million, from time to time, through an "at the market" equity offering program under which Jefferies will act as sales agent. As of December 31, 2023, we have made no sales pursuant to the Sales Agreement.
 • In December 2023, we sold 4.2 million shares of common stock in an underwritten public offering at a price of $30.00 per share for aggregate net proceeds of $118.1 million.
 • In March 2024, we entered into the Loan Agreement for up to $175.0 million in debt financing.
 Sources of Liquidity
 Cash Flows
 The following table summarizes our cash flow activity:

 2024
 2023

 Net cash used in operating activities
 $
 (260,020)
 $
 (235,046)

 Net cash provided by investing activities

 3,897
 154,950

 Net cash provided by financing activities

 87,469
 196,248

 Increase (decrease) in cash, cash equivalents and restricted cash

 $
 (168,654)
 $
 116,152

 Operating Activities. The net cash used in operating activities was $260.0 million for the year ended December 31, 2024 and primarily consisted of a net loss of $240.7 million, change in net working capital of $130.0 million, adjusted for non-cash items of $110.7 million, which is primarily driven by depreciation and amortization of $61.2 million, non-cash items related to operating leases of $24.2 million, stock-based compensation of $13.7 million, and the recognition of a reserve for excess inventories of $10.9 million.
 The net cash used in operating activities was $235.0 million for the year ended December 31, 2023 and primarily consisted of a net loss of $211.9 million, change in net working capital of $49.7 million, adjusted for non-cash items of $26.6 million, which is primarily driven by non-cash items related to operating leases of $29.8 million, depreciation and amortization of $28.5 million, non-cash items related to finance leases of $21.2 million, stock-based compensation of $19.4 million, the recognition of a reserve for excess inventories of $15.4 million, and proceeds from factoring arrangement of accounts receivable of $5.0 million, offset by a gain from the sale of priority review voucher of $92.9 million.

 Investing Activities. Net cash provided by investing activities for the year ended December 31, 2024 was $3.9 million and was primarily due to proceeds from previously transferred invoices pursuant to our factoring agreement of $6.5 million offset by the purchase of $2.6 million of property, plant and equipment.
 Net cash provided by investing activities for the year ended December 31, 2023 was $155.0 million and was primarily due to proceeds from the maturities of available-for-sale marketable securities of $108.5 million, sale of priority review voucher of $92.9 million, and proceeds from sales of marketable securities of $5.9 million, offset by the purchase of $43.3 million of marketable securities, $4.2 million of property, plant and equipment and the capitalization of two FDA approval milestones related to SKYSONA and ZYNTEGLO of $4.9 million.
 Financing Activities: Net cash provided by financing activities for the year ended December 31, 2024 was $87.5 million and was primarily due to proceeds from the issuance of debt and warrants, net of issuance costs of $71.4 million, and proceeds from factoring arrangement of $102.0 million, offset by $86.0 million in principal payments on finance leases.
 Net cash provided by financing activities for the year ended December 31, 2023, was $196.2 million and was primarily due to proceeds from the secondary public offering, net of issuance costs of $248.2 million and proceeds from factoring arrangement of $2.5 million, offset by offset by $54.4 million in principal payments on finance leases.

 Contractual Obligations and Commitments
 Operating lease commitments
 50 Binney Street sublease & sub-sublease
 In April 2019, we entered into a sublease agreement with Aventis, Inc. for office space located at 50 Binney Street in Cambridge, Massachusetts (the "50 Binney Street Sublease") to supplement our then-current corporate headquarters located at 60 Binney Street in Cambridge, Massachusetts. Under the terms of the 50 Binney Street Sublease, we leased 267,278 square feet of office space for $99.95 per square foot, or $26.7 million per year in base rent subject to certain operating expenses, taxes and annual rent increases of approximately 3%. The lease commenced in April 2022. Upon signing the 50 Binney Street Sublease, we executed a $40.1 million cash-collateralized letter of credit. The $40.1 million of cash collateralizing the letter of credit is classified as restricted cash and other non-current assets on our consolidated balance sheets as of December 31, 2024. Refer to Note 21, Subsequent Events, for further information on changes to the Company's letter of credit activity after December 31, 2024.
 In December 2021, we entered into a sub-sublease agreement (the "Sub-Sublease") with Meta Platforms. Inc. ("Meta"). Under the terms of the Sub-Sublease, we subleased the entirety of the 50 Binney Street premises which we had rights to under the 50 Binney Street Sublease. We sub-subleased the premises for $29.4 million in the first year (inclusive of parking costs) with 3% annual increases in each subsequent year. Meta received access to 50 Binney Street at the lease commencement date, which is the same point that we received access under the 50 Binney Street Sublease. As of December 31, 2024, we remained liable under the 50 Binney Street Sublease, including for the maintenance of the $40.1 million collateralized letter of credit. The Company recognized monthly sublease income of $2.6 million in other income, net for the sub-subleased space.
 In February 2025, we terminated the 50 Binney Street Sublease and the Sub-Sublease. In connection with the termination, we amended the $40.1 million collateralized letter of credit to reduce the amount thereunder to $10 million. The reduced letter of credit will remain in place until the earlier of: (i) the termination of the prime lease between the 50 Binney Street landlord and Aventis. Inc. or (ii) December 21, 2030. Refer to Note 21, Subsequent Events, for further information.
 Assembly Row lease
 In November 2021, we entered into a lease agreement with Assembly Row 5B, LLC ("Landlord") for office space located at 455 Grand Union Boulevard in Somerville, Massachusetts to serve as our corporate headquarters. Under the terms of the arrangement, we lease approximately 61,180 square feet starting at an annual rate of $45 per square foot, subject to annual increases of 2.5%, plus operating expenses and taxes. In addition, we are eligible to receive a tenant work allowance of $160 per rentable square foot of the premises. The lease commenced on March 1, 2022.
 Hood Park lease
 In October 2022, we entered into a sublease with Finch Therapeutics, Inc. ("Finch") for office and laboratory space at Finch's corporate headquarters located at 100 Hood Park Drive, Charlestown, Massachusetts. Under the terms of the

 arrangement, we lease 42,261 square feet for $55 per square foot, subject to annual increases of 3.0%, plus operating expenses and taxes. This sublease commenced December 15, 2022 and is expected to terminate on December 14, 2025.
 Finance lease commitments – Embedded leases
 Drug Product Manufacturing

 In June 2016, we entered into a manufacturing agreement for the future commercial production of our ZYNTEGLO and SKYSONA drug products with a CMO. Under this 12-year agreement, the CMO will complete the design, construction, validation and process validation of the leased suites prior to anticipated commercial launch of the product candidates. From 2016 through March 2018, while the suites were under construction, we paid a total of $12.0 million in contractual milestone payments. Construction was completed in March 2018, and beginning in April 2018 we paid $5.1 million per year in fixed suite reservation fees and certain fixed labor, raw materials, testing and shipping costs for manufacturing services. We may terminate this agreement at any time upon payment of a one-time termination fee and up to 24 months of slot fees and 12 months of labor fees. We concluded that this agreement contains an embedded lease as the suites are designated for our exclusive use during the agreement's term, that we were not the deemed owner during construction, and the lease was not a capital lease under ASC 840-10, Leases – Overall. As a result, we initially accounted for the agreement as an operating lease under ASC 840 and recognized straight-line rent expense over the non-cancellable term of the embedded lease. As part of our adoption of ASC 842, effective January 1, 2019, we carried forward the existing lease classification under ASC 840. The lease was modified and reclassified as a finance lease as of March 2019. In September 2023, we amended our agreement with the CMO to change the fee structure in the arrangement from a fixed suite reservation fee to a fixed slot manufacturing fee. In addition, separate from the suite and existing equipment, we also have a forward starting embedded equipment lease that has not yet commenced. As the CMO is required to provide operational equipment throughout the contract term, the forward starting lease was established to account for the equipment that the CMO is obligated to lease to us in the future once the current equipment reaches the end of its useful life and the lease expires. This forward starting lease is expected to commence in 2025 with an initial lease term of three years and has fixed commitments of approximately $60.1 million. We have prepaid approximately $3.7 million, which is accounted for as prepaid asset on the Company's balance sheet that would adjust the right-of-use asset when the forward starting embedded equipment lease commences in 2025. The lease has been subsequently modified based on changes in the delivery of non-lease component services, which have been combined with lease components under our accounting policy.
 During July 2020, we amended an existing CMO arrangement to reserve additional manufacturing capacity for LYFGENIA. We concluded that this amendment contains an embedded lease as a controlled environment room at the facility is designated for our exclusive use during the term of the agreement, with the option to sublease the space if we provide notice that we will not utilize it for a specified duration of time. Under the amended agreement, we are required to pay up to $5.4 million per year in maintenance fees in addition to the cost of any services provided and may terminate this agreement with eighteen months' notice. The term of the agreement is five years, with the option to extend. When the additional manufacturing capacity became available that served as lease commencement in March 2021, we classified the embedded lease as a finance lease.
 In February 2021, we amended an agreement to reserve additional manufacturing capacity. We concluded that this amended agreement contains an embedded lease as a controlled environment room at the facility is designated for our exclusive use during the agreement's term. Under the amended agreement, we must pay $4.2 million per year in maintenance fees and per-batch fees for the cost of any services provided. Either party may terminate this agreement with eighteen months' notice at any time or with eight months' notice after defined milestones in the agreement have been met. The term of the agreement is five years, with the option to extend. The lease commenced in November 2021 when the suites became available, and upon commencement we classified it as finance lease. The lease has been subsequently modified based on changes in the delivery of non-lease component services, which have been combined with lease components under our accounting policy.
 In August 2022, we amended an agreement to reserve additional controlled environmental rooms. We concluded this amended agreement contains an embedded finance lease as the controlled environment room at the facility is designated for our exclusive use during the agreement's term. Under this amended agreement, an existing deposit of $10.8 million was applied towards the monthly lease payments through September 2023. The term of the agreement was 14 months, with an option to extend. We exercised the extension option to extend through December 31, 2023, and subsequently extended the agreement for an additional 14 months into March 2025.

 In October 2024, we amended the CMO arrangement to include the delivery of additional non-lease component services, which have been combined with lease components under our accounting policy. These non-lease component services are expected to be completed in July 2025, which extended the lease term through July 2025 for certain of the lease components related to this CMO arrangement.

 Drug Substance Manufacturing
 In November 2017, we entered a commercial manufacturing services agreement with a CMO to establish commercial production of our suspension vector. We concluded this agreement contained an embedded finance lease when production commenced in the new facility in 2019 as we have dedicated suite space and reserved production capacity at a rate that allows us to take more than substantially all the capacity of certain manufacturing space and equipment within the facility. Under the agreement, we are required to pay capacity reservation fees, minimum purchase commitment fees, and milestone fees for achievement of certain activities. In addition, we prepaid approximately 13.5 million between 2018 and 2019 towards certain milestone payments and in exchange for production credits. As of December 31, 2021, those credits have been fully used. We modified the lease to extend its term in October 2022, April 2023, October 2023, and in March 2024, which extended the lease term to end in September 2024. In September 2024, we entered into a 5-year master contract services agreement ("MCSA") with the CMO. The MCSA does not grant us an additional right of use, thus, the MCSA is not a separate contract. The MCSA is accounted for as a lease modification as it effectively requires the vendor to perform additional services incremental to the terms of the existing agreement by extending the lease term, in addition to changes in the delivery of non-lease component services, which have been combined with lease components under our accounting policy.
 In January 2018, we entered a clinical and commercial supply agreement with a CMO to manufacture ZYNTEGLO and SKYSONA vector products. We concluded this agreement contained an embedded finance lease. We agreed to wind down manufacturing activities with the CMO originally in December 2021. In December 2022, we reestablished this manufacturing agreement and concluded the revised arrangement contains an embedded finance lease as we are using the entire capacity of a manufacturing suite at the facility. The original term of the agreement was three years and required us to pay suite reservation fees of $13.5 million in 2023 and $18.0 million per year in 2024 and 2025, in addition to the cost of any services provided. The lease has been subsequently modified based on changes in the delivery of non-lease component services, which have been combined with lease components under our accounting policy. In August 2024, we provided notice to this CMO of our intention to wind down adherent LVV manufacturing for ZYNTEGLO and SKYSONA, as we pursue alternative manufacturing methods and plans for LVV for these products. The CMO will continue to manufacture LVV for approximately twelve months (through August 2025) pursuant to the notice period under the applicable work order and the Clinical and Commercial Supply Agreement remains in place. Additionally, the terms were modified to reduce the suite reservation fees to $12.0 million in 2025.
 Quality Testing
 In 2018, we entered a MCSA with a CTO to provide clinical development services (other than manufacturing services). The original MCSA expired in June 2020 but was reinstated through December 2024 under the amendment of the MCSA effective in April 2021. In December 2024, the MCSA was extended to June 2025. However, the lease term ends December 2026 due to reserved capacity commitments. We concluded this agreement contained an embedded finance lease as we had certain lab suites implicitly dedicated to us for various clinical testing procedures. We are required to pay the fixed price outlined in each of the various work orders covering quality, stability and other services. The lease has been subsequently modified based on changes in the delivery of non-lease component services, which have been combined with lease components under our accounting policy.
 Contingent Milestone and Royalty Payments
 We also have obligations to make future payments to third parties that become due and payable on the achievement of certain development, regulatory and commercial milestones (such as the start of a clinical trial, filing of a BLA, approval by the FDA or product launch). We do not recognize these commitments in our financial statements until they become payable or have been paid.
 Research and development costs are expensed as incurred. These expenses include the costs of our proprietary research and development efforts, as well as costs incurred in connection with certain licensing arrangements. Before a product candidate receives regulatory approval, we record upfront and milestone payments we make to third parties under licensing arrangements as expense. Upfront payments are recorded when incurred, and milestone payments are recorded when the specific milestone has been achieved. Once a product receives regulatory approval, we record any milestone payments in identifiable intangible assets, less accumulated amortization and, unless the asset is determined to have an indefinite life, we typically amortize the payments on a straight-line basis over the remaining agreement term or the expected product life cycle, whichever is shorter.
 Based on our development plans as of December 31, 2024, we may be obligated to make future development, regulatory and commercial milestone payments and royalty payments on future sales of specified products associated with our collaboration and license agreements. Payments under these agreements generally become due and payable upon the

 achievement of such milestones or sales. Because the achievement of these milestones or sales had not occurred as of December 31, 2024, such contingencies have not been recorded in our financial statements. Amounts related to contingent milestone payments and sales-based royalties are not yet considered contractual obligations as they are contingent upon success.
 • Under a license agreement with Inserm-Transfert pursuant to which we license certain patents and know-how for use in adrenoleukodystrophy therapy, we will be required to make payments based upon development, regulatory and commercial milestones for any products covered by the in-licensed intellectual property. To date, we have paid 1.3 million pursuant to the terms of this license agreement, and we may be obligated to pay up to 0.8 million for future milestones. We will also be required to pay a royalty on net sales of products covered by the in-licensed intellectual property in the low single digits.
 • Under a license agreement with Institut Pasteur pursuant to which we license certain patents for use in ex vivo gene therapy, we are required to make payments per product covered by the in-licensed intellectual property upon the achievement of development and regulatory milestones, depending on the indication and the method of treatment. The maximum aggregate payments we may be obligated to pay for each of these milestone categories per product is 0.7 and 3.5 million, respectively. To date, we have paid 0.9 million pursuant to the terms of such license arrangement, and we may be obligated to pay up to 0.3 million for future milestones. We are also required to pay a royalty on net sales of products covered by the in-licensed intellectual property in the low single digits, which varies slightly depending on the indication of the product. We have the right to sublicense our rights under this agreement, and we will be required to pay a percentage of such license income varying from the low single digits to mid-range double digits depending on the nature of the sublicense and stage of development. We are required to make an annual maintenance payment, which is offset by royalty payments on a year-by-year basis.
 • Under a license agreement with the Board of Trustees of the Leland Stanford Junior University ("Stanford") pursuant to which we license the HEK293T cell line for use in gene therapy products, we are required to pay a royalty on net sales of products covered by the in-licensed intellectual property in the low single digits that varies with net sales. The royalty is reduced for each third-party license that requires payments by us with respect to a licensed product, provided that the royalty to Stanford is not less than a specified percentage that is less than one percent. We have been paying Stanford an annual maintenance fee, which will be creditable against our royalty payments.
 • Under a license agreement with Research Development Foundation pursuant to which we license patents that involve LVV, we will be required to make payments of $1.0 million based upon a regulatory milestone for each product covered by the in-licensed intellectual property. To date, we have paid $2.0 million pursuant to the terms of this license agreement. We will also be required to pay a royalty on net sales of products covered by the in-licensed intellectual property in the low single digits, which is reduced by half if during the ten years following first marketing approval the last valid claim within the licensed patent that covers the licensed product expires or ends.
 • Under a license agreement with SIRION Biotech GmbH ("Sirion") pursuant to which we license certain patents directed to manufacturing of gene therapy products, we are required to make certain payments related to certain development milestone obligations. We may be obligated to pay up to $13.4 million in the aggregate for each product covered by the in-licensed intellectual property. To date, we have paid $16.0 million pursuant to the terms of this license agreement. Should we seek regulatory approval outside the U.S., we may be obligated to pay up to $8.0 million for future milestones. Upon commercialization of our products covered by the in-licensed intellectual property, we became obligated to pay Sirion a percentage of net sales as a royalty in the low single digits. The royalties payable under this license agreement are subject to reduction for any third-party payments required to be made, with a minimum floor in the low single digits.

 Item 7A. Quantitative and Qualitative Disclosures About Market Risks
 We are exposed to market risk related to changes in interest rates. As of December 31, 2024 and 2023, we had cash and cash equivalents of $62.3 million and $221.8 million, respectively, primarily held in cash and money market accounts at multiple banking and asset management institutions. Our primary exposure to market risk is interest rate sensitivity, which is affected by changes in the general level of U.S. interest rates, particularly because our investments are in short-term securities.

 Item 8. Financial Statements and Supplementary Data
 The financial statements required to be filed pursuant to this Item 8 are appended to this report. An index of those financial statements is found in Item 15.

 Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure
 None.

 Item 9A. Controls and Procedures
 Limitations on Effectiveness of Controls and Procedures
 In designing and evaluating our disclosure controls and procedures, our management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving the desired control objectives. In addition, the design of disclosure controls and procedures must reflect the fact that there are resource constraints and that management is required to apply judgment in evaluating the benefits of possible controls and procedures relative to their costs.
 Evaluation of Disclosure Controls and Procedures
 Our management, with the participation of our principal executive officer and principal financial officer, has evaluated the effectiveness of our disclosure controls and procedures (as defined in Rules 13(a)- 15(e) and 15(d)- 15(e) under the Securities Exchange Act of 1934, as amended (the "Exchange Act")), as of the end of the period covered by this Annual Report on Form 10-K. Based on such evaluation, our principal executive officer and principal financial officer have concluded that as of such date, our disclosure controls and procedures were not effective at the reasonable assurance level due to the material weakness in our internal control over financial reporting described below.
 Management's Annual Report on Internal Control Over Financial Reporting
 Our management is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Rules 13(a)-15(f) and 15(d)-15(f) under the Exchange Act. Our internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.
 Management conducted an evaluation of the effectiveness of our internal control over financial reporting as of December 31, 2024 based on the framework in Internal Control-Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). Based on that evaluation, management has concluded that the Company's internal control over financial reporting was not effective as of December 31, 2024 due to the material weakness described below.
 In connection with the Company's preparation of its financial statements for the year ended December 31, 2023 and the restatement, the Company identified a material weakness in its internal control over financial reporting, which failed to prevent or detect the identified misstatements requiring restatement.
 A material weakness is a deficiency, or a combination of deficiencies, in internal control over financial reporting, such that there is a reasonable possibility that a material misstatement of the Company's annual or interim financial statements will not be prevented or detected on a timely basis.
 Our management concluded that a material weakness still existed as of December 31, 2024, and in prior periods, with respect to the design and operating effectiveness of the Company's controls over the accounting for arrangements that contain a lease. Specifically, as previously disclosed, the Company did not: (i) design controls to properly apply the Company's accounting policy to combine lease and non-lease components in lease arrangements, including embedded leases, (ii) operate controls to review the identification of leases and lease elements and accounting for lease arrangements, including embedded leases and lease modifications, by individuals with appropriate knowledge and competency, and (iii) operate controls to review the accounting for embedded leases with contract manufacturing organizations and contract testing organizations by individuals with appropriate knowledge and competency to determine the appropriate lease classification, presentation and commencement date.
 This material weakness resulted in the restatement of the Company's consolidated financial statements as of and for the year ended December 31, 2022, and the unaudited condensed consolidated financial information for each of the first three

 quarters of 2023 and 2022. Additionally, the material weakness could result in misstatements to the Company's accounts and disclosures that would result in a material misstatement of the annual or interim consolidated financial statements that would not be prevented or detected.
 As a "non-accelerated filer", we are not required to provide an attestation report of our registered public accounting firm on the effectiveness of our internal control over financial reporting.
 Remediation Plan
 Our management is committed to maintaining a strong internal control environment. In response to the identified material weakness above, management has begun to take comprehensive actions to remediate the material weakness in internal control over financial reporting, including:
 • reassessing and enhancing the design of existing internal controls over lease accounting and has begun to design and implement new and modified internal controls to ensure that financial statement assertion level risks (e.g. valuation, completeness, accuracy, presentation and disclosure) related to leases are addressed;
 • strengthening the lease accounting technical knowledge and experience within the Company's accounting function to enhance the oversight of the processes related to accounting for leases and arrangements that could contain embedded leases or lease modifications;
 • conduct ongoing training for individuals responsible for performing and reviewing the accounting and presentation for leases and arrangements with contract manufacturing and contract testing organizations which could contain embedded leases or modifications.
 The remediation plan includes a number of enhanced activities that reflect a continuation of activities the Company has started to undertake during the 2023 financial close process, which, due to the delayed filing of its 2023 financial statements, had started during the third quarter of 2024. We believe that the actions outlined above will remediate the material weakness once a sufficient period of time has passed for management to conclude, through testing, that these controls are operating effectively. The material weakness will not be considered remediated, however, until the applicable controls operate for a sufficient period of time and management has concluded, through testing, that these controls are operating effectively. We may also conclude that additional measures may be required to remediate the material weakness in our internal control over financial reporting, which may necessitate additional implementation and evaluation time. We will continue to assess the effectiveness of our internal control over financial reporting and take steps to remediate the material weakness expeditiously.
 Changes in Internal Control over Financial Reporting
 Other than the changes associated with the material weakness and corresponding remediation procedures described above, there have been no changes in our internal control over financial reporting, as such term is defined in Rules 13(a)-15(f) and 15(d)-15(f) promulgated under the Securities Exchange Act of 1934, during the fourth quarter of 2024 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

 Item 9B. Other Information
 (a) Disclosure in lieu of reporting on a Current Report on Form 8-K
 None.
 (b) Insider Trading Arrangement and Policies.
 During the three months ended December 31, 2024, no director or "officer" (as defined in Rule 16a-1(f) under the Exchange Act) of the Company adopted or terminated a "Rule 10b5-1 trading arrangement" or "non-Rule 10b5-1 trading arrangement," as each term is defined in Item 408(a) of Regulation S-K.

 Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections
 Not applicable.

 Item 10. Directors, Executive Officers and Corporate Governance
 The following table sets forth the name, age and position of each of our executive officers and directors.

 Name
 Age
 Position(s)

 Executive Officers:

 President, Chief Executive Officer and Director (Principal Executive Officer)

 O. James Sterling

 Chief Financial Officer (Principal Financial Officer and Principal Accounting Officer)

 Richard A. Colvin, M.D., Ph. D.
 Chief Medical Officer

 Chief Commercial and Operating Officer

 Chief Legal and Business Officer

 Non-Employee Directors:

 Mark Vachon (1) (2)
 Chair of the Board of Directors

 John O. Agwunobi, M.D. (1) (3)

 Michael Cloonan

 Charlotte Jones-Burton, M.D., M.S. (3)

 Elisabeth Leiderman, M.D. (1) (2)

 Nick Leschly

 Richard Paulson

 Najoh Tita-Reid (2) (3)

 (1) Member of the Audit Committee
 (2) Member of the Compensation Committee
 (3) Member of the Nominating & Corporate Governance Committee

 Executive Officers
 Andrew Obenshain – Mr. Obenshain has served as our President, Chief Executive Officer and member of our Board of Directors (the "Board") since November 2021. Mr. Obenshain previously served as bluebird's President, Severe Genetic Diseases from August 2020 to November 2021, and as bluebird's Senior Vice President, Head of Europe from 2016 to August 2020. Prior to that, from September 2015 to September 2016, Mr. Obenshain was the general manager of France and Benelux at Shire Pharmaceuticals, Inc. and from 2007 to 2015, he held roles of increasing responsibility at Genzyme/Sanofi. Mr. Obenshain received his M.B.A. from Northwestern University's Kellogg School of Management, and his B.A. in genetics, cell and developmental biology from Dartmouth College. Mr. Obenshain has deep operating and historical experience with our Company gained from serving as our President, Chief Executive Officer and in other roles. Mr. Obenshain also has significant management experience in the biotechnology and pharmaceutical fields.
 O. James Sterling – Mr. Sterling has served as our Chief Financial Officer since June 2024. Previously, Mr. Sterling served as Chief Financial Officer of Renalytix plc from November 2018 to June 2024, where he led the finance department. From 2015 to 2018, Mr. Sterling served as managing partner of Renwick Capital LLC. Prior to that, he served as a managing director at investment banks Brock Capital Group LLC and Aleutian Capital Group. Mr. Sterling is currently a director of Star Mountain Lower Middle-Market Capital Corp. Mr. Sterling received his B.A. from Boston University and an M.B.A. from Columbia Business School.
 Richard A. Colvin, M.D., Ph. D. – Dr. Colvin joined bluebird bio in October 2018 and has served as our Chief Medical Officer since October 2022. Previously, Dr. Colvin was our interim Chief Medical Officer from March 2021 through September 2022 and our Vice President and head of severe genetic diseases clinical research and development from January 2020 to March 2021. Dr. Colvin is on faculty at Harvard Medical School and also sees patients at the Infectious Diseases Clinic at Massachusetts General Hospital Chelsea Health Care Center. Prior to joining bluebird, Dr. Colvin was an executive director in translational medicine at Novartis, where he led anti-infective drug development programs for the treatment of patients with certain infections from 2014 to 2018. Previously, Dr. Colvin completed his clinical and research fellowships in the Mass General Brigham Infectious Diseases Program and completed his internship and residency at the Brigham and Women's

 Hospital. Dr. Colvin received his M.D. and Ph. D. from Duke University School of Medicine and his B.S. in Biology from Cornell University.
 Thomas J. Klima – Mr. Klima has served as our Chief Operating Officer since September 2022 and our Chief Commercial Officer since May 2021. Prior to joining bluebird, Mr. Klima served as Chief Commercial Officer at Gamida Cell Ltd. from January 2019 to December 2020, where he led the strategic vision and commercial growth transforming its R&D organization to a commercially ready company. In 2018, Mr. Klima served as senior vice president of global commercial planning and operations at Atara Biotherapeutics. From 2015 to 2017, Mr. Klima served as senior vice president and chief commercial officer at Navidea Biopharmaceuticals Ltd. (acquired by Cardinal Health). Before that, Mr. Klima served as head of sales and commercial operations at Algeta U.S. (acquired by Bayer Healthcare) from 2012 to 2015. Before Algeta, he held various commercial leadership positions at Dendreon from 2009 to 2012. Mr. Klima began his pharmaceutical career at Eli Lilly where he held several positions of increasing responsibility from 2000 to 2009. Mr. Klima received a B.A. in Business Administration and Marketing from Western State College.
 Joseph Vittiglio, Esq. – Mr. Vittiglio has served as our Chief Legal and Business Officer since January 2023. Prior to joining bluebird, Mr. Vittiglio served as Chief Business and Legal Officer at Finch Therapeutics from December 2020 to December 2022 where he guided its initial public offering in 2021. Prior to joining Finch, Mr. Vittiglio was the General Counsel and Chief Business Officer for AMAG Pharmaceuticals from August 2015 to November 2020 where he led its legal and business initiatives, including its successful sale to private equity investors and multiple out-licensing and partnership collaborations. Prior to AMAG, Mr. Vittiglio held leadership roles at Flexion Therapeutics, AVEO Pharmaceuticals, and Oscient Pharmaceuticals. Mr. Vittiglio began his career as a corporate and securities attorney at Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. Mr. Vittiglio received a B.A. in International Relations from Tufts University and a J.D. from Northeastern University School of Law.
 Non-Employee Directors
 Mark Vachon – Mr. Vachon has served on our Board since 2014. He spent over 30 years at General Electric in a range of senior leadership roles, becoming a company officer in 1999 and a member of GE's Corporate Executive Council. His leadership included serving as President and CEO of GE Healthcare Americas (2009–2010) and President and CEO of Global Diagnostics Imaging, GE Healthcare (2006–2009). Prior to that, he was Executive Vice President and CFO of GE Healthcare (2003–2006). Mr. Vachon currently serves on the boards of Beacon Mobility and Panoramic Health. He holds a B.S. in Finance from Northeastern University and an M.A. from Boston College. With deep expertise in corporate leadership, finance, and global healthcare operations, he brings valuable strategic and financial insights to the Board. Additionally, he is recognized as an "audit committee financial expert."
 John O. Agwunobi, M.D. – Dr. Agwunobi has served on our Board since 2017. He was Chief Executive Officer and Chairman of the Board of Herbalife Nutrition Inc. from 2020 to 2022. Previously, Dr. Agwunobi served as Co-President of Herbalife from May 2018 to 2020. He also served as Chief Health and Nutrition Officer at Herbalife, responsible for training, education, science strategy and product development from 2016 to 2018. Prior to joining Herbalife, Dr. Agwunobi was an independent consultant, advising a number of privately-held health-related companies, including serving as an advisory board member of Shopko Stores Operating Co., LLC on behalf of the private equity firm Sun Capital Partners. From September 2007 to April 2014, Dr. Agwunobi served as Senior Vice President and President of Health and Wellness for Wal-Mart (NYSE: WMT) in the United States where he grew the business and provided insight and advice on the company's health reform position. From December 2005 to September 2007, he served as the Assistant Secretary of Health for the U.S. Department of Health and Human Services, where he was responsible for disease prevention and health promotion. His responsibilities included the oversight of the Centers for Disease Control, National Institute of Health, the U.S. Food and Drug Administration, the Office of the U.S. Surgeon General, and numerous other public health offices and programs. Dr. Agwunobi also serves on the Board of the Ensign Group, Inc. and is a member of the Audit Committee and the Quality Assurance Committee as well as the Board of the U.S. African Development Foundation and is a member of the Audit Committee. Dr. Agwunobi has significant experience as a senior executive and board member in the health and wellness field. In addition, he has deep expertise in public health programs and governmental agencies relevant to the healthcare industry, from his prior service and experience with the public sector. The insights he has developed from these roles provides our Board with important perspectives on the issues facing our company.

 Michael Cloonan – Mr. Cloonan has served on our Board since 2024. Since May 2021, Mr. Cloonan has served as President and Chief Executive Officer at Sionna Therapeutics and a member of its Board of Directors, where he leads company strategy and operations. From May 2017 to April 2021, Mr. Cloonan served first as the Chief Business Officer and then as Chief Operating Officer at Sage Therapeutics, where he led all business functions (commercial, medical affairs, government affairs, business development, technical operations, strategy and program management) as well as general and administrative

 functions. Prior to Sage, Mr. Cloonan served in various business and commercial roles at Biogen for fourteen years, including most recently as Senior Vice President, U.S. Commercial, where he was the general manager of the multi-billion-dollar multiple sclerosis, hemophilia, and spinal muscular atrophy franchises. Prior to Biogen, Mr. Cloonan worked at Bain & Company as a consultant specializing in healthcare. Mr. Cloonan earned his M.B.A. from the Darden Graduate School of Business Administration at the University of Virginia and a B.A. from College of the Holy Cross. Mr. Cloonan has extensive operating experience gained from serving as President and Chief Executive Officer at Sionna and leadership roles at Sage and Biogen.
 Charlotte Jones-Burton, M.D., M.S. – Dr. Jones-Burton has served on our Board since 2022. Since May 2024, Dr. Jones-Burton has been Director and Head of Life Science Product Development and Strategy at 2Flo Ventures, an emerging venture capital firm and startup studio focused on the discovery, development, and commercialization of healthcare solutions. From January 2022 to November 2023, Dr. Jones-Burton served as Senior Vice President, Product Development and Strategy at Chinook Therapeutics, a clinical-stage biotechnology company discovering, developing and commercializing precision medicines for rare, severe kidney diseases. Prior to her role at Chinook Therapeutics she was VP, Global Clinical Development Head, Nephrology at Otsuka Pharmaceutical Development & Commercialization, Inc. from September 2019 to December 2021. From October 2016 until September 2019, Dr. Jones-Burton held various positions at Bristol-Myers Squibb Company with increasing responsibilities, most recently as Executive Director, Full Development Team Leader of Cardiovascular, Anti-Thrombosis. Prior to that, Dr. Jones-Burton was with Merck & Co. from 2007 to May 2011. With more than 20 years of experience as a clinical development leader, internal medicine and nephrology physician and academician, Dr. Jones-Burton is dedicated to creating healthier communities through drug development, patient advocacy and people engagement. Dr. Jones-Burton is also active in numerous professional associations and organizations and founded Women of Color in Pharma (WOCIP), a non-profit professional society focused women of color in the pharmaceutical industry. Dr. Jones-Burton also servbes as a member of the American Kidney Fund and as an advisor for the BOW Collective. Dr. Jones-Burton earned a medical degree and Master of Science degree in Epidemiology and Preventive Medicine, with a concentration in Clinical Research, from the University of Maryland School of Medicine. Dr. Jones-Burton's postgraduate training included an internal medicine residency and a nephrology fellowship at the University of Maryland Medical Systems. Dr. Jones-Burton has extensive experience as an executive in the pharmaceutical industry in drug development, physician and patient engagement and advocacy. The insights she has developed in her work, together with her involvement in professional service organizations, also provide her with important perspectives on the issues facing our company in the development and potential commercialization of our therapies, as well as matters of diversity, equity and inclusion.
 Elisabeth Leiderman, M.D. – Dr. Leiderman has served on our Board since 2021. Since June 2024, Dr. Leiderman has been Chief Financial Officer and Corporate Development Officer at Dewpoint Therapeutics, a biotechnology company applying biomolecular condensates to drug discovery. From October 2022 to November 2023, Dr. Leiderman served as Chief Financial Officer and Chief Business Officer at Atsena Therapeutics, a clinical-stage gene therapy company. Before joining Atsena, from September 2020 to October 2022, Dr. Leiderman was Chief Financial Officer and Head of Corporate Development and Corporate Secretary at Decibel Therapeutics, a clinical stage biotechnology company developing novel gene therapeutics for restoration of hearing loss and balance disorders. From January 2020 to August 2020, Dr. Leiderman served as Chief Business Officer for Complexa, Inc., a clinical stage biopharmaceutical company focused on life-threatening fibrosis and inflammatory diseases. Prior to Complexa, Dr. Leiderman was Senior Vice President, Head of Corporate Development at Fortress Biotech from November 2016 to November 2019. Earlier in her career from 2007 to 2016, Dr. Leiderman developed her transaction and capital markets expertise in the healthcare investment banking groups at Nomura, Credit Suisse, Jefferies and UBS. Dr. Leiderman began her career in medical affairs at AstraZeneca, where she analyzed product and industry trends related to the central nervous system. Since December 2023, Dr. Leiderman has served on the Board of Directors of Autolus Therapeutics and is a member of the Audit Committee. Dr. Leiderman earned an M.D. from the American Medical Program at Tel Aviv University, an M.B.A. from The Wharton School at the University of Pennsylvania and a B.A. from The University of Pennsylvania. Dr. Leiderman has over 20 years of experience in finance, strategy and business development in the life sciences industry. She is an "audit committee financial expert" with particular experience in matters faced by the audit committee of a life sciences company.
 Nick Leschly – Mr. Leschly has served on our Board since 2010. He is Chairman of the Board of 2seventy bio, Inc., a cell and gene therapy company, and from November 2021 to March 2024, Mr. Leschly served as its Chief Executive Officer. Mr. Leschly previously served as bluebird's President and Chief Executive Officer from October 2010 to November 2021. From 2017 to 2025, Mr. Leschly served on the Board of Directors of Synlogic Therapeutics and was a member of the Compensation Committee from 2019 to 2025. Formerly a partner of Third Rock Ventures, L.P. since its founding in 2007 until 2010, Mr. Leschly played an integral role in the overall formation, development and business strategy of several of Third Rock's portfolio companies, including Agios Pharmaceuticals, Inc. and Edimer Pharmaceuticals, Inc. Prior to joining Third Rock, he worked at Millennium Pharmaceuticals, Inc. (now a subsidiary of Takeda), leading several early-stage drug development programs and served as the product and alliance leader for VELCADE. Mr. Leschly also founded and served as Chief Executive Officer of MedXtend Corporation. He received his B.S. in molecular biology from Princeton University and his M.B.A. from The

 Wharton School of the University of Pennsylvania. Mr. Leschly has deep operating and historical experience with our Company gained from serving as our President, Chief Executive Officer and member of the Board. In addition, Mr. Leschly also has significant experience in the venture capital industry and drug research and development.
 Richard Paulson – Mr. Paulson has served on our Board since 2023. Since 2021, Mr. Paulson has been President and Chief Executive Officer at Karyopharm Therapeutics, a commercial-stage pharmaceutical company, and has served as a member of its Board of Directors since 2020. Previously, Mr. Paulson was Executive Vice President of Ipsen Pharmaceuticals and Chief Executive Officer of Ipsen North America from 2018 to 2021 where he focused on innovative therapies and specialty care for oncology, neuroscience and rare diseases. Before joining Ipsen, Mr. Paulson work at Amgen for 10 years holding various leadership positions across Europe and North America. Mr. Paulson received his M.B.A. from the University of Toronto and his B.Com in marketing and finance from the University of Saskatchewan. Mr. Paulson has deep operating experience gained from serving as President, Chief Executive Officer and Director at Karyopharm and leadership roles at Ipsen and Amgen. Mr. Paulson also has significant experience in sales, marketing, and market access in the biotechnology and pharmaceutical fields.
 Najoh Tita-Reid – Ms. Tita-Reid has served on our Board since 2021. Since November 2023, Ms. Tita-Reid has served as Chief Brand and Experience Officer at Mars Petcare, to lead brand, experience, digitalization and technology to drive business transformation. From 2020 to 2023, Ms. Tita-Reid led global marketing as Global Chief Marketing Officer for Logitech, a global manufacturer of computer peripherals, software and services. Also at Logitech, she previously held the roles of Global Commercial Marketing Head, where she developed the first global commercial organization, and leader of the Global Marketing Reinvention team. Previously, Ms. Tita-Reid served as Global Chief Marketing Officer and Executive Board Member for Hero-AG, a family-run healthy food company. In this role, she developed the organization's marketing function and brand strategy and built the first global innovation pipeline while overseeing the R&D, innovation, sustainability and quality functions. Prior to Hero-AG, Ms. Tita-Reid held leadership positions at Bayer PLC, where she served as Vice President-Country Division Head for Consumer Care in the UK and Ireland, and at Merck & Co, Inc., where she served in various roles, including General Manager for Western Europe. Earlier in her career, Ms. Tita-Reid spent 19 years at Procter & Gamble, where she managed a number of multi-billion dollar consumer brands in the baby and feminine care categories, spearheaded multi-cultural marketing strategy across 15 billion-dollar brands, and led the multi-brand business unit for Hispanic and African American consumers. During her tenure, Ms. Tita-Reid trained and developed the P&G marketing function on ethnic marketing and created breakthrough marketing strategies. Ms. Tita-Reid graduated with a Bachelor of Arts from Spelman College and holds an M.B.A. from Fuqua School of Business at Duke University. Ms. Tita-Reid has extensive experience as a multi-faceted executive with global marketing expertise, she has a record of strategic and operational ingenuity and transformation across complex organizations and a breadth of experience across the US and Europe.
 Family Relationships
 There are no family relationships among any of our executive officers or directors.
 Code of Business Conduct and Ethics
 We have adopted a Code of Business Conduct and Ethics for our directors, officers and employees, including our President and Chief Executive Officer, Principal Financial Officer, Principal Accounting Officer, and Controller (or persons performing an equivalent function). We provide mandatory online training for our employees with respect to the Code of Business Conduct and Ethics on an annual basis to ensure understanding and the importance of adhering to such guidelines. A copy of our Code of Business Conduct and Ethics may be accessed free of charge by visiting the Company's website at www.bluebirdbio.com and going to the Investors & Media—Corporate Governance section or by requesting a copy in writing to Joseph Vittiglio, Secretary, at our Somerville, Massachusetts office. We intend to post on our website any amendment to, or waiver under, a provision of the Code of Business Conduct and Ethics that applies to our President and Chief Executive Officer, Principal Financial Officer, Principal Accounting Officer, or Controller (or persons performing an equivalent function) within four business days following the date of such amendment or waiver. The information on our website is not incorporated by reference herein.
 Insider Trading Policy
 We have adopted an insider trading policy governing the purchase, sale and other dispositions of our securities by directors, officers, and employees. We believe that our insider trading policy is reasonably designed to promote compliance with insider trading laws, rules and regulations, and listing standards applicable to us. A copy of our insider trading policy is filed as Exhibit 19.1 to this Form 10-K.

 Audit Committee and Audit Committee Financial Expert
 We have a separately designated standing audit committee ("Audit Committee"). The members of the Audit Committee are Elisabeth Leiderman, M.D., John O. Agwunobi, M.D. and Mark Vachon. Dr. Leiderman serves as the Chairperson of the Audit Committee. Each member of the Audit Committee meets the independence requirements under applicable Nasdaq and Securities and Exchange Commission rules, including for purposes of serving on an audit committee. The members of our Audit Committee meet the requirements for financial literacy under the applicable Nasdaq rules. In addition, our Board of Directors has determined that Dr. Leiderman and Mr. Vachon each qualify as an "audit committee financial expert," as such term is defined in Item 407(d)(5) of Regulation S-K.

 Item 11. Executive Compensation
 This section discusses the material components of the executive compensation program for our current and former executive officers who are named in the 2024 Summary Compensation Table below. In 2024, our "named executive officers" and their positions were as follows:

 • Andrew Obenshain, President and Chief Executive Officer;
 • Thomas J. Klima, Chief Commercial and Operating Officer; and
 • Joseph Vittiglio, Chief Legal and Business Officer

 Summary Compensation Table

 The following table sets forth the total compensation awarded to, earned by and paid during the fiscal years ended December 31, 2024 and December 31, 2023 for each of our named executive officers.

 Name and Principal Position
 Year
 Salary ($)
 Bonus
($)(1)
 Option Awards ($) (2)
 Stock Awards ($) (2)
 Non-equity incentive plan compensation ($) (3)
 All other compensation ($) (4)
 Total ($)

 2024
 729,085
 —
 753,977
 324,935
 —
 17,520
 1,825,517

 Chief Executive Officer
 2023

 681,657
 —
 1,142,440
 863,590
 348,024
 13,470
 3,049,181

 2024
 510,404
 —
 230,817
 91,975
 —
 17,520
 850,716

 Chief Commercial and Operating Officer
 2023
 479,615
 —
 371,800
 281,050
 183,600
 13,470
 1,329,535

 2024
 441,346
 481,973
 75,000
 230,817
 91,975
 —
 17,520
 897,285

 Chief Legal and Business Officer

 (1) Amount represents the portion of Mr. Vittiglio's sign-on bonus that was payable to him in 2024.
 (2) The amounts reported in the Option Awards and Stock Awards columns above represent the aggregate grant date fair value of the stock options and restricted stock units granted to such named executive officers during 2023 and 2024 as computed in accordance with FASB ASC 718, not including any estimates of forfeitures related to service-based vesting conditions. See note 16 of Notes to Consolidated Financial Statements elsewhere in this Annual Report for a discussion of assumptions made by the Company in determining the aggregate grant date fair value of our stock option and restricted stock unit awards. Note that the amounts reported in these columns reflect the accounting cost for these stock options and restricted stock units, and do not correspond to the actual economic value that may be received by the named executive officers from the stock options and restricted stock units. We also granted performance-based restricted stock unit awards to Mr. Obenshain in 2023 and 2024, and to Mr. Vittiglio and Mr. Klima in 2024. The grant date fair value computed in accordance with FASB ASC 718 of these awards based on probable outcome as of the grant date is equal to their maximum grant date fair values.
 (3) Amounts represent cash payment under our annual cash incentive program earned in respect of 2023, based on achievement of performance goals. No bonus amounts under the cash incentive program were approved for 2024. Please see the description of the annual cash incentive program under which bonuses were paid to the named executive officers in the "Annual Incentive Program" section below.

 (4) Amounts represent employer matching contributions to the executive's 401(k) plan account and certain other employee fringe benefits.

 Narrative Disclosure to Summary Compensation Table
 Base Salary
 We provide base salaries to our named executive officers to compensate them with a fair and competitive base level of compensation for services rendered during the year. Our Compensation Committee typically determines the base salary for each executive based on the executive's responsibilities, experience and, if applicable, the base salary level of the executive prior to joining bluebird. In addition, our Compensation Committee reviews and considers the level of base salary paid by companies in our peer group for similar positions. Our Compensation Committee's assessment of our named executive officers' base salary takes into account our compensation objectives and philosophy to retain highly qualified executives, to motivate them to achieve our business goals, and to reward them for superior short- and long-term performance.
 In December of 2023, our Compensation Committee reviewed the compensation for our Chief Executive Officer and each of our other named executive officers. With respect to Mr. Obenshain, our Compensation Committee reviewed his overall compensation and determined to increase his annual base salary for 2024 from $682,400 to $730,000. This determination was based on his critical role at the Company, market conditions, company performance throughout 2023 in meeting key milestones and objectives, as well as consideration of the critical upcoming execution and risk inflection points throughout 2024. The Compensation Committee also approved merit increases in base salary for each of our other named executive officers serving at that time based on several factors including the Company's performance against the 2023 company goals, and each named executive officer's achievement of individual goals in 2023, as well as a consideration of the market conditions and a comparison of the executives' base salaries to similarly situated executives in our peer group. The table below sets forth the adjustments to the base salary, in dollars and as a percentage, for each of our named executive officers:

 Name
 2023
Base Salary ($)
 2024
Base Salary ($)
 Aggregate Increase (%)

 682,400
 730,000
 7.0

 480,000
 511,000
 6.5

 450,000
 482,600
 7.2

 Annual Incentive Program
 In early 2024, our Board approved the Company's corporate goals for 2024. Consistent with past practice, the Company's annual incentive program for 2024 was structured based on Company-wide achievement of the Company's corporate goals and our employees' achievement of their individual goals during 2024. For 2024, our employees, including our named executive officers, had the opportunity to earn cash incentive awards calculated as a percentage of pre-established bonus targets based on the Company's performance against the Company's corporate goals (based on drug delivery and manufacturing targets, financial progress, and employee engagement) and/or such employee's individual performance against their own pre-established individual goals.
 For fiscal year 2024, the incentive award for our Chief Executive Officer was based 100% on the Company's performance against the corporate goals and the award for our other named executive officers was based 80% on the Company's performance against the corporate goals and 20% on such named executive officer's performance against their individual goals. Our Compensation Committee, however, reserves the discretion to adjust upward or downward any cash incentive award as it deems appropriate, provided that bonuses are capped at 150% of target amounts.
 Given the Company's performance and financial position, the Compensation Committee has not approved bonus payments pursuant to the Company's annual incentive program for the fiscal year 2024.
 Long-Term Incentive Awards
 Our long-term incentive equity awards are generally in the form of stock options and restricted stock units, which deliver equivalent value while using fewer authorized shares. Beginning in 2021, we granted performance-based restricted stock units based on relative total shareholder return to our Chief Executive Officer, and beginning in 2024, we extended these grants to our other executive officers, in each case to further tie executive compensation to stock price performance and in response to stockholder feedback. We typically make equity award grants to each of our executive officers upon commencement of employment, and annually in conjunction with our review of their individual performance. Additional equity award grants may

 be made in connection with a promotion, or as a special incentive. Our executives benefit from stock options only if our stock price increases through the creation of stockholder value, and the value of restricted stock units increase as our stock price increases. Accordingly, we believe stock options and restricted stock units provide meaningful incentives to our executives to achieve increases in the value of our stock over time, while performance-based restricted stock units further align our executive officers' interests with long-term stockholders' interests and company performance. In addition, the vesting feature of our long-term incentive grants contributes to executive retention by providing an incentive to our executives to remain employed by us during the vesting period.
 All equity awards to our executive officers are approved by our Compensation Committee. The size of equity awards varies among our executive officers based on their positions, competitive market data, and annual performance assessments. All stock options granted by bluebird have exercise prices equal to the fair market value of our common stock on the date of grant, so that the recipient will not realize any value from his or her options unless our share price increases above the stock price on the date of grant. Accordingly, this portion of our executive officers' compensation is at risk and is directly aligned with stockholder value creation.
 As part of the ongoing review of our compensation strategy and practices, the Compensation Committee determines the appropriate mix of the type of equity awards, based in part on recommendations from Aon, its independent compensation consultant. Because of the volatility of our stock price in relation to when equity grants are made, our equity compensation guidelines set forth aggregate grant targets reflecting stock options plus restricted stock units based on number of shares (rather than value of the equity grants), and these guidelines are developed based on and in reference to our equity grant data for our peer companies. The target mix for annual long-term incentive equity grants to our executive officers is generally split approximately one-half in stock options and one-half in restricted stock units (including performance-based restricted stock units). Since 2021, our Chief Executive Officer has received a portion of his restricted stock units as performance-based restricted stock units and in 2024, all of our executives received a portion of their restricted stock units as performance-based restricted stock units. The Compensation Committee believes that this deliberate mix of equity ensures that compensation remains tied to stock performance and promotes retention. The Compensation Committee may adjust the mix of award types or approve different award types as part of the overall compensation strategy. Awards made in connection with a new, extended or expanded employment relationship may involve a different mix of equity awards, depending on the Compensation Committee's assessment of the total compensation package being offered.
 In addition, long-term equity incentive grants of stock options and restricted stock units to our executive officers typically vest over four years, which we believe provides an incentive to our executives to add value to the Company over the long-term and to remain with bluebird. Typically, the stock options we grant to our executives have a ten-year term and vest as to 25% of the shares on the first anniversary of the date of grant and then the remaining shares vest in equal monthly installments thereafter until the fourth anniversary of such date. Vesting of option grants to employees ceases upon termination of employment and exercise rights typically cease three months following termination of employment, except in the case of death or disability. Prior to the exercise of an option, the stock option holder does not have any rights as a stockholder with respect to the shares subject to such option, including voting rights or the right to receive dividends or dividend equivalents. Annual restricted stock units granted to our executives generally vest in equal annual installments beginning on or about the first anniversary of the day of grant, until the fourth anniversary of such date.
 2024 Equity Awards
 In 2024, we granted each of our named executive officers a performance-based restricted stock unit award, to further align such officer's compensation with stockholder interests and company performance (the "2024 Performance-Based RSU Awards"). Each named executive officer's 2024 Performance-Based RSU Award is earned based on total shareholder return compared to a selected group of companies that are considered relevant peers across business segment and size metrics, with a focus on industry classifications, revenue, and market capitalization, and which was developed in consultation with Aon (our "Named Peer Group"). The multiplier used to determine the number of earned restricted stock units could range between 0% and 200%, with a threshold achievement level at -25th percentile (as compared to the peer median) required to earn any restricted stock units, target achievement level equal to the peer median, and a ceiling achievement level at the +50th percentile (as compared to the peer median). The 2024 Performance-Based RSU Awards, to the extent earned, each vest in full on approximately the third anniversary of the grant date on the date performance achievement is certified by our Compensation Committee, subject to the grantee's continued service. Additionally, in connection with a sale event that occurs prior to the end of the performance period, a number of 2024 Performance-Based RSU Awards shall be earned and vested assuming that the applicable performance goals have been deemed to be achieved at the greater of target and actual level of performance. The target number of shares subject to the 2024 Performance-Based RSU Awards are as follows:

 Name
 2024 Performance-Based RSU Award

 9,750

 2,500

 2,500

 Under the terms of the 2024 Performance Based-RSU Awards, the number of performance-based restricted stock units earned is calculated by multiplying the target number of performance-based restricted stock units by a performance multiplier.
 In its design of the performance-based restricted stock units, the Compensation Committee considered various design elements and alternative approaches including milestone-based approaches. Given the stage of the Company, early in its commercial product launches, the Compensation Committee felt that an overall relative stock performance metric best captures the value inflections that would potentially be unlocked through exceptional company performance, and is fully aligned with stockholder interests. Furthermore, a three-year measurement period provides an incentive for our executives to take a long-term view with respect to company performance.
 In connection with the annual review of our named executive officers' performance during 2023 and consistent with our compensation philosophy, in 2024 our Compensation Committee approved the annual long-term equity incentive awards granted to our named executive officers serving at that time as set forth in the table below:

 2024 Option Award

 2024 RSU Award

 2024 Performance-Based RSU Award

 Name
 # Shares
 Grant date fair value
 # Shares
 Grant date fair value
 Target # Shares
 Grant Date Fair value

 32,500
 $753,977
 6,500
 $67,535
 9,750
 $128,700

 9,950
 $230,817
 2,500
 $25,975
 2,500
 $33,000

 9,950
 $230,817
 2,500
 $25,975
 2,500
 $33,000

 The grant date fair values of the awards presented above and shown in the Summary Compensation Table below were determined in accordance with Financial Accounting Standards Board (FASB), Accounting Standards Codification (ASC), Topic 718.
 Benefits and Other Compensation
 Other compensation to our executives consists primarily of the broad-based benefits we provide to all full-time employees in the United States, including medical, dental and vision insurance, group life and disability insurance, an employee stock purchase plan and a 401(k) plan. Pursuant to our employee stock purchase plan, employees, including our named executive officers, have an opportunity to purchase our common stock at a discount on a tax-qualified basis through payroll deductions. The employee stock purchase plan is designed to qualify as an "employee stock purchase plan" under Section 423 of the Internal Revenue Code. The purpose of the employee stock purchase plan is to encourage our employees, including our named executive officers, to become our stockholders and better align their interests with those of our other stockholders. Pursuant to our 401(k) plan, employees, including our named executive officers, may elect to defer a portion of their current compensation up to the statutorily prescribed annual limit (which was $23,000 in 2024), with additional salary deferrals not to exceed $30,500 available to those employees 50 years of age or older, and to have the amount of this deferral contributed to our 401(k) plan. We make discretionary matching contributions and other employer contributions on behalf of eligible employees under our 401(k) plan. For fiscal year 2024, we expect to match a portion of eligible employee contributions equal to 100% of the first 5% of eligible contributions pursuant to our 401(k) plan's matching formula.
 Currently, we do not view perquisites or other personal benefits as a significant component of our executive compensation program. Accordingly, we do not provide perquisites to our named executive officers, except in situations where we believe it is appropriate to assist an individual in the performance of his or her duties, to make him or her more efficient and effective, and for recruitment and retention purposes. All future practices with respect to perquisites or other personal benefits will be approved and subject to periodic review by our Compensation Committee.
 Certain executives, including our named executive officers, may be entitled to certain severance and/or change in control protections pursuant to their employment agreements, which are described below under —Employment Arrangements with Our Named Executive Officers. Our goal in providing severance and change in control benefits is to offer sufficient cash continuity protection such that our executives will focus their full time and attention on the requirements of the business rather than the potential implications for their respective position. We prefer to have certainty regarding the potential severance amounts

 payable to the named executive officers, rather than negotiating severance at the time that a named executive officer's employment terminates.
 Outstanding Equity Awards at Fiscal Year End
 The following table sets forth information concerning the outstanding equity awards held by each of the named executive officers as of December 31, 2024.

 Option Awards
 Stock Awards

 Name
 Award Grant Date
 Number of securities underlying unexercised options ((#) exercisable)
 Number of securities underlying unexercised options (#) unexercisable)
 Option exercise price ($/share)
 Option expiration date
 Number of shares or units of stock that have not vested (#)
 Market value of shares or units of stock that have not vested ($)(1)

 Equity incentive plan awards: number of unearned shares, units or other rights that have not vested (#)
 Equity incentive plan awards: market or payout value of unearned shares, units or other rights that have not vested ($)(1)

 12/1/2016
 —
 $684.00
 12/1/2016

 2/1/2018
 —
 $2,044.80
 2/1/2028

 2/1/2019
 —
 $1,341.20
 2/1/2029

 3/2/2020
 —
 $735.60
 3/2/2030

 11/2/2020
 1,033
 —
 $529.00
 11/2/2030

 2/16/2021
 2,948
 (2)
 $283.40
 2/16/2031

 2/16/2021
 (3)
 3,144

 8/2/2021
 17,050
 3,026
 (4)
 $255.20
 8/2/2031

 8/2/2021
 2,509
 (5)
 20,925

 3,190
 1,309
 (6)
 $156.00
 2/1/2032

 (7)
 3,753

 1,350
 (8)
 11,259

 7,393
 9,506
 (6)
 $102.20
 3/1/2033

 2,535
 (7)
 21,142

 5,070
 (8)
 42,284

 3/1/2024
 —
 32,499
 (6)
 $31.30
 3/1/2034

 6,500
 (7)
 54,210

 9,750
 (8)
 81,315

 6/1/2021
 4,500
 (9)
 $310.00
 6/1/2031

 6/1/2021
 (7)
 5,229

 1,770
 (6)
 $156.00
 2/1/2032

 (7)
 5,213

 9/1/2022
 (6)
 $131.00
 9/1/2032

 9/1/2022
 (7)
 2,294

 2,406
 3,093
 (6)
 $102.20
 3/1/2033

 2,063
 (7)
 17,205

 3/1/2024
 —
 9,949
 (6)
 $31.30
 3/1/2034

 2,500
 (7)
 20,850

 2,500
 (8)
 20,850

 2/1/2023
 2,292
 2,707
 (6)
 $127.60
 2/1/2033

 2/1/2023
 1,875
 (7)
 15,638

 3/1/2024
 —
 9,949
 (6)
 $31.30
 3/1/3034

 2,500
 (7)
 20,850

 2,500
 (8)
 20,850

 (1) All unvested stock options and restricted stock awards were granted under our 2013 Stock Option and Incentive Plan, 2023 Incentive Award Plan, or our 2021 Inducement Plan. The market value of restricted stock units that have not vested is

 based on the closing price of $8.34 per share for our common stock on December 31, 2024, as reported on the NASDAQ Global Select Market.
 (2) The shares underlying these options vest as follows: 25% vested on January 4, 2022, with the remainder of the shares vesting in equal monthly installments over the following three years through January 4, 2025, subject to the grantee's continued service with us through each applicable vesting date.
 (3) These restricted stock unit awards vest in four equal annual installments of 25% starting on January 4, 2022 through January 4, 2025, subject to the grantee's continued service with us through each applicable vesting date.
 (4) This performance-based option was earned based on performance criteria related to the separation of 2seventy bio. The shares underlying this option vest as follows: 25% vested on August 2, 2022, with the remainder of the shares vesting in equal monthly installments over the following three years through August 2, 2025, subject to the grantee's continued service with us through each applicable vesting date.
 (5) This performance-based restricted stock unit award was earned based on performance criteria related to the separation of 2seventy bio. The performance-based restricted stock unit vests in four equal annual installments of 25% starting on August 2, 2022 through August 2, 2025, subject to the grantee's continued service with us through each applicable vesting date.
 (6) The shares underlying these options vest as follows: 25% vest on the one-year anniversary of the grant date, with the remainder of the shares vesting in equal monthly installments over the following three years, subject to the grantee's continued service with us through each applicable vesting date.
 (7) These restricted stock unit awards vest in four equal annual installments of 25% starting on the one-year anniversary of the award grant date, subject to the grantee's continued service with us through each applicable vesting date.
 (8) These performance-based restricted stock unit awards are earned based on relative total shareholder return compared to a peer group of companies in the Standard & Poor Biotechnology Index and, to the extent earned, will vest approximately three years from the grant date, subject to the grantee's continued service with us on the applicable vesting date.
 (9) The shares underlying this option vest as follows: 25% vested on May 10, 2022, with the remainder of the shares vesting in equal monthly installments over the following three years through May 10, 2025, subject to the grantee's continued service with us through each applicable vesting date.
 Employment Arrangements with our Named Executive Officers
 Andrew Obenshain. We have entered into an employment agreement, effective as of January 7, 2021, with Mr. Obenshain providing for his employment as the Company's President, Severe Genetic Disease. Mr. Obenshain currently serves as our Chief Executive Officer and Principal Executive Officer. Under his agreement Mr. Obenshain was initially entitled to receive a base salary of $435,000 (which has been subsequently increased as described above), subject to adjustment at the discretion of the Compensation Committee. Mr. Obenshain is also currently eligible for an annual cash incentive award targeted at 60% of his annual base salary. Mr. Obenshain is eligible to participate in our employee benefit plans, subject to the terms of those plans.
 Thomas J. Klima. We have entered into an employment agreement, effective as of April 20, 2021, with Mr. Klima providing for his employment as the Company's Chief Commercial Officer. Mr. Klima currently serves as our Chief Commercial and Operating Officer. Under his agreement Mr. Klima is entitled to receive a base salary of $400,000 (which has been subsequently increased as described above), subject to adjustment at the discretion of the Compensation Committee. Mr. Klima is also eligible for an annual cash incentive award targeted at 45% of his annual base salary. Mr. Klima's employment agreement also provides for an initial grant of stock options and restricted stock units and his eligibility to participate in our employee benefit plans, subject to the terms of those plans.
 Joseph Vittiglio. We have entered into an employment agreement, effective as of January 1, 2023, with Mr. Vittiglio providing for his employment as the Company's Chief Legal and Business Officer. Under his agreement Mr. Vittiglio is entitled to receive a base salary of $450,000 (which has been subsequently increased as described above), subject to adjustment at the discretion of the Compensation Committee. Mr. Vittiglio is also eligible for an annual cash incentive award targeted at 45% of his annual base salary. Mr. Vittiglio is eligible to participate in our employee benefit plans, subject to the terms of those plans.
 These employment agreements also contain provisions that provide for certain payments and benefits in the event of an involuntary termination of employment. In addition, the named executive officers may be entitled to accelerated vesting of their outstanding and unvested awards in certain circumstances as described below.

 Involuntary termination of employment
 Pursuant to their employment agreements, each named executive officer is eligible to receive certain payments and benefits in the event his employment is terminated by us without "cause" (as defined in the employment agreements) or in the event he terminates his employment with "good reason" (as defined in the employment agreements). Upon the timely execution of a severance agreement, including a general release of claims, each named executive officer is eligible to receive the following payments and benefits:
 •12 months of base salary continuation; and
 • if he elects to continue his or her group healthcare benefits, to the extent authorized by and consistent with COBRA, we will pay the named executive officer a monthly cash payment equal to the monthly employer contribution we would have made to provide him health insurance if he had remained employed by us until the earlier of (1) 12 months following the date of termination, or (2) the end of the named executive officer's COBRA health continuation period.
 Involuntary termination of employment in connection with a sale event
 In addition, in the event that any of our named executive officers terminates his or her employment with us for good reason or his or her employment with us is terminated by us without "cause", in either case within 12 months following a "sale event" (as defined in the 2013 Stock Option and Incentive Plan (now referred to as a "change in control" under the 2023 Incentive Award Plan)), he will be entitled to receive the following payments and benefits (in lieu of the payments and benefits described above) upon the timely execution of a severance agreement, including a general release of claims:
 • a lump sum cash payment equal to one times the sum of (1) the named executive officer's then-current base salary (or base salary in effect immediately prior to the sale event, if higher) and (2) the named executive officer's target annual cash incentive compensation; and
 • if he elects to continue his or her group healthcare benefits, to the extent authorized by and consistent with COBRA, we will pay the named executive officer a monthly cash payment equal to the monthly employer contribution we would have made to provide him or her health insurance if he had remained employed by us until the earlier of (1) 12 months following the date of termination or (2) the end of the named executive officer's COBRA health continuation period; and
 • all stock options and other stock-based awards granted to the named executive officer after the date of his or her employment agreement will become fully exercisable and non-forfeitable as of the date of the named executive officer's termination.
 Non-Employee Director Compensation
 The Compensation Committee of our Board is responsible for making recommendations to our Board on appropriate compensation levels and arrangements for our non-employee directors, ensuring they are consistent with our compensation policy and remain competitive with our peer companies. The Compensation Committee reviews our non-employee director compensation on an annual basis. In making recommendations, the Compensation Committee takes various factors into consideration, including:
 • Non-employee directors' responsibilities and the form and amount of compensation paid to directors at our peer companies;
 • Ability to retain and attract the most qualified and experienced non-employee directors to oversee the management of our business operations; and
 • Advice of an independent compensation consultant to review our non-employee director compensation program and promote alignment with market practice and stockholder interests.
 Our goal is to appropriately compensate non-employee directors for their leadership and expertise while aligning non-employee director interests with those of our stockholders. In line with this goal, our non-employee director compensation policy is underpinned by the same philosophy and principles that govern our executive compensation program. The Compensation Committee generally targeted non-employee director compensation near the 50th percentile of compensation paid non-employee directors with the companies in our peer group.
 Our non-employee director compensation program is designed to:
 Align non-employee director and stockholder interests through grants of non-statutory stock option awards and restricted stock units;

 Encourage a vested interest in our long-term business performance through stock ownership requirements;
 Align non-employee director compensation with our peer companies of comparable stage of development, market capitalization and size;
 Ensure a robust non-employee director compensation governance framework is in place; and
 Help us attract and retain talent for Board service to support the long-term value of the Company.
 Based on these considerations, our Board has adopted a non-employee director compensation policy, which provides for annual cash retainers. The non-executive chair of our Board and the chair of each of our committees is entitled to greater compensation for his or her services than other members of our Board, which we believe is commensurate with the additional time commitment and additional responsibility required by the position held and is consistent with the compensation practices of our peer group companies. The table below sets forth the cash retainer applicable to our directors in 2024.

 Annual cash retainers under the Non-Employee Director Compensation Policy
 2024 Cash Retainer ($)

 Board:

 All non-employee members of the Board
 $
 45,000

 Additional retainer for non-executive chair of the Board
 $
 35,000

 Audit Committee:

 Additional retainer for chair of the Audit Committee
 $
 20,000

 Additional retainer for other members of the Audit Committee
 $
 10,000

 Compensation Committee:

 Additional retainer for chair of the Compensation Committee
 $
 15,000

 Additional retainer for other members of the Compensation Committee
 $
 7,500

 Nominating and Corporate Governance Committee:

 Additional retainer for chair of the Nominating and Corporate Governance Committee
 $
 10,000

 Additional retainer for other members of the Nominating and Corporate Governance Committee
 $
 5,000

 In addition, under our non-employee director compensation policy, new members of our Board are eligible for an initial equity grant under our stock option plan. The initial equity grant takes the form of a grant of stock options and restricted stock units that vest in equal annual installments over a three-year period, subject to the non-employee director's continued service. In addition, on the date of the annual meeting of stockholders, each continuing non-employee director who has served on the Board for the previous six months will be eligible to receive an annual equity grant in the form of stock options and restricted stock units. These annual equity grants will vest in full upon the earlier of the first anniversary of the date of grant or the date of the following annual meeting of stockholders, subject to the non-employee director's continued service. The number of shares subject to the initial equity grants and the annual equity grants are summarized in the table below (as adjusted to reflect the reverse stock split). In the case of each initial equity grant and annual equity grant, the Board or Compensation Committee may exercise their discretion to provide for a different number of shares subject to equity awards in the event they determine a variation from the stated amount is warranted. All of the foregoing options are granted with an exercise price equal to the fair market value of our common stock on the date of grant. The number of equity grants under the policy applicable to our directors in 2024 is summarized below (as adjusted to reflect the reverse stock split).

 Equity grants under the Non-Employee Director Compensation Policy
 Stock options (# of shares)
 Restricted Stock Units (# of shares)

 Initial equity grant
 3,738
 1,867

 Annual equity grant
 2,492
 1,245

 The following table sets forth the compensation we paid to our non-employee directors during the year ended December 31, 2024. Other than as set forth in the table we did not pay any compensation, reimburse any expense of (other than reasonable out-of-pocket expenses to attend meetings of the Board or any committee), make any equity awards or non-equity awards to, or pay any other compensation to any of the other non-employee members of our Board in the year ended December 31, 2024. Mr. Obenshain, our current Chief Executive Officer, received no compensation for his service as a director, and, consequently, is not included in this table. The compensation received by Mr. Obenshain as an employee during the year ended December 31, 2024 is presented in the Summary Compensation Table above.

 Name(1)
 Fees earned or paid in cash($)
 Stock
awards($)(2)
 Option
awards($)(2)
 Total($)

 John O. Agwunobi, M.D.
 65,000
 92,403

 Mark Vachon
 105,000
 132,403

 Michael Cloonan (3)
 23,875
 19,398
 47,099
 90,372

 Elisabeth Leiderman, M.D.
 72,500
 99,903

 Najoh Tita-Reid
 57,500
 84,903

 Charlotte Jones-Burton, M.D., M.S.
 50,000
 77,403

 Richard Paulson
 45,000
 72,403

 Nick Leschly
 —
 (4)

 27,403

 (1) The aggregate number of shares of our common stock underlying stock options outstanding as of December 31, 2024 for the non-employee directors were: Dr. Agwunobi: 5,388, Mr. Vachon: 5,527, Mr. Cloonan: 3,738, Dr. Leiderman: 4,574, Ms. Tita-Reid: 4,574, Dr. Jones-Burton: 4,197, Mr. Paulson: 2,867, and Mr. Leschly: 35,815. The aggregate number of restricted stock units outstanding as of December 31, 2024 for the non-employee directors was: Dr. Agwunobi: 1,245, Mr. Vachon: 1,245, Mr. Cloonan: 1,867, Dr. Leiderman: 1,245, Ms. Tita-Reid: 1,245, Dr. Jones-Burton: 1,323, Mr. Paulson: 1,401, and Mr. Leschly: 1,245. Mr. Leschly's stock option and restricted stock unit amounts include equity awards granted to him from his time as our former Chief Executive Officer.
 (2) The amounts reported represent the aggregate grant date fair value of the stock options and restricted stock units granted to our non-employee directors during 2024 as computed in accordance with FASB ASC Topic 718, not including any estimates of forfeitures. See note 16 of Notes to Consolidated Financial Statements in elsewhere in this Annual Report for a discussion of assumptions made by the Company in determining the aggregate grant date fair value of our stock option and restricted stock unit awards for the fiscal year ended December 31, 2024. Note that the amounts reported in this column reflect the accounting cost for these grants, and do not correspond to the actual economic value that may be received by the non-employee directors from the exercise of the options or vesting of the restricted stock units.
 (3) Mr. Cloonan joined our Board on June 20, 2024.
 (4) Mr. Leschly elected to not receive the cash portion of his compensation.
 Compensation Recovery Policy
 Effective October 2023, our Board adopted a Policy for Recovery of Erroneously Awarded Compensation (the "Clawback Policy") to implement final clawback rules issued by the SEC. The Clawback Policy applies to our current and former executive officers and subjects their incentive-based compensation received on or after October 2, 2023 to clawback in the event our company is required to prepare an accounting restatement to correct its material noncompliance with any financial reporting requirement under U.S. securities laws. In these circumstances, the Clawback Policy requires the Company to recover, reasonably promptly, the portion of incentive-based compensation that is deemed to have been erroneously awarded, unless the Compensation Committee (which administers the policy) determines that recovery would be impracticable and that one or more of the allowable impracticability conditions under SEC rules has been met.
 In connection with the filing of the Company's Annual Report on Form 10-K for the year ended December 31, 2023, the Company restated its consolidated financial statements as of and for the year ended December 31, 2022, and for each of the first three quarters of 2022 and 2023. The Company determined that this restatement would not result in the recoupment of any compensation because the restatement did not affect any incentive compensation approved, awarded or granted after October 2, 2023.
 Equity Grant Practices
 We do not grant equity awards in anticipation of the release of material nonpublic information or time the release of material nonpublic information for the purpose of affecting the value of executive compensation. During fiscal year 2024, we did not grant stock options, stock appreciation rights, or similar option-like instruments to our named executive officers during the four business days prior to or the one business day following the filing of our periodic reports or the filing or furnishing of a Form 8-K that discloses material nonpublic information.

 Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters
 Equity compensation plan information
 The following table presents aggregate summary information as of December 31, 2024, regarding our existing equity compensation plans.

 Plan Category
 Number of Securities to be Issued Upon Exercise of Outstanding Options, Restricted Stock Units and Other Rights
(a)
 Weighted Average Exercise Price of Outstanding Options
(b)
 Number of Securities Remaining Available for Future Issuance Under Equity Compensation Plans (excluding securities reflected in column (a))
(c)

 Equity Compensation Plans Approved by Stockholders (1)
 533,480
 (2)
 $
 162.76
 (3)
 877,847
 (4)

 Equity Compensation Plans Not Approved by Stockholders (5)
 38,689
 (6)
 $
 86.17
 21,611

 Total
 572,169
 $
 157.66
 899,458

 (1) Consists of shares of common stock underlying equity awards under the 2013 Stock Option and Incentive Plan, the 2013 Employee Stock Purchase Plan (the "ESPP") and the 2023 Incentive Award Plan, as amended. Our 2013 Stock Option and Incentive Plan expired in June 2023 and no further shares were available for issuance thereunder after such date.
 (2) Includes 226,017 shares subject to restricted stock units (based on the target performance level for performance-vesting restricted stock units) and 307,463 shares to be issued upon the exercise of outstanding stock options.
 (3) The calculation does not take into account the 226,017 shares of common stock subject to outstanding restricted stock units. Such shares will be issued at the time the restricted stock units vest, without any cash consideration payable for those shares.
 (4) Consists of shares available for future issuance under the ESPP and the 2023 Incentive Award Plan. As of December 31, 2024, 49,871 shares of common stock were available for issuance under the ESPP, and 827,976 shares of common stock were available for issuance under the 2023 Incentive Award Plan.
 (5) We established an Inducement Plan in May 2021 (the "Inducement Plan") to be used exclusively for the grant of equity awards to prospective officers and employees who were not previously an employee or non-employee director as an inducement material to each such individual entering into employment with us. The Inducement Plan initially reserved 30,000 shares, which was later increased to an aggregate of 62,250 shares in March 2022 (adjusted for the reverse stock split), for the issuance of awards to such individuals of non-qualified stock options, stock appreciation rights, restricted stock units, restricted stock awards, stock awards and/or dividend equivalent rights in the discretion of the plan administrator and in accordance with Nasdaq rules. Our Compensation Committee currently administers the Inducement Plan.
 (6) Includes 16,762 shares subject to restricted stock units (none of which are subject to performance vesting) and 21,927 shares to be issued upon the exercise of outstanding stock options.

 Security Ownership of Certain Beneficial Owners and Management
 The following table sets forth the amount of common stock of bluebird beneficially owned, directly or indirectly, as of March 21, 2025, by (i) each current director of bluebird, (ii) each named executive officer of bluebird, (iii) all directors and executive officers of bluebird as a group, and (iv) each person who is known to bluebird to beneficially own more than five percent (5%) of the outstanding shares of common stock of bluebird, as determined through SEC filings, and the percentage of the common stock outstanding represented by each such amount. All shares of common stock shown in the table reflect sole voting and investment power except as otherwise noted. Share counts give effect to a reverse stock split of our common stock at a ratio of 1-for-20 effective on December 12, 2024, including any information reported below from sources pre-dating the reverse stock split.

 Beneficial ownership is determined by the rules of the SEC and includes voting or investment power of the securities. As of March 21, 2025, bluebird had 9,790,070 shares of common stock outstanding. Shares of common stock subject to options to purchase, which are now exercisable or are exercisable within 60 days after March 21, 2025, or restricted stock units vesting within 60 days after March 21, 2025, are to be considered outstanding for purposes of computing the percentage ownership of the persons holding these options or other rights but are not to be considered outstanding for the purpose of computing the percentage ownership of any other person. Unless otherwise indicated, the address for each person listed below is c/o bluebird bio, Inc., 455 Grand Union Boulevard, Somerville, Massachusetts 02145.

 Name and Address of Beneficial Owner
 Number of Shares
Beneficially Owned
 Percentage of Shares
Beneficially Owned

 5% Stockholders

 BlackRock, Inc. (1)
 772,188
 8.0%

 The Vanguard Group (2)
 523,700
 5.4%

 Directors and Named Executive Officers

 Nick Leschly (3)
 48,051
 *

 John Agwunobi, M.D. (4)
 4,219
 *

 Charlotte Jones-Burton, M.D., M.S. (5)
 2,633
 *

 Elisabeth Leiderman, M.D. (6)
 3,194
 *

 Richard Paulson (7)
 *

 Najoh Tita-Reid (8)
 3,245
 *

 Mark Vachon (9)
 4,287
 *

 Michael Cloonan

 —
 *

 Thomas J. Klima (10)
 17,083
 *

 Andrew Obenshain (11)
 37,454
 *

 Joseph Vittiglio (12)
 6,861
 *

 All executive officers and directors as a group (13 persons) (13)
 142,926
 1.5%

 _________________________

 * Represents holdings of less than 1%.
 (1) Based solely on a Schedule 13G reporting beneficial ownership as of September 30, 2024, filed with the SEC on November 8, 2024, with sole voting power with respect to 761,527 shares and sole dispositive power with respect to 772,188 shares. The address of BlackRock, Inc. is 50 Hudson Yards, New York, New York 10001.
 (2) Based solely on a Schedule 13G reporting beneficial ownership as of September 30, 2024, filed with the SEC on November 13, 2024, with shared voting power with respect to 4,377 shares, sole dispositive power with respect to 516,541 shares, and shared dispositive power with respect to 7,159 shares. The address of The Vanguard Group is 100 Vanguard Boulevard, Malvern, Pennsylvania 19355.
 (3) Consists of 14,416 shares of common stock and 25,201 shares of common stock underlying options exercisable within 60 days of March 21, 2025. Such shares include 2,284 shares of common stock held in the Nick Leschly 2001 Trust for which Mr. Leschly is co-trustee with his spouse, and with whom he shares voting and dispositive power, and 6,150 shares of common stock held in the Nick Leschly Irrevocable GST Trust of 2019 for which Mr. Leschly is co-trustee with his spouse, and with whom he shares voting and dispositive power.
 (4) Consists of 1,323 shares of common stock and 2,896 shares of common stock underlying options exercisable and restricted stock units vesting within 60 days of March 21, 2025.
 (5) Consists of 928 shares of common stock and 1,705 shares of common stock underlying options exercisable and restricted stock units vesting within 60 days of March 21, 2025.
 (6) Consists of 1,112 shares of common stock and 2,082 shares of common stock underlying options exercisable and restricted stock units vesting within 60 days of March 21, 2025.
 (7) Consists of 77 shares of common stock and 250 shares of common stock underlying options exercisable and restricted stock units vesting within 60 days of March 21, 2025.
 (8) Consists of 1,163 shares of common stock and 2,082 shares of common stock underlying options exercisable and restricted stock units vesting within 60 days of March 21, 2025.

 (9) Consists of 1,252 shares of common stock and 3,035 shares of common stock underlying options exercisable and restricted stock units vesting within 60 days of March 21, 2025.
 (10) Consists of 3,414 shares of common stock and 13,669 shares of common stock underlying options exercisable and restricted stock units vesting within 60 days of March 21, 2025.
 (11) Consists of 9,027 shares of common stock and 28,427 shares of common stock underlying options exercisable and restricted stock units vesting within 60 days of March 21, 2025.
 (12) Consists of 1,143 shares of common stock and 5,718 shares of common stock underlying options exercisable and restricted stock units vesting within 60 days of March 21, 2025.
 (13) Consists of 45,841 shares of common stock and 97,085 shares of common stock underlying options exercisable and restricted stock units vesting within 60 days of March 21, 2025.

 Item 13. Certain Relationships and Related Transactions and Director Independence
 Procedures for related party transactions
 We have adopted a related person transaction approval policy that governs the review of related person transactions at bluebird. Pursuant to this policy, if we want to enter into a transaction with a related person or an affiliate of a related person, our Chief Legal and Business Officer will review the proposed transaction to determine, based on applicable Nasdaq and SEC rules, if such transaction requires pre-approval by the Audit Committee and/or Board. If pre-approval is required, such matters will be reviewed at the next regular or special Audit Committee and/or Board meeting. In addition, our Compensation Committee charter requires that compensation arrangements with our executive officers be approved by our Compensation Committee. We may not enter into a related person transaction unless our Chief Legal and Business Officer has either specifically confirmed in writing that no further reviews are necessary or has confirmed that all requisite corporate reviews have been obtained.
 Transactions with related persons
 The following are certain transactions, arrangements and relationships with our directors, executive officers and stockholders owning 5% or more of our outstanding common stock, or any member of the immediate family of any of the foregoing persons, since January 1, 2023, other than equity and other compensation, termination, change in control and other arrangements, which are described under "Item 11. Executive Compensation."
 In connection with the 2021 separation of our severe genetic disease and oncology programs into two independent, publicly traded companies (the "Separation"), we entered into a separation agreement with 2seventy bio that, among other things, set forth bluebird's agreements with 2seventy bio regarding the principal actions to be taken in connection with the Separation. Nick Leschly, a member of our Board, is Chairman of the Board of Directors of 2seventy bio. The separation agreement identified assets transferred to, liabilities assumed by and contracts assigned to 2seventy bio as part of the Separation, and it provided for when and how these transfers, assumptions and assignments occurred. The purpose of the separation agreement was to provide 2seventy bio and bluebird with assets to operate their respective businesses and retain or assume liabilities related to those assets. Each of 2seventy bio and bluebird agreed to releases, with respect to pre-Separation claims, and cross indemnities, with respect to post-Separation claims, that were principally designed to place financial responsibility for the obligations and liabilities allocated to 2seventy bio under the separation agreement with 2seventy bio and financial responsibility for the obligations and liabilities allocated to bluebird under the separation agreement with bluebird. bluebird and 2seventy bio are also each subject to mutual 12-month employee non-solicit and non-hire restrictions, subject to certain customary exceptions.
 In connection with the Separation, we also entered into two transition services agreements with 2seventy bio. Pursuant to the transition services agreements, we are obligated to provide and are entitled to receive certain transition services related to corporate functions, such as finance, human resources, internal audit, research and development, financial reporting, and information technology. Services provided by us to 2seventy bio will continue for an initial term of up to two years, unless earlier terminated or extended according to the terms of the transition services agreement. Services received and performed are paid at a mutually agreed upon rate. During the years ended December 31, 2024 and 2023, we incurred $0.0 million and $5.0 million, respectively, of net expense for services provided by 2seventy bio. In April 2022, we and 2seventy bio agreed to amend certain terms of the transition services agreement to reduce our occupancy of a shared facility with 2seventybio and reduce the related fees.
 We also entered into a tax matters agreement with 2seventy bio governing bluebird's and 2seventy bio's respective rights, responsibilities and obligations with respect to taxes (including taxes arising in the ordinary course of business and taxes, if any,

 incurred as a result of any failure of the distribution and certain related transactions to qualify as tax-free for U.S. federal income tax purposes), tax attributes, the preparation and filing of tax returns, the control of audits and other tax proceedings, and assistance and cooperation in respect of tax matters.
 In addition, we entered into an employee matters agreement with 2seventy bio. The employee matters agreement allocates assets, liabilities and responsibilities relating to the employment, compensation and employee benefits of bluebird and 2seventy bio employees, and other related matters, in connection with the Separation, including the treatment of outstanding bluebird incentive equity awards and certain retirement and welfare benefit obligations. The employee matters agreement generally provides that, unless otherwise specified, 2seventy bio is responsible for liabilities associated with employees who transfer to 2seventy bio and employees whose employment terminated prior to the distribution but who primarily supported the 2seventy bio business, and bluebird is responsible for liabilities associated with other employees, including employees retained by bluebird. Pursuant to the employee matters agreement, the outstanding bluebird equity awards held by 2seventy bio and bluebird employees were adjusted immediately prior to the distribution, with the intent to maintain, immediately following the distribution, the economic value of the awards immediately before the distribution date.
 We additionally entered into an intellectual property license agreement with 2seventy bio, pursuant to which each party granted a license to certain intellectual property and technology to the other. bluebird granted 2seventy bio a perpetual, worldwide, non-exclusive, royalty-free, fully paid-up license (or, as the case may be, sublicense) to certain intellectual property to allow 2seventy bio to use such intellectual property in connection with 2seventy bio's ongoing and future research and development activities and product candidates. 2seventy bio granted bluebird a perpetual, worldwide, non-exclusive, royalty-free, fully paid-up license (or, as the case may be, sublicense) to certain intellectual property for use in bluebird's existing products and product candidates. Such licenses between the parties generally allow current or future uses of the intellectual property in connection with each party's respective fields.
 Board Independence
 Our Board has determined, upon the recommendation of our Nominating and Corporate Governance Committee, that each of our directors, other than Andrew Obenshain, who serves as our President and Chief Executive Officer, has no relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director and is independent within the meaning of the director independence standards of the Nasdaq rules. In addition, all members of the Audit Committee, Compensation Committee, and Nominating and Corporate Governance Committee satisfy the applicable independence criteria of the SEC and Nasdaq rules.

 Item 14. Principal Accountant Fees and Services
 Independent Registered Public Accounting Firm Fees
 The following is a summary and description of fees billed by Ernst & Young LLP for the fiscal years ended December 31, 2024 and 2023.

 Fiscal Year
2024
 Percentage of 2024
Services Approved
by Audit Committee
 Fiscal Year
2023
 Percentage of 2023
Services Approved
by Audit Committee

 Audit fees (1)
 $
 1,969,058
 100%
 $
 4,105,605
 100%

 Audit-related fees
 $
 —
 100%
 $
 —
 100%

 Tax fees (2)
 $
 147,162
 100%
 $
 104,022
 100%

 All other fees
 $
 —
 100%
 $
 —
 100%

 Total fees
 $
 2,116,220
 100%
 $
 4,209,627
 100%

 ___________________
 (1) Audit fees in 2024 and 2023 include fees for our annual audit, and quarterly review procedures. Additionally, audit fees in 2024 and 2023 include fees incurred in connection with our public equity offerings, including registration statements, comfort letters and consents.
 (2) Tax fees are related to tax return preparation, tax advisory services and international tax compliance.

 Item 15. Exhibits and Financial Statement Schedules
 (a)(1) Financial Statements.
 The response to this portion of Item 15 is set forth under Item 8 above.
 (a)(2) Financial Statement Schedules.
 All schedules have been omitted because they are not required or because the required information is given in the Consolidated Financial Statements or Notes thereto set forth under Item 8 above.
 (a)(3) Exhibits.
 See the Exhibit Index immediately before the signature page of this Annual Report on Form 10-K. The exhibits listed in the Exhibit Index are filed or incorporated by reference as part of this Annual Report on Form 10-K.

 Item 16. Form 10-K Summary
 Not applicable.

 Index to Consolidated Financial Statements
 Pages

 Report of Independent Registered Public Accounting Firm (PCAOB ID: 42)

 Consolidated Balance Sheets

 Consolidated Statements of Operations and Comprehensive Loss

 Consolidated Statements of Stockholders' Equity (Deficit)

 Consolidated Statements of Cash Flows

 Notes to Consolidated Financial Statements

 Report of Independent Registered Public Accounting Firm
 To the Stockholders and the Board of Directors of bluebird bio, Inc.
 Opinion on the Financial Statements
 We have audited the accompanying consolidated balance sheets of bluebird bio, Inc. (the Company) as of December 31, 2024 and 2023, the related consolidated statements of operations and comprehensive loss, stockholders' equity (deficit) and cash flows for each of the two years in the period ended December 31, 2024, and the related notes (collectively referred to as the "consolidated financial statements"). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2024 and 2023, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2024, in conformity with U.S. generally accepted accounting principles.
 The Company's Ability to Continue as a Going Concern
 The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern. As discussed in Note 1 to the financial statements, the Company has suffered recurring operating losses and negative operating cash flows, projects non-compliance with covenants in the Loan and Security Agreement and has stated that substantial doubt exists about the Company's ability to continue as a going concern. Management's evaluation of the events and conditions and management's plans regarding these matters are also described in Note 1. The consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty.
 Basis for Opinion
 These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.
 We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. Accordingly, we express no such opinion.
 Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.
 Critical Audit Matter
 The critical audit matter communicated below is a matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective or complex judgments. The communication of the critical audit matter does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

 Embedded Leases in Contract Manufacturing Agreements

 Description of the Matter
 As discussed in Notes 2 and 11 to the consolidated financial statements, the Company has elected to combine lease and non-lease components of agreements containing a lease, including certain contract manufacturing agreements, and allocate all the contract consideration to the lease components. The Company has recognized right-of-use finance lease assets and finance lease liabilities associated with those leases within contract manufacturing agreements. Finance lease assets, which are classified within Property, plant and equipment, net on the consolidated balance sheet, and finance lease liabilities were $139.4 million and $96.7 million as of December 31, 2024.

Auditing the Company's accounting for embedded leases was complex due to the judgment and additional audit effort required in determining whether new or amended agreements with contract manufacturing organizations contained an embedded lease and was also complex and challenging due to the volume of amendments to the agreements. There was significant judgment involved in determining whether the agreements provided the Company with (i) the right to obtain substantially all of the economic benefits from the use of the asset throughout the period of use and (ii) the right to direct how and for what purpose the identified asset is used throughout the period of use. Auditing the measurement of these embedded leases required additional audit effort to test the measurement of the right-of-use assets and lease liabilities. Auditing the accounting for embedded leases was also especially challenging due to the material weakness identified by the Company over the accounting for leases. The material weakness required an increased extent of audit effort to test the identification of embedded leases and the accounting for agreements, including amendments, with contract manufacturing organizations.

 How We Addressed the Matter in Our Audit
 Our audit procedures included, among others, testing the completeness of the Company's identification of agreements with embedded leases and amendments by reading new or amended agreements with contract manufacturing organizations, evaluating the nature of the Company's relationship with vendors to which significant recurring payments were made, and evaluating the Company's conclusion about whether there was an embedded lease. In order to evaluate the Company's judgement as to whether new or amended agreements contained an embedded lease, we performed inquiries with members from the legal department and operations personnel involved in the manufacturing process. In addition, for certain new or amended contracts, we tested management's evaluation of underlying agreements by confirming the Company's rights to obtain substantially all of the economic benefits from the use of the assets throughout the period of use and rights to direct how and for what purpose the identified assets are used throughout the period of use with relevant third-party contract organizations. To test the accuracy of the Company's measurement of right-of-use assets and lease liabilities, we read a sample of agreements, compared the contractual information to the inputs included in the Company's lease calculations and recalculated the Company's measurements. Because of the material weakness, we performed incremental audit procedures by increasing our sample sizes for the aforementioned procedures.

 /s/ Ernst & Young LLP
 We have served as the Company's auditor since 2012.
 Boston, Massachusetts

 Consolidated Balance Sheets
 (in thousands, except per share amounts)

 2024
 2023

 Assets

 Current assets:

 $
 $

 Prepaid expenses
 10,634
 14,800

 Inventory

 65,017
 22,919

 Due from factor
 3,094

 Receivables and other current assets

 13,618
 21,651

 Total current assets
 154,668
 281,685

 Property, plant and equipment, net
 60,848
 65,936

 Intangible assets, net
 9,547
 10,438

 Goodwill
 5,646
 5,646

 Operating lease right-of-use assets
 176,883
 201,113

 Restricted cash and other non-current assets
 52,640
 54,343

 Total assets
 $
 460,232
 $
 619,161

 Liabilities and Stockholders' Equity (Deficit)

 Current liabilities:

 Accounts payable
 $
 34,316
 $
 18,498

 Due to factor

 15,660
 2,520

 Accrued expenses and other current liabilities
 85,975
 73,188

 Operating lease liability, current portion

 25,127
 21,202

 Finance lease liability, current portion

 88,877
 84,705

 Term loan debt
 71,507
 —

 Total current liabilities
 321,462
 200,113

 Operating lease liability, net of current portion

 161,561
 186,687

 Finance lease liability, net of current portion

 7,796
 37,732

 Other non-current liabilities

 Total liabilities
 491,766
 424,624

 Commitments and contingencies Note 12

 Stockholders' equity (deficit):

 Preferred stock, $ 0.01 par value, 5,000 shares authorized; 0 shares issued and
 outstanding at December 31, 2024 and December 31, 2023

 $
 —
 $
 —

 Common stock, $ 0.01 par value, 250,000 and 250,000 shares authorized; 9,728 and
 9,639 shares issued and outstanding at December 31, 2024 and December 31, 2023,
 respectively

 1,923
 1,905

 Additional paid-in capital
 4,469,719
 4,454,756

 Accumulated other comprehensive loss
 ( 2,133)
 ( 1,796)

 Accumulated deficit
 ( 4,501,043)
 ( 4,260,328)

 Total stockholders' equity (deficit)
 ( 31,534)
 194,537

 Total liabilities and stockholders' equity (deficit)
 $
 460,232
 $
 619,161

 S
 See accompanying notes to consolidated financial statements.

 Consolidated Statements of Operations and Comprehensive Loss
 (in thousands, except per share amounts)

 2024
 2023

 Revenue:

 Product revenue, net

 $
 83,795
 $
 29,065

 Other revenue

 Total revenues
 83,807
 29,497

 89,380
 33,527

 Gross margin
 ( 5,573)
 ( 4,030)

 Operating expenses:

 Selling, general and administrative
 167,874
 165,510

 Research and development
 94,252
 167,652

 Restructuring expense
 2,762
 —

 Total operating expenses
 264,888
 333,162

 Gain from sale of priority review voucher, net
 —
 92,930

 Loss from operations

 ( 270,461)
 ( 244,262)

 Interest income

 8,218
 9,869

 ( 22,579)
 ( 16,353)

 Other income, net

 44,177
 38,707

 Loss before income taxes
 ( 240,645)
 ( 212,039)

 Income tax benefit (expense)

 ( 70)

 ( 240,715)
 ( 211,913)

 Net loss per share—basic

 $
 ( 24.84)
 $
 ( 38.59)

 Net loss per share—diluted

 $
 ( 24.84)
 $
 ( 38.59)

 Weighted-average number of common shares used in computing net loss per share—basic

 9,689
 5,491

 Weighted-average number of common shares used in computing net loss per share—diluted

 9,689
 5,491

 Other comprehensive income (loss):

 Other comprehensive income (loss), net of tax benefit (expense) of
 $ 0.0 million and $ 0.0 million for the years ended
 December 31, 2024 and 2023, respectively

 ( 337)
 2,274

 Total other comprehensive income (loss)
 ( 337)
 2,274

 Comprehensive loss

 $
 ( 241,052)
 $
 ( 209,639)

 See accompanying notes to consolidated financial statements.

 Consolidated Statements of Stockholders' Equity (Deficit)
 Common stock
 Additional
paid-in
capital
 Accumulated
other
comprehensive
loss
 Accumulated
deficit
 Total
stockholders'
equity

 Shares
 Amount

 Balances at December 31, 2022
 4,146
 $
 $
 4,185,988
 $
 ( 4,070)
 $
 ( 4,048,415)
 $
 134,333

 Vesting of restricted stock
 ( 206)
 —
 —
 ( 196)

 Exercise of stock options
 —
 —
 —

 Purchase of shares under ESPP
 —
 —

 Issuance of common stock
 5,317
 1,063
 247,304
 —
 —
 248,367

 Exercise of warrants
 —
 —
 —
 —
 —

 —
 —
 21,151
 —
 —
 21,151

 Other comprehensive income

 —
 —
 —
 2,274
 —
 2,274

 —
 —
 —
 —
 ( 211,913)
 ( 211,913)

 Balances at December 31, 2023
 9,639
 $
 1,905
 $
 4,454,756
 $
 ( 1,796)
 $
 ( 4,260,328)
 $
 194,537

 Vesting of restricted stock
 ( 18)
 —
 —
 ( 2)

 Purchase of shares under ESPP
 —
 —

 Issuance of warrants
 —
 —
 —
 —

 —
 —
 14,257
 —
 —
 14,257

 Other comprehensive income
 —
 —
 —
 ( 337)
 —
 ( 337)

 —
 —
 —
 —
 ( 240,715)
 ( 240,715)

 Balances at December 31, 2024
 9,728
 $
 1,923
 $
 4,469,719
 $
 ( 2,133)
 $
 ( 4,501,043)
 $
 ( 31,534)

 See accompanying notes to consolidated financial statements.

 bluebird bio, Inc
 Consolidated Statements of Cash Flows

 2024
 2023

 Cash flows from operating activities:

 $
 ( 240,715)
 $
 ( 211,913)

 Adjustments to reconcile net loss to net cash used in operating activities:

 Change in fair value of contingent consideration
 —
 —

 Depreciation and amortization
 61,244
 28,525

 13,737
 19,429

 Noncash research and development expense (finance lease)
 —
 21,198

 Noncash operating lease expense
 24,230
 29,772

 Gain from sale of priority review voucher
 —
 ( 92,930)

 Unrealized loss on equity securities
 —
 —

 Excess inventory reserve
 10,882
 15,363

 Non-cash interest expense
 2,874
 —

 Other non-cash items
 ( 156)

 Gain on foreign currency exchange rates
 ( 2,071)

 Proceeds from sale of accounts receivable
 —
 5,040

 Changes in operating assets and liabilities:

 Accounts receivable
 —
 —

 Prepaid expenses and other assets
 4,699
 ( 3,334)

 Transfer of invoices to Factor
 ( 111,039)
 ( 560)

 Inventory
 ( 52,460)
 ( 36,560)

 Accounts payable
 16,504
 2,841

 Operating lease liabilities
 ( 21,202)
 ( 28,887)

 Accrued expenses and other liabilities
 23,718
 13,353

 Accrued interest payable under finance lease
 9,735
 3,426

 Net cash used in operating activities
 ( 260,020)
 ( 235,046)

 Cash flows from investing activities:

 Purchase of property, plant and equipment
 ( 2,599)
 ( 4,189)

 Proceeds from previously transferred invoices
 6,496
 —

 Purchases of marketable securities
 —
 ( 43,297)

 Proceeds from maturities of marketable securities
 —
 108,521

 Proceeds from sales of marketable securities
 —
 5,853

 Purchase of intangible assets
 —
 ( 4,868)

 Proceeds from sale of priority review voucher
 —
 92,930

 Net cash provided by investing activities
 3,897
 154,950

 Cash flows from financing activities:

 Proceeds from the issuance of debt, net of fees paid to lender
 71,316
 —

 Proceeds allocated to detachable warrants issued in conjunction with debt
 2,669
 —

 Payments of debt issuance costs
 ( 2,576)
 —

 Proceeds from public offering of common stock, net of issuance costs
 —
 248,198

 Proceeds from the transfer of invoices
 102,010
 2,520

 Principal payments on finance leases
 ( 85,950)
 ( 54,367)

 Other financing activities
 —
 ( 103)

 Net cash provided by financing activities
 87,469
 196,248

 Increase (decrease) in cash, cash equivalents and restricted cash
 ( 168,654)
 116,152

 Cash, cash equivalents and restricted cash at beginning of year
 274,597
 158,445

 Cash, cash equivalents and restricted cash at end of year
 $
 105,943
 $
 274,597

 Reconciliation of cash, cash equivalents and restricted cash:

 $
 $

 Restricted cash included in receivables and other current assets
 9,202

 Restricted cash included in restricted cash and other non-current assets
 43,605
 43,640

 Total cash, cash equivalents and restricted cash
 $
 105,943
 $
 274,597

 Supplemental cash flow disclosures:

 Right-of-use assets obtained in exchange for operating lease liabilities
 —
 ( 708)

 Purchases of property, plant and equipment included in accounts payable and accrued expenses

 Purchases of intangible assets included in accrued expenses
 —
 1,221

 Right-of-use assets obtained in exchange for finance lease liabilities
 54,340
 21,929

 Offering expenses included in accounts payable and accrued expenses
 —

 Beneficiary interest obtained in transferred invoices
 10,030

 Cash paid (refunded) during the period for income taxes
 ( 10)
 ( 42)

 See accompanying notes to consolidated financial statements.

 Notes to Consolidated Financial Statements
 For the Years Ended December 31, 2024 and 2023

 1. Description of the business
 bluebird bio, Inc. (the "Company" or "bluebird") was incorporated in Delaware on April 16, 1992, and is headquartered in Somerville, Massachusetts. The Company is a biotechnology company committed to commercializing potentially curative gene therapies for severe genetic diseases based on its proprietary lentiviral vector ("LVV") gene addition platform. Since its inception, the Company has devoted substantially all of its resources to its research and development efforts relating to its product candidates, and commercialization of its approved products, including activities to manufacture product candidates, conduct clinical studies of its product candidates, perform preclinical research to identify new product candidates, provide selling, general and administrative support for these operations and market and commercially manufacture and distribute its approved products.
 The Company's programs in severe genetic diseases include ZYNTEGLO (betibeglogene autotemcel, also known as beti-cel) as a treatment for -thalassemia; LYFGENIA (lovotibeglogene autotemcel, also known as lovo-cel) as a treatment for sickle cell disease ("SCD"); and SKYSONA (elivaldogene autotemcel, also known as eli-cel) as a treatment for cerebral adrenoleukodystrophy ("CALD"). On August 17, 2022, ZYNTEGLO was approved by the U.S. Food and Drug Administration ("FDA") for the treatment of adult and pediatric patients with -thalassemia who require regular red blood cell transfusions. On September 16, 2022, the FDA granted Accelerated Approval of SKYSONA to slow the progression of neurologic dysfunction in boys 4-17 years of age with early, active CALD. On December 8, 2023, the FDA approved LYFGENIA for the treatment of patients 12 years of age or older with sickle cell disease and with a history of vaso-occlusive events.
 In August 2023, the Company entered into an Open Market Sales Agreement (the "Sales Agreement") with Jefferies LLC ("Jefferies") to sell shares of the Company's common stock up to $ 125.0 million, from time to time, through an "at the market" equity offering program under which Jefferies will act as sales agent. As of December 31, 2024, the Company has made no sales pursuant to the Sales Agreement.
 In December 2023, the Company entered into an underwriting agreement (the "Underwriting Agreement") with Goldman and J.P. Morgan Securities LLC, to sell 83.3 million shares of the Company's common stock. The Company received net proceeds of approximately $ 118.1 million.
 In March 2024, the Company entered into a five-year term loan facility agreement with Hercules Capital, Inc. to secure debt financing for up to $ 175.0 million, available in four tranches. This is described in Note 10, Term Loan Debt, in the Notes to Condensed Consolidated Financial Statements appearing elsewhere in this Quarterly Report on Form 10-K.
 In September 2024, the Company's board of directors approved a restructuring action (the "Restructuring") following a comprehensive review of the Company's operations, which resulted in a reduction of the Company's workforce by 92 employees, or approximately 25 % of employees. The Restructuring is designed to support the Company's commercial focus and reduce its cash operating expenses. Refer to Note 19, Reduction in workforce, for more information on the Restructuring.
 On February 21, 2025, the Company announced that it had entered into an Agreement and Plan of Merger (the "Merger Agreement") with Beacon Parent Holdings, L.P., a Delaware limited partnership ("Parent"), and Beacon Merger Sub, Inc., a Delaware corporation ("Merger Sub"). Pursuant to the Merger Agreement, Merger Sub will conduct a cash tender offer to acquire any and all of the outstanding shares of the Company's common stock, for (i) $ 3.00 in cash per share, plus (ii) one contingent value right (each, a "CVR") per share, representing the right to receive a non-tradeable contingent payment of $ 6.84 in cash, in each case subject to any applicable withholding taxes and without interest thereon (the "Merger Transaction"). On March 7, 2025, Parent and Merger Sub commenced a cash tender offer to acquire any and all of the outstanding shares of the Company's common stock. The Company expects the Merger Transaction will be completed in the first half of 2025, and as such, it is not included in the Company's going concern assessment.
 Since its inception, the Company has incurred significant operating losses and negative operating cash flows. As of December 31, 2024, the Company had an accumulated deficit of $ 4.5 billion. During the twelve months ended December 31, 2024, the Company incurred a net loss of $ 240.7 million and used $ 260.0 million of cash in operations. As of December 31, 2024, the Company had cash and cash equivalents of $ 62.3 million, as well as $ 43.6 million in restricted cash, $ 30.1 million of which was released to the Company in February 2025. Of the $ 43.6 million restricted cash that was unavailable for use as of December 31, 2024, $ 13.5 million is unlikely to be released in the near term.
 In accordance with Accounting Standards Codification ("ASC") 205-40, Going Concern, the Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company's ability to continue as a going concern within one year after the date the financial statements are issued.

 This evaluation initially does not take into consideration the potential mitigating effect of management's plans that have not been fully implemented as of the date the financial statements are issued. When substantial doubt exists under this methodology, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the Company's ability to continue as a going concern. The mitigating effect of management's plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity's ability to continue as a going concern within one year after the date that these consolidated financial statements are issued.
 The Company's history of recurring operating losses and negative operating cash flows, its expectation to generate operating losses and negative operating cash flows, its projection that it may not maintain the minimum cash coverage related to the Loan and Security Agreement (the "LSA"), and the need for additional funding to support its planned operations raise substantial doubt regarding the Company's ability to continue as a going concern for a period of one year after the date that these consolidated financial statements are issued. Accordingly, the Company has concluded that substantial doubt exists about the Company's ability to continue as a going concern for a period of at least 12 months from the date of issuance of these consolidated financial statements.
 The Company has based the estimated cash needs on assumptions that may prove to be wrong, and its operating plan may change as a result of many factors currently unknown to it. As a result, the Company could deplete its capital resources sooner than it currently expects. If the Company is unable to complete the Merger Transaction, the Company may be required to further revise its business plan and strategy, which may result in the Company significantly curtailing, delaying or discontinuing the commercialization of any products or may result in the Company being unable to continue its operations or otherwise capitalize on its business opportunities. In addition, if the Merger Transaction is not completed within the expected timeframe, or at all, the Company will be at risk of liquidation or bankruptcy.
 The Company will assess on a quarterly basis whether the determination for estimates remain appropriate based on actual data observed. However, the Company has based this estimate on assumptions that may prove to be wrong, and its operating plan may change as a result of many factors currently unknown to it. As a result, the Company could deplete its capital resources sooner than it currently expects. The Company expects to finance its future cash needs through the Merger Transaction.
 The accompanying financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of the uncertainties described above.

 2. Summary of significant accounting policies and basis of presentation
 Basis of presentation
 The Company's consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States ("GAAP"). The accompanying consolidated financial statements include the accounts of the Company and its wholly owned or controlled subsidiaries. All intercompany accounts and transactions have been eliminated. Any reference in these notes to applicable guidance is meant to refer to the authoritative United States GAAP as included in the Accounting Standard Codification ("ASC") and the Accounting Standards Updates ("ASUs") of the Financial Accounting Standards Board ("FASB").
 Amounts reported are computed based on thousands, except percentages, per share amounts, or as otherwise noted. As a result, certain totals may not sum due to rounding.
 Reverse stock split
 On December 12, 2024, the Company filed a Certificate of Amendment to its Amended and Restated Certificate of Incorporation, as amended, with the Secretary of State of the State of Delaware to effect a 1-for-20 reverse stock split ("Reverse Stock Split") of its common stock, effective December 12, 2024 at 5:00 p.m. Adjustments have been made to the Company's outstanding options, restricted stock units, and warrant agreement to reflect the Reverse Stock Split. Additionally, all share and per-share amounts have been retroactively adjusted to reflect the Reverse Stock Split in these consolidated financial statements.

 Principles of consolidation
 The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries.
 Use of estimates
 The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Actual results could materially differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including: expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. This process may result in actual results differing materially from those estimated amounts used in the preparation of the financial statements.
 Estimates and judgments are used in the following areas, among others: the alternative future use of assets used in research and development activities, realizability of inventories, future undiscounted cash flows and subsequent fair value estimates used to assess potential and measure any impairment of long-lived assets, including goodwill and intangible assets, and the measurement of right-of-use assets and lease liabilities, gross-to-net revenue calculations, stock-based compensation expense, accrued expenses, income taxes, the assessment of the Company's ability to fund its operations for at least the next twelve months from the date of issuance of these financial statements, and the assessment of the likelihood and magnitude of losses that may be sustained upon resolution of contingencies.
 Foreign currency translation
 The financial statements of the Company's subsidiaries with functional currencies other than the U.S. dollar are translated into U.S. dollars using period-end exchange rates for assets and liabilities, historical exchange rates for stockholders' equity (deficit) and weighted average exchange rates for operating results. Translation gains and losses are included in other comprehensive income (loss) in stockholders' equity (deficit). Foreign currency transaction gains and losses are included in other income, net in the results of operations.
 Segment information
 The Company operates in a single segment, focusing on researching, developing and commercializing potentially transformative gene therapies for severe genetic diseases. Consistent with its operational structure, its chief operating decision maker ("CODM"), the Chief Executive Officer, manages and allocates resources at a global, consolidated level. Therefore, results of the Company's operations are reported on a consolidated basis for purposes of segment reporting. All material long-lived assets of the Company reside in the United States. The CODM assesses the segment's performance and decides how to allocate resources based on consolidated net income that is reported in our consolidated statements of income. The measure of segment assets is reported on the consolidated balance sheet as total consolidated assets. The significant expense categories regularly provided to the CODM include cost of sales, research and development, and selling, general and administrative expenses. These expense categories are reported as separate line items in our consolidated statements of income.
 The Company considers all highly liquid investments purchased with original final maturities of 90 days or less from the date of purchase to be cash equivalents. Cash equivalents comprise marketable securities with maturities of less than 90 days when purchased. Cash equivalents are reported at fair value.
 Marketable securities
 The Company's marketable securities are maintained by investment managers and consist of U.S. government agency securities and treasuries, equity securities, corporate bonds and commercial paper. Debt securities are carried at fair value with the unrealized gains and losses included in other comprehensive income (loss) as a component of stockholders' equity (deficit) until realized. Any premium arising at purchase is amortized to the earliest call date and any discount arising at purchase is accreted to maturity. Amortization and accretion of premiums and discounts are recorded in interest income, net. Equity

 securities with readily determinable fair values are also carried at fair value with unrealized gains and losses included in other income, net. Realized gains and losses on both debt and equity securities are determined using the specific identification method and are included in other income, net.
 The Company classifies equity securities with readily determinable fair values, which would be available for use in its current operations, as current assets even though the Company may not dispose of such marketable securities within the next 12 months. Equity securities are included in the balance of marketable securities on the Company's consolidated balance sheets. The Company classifies marketable securities with a remaining maturity when purchased of greater than three months as available-for-sale. Marketable securities with a remaining maturity date greater than one year are classified as non-current assets.
 The Company assesses its available-for-sale debt securities under the available-for-sale debt security impairment model in ASC 326 as of each reporting date in order to determine if a portion of any decline in fair value below carrying value recognized on its available-for-sale debt securities is the result of a credit loss. The Company records credit losses in the consolidated statements of operations and comprehensive loss as credit loss expense within other income, net, which is limited to the difference between the fair value and the amortized cost of the security. To date, the Company has not recorded any credit losses on its available-for-sale debt securities.
 Accrued interest receivable related to the Company's available-for-sale debt securities is presented within receivables and other current assets on the Company's consolidated balance sheets. The Company has elected the practical expedient available to exclude accrued interest receivable from both the fair value and the amortized cost basis of available-for-sale debt securities for the purposes of identifying and measuring any impairment. The Company writes off accrued interest receivable once it has determined that the asset is not realizable. Any write-offs of accrued interest receivable are recorded by reversing interest income, recognizing credit loss expense, or a combination of both. To date, the Company has not written off any accrued interest receivables associated with its marketable securities.
 Concentrations of counter-party and liquidity risk
 To reduce exposure to counter-party and liquidity risk, the Company maintains concentration limits across all of its overnight bank deposits. As of December 31, 2024, the Company's restricted cash balances were held in bank deposits. The remaining balance of cash and cash equivalents are invested in money market funds, U.S. government agency securities and treasuries, and investment grade commercial paper in line with the company's board approved investment policy. The Company has not experienced any credit losses on its deposits of cash and cash equivalents.
 Periodically, the Company reviews the credit risk of its deposits based on public information including credit agency reports and public financial reporting.
 Fair value of financial instruments
 The Company has certain financial assets and liabilities recorded at fair value which have been classified as Level 1, 2 or 3 within the fair value hierarchy as described in the accounting standards for fair value measurements:
 Level 1—Fair values are determined utilizing quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.
 Level 2—Fair values are determined utilizing quoted prices for identical or similar assets or liabilities in active markets or other market observable inputs such as interest rates, yield curves and foreign currency spot rates.
 Level 3—Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.
 To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument's level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.
 Items measured at fair value on a recurring basis include marketable securities (see Note 4, Fair value measurements). The carrying amounts of accounts payable and accrued expenses approximate their fair values due to their short-term nature.

 Goodwill
 Goodwill represents the excess of the purchase price over the fair value of the net assets acquired when accounted for using the acquisition method of accounting for business combinations. Goodwill is not amortized but is evaluated for impairment within the Company's single reporting unit on an annual basis, during the fourth quarter, or more frequently if an event occurs or circumstances change that would more-likely-than-not reduce the fair value of the Company's reporting unit below its carrying amount. The Company performs a one-step quantitative test and records the amount of goodwill impairment, if any, as the excess of a reporting unit's carrying amount over its fair value, not to exceed the total amount of goodwill allocated to the reporting unit. As of December 31, 2024, the carrying value of the Company was $( 31.5) million. The Company has no t recognized any impairment charges related to goodwill to date.
 A significant sustained decrease in the Company's common stock, may in the future be a potential indicator that all or a portion of our goodwill is impaired and may require a quantitative impairment assessment of the Company's goodwill at an interim date, which may result in an impairment charge in future periods. While management cannot predict if or when future goodwill impairments may occur, an impairment could have material adverse effects on the Company's financial condition, operating income, net assets, and/or the Company's cost of, or access to, capital.
 Intangible assets, net
 Intangible assets, net consist of in-licensed rights with finite lives, net of accumulated amortization. The Company amortizes its intangible assets using the straight-line method over their estimated economic lives and periodically reviews for impairment.
 Property, plant and equipment
 Property, plant and equipment is stated at cost. Maintenance and repairs that do not improve or extend the lives of the respective assets are expensed to operations as incurred. Depreciation and amortization is calculated using the straight-line method over the estimated useful lives of the assets, which are as follows:

 Asset
 Estimated useful life

 Building
 40 years

 Computer equipment and software
 3 years

 Furniture and fixtures
 5 years

 Laboratory equipment
 3 - 5 years

 Finance lease right-of-use asset

 Shorter of the useful life or remaining lease term

 Leasehold improvements
 Shorter of the useful life or remaining lease term

 Impairment of long-lived assets
 The Company reviews long-lived assets when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparison of the book values of the assets to future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceed their fair value.
 Leases
 At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease and its classification based on the unique facts and circumstances present in the arrangement. Leases with a term greater than one year are recognized on the balance sheet as right-of-use assets and current and non-current lease liabilities, as applicable. Right-of-use assets associated with finance leases used in the performance of research and development activities without alternative future use at lease commencement or at lease modification are immediately expensed to research and development expense pursuant to the guidance under ASC 730, Research and Development Costs.
 Lease liabilities and their corresponding right-of-use assets are initially recorded based on the present value of lease payments over the expected remaining lease term. Certain adjustments to the right-of-use asset may be required for items such as incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rate to discount lease payments, which reflects the fixed rate at which the Company

 could borrow on a collateralized basis the amount of the lease payments in the same currency, for a similar term, in a similar economic environment. To estimate its incremental borrowing rate, a credit rating applicable to the Company is estimated using a synthetic credit rating analysis since the Company does not currently have a rating agency-based credit rating. Subsequent to the initial measurement, the Company will continue to account for:
 • the lease liability at the net present value using the incremental borrowing rate that was in effect as of the lease commencement, lease modification, or transition date, and;
 • the finance lease right-of-use asset and operating lease expense on a straight line basis.
 The Company has elected not to recognize leases with an original term of one year or less on the balance sheet. The Company typically only includes an initial lease term in its assessment of a lease arrangement. Options to renew a lease are not included in the Company's assessment unless there is reasonable certainty that the Company will renew.
 Assumptions made by the Company at the commencement date are re-evaluated upon occurrence of certain events, including a lease modification. A lease modification results in a separate contract when the modification changes the scope of or consideration for a lease or non-lease component under the agreement, such as when the lessor grants the lessee an additional right-of-use not included in the original lease and when lease payments increase commensurate with the standalone price for the additional right-of-use. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease.
 In accordance with ASC 842, components of a lease should be split into three categories: lease components, non-lease components, and non-components. The fixed and in-substance fixed contract consideration (including any consideration related to non-components) must be allocated based on the respective relative fair values to the lease components and non-lease components.
 Entities may elect not to separate lease and non-lease components. Rather, entities would account for each lease component and related non-lease component together as a single lease component. The Company has elected to account for lease and non-lease components together as a single lease component for real-estate leases and embedded CMO and CTO agreements and to allocate all the contract consideration to the lease component only, or to individual lease components on a relative standalone selling price basis when the lease terms associated with the individual lease components are not otherwise co-terminus. Lease modifications associated with embedded leases in contract manufacturing and testing arrangements arise with frequency based on the complexity of the gene therapy manufacturing processes and the related services provided by contract manufacturing and testing organizations, which are combined with lease components. The Company applies judgment in determining whether the contractual terms for the delivery of services represent a change in the scope or consideration of the arrangements, which are accounted for as lease modifications, or represent variable lease payments, which are recognized as incurred.
 ASC 842 allows for the use of judgment in determining whether the assumed lease term is for a major part of the remaining economic life of the underlying asset and whether the present value of lease payments represents substantially all of the fair value of the underlying asset. The Company applies the guidance in ASC 842-10-55-2 to assist in determining lease classification across its portfolio of leases.
 Inventory
 Inventories are stated at the lower of cost or net realizable value under the first-expired, first-out ("FEFO") methodology. Given human gene therapy products are a new and novel category of therapeutics and future economic benefit is not probable until regulatory approval for the product has been obtained, the Company has only considered inventory for capitalization upon regulatory approval. Manufacturing costs incurred prior to regulatory approval for pre-launch inventory that did not qualify for capitalization and clinical manufacturing costs are charged to research and development expense in the Company's consolidated statements of operations and comprehensive loss as costs are incurred. Additionally, inventory that initially qualifies for capitalization but that may ultimately be used to produce clinical drug product is expensed as research and development expense when it has been designated for the manufacture of clinical drug product.
 Inventory consists of cell banks, plasmids, LVV, other materials and compounds sourced from third party suppliers and utilized in the manufacturing process, and drug product which has been produced for the treatment of specific patients, that are owned by the Company until infusion.
 Management periodically reviews inventories for excess or obsolescence, considering factors such as sales forecasts compared to quantities on-hand and firm purchase commitments as well as remaining shelf life of on-hand inventories. The

 Company writes down its inventory that is in excess, obsolete or otherwise unmarketable to its estimated net realizable value in the period in which the impairment is first identified. Any such adjustments are included as a component of cost of goods sold within cost of product revenue in the Company's consolidated statements of operations and comprehensive loss.
 Revenue recognition
 Under ASC Topic 606, Revenue from Contracts with Customers ("Topic 606"), an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration to which it is entitled in exchange for the goods or services it transfers to the customer.
 Once a contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations. Arrangements that include rights to additional goods or services that are exercisable at a customer's discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered performance obligations.
 The Company assesses whether each promised good or service is distinct to identify the performance obligations in the contract. This assessment involves subjective determinations and requires management to make judgments about the individual promised goods or services and whether such are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (that is, the good or service is capable of being distinct) and (ii) the entity's promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (that is, the promise to transfer the good or service is distinct within the context of the contract).
 The transaction price is then determined and allocated to the identified performance obligations in proportion to their standalone selling prices ("SSP") on a relative SSP basis. SSP is determined at contract inception and is not updated to reflect changes between contract inception and when the performance obligations are satisfied.
 If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the adjustment period.
 In determining the transaction price, the Company adjusts consideration for the effects of the time value of money if the timing of payments provides the Company with a significant benefit of financing. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the licensees and the transfer of the promised goods or services to the licensees will be one year or less. The Company assessed each of its revenue generating arrangements to determine whether a significant financing component exists and concluded that a significant financing component does not exist in any of its arrangements.
 The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) each performance obligation is satisfied, either at a point in time or over time, and if over time recognition is based on the use of an output or input method.
 Product revenue
 The amount of revenue recognized by the Company is equal to the amount of consideration that is expected to be received from the sale of product to its customers. The Company uses Specialty Distributors ("SD") and Specialty Pharmacies ("SP") to deliver product to the Qualified Treatment Centers ("QTC"). Revenue is only recognized when the performance obligation is satisfied. The Company recognizes revenue upon infusion to the patient. To determine whether a significant reversal will occur

 in future periods, the Company will assess both the likelihood and magnitude of any such potential reversal of revenue. Gross product revenue is reduced by outcomes-based rebates, other rebates and distributor fees.
 Constraint of Variable Consideration
 Revenues from product sales are recorded at the net sales price, or the transaction price, which includes estimates of variable consideration for which reserves are established and which result from discounts, rebates, and co-pay assistance that are offered within contracts between us and our customers, health care providers and other indirect customers relating to the sale of ZYNTEGLO, SKYSONA and LYFGENIA. These reserves are based on the amounts earned or to be claimed on the related sales and are classified as reductions of accounts receivable (if the amount is payable to the customer) or a current liability (if the amount is payable to a party other than a customer). Where appropriate, these estimates take into consideration a range of possible outcomes that are probability-weighted for relevant factors such as our historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns. Overall, these reserves reflect our best estimates of the amount of consideration to which we are entitled based on the terms of the contract. The amount of variable consideration that is included in the transaction price may be constrained and is included in the net sales price only to the extent that it is considered probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Actual amounts of consideration ultimately received may differ from our estimates. If actual results in the future vary from our estimates, we will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known.
 The following are the components of variable consideration related to product revenue:
 Government rebates
 The Company is subject to discount obligations under government programs, including U.S. Medicaid programs, Medicare and Tricare in the United States as well as certain government rebates. The Company estimates these rebates based upon a range of possible outcomes that take into consideration the estimated payer mix. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a liability that is included in accrued expenses and other current liabilities on our condensed consolidated balance sheets.
 Outcome based rebates
 The Company has agreements with certain payers that may entitle payers to additional rebates in the event that patients experience unsuccessful outcomes after being infused with the Company's products. The Company estimates these rebates upon a range of possible outcomes, and may vary based on the rebates afforded to each payer in accordance with the specific outcome based rebate agreement. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a liability that is included in accrued expenses and other current liabilities on our condensed consolidated balance sheets.
 Distribution Fees
 The Company pays for various distribution services from our customers in the distribution channel. For services that are not distinct from the sale of our product, such fees are classified as a reduction of product revenue.
 Distributor fees
 The Company pays distributor fees to SDs and SPs in connection with the sales of our product. These distributor fees are based on a contractually determined fixed percentage of sales.
 Product returns
 The Company's customers have limited return rights related to the product's damage or defect. Based on the distribution model for ZYNTEGLO, SKYSONA and LYFGENIA, the Company has experienced no returns to date and believes there will be minimal returns in the future. As a result, the Company has not recorded any reserves for product returns to date.
 Other incentives
 Other incentives include co-payment assistance the Company provides to patients with commercial insurance that have coverage and reside in states that allow co-payment assistance. The calculation of the accrual for co-pay assistance is based on

 an estimate of claims and the cost per claim that we expect to receive associated with product that has been recognized as revenue. The estimate is recorded as a reduction of revenue in the same period the related revenue is recognized.
 Provisions for trade discounts and allowances are recorded as reductions to accounts receivable, and returns, government rebates, and other incentives are recorded as a component of accrued expenses.
 Other revenue
 In 2021, the Company entered into a grant agreement with the Bill and Melinda Gates Foundation. The Company recognizes grant revenue in accordance with ASC 958-605, Revenue Recognition Not-for-Profit Entities, when qualifying costs are incurred and barriers to restriction have been overcome. When grant funds are received after costs have been incurred, the Company records revenue and a corresponding grant receivable. Cash received from grants in advance of incurring qualifying costs is recorded as deferred revenue and recognized as revenue when qualifying costs are incurred. In 2023, the Company ceased further research work associated with this grant agreement.
 Factoring agreement
 In December 2023, the Company entered into a factoring agreement with a non-bank financial institution. The proceeds from the factoring agreement are used to fund general working capital needs. The factoring agreement provides the Company access to up to $ 100.0 million on a revolving basis, measured by the outstanding balance of purchased accounts sold on the purchase dates from time to time. Refer to Note 6, Factoring agreement, for more information.
 The Purchased Assets are not available to our creditors to satisfy any of our obligations.
 Selling, general and administrative expenses
 Selling, general and administrative expenses are expensed as incurred. Selling, general and administrative expenses consist primarily of salaries and related costs for personnel, including stock-based compensation and travel expenses for the Company's employees in executive, operational, finance, legal, business development, commercial, information technology, and human resource functions. Other selling, general and administrative expenses include facility-related costs, professional fees for accounting, tax, legal and consulting services, directors' fees and expenses associated with obtaining and maintaining patents.
 The Company expenses the costs of advertising, which relates to advertising agency expenses, as incurred. Advertising expenses for the years ended December 31, 2024 and 2023 were immaterial.
 Research and development expenses
 Research and development costs are charged to expense as costs are incurred in performing research and development activities, including salaries and benefits, facilities costs, overhead costs, clinical study and related clinical manufacturing costs, CMO and CTO costs, contract research organization ("CRO") costs, license and milestone fees, contract services, manufacturing costs for pre-launch inventory that did not qualify for capitalization, and other related costs. Up-front fees and milestones paid to third parties in connection with technologies which have not reached technological feasibility and do not have an alternative future use are expensed as research and development expense as incurred. In circumstances where amounts have been paid in excess of costs incurred, the Company records a prepaid expense. The Company accrues costs for clinical trial activities based upon estimates of the services received and related expenses incurred that have yet to be invoiced by the contract research organizations, clinical study sites, laboratories, consultants, or other clinical trial vendors that perform the activities.
 All costs directly related to the manufacturing and delivery of the product to our qualified treatment centers are included in cost of product revenue which are associated with the sale of ZYNTEGLO, LYFGENIA, and SKYSONA in the United States. Reserves for excess inventories are also included in cost of product revenue.

 Stock-based compensation
 The Company's share-based compensation programs grant awards that have included stock options, restricted stock units, restricted stock awards, unrestricted stock awards and shares issued under its employee stock purchase plan. Grants are awarded to employees and non-employees, including the Company's board of directors.
 The Company accounts for its stock-based compensation awards in accordance with FASB ASC Topic 718, Compensation—Stock Compensation ("ASC 718"). ASC 718 requires all stock-based payments, including grants of stock options and restricted stock units and modifications to existing stock options, to be recognized in the consolidated statements of operations and comprehensive loss based on their fair values.
 The Company's stock-based awards are subject to either service or performance-based vesting conditions. Compensation expense related to awards with service-based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated service period of the award, which is generally the vesting term. Compensation expense related to awards with performance based vesting conditions is recognized based on the grant date fair value over the requisite service period using the accelerated attribution method to the extent achievement of the performance condition is probable.
 The Company estimates the fair value of its option awards using the Black-Scholes option pricing model, which requires the input of subjective assumptions, including (i) the expected stock price volatility, (ii) the calculation of expected term of the award, (iii) the risk-free interest rate, and (iv) expected dividends. Effective January 1, 2020, the Company eliminated the use of a representative peer group and uses only its own historical volatility data in its estimate of expected volatility given that there is now a sufficient amount of historical information regarding the volatility of its own stock price. For both employee and non-employee awards, the measurement date is the date of grant. The Company has estimated the expected term of its employee stock options using the "simplified" method, whereby, the expected term equals the arithmetic average of the vesting term and the original contractual term of the option due to its lack of sufficient historical data. The risk-free interest rates for periods within the expected term of the option are based on the U.S. Treasury securities with a maturity date commensurate with the expected term of the associated award. The Company has never paid, and does not expect to pay, dividends in the foreseeable future.
 The Company accounts for forfeitures as they occur. Stock-based compensation expense recognized in the financial statements is based on awards for which performance or service conditions are expected to be satisfied.
 Conversion and modification of equity awards outstanding at date of separation of 2seventy bio
 In connection with the separation of 2seventy bio on November 4, 2021 (the "Separation"), under the provisions of the existing plans, the Company adjusted its outstanding equity awards in accordance with the terms of the Employee Matters Agreement (an equitable adjustment) to preserve the intrinsic value of the awards immediately before and after the Separation. These modified awards otherwise retained substantially the same terms and conditions, including term and vesting provisions. The Company will recognize future expense for awards denominated in bluebird stock and 2seventy bio stock granted to the Company's employees as a result of the separation of 2seventy bio. Expense related to awards denominated in bluebird stock granted to 2seventy bio employees will be incurred by 2seventy bio.
 Stock-based compensation expense related to modified awards is measured based on the fair value for the awards as of the modification date. Any incremental stock-based compensation expense arising from the excess of the fair value of the awards on the modification date compared to the fair value of the awards immediately before the modification date is recognized at the modification date or ratably over the requisite remaining service period, as appropriate.
 Interest income
 Interest income consists primarily of interest income earned on investments.
 Interest expense consists primarily of the interest expense on finance lease arrangements, factoring agreement, and term loan debt.

 Other income, net
 Other income, net consists primarily of sublease income, gains and losses on disposal of assets, gains and losses on the change in fair value of warrants, and gains and losses on foreign currency.
 Net loss per share
 Basic net loss per share is calculated by dividing net loss attributable to common stockholders by the weighted average number of common shares outstanding during the period, including the shares of common stock issuable upon the exercise of warrants that are exercisable for little or no consideration. Diluted net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common equivalent shares outstanding for the period, including the shares of common stock issuable upon the exercise of warrants that are exercisable for little or no consideration as well as any dilutive effect from outstanding stock options, unvested restricted stock, restricted stock units, and employee stock purchase plan stock using the treasury stock method. Given that the Company recorded a net loss for each of the periods presented, there is no difference between basic and diluted net loss per share since the effect of common stock equivalents would be anti-dilutive and are, therefore, excluded from the diluted net loss per share calculation.
 Income taxes
 Income taxes are recorded in accordance with FASB ASC Topic 740, Income Taxes ("ASC 740"), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are provided, if based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized.
 The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. The Company accrues for potential interest and penalties related to unrecognized tax benefits in income tax expense.
 Comprehensive loss
 Comprehensive loss is composed of net loss and other comprehensive income (loss). Other comprehensive income (loss) consists of unrealized gains and losses on debt securities, foreign currency translation adjustments and other items.
 Restructuring expenses
 The Company records costs and liabilities associated with exit and disposal activities in accordance with FASB ASC Topic 420, Exit or Disposal Cost Obligations ("ASC 420") and Topic 712, Compensation - Nonretirement Postemployment Benefits ("ASC 712"). Such costs are based on estimates of fair value in the period liabilities are incurred. The Company evaluates and adjusts these costs as appropriate for changes in circumstances as additional information becomes available. Refer to Note 19, Reduction in workforce, for more information.
 Recent accounting pronouncements
 In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures to update reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses and information used to assess segment performance and requires companies to disclose all annual disclosures about segments in interim periods. The ASU also requires companies with a single reportable segment to provide all disclosures required by Topic 280 – Segment Reporting. This update is effective beginning with the Company's 2024 fiscal year annual reporting period and interim periods beginning thereafter. The Company has adopted this standard and has determined there are no changes in its current reporting on its consolidated financial statements and disclosures.
 In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. This ASU expands disclosures in an entity's income tax rate reconciliation table and disclosures regarding taxes paid both in

 the U.S. and foreign jurisdictions. This update is effective beginning with the Company's 2025 fiscal year annual reporting period. The Company is currently evaluating the impact to its income tax disclosures.
 In March 2024, the FASB issued ASU 2024-02 "Codification Improvements—Amendments to Remove References to the Concepts Statements", which removes various references to concepts statements from the FASB Accounting Standards Codification. This ASU is effective for the Company beginning in the first quarter of fiscal year 2026, with early adoption permitted. The Company expects the new guidance will have an immaterial impact on its consolidated financial statements and intends to adopt the guidance when it becomes effective in the first quarter of fiscal year 2026.
 In November 2024, the FASB issued ASU 2024-03 "Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses". This ASU requires expanded disclosures of specific income statement expense categories such as cost of product revenue, selling, general, and administrative expenses, and research and development expenses. This update is effective for annual periods beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted.

 3. Product revenue and reserves
 For the years ended December 31, 2024 and 2023, the Company recorded $ 83.8 million and $ 29.1 million, respectively, of product revenue. Product revenue by therapy represents:
 For the year ended December 31,

 2024
 2023

 ZYNTEGLO

 $
 62,273
 $
 16,692

 LYFGENIA
 11,605
 —

 SKYSONA

 9,917
 12,373

 Total product revenue, net
 $
 83,795
 $
 29,065

 Four individual customers accounted for 51 % of product revenue for the year ended December 31, 2024, and two individual customers accounted for 84 % of product revenue for the year ended December 31, 2023.
 The Company considers there to be revenue concentration risks for customers that represent product revenues that exceed 10% of total product revenue. The concentration of the Company's product revenue with a particular customer may have a material adverse effect on the Company's revenue and results of operations if sales with the respective customer experience difficulties. All product revenue during 2024 and 2023 were within the United States.
 The following table summarizes an analysis of the change in reserves for gross to net deductions for the periods indicated:

 Total

 Balance at December 31, 2023

 $
 5,365

 Provision for rebates

 21,447

 Payments/credits

 ( 1,160)

 Balance at December 31, 2024

 $
 25,652

 4. Fair value measurements
 The following table sets forth the Company's assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2024 and 2023 (in thousands):
 Total
 Quoted
prices in
active
markets
(Level 1)
 Significant
other
observable
inputs
(Level 2)
 Significant
unobservable
inputs
(Level 3)

 December 31, 2024

 Assets:

 $
 $
 $
 —
 $
 —

 Due from factor:

 Beneficiary interest in factored invoices
 3,094
 —
 —
 3,094

 Other non-current liabilities

 Warrant liability

 Total assets
 $
 66,255
 $
 $
 —
 $
 3,950

 December 31, 2023

 Assets:

 $
 $
 $
 —
 $
 —

 Due from factor:

 Beneficiary interest in factored invoices
 —
 —

 Total assets
 $
 222,315
 $
 $
 —
 $

 The Company considers all highly liquid securities with original final maturities of 90 days or less from the date of purchase to be cash equivalents. As of December 31, 2024, cash and cash equivalents comprise funds in cash and money market accounts held at multiple banking and asset management institutions.
 Factoring agreement
 Due from factor classified as Level 3 within the valuation hierarchy consists of beneficiary interest in transferred invoices. The Company estimates the fair value of the beneficiary interest based on the estimated cash flows after applying counterparty and credit risk adjustments associated with the factoring agent and distributors, respectively. As of December 31, 2024, no adjustment to the beneficiary interest in invoices sold was deemed an unobservable input and was determined based from ongoing credit evaluations and historical experience with aging of such invoices, among other factors. A significant change to this input could result in a significantly lower fair value measurement.
 The following table shows a reconciliation of the beginning and ending balances for due from factor Level 3 financial liabilities measured at fair value on a recurring basis for the year ended December 31, 2024:

 For the year ended
 December 31,

 2024

 Level 3 financial assets, beginning of period
 $

 Beneficiary interest obtained in transferred invoices
 10,030

 Beneficiary interests derecognized from previously transferred invoices
 ( 7,090)

 Accrual for anticipated loss on sale of invoices
 ( 406)

 Level 3 financial assets, end of period
 $
 3,094

 Common stock warrants
 On March 15, 2024, in connection with its debt issuance (see Note 10, Term loan debt), the Company issued warrants to a lender to purchase shares of the Company's common stock at an exercise price of $ 29.00 per share. On August 13, 2024, the Company amended the exercise price of the warrants to be the lesser of $ 20.60 per share and the price per share of the Company's first financing event within six months of August 13, 2024 or February 13, 2025. As a result of the modification, the warrants were reclassified from additional paid-in-capital within stockholders' equity (deficit) to other non-current liabilities on the condensed consolidated balance sheet at their fair value as of the modification date. The warrants are adjusted to fair value at period end through "other income (expense)" on the condensed consolidated statements of operations and comprehensive loss.
 The warrants have been recorded at their fair value using the Black-Scholes option-pricing model and the following assumptions: no dividend yield, probability-weighted exercise price ranging between $ 8.34 and $ 20.60, stock price of $ 8.34 per share, expected volatility of 96.0 %, risk free rate of 4.4 %, and expected term of 6 years, equal to the life of the warrant.
 The following table shows a reconciliation of the beginning and ending balances for other non-current liabilities due from factor Level 3 financial liabilities measured at fair value on a recurring basis for the year ended December 31, 2024:

 For the year ended December 31,

 2024

 Balance at December 31, 2023

 $
 —

 Warrant modification and reclassification to liabilities
 2,100

 Change in fair value
 ( 1,244)

 Balance at December 31, 2024

 $

 5. Inventory
 Inventory, net, consists of the following (in thousands):

 2024
 2023

 Raw materials
 $
 2,785
 $
 2,329

 Work in progress
 58,665
 17,375

 Finished goods
 3,567
 3,215

 Inventory
 $
 65,017
 $
 22,919

 Raw materials inventory consists of completed materials purchased directly from third party suppliers. Work in progress inventory consists of materials manufactured at CMOs that are either partially completed, fully manufactured but are pending quality acceptance, or completed meeting quality acceptance standards to be used in the manufacture of drug product and drug products that are either partially completed or fully manufactured but are pending quality acceptance. Finished goods are completed and quality approved drug products that are either awaiting shipment, in-transit or delivered to a qualified treatment center, but have not yet been infused in a patient.

 6. Factoring agreement
 The Company sells rights to future revenues associated with invoices issued upon delivery of drug product to QTCs. The Company sells 100 % of the invoice, and the upfront purchase price is 90 % of the invoice amount. The remaining 10 %, less applicable fees, is payable to the Company when the factor receives full payment from the customer. The upfront payments are treated as a short-term liability, presented as due to factor on the Company's consolidated balance sheets until infusion when the right to consideration from the customer is deemed unconditional. The remaining invoice amount payable to the Company at infusion is considered a beneficial interest in the factored invoice and represents the extent of our continued involvement in the sale of invoices.

 Due to Factor
 For the year ended December 31, 2024, the Company collected $ 102.0 million in cash receipts prior to an unconditional right to consideration and derecognized $ 90.3 million of due to factor amounts as a result of patient drug product infusions. For the year ended December 31, 2023, the Company collected $ 7.6 million in cash receipts prior to an unconditional right to consideration and derecognized $ 5.0 million of due to factor amounts as a result of patient drug product infusions.
 Amounts presented as due to factor on the condensed consolidated balance sheets would be subject to payment based on the repurchase requirements that exist prior to the infusion date in the factoring agreement.
 Due from Factor
 For the year ended December 31, 2024, the Company obtained $ 10.0 million of beneficiary interest in invoices and derecognized $ 7.1 million in beneficiary interest in invoices. For the year ended December 31, 2023, the Company obtained $ 0.6 million of beneficiary interest in invoices and did not derecognize any beneficiary interest in invoices.
 Uncollected amounts presented as due from factor on the consolidated balance sheets are net of accrued fees of $ 0.4 million and $ 0.0 million at December 31, 2024 and 2023, respectively. The maximum loss exposure is $ 3.5 million and $ 0.6 million at December 31, 2024 and 2023, respectively.
 The total loss from the sale of customer invoices is estimated on the patient infusion date of the drug product and was $ 2.4 million, and $ 0.0 million, for the years ended December 31, 2024 and December 31, 2023, respectively. In addition to the loss from the sale of invoices, the Company incurred $ 1.0 million and $ 0.0 million in servicing fees for the years ended December 31, 2024 and 2023, respectively.

 7. Property, plant and equipment, net
 Property, plant and equipment, net, consists of the following (in thousands):

 2024
 2023

 Finance lease right of use assets

 $
 139,391
 $
 84,524

 Laboratory equipment
 14,502
 14,636

 Office equipment
 4,791
 4,767

 Computer equipment and software
 2,001
 2,005

 Leasehold improvements
 1,361
 1,251

 Construction-in-progress
 1,410

 Total property, plant and equipment
 163,456
 107,746

 Less accumulated depreciation and amortization
 ( 102,608)
 ( 41,810)

 Property, plant and equipment, net
 $
 60,848
 $
 65,936

 Depreciation and amortization expense related to property, plant and equipment was $ 60.3 million and $ 28.0 million for the years ended December 31, 2024 and 2023, respectively.

 8. Restricted cash
 As of December 31, 2024 and 2023, the Company had total restricted cash of $ 43.6 million and $ 52.8 million, of which $ 43.6 million and $ 51.2 million, respectively, pertained to letters of credit which are collateralized with bank accounts at financial institutions in accordance with the agreements. The following table discloses the Company's total restricted cash as of

 December 31, 2024 and 2023 (in thousands):

 2024
 2023

 50 Binney Street lease
 $
 40,072
 $
 40,072

 Assembly Row lease
 2,753
 2,753

 Embedded lease

 —
 7,632

 Other
 2,385

 Total restricted cash
 $
 43,638
 $
 52,842

 Refer to Note 11, Leases, for further information on the Company's letters of credit and Note 21, Subsequent Events, for further information on changes to the Company's letter of credit activity after December 31, 2024. The Company presents the current portion of restricted cash in receivables and other current assets.

 9. Accrued expenses and other current liabilities
 Accrued expenses and other current liabilities consist of the following (in thousands):

 2024
 2023

 Accrued CMO and CRO costs

 $
 30,625
 $
 24,824

 Accrued employee compensation

 14,437
 19,972

 Accrued goods and services
 1,475
 8,391

 Accrued professional fees
 5,354
 2,531

 Accrued rebates (reserved)
 25,652
 5,365

 Other sublease rent liability
 3,370
 3,310

 Accrued refund liability

 —
 5,600

 Other
 5,062
 3,195

 Total accrued expenses and other current liabilities
 $
 85,975
 $
 73,188

 10. Term loan debt
 2024 Term Loan
 On March 15, 2024 (the "Effective Date"), the Company entered into the LSA and a Warrant Agreement (the "Warrant Agreement") with Hercules Capital and funds managed by Hercules Capital (collectively, "Hercules" or "the lenders"). Under the terms of the LSA, the Company may borrow up to an aggregate principal amount of $ 175.0 million over the term of the agreement, in four separate tranches (the "Term Loans") dependent on the achievement of certain milestones. On the Effective Date, the Company drew down the initial $ 75.0 million of gross proceeds ("Initial Loan"), and paid initial debt issuance costs of $ 3.5 million, inclusive of legal fees of approximately $ 2.7 million and the original issuance discount ("OID") of $ 0.8 million, or 1 % of the drawn amount, in accordance with the terms of the LSA.
 On August 13, 2024, the Company and Hercules entered into an amendment to the LSA (the "Third Amendment"), pursuant to which the parties agreed to, among other things, revised terms for the availability of the second and third tranches of funding under the LSA and an increase to the minimum cash coverage requirement.
 Originally, and in accordance with this Third Amendment, the Company was able to draw the second tranche of $ 25.0 million during the period commencing on the date the Company has (x) received at least $ 75.0 million in gross cash proceeds from qualified financing transactions by December 20, 2024 and (y) completed patient starts (cell collections) for at least 50 LYFGENIA patients by March 31, 2025 or 70 LYFGENIA patients by June 30, 2025 (collectively, the "Tranche 2 Milestone") and ending on the earlier of (i) the date that is 30 days immediately following achievement of the Tranche 2 Milestone and (ii) July 31, 2025. The Company did not reach $ 75.0 million in gross cash proceeds from qualified financing transactions by December 20, 2024, and as such this second tranche is no longer available.
 Additionally, the Company may draw the third tranche of $ 25.0 million during the period commencing on the date the Company has (x) received at least $ 100.0 million in gross cash proceeds from qualified financing transactions by December 20, 2024 or at least $ 125.0 million by June 30, 2025 and (y) completed 70 drug product deliveries within a given six-month period ending no later than December 31, 2025, at least 40 of which are for LYFGENIA (collectively, the "Tranche 3 Milestone") and

 ending on the earlier of (i) the date that is 30 days immediately following the date the Company achieves the Tranche 3 Milestone and (ii) December 31, 2025. The Company may request up to an additional $ 50.0 million through December 15, 2026 from Hercules ("Tranche 4"). The lenders have no obligation to fund any amounts under Tranche 4 as funding is conditioned on approval by the lenders' investment committee.
 The 2024 Term Loan is collateralized by substantially all the Company's assets. In addition to other covenants, the 2024 Term Loan contains affirmative covenants as well as certain financial covenants, including a minimum cash coverage requirement of 45 % of the outstanding principal of the term loan. The Company was in compliance with the minimum cash coverage covenant as of December 31, 2024, but the Company projects that it may not maintain its minimum cash coverage requirement within the next 12 months (see the Company's going concern assessment in Note 1, Description of the business). As such, the Term Loan is presented as a current liability as of December 31, 2024.
 The Term Loans bear both cash interest and paid-in-kind interest ("PIK"). The cash interest is due on the first business day of each month ("Payment Date") and will be equal to the WSJ prime rate ("prime rate") plus 1.45 % (floored at 9.95 %). The PIK interest is fixed at 2.45 % and is to be capitalized and added to the outstanding principal on each Payment Date. Unless prepaid by the Company at their discretion, subject to certain prepayment penalties and conditions, the Term Loans are repayable in monthly interest-only payments until April 1, 2027, or April 1, 2028, if the Company has achieved, no later than December 31, 2026, certain financial metrics (the "Performance Milestone"). After the expiration of the interest-only payment period, the Term Loans are repayable in equal monthly payments of principal and accrued interest until maturity. The Term Loans will mature on April 1, 2029.
 The Company also issued warrants under the Warrant Agreement for the right to purchase shares of the Company's common stock to Hercules, with the number of shares to be based on the amounts borrowed under the LSA (the "Warrants"). The Warrants are exercisable for a number of shares of common stock equal to the quotient of (i.) 5 % times the aggregate original principal of amounts drawn under the LSA divided by (ii.) the exercise price of $ 29.00 per share.
 Upon issuance, during the period ended March 31, 2024, the Warrants were recorded at their relative fair value using the Black-Scholes option-pricing model and the following assumptions: no dividend yield, expected volatility of 81.1 %, risk free rate of 4.3 %, and expected term of 7 years, equal to the life of the warrant. The relative fair value allocated to the initial warrants was $ 2.7 million, which was classified as additional-paid-in-capital and recorded as a debt discount which will be amortized, together with debt issuance costs, to interest expense using the effective interest method over the life of the loan at an effective interest rate of 15.7 %.
 In connection with the Third Amendment, the Company agreed to amend the exercise price of the Warrants to purchase shares of the Company's common stock from $ 29.00 per share to the lesser of the volume weighted average price ("VWAP") of the Company's common stock for the ten-day period preceding August 13, 2024 (determined to be $ 20.60), and the price per share of the Company's first financing event within six months of the Third Amendment date, or February 13, 2025. As the modification only impacts the exercise price, the amendment does not impact the number of shares the lenders may purchase pursuant to the Warrants. As of December 31, 2024, the Company had issued 2.6 million warrants associated with the Initial Loan ("Initial Warrants") to purchase common stock and a contractual life of 7 years from the Effective Date.
 As a result of the Third Amendment, the price adjustment feature on the warrant exercise price is affected by variables that are extraneous to the pricing of a fixed-for-fixed option or forward contract on common shares, and therefore, the Initial Warrants were reclassified from additional paid-in-capital within stockholders' equity (deficit) to other non-current liabilities on the Condensed Consolidated Balance Sheet (see Note 4, Fair value measurements). Upon modification of the warrants at the Third Amendment date, the Company recorded the incremental increase in fair value of $ 0.2 million as debt discount which will be amortized over the life of the Initial Loan at an effective interest rate of 16 %. The fair value of the Initial Warrants is required to be revalued at each measurement period. Refer to Note 4, Fair value measurements for further information.
 For the year ended December 31, 2024, the Company recorded approximately $ 9.0 million in interest expense associated with the Term Loan, inclusive of amounts related to the debt discount.
 Refer to Note 21, Subsequent Events, for further discussion on the amendments to the LSA and the Warrant Agreement subsequent to the twelve months ended December 31, 2024.

 11. Leases
 The Company leases certain office and laboratory space. Additionally, the Company entered into CMO and CTO agreements which have been determined to contain an embedded lease.

 Operating lease commitments
 50 Binney Street sublease & sub-sublease
 In April 2019, the Company entered into a sublease agreement for office space located at 50 Binney Street in Cambridge, Massachusetts (the "50 Binney Street Sublease") to supplement the Company's then-current corporate headquarters located at 60 Binney Street in Cambridge, Massachusetts. Under the terms of the 50 Binney Street Sublease, the Company leased 267,278 square feet of office space for $ 99.95 per square foot, or $ 26.7 million per year in base rent subject to certain operating expenses, taxes and annual rent increases of approximately 3 %. The lease commenced in April 2022 and lease payments began in July 2022. The lease was terminated in February 2025. Upon signing the 50 Binney Street Sublease, the Company executed a $ 40.1 million cash-collateralized letter of credit, which was classified as restricted cash and other non-current assets on the Company's consolidated balance sheets as of December 31, 2024. Refer to Note 21, Subsequent Events, for further information on changes to the Company's letter of credit activity after December 31, 2024.
 In December 2021, the Company entered into a sub-sublease agreement (the "Sub-Sublease") with Meta Platforms, Inc. ("Meta"). Under the terms of the Sub-Sublease, the Company subleased the entirety of the 50 Binney Street premises which it had rights to under the 50 Binney Street Sublease. The Company sub-subleased the premises for $ 29.4 million in the first year (inclusive of parking costs) with 3 % annual increases in each subsequent year. Meta received access to 50 Binney Street at the lease commencement date, which is the same point that the Company received access under the 50 Binney Street Sublease. The Company recognized monthly sublease income of $ 2.6 million in other income, net for the sub-subleased space.

 In February 2025, the Company terminated the 50 Binney Street Sublease and the Sub-Sublease. In connection with the termination, the Company amended the $ 40.1 million collateralized letter of credit to reduce the amount thereunder to $ 10 million. The reduced letter of credit will remain in place until the earlier of: (i) the termination of the prime lease between the 50 Binney Street landlord and Aventis. Inc. or (ii) December 21, 2030. Refer to Note 21, Subsequent Events, for further information.
 Assembly Row lease
 In November 2021, the Company entered into a lease agreement with Assembly Row 5B, LLC ("Landlord") for office space located at 455 Grand Union Boulevard in Somerville, Massachusetts to serve as the Company's future corporate headquarters. Under the terms of the arrangement, the Company leases approximately 61,180 square feet starting at an annual rate of $ 45 per square foot, subject to annual increases of 2.5 %, plus operating expenses and taxes. In addition, the Company is eligible to receive a tenant work allowance of $ 160 per rentable square foot of the premises. The lease commenced on March 1, 2022, the date on which the Landlord tendered possession of the premises to the Company with any tenant work required to be performed by the Landlord substantially completed. Since the lease commencement date, the Company has recognized rent expense of $ 0.3 million monthly.
 Hood Park lease
 In October 2022, the Company entered into a sublease with Finch Therapeutics, Inc. ("Finch") for office and laboratory space at Finch's corporate headquarters located at 100 Hood Park Drive, Charlestown, Massachusetts. Under the terms of the arrangement, the Company leases 42,261 square feet for $ 55 per square foot, subject to annual increases of 3.0 %, plus operating expenses and taxes. This sublease commenced December 15, 2022, the date on which the landlord tendered possession of the premises to the Company and is expected to terminate on December 14, 2025. Since the lease commencement date, the Company has recognized substantially all of the monthly $ 0.2 million costs as rent expense.
 Finance lease commitments - Embedded leases
 The Company has five embedded CMO and CTO arrangements. The details are noted below.
 Drug Product Manufacturing
 Embedded Lease No. 1:
 In June 2016, the Company entered into a manufacturing agreement for the future commercial production of the Company's ZYNTEGLO and SKYSONA drug products with a CMO. Under this 12 -year agreement, the CMO will complete the design, construction, validation and process validation of the leased suites prior to anticipated commercial launch of the product candidates. From 2016 through March 2018, while the suites were under construction, the Company paid a total of $ 12.0 million in contractual milestone payments. Construction was completed in March 2018, and beginning in April 2018, the

 Company paid $ 5.1 million per year, in fixed suite reservation fees as well as certain fixed labor, raw materials, testing and shipping costs for manufacturing services. The Company may terminate this agreement at any time upon payment of a one-time termination fee and up to 24 months of slot fees and 12 months of labor fees. The Company concluded that this agreement contains an embedded lease as the suites are designated for the Company's exclusive use during the agreement's term, that it was not the deemed owner during construction, and the lease was not a capital lease under ASC 840-10, Leases - Overall. As a result, the Company initially accounted for the agreement as an operating lease under ASC 840 and recognized straight-line rent expense over the non-cancellable term of the embedded lease. As part of the Company's adoption of ASC 842, effective January 1, 2019, the Company carried forward the existing lease classification under ASC 840. The lease was modified and reclassified as a finance lease as of March 2019. In September 2023, the agreement was amended to change the fee structure in the arrangement from a fixed suite reservation fee to a fixed slot manufacturing fee. In addition, separate from the suite and existing equipment, the Company also has certain forward starting embedded equipment leases that have not yet commenced as of December 31, 2024. As the CMO is required to provide operational equipment throughout the contract term, the forward starting leases were established to account for the equipment that the CMO is obligated to lease to the Company in the future once the current equipment reaches its useful life and the lease expires. These forward starting leases are expected to commence in 2025 with an initial lease term of three years and has fixed commitments of approximately $ 60.1 million. The Company has prepaid approximately $ 3.7 million, which is accounted for as prepaid asset on the Company's balance sheet that would adjust the right-of-use asset when the forward starting embedded equipment lease commences in 2025. The lease has been subsequently modified based on changes in the delivery of non-lease component services, which have been combined with lease components under our accounting policy.
 Embedded Lease No. 2:
 During July 2020, the Company amended an existing CMO arrangement to reserve additional manufacturing capacity for LYFGENIA. The Company concluded that this amendment contains an embedded lease as a controlled environment room at the facility is designated for the Company's exclusive use during the term of the agreement, with the option to sublease the space if the Company provides notice that it will not utilize it for a specified duration of time. Under the amended agreement, the Company is required to pay up to $ 5.4 million per year in maintenance fees in addition to the cost of any services provided and may terminate this agreement with eighteen months ' notice. The term of the agreement is five years with the option to extend. When the additional manufacturing capacity became available that served as lease commencement in March 2021, the Company classified the embedded lease as a finance lease.
 In February 2021, the Company amended the CMO arrangement to reserve additional manufacturing capacity. The Company concluded that this amended agreement contains an embedded lease as a controlled environment room at the facility is designated for the Company's exclusive use during the agreement's term. Under the amended agreement, the Company must pay $ 4.2 million per year in maintenance fees and per-batch fees for the cost of any services provided. Either party may terminate this agreement with eighteen months ' notice at any time or with eight months ' notice after defined milestones in the agreement have been met. The term of the agreement is five years, with the option to extend. The lease commenced in November 2021 when the suites became available, and upon commencement the Company classified the embedded lease as a finance lease. The lease has been subsequently modified based on changes in the delivery of non-lease component services, which have been combined with lease components under our accounting policy.
 In August 2022, the Company amended another arrangement with this CMO to reserve additional controlled environmental rooms. The Company concluded that this amended agreement contains an embedded finance lease as the controlled environment room at the facility is designated for the Company's exclusive use during the agreement's term. Under the amended agreement, an existing deposit of $ 10.8 million was applied towards the monthly lease payments through September 2023. The term of the agreement was 14 months with an option to extend. The Company exercised the option to extend through December 31, 2023, and subsequently extended the agreement for an additional 14 months into March 2025.
 In October 2024, the Company amended the CMO arrangement to include the delivery of additional non-lease component services, which have been combined with lease components under our accounting policy. These non-lease component services are expected to be completed in July 2025, which extended the lease term through July 2025 for certain of the lease components related to this CMO arrangement.
 Drug Substance Manufacturing
 Embedded Lease No. 3:
 In November 2017, the Company entered a commercial manufacturing services agreement with a CMO to establish commercial production of the Company's suspension vector. The Company concluded this agreement contained an embedded finance lease when production commenced in the new facility in 2019 as the Company has dedicated suite space and reserved

 production capacity at a rate that allows the Company to take more than substantially all the capacity of certain manufacturing space and equipment within the facility. Under the agreement, the Company must pay capacity reservation fees, minimum purchase commitment fees, and milestone fees for achievement of certain activities. In addition, the Company prepaid approximately 13.5 million between 2018 and 2019 towards certain milestone payments and in exchange for production credits. As of December 31, 2021, those credits have been fully used by the Company. The Company modified the lease to extend its term in October 2022, April 2023, October 2023, and in March 2024, which extended the lease term to end in September 2024. In September 2024, the Company entered into a 5-year master contract services agreement ("MCSA") with the CMO. The MCSA does not grant an additional right of use to the Company, thus, the MCSA is not a separate contract. The MCSA is accounted for as a lease modification as it effectively requires the vendor to perform additional services incremental to the terms of the existing agreement by extended the lease term, in addition to changes in the delivery of non-lease component services, which have been combined with lease components under the Company's accounting policy.
 Embedded Lease No. 4:
 In January 2018, the Company entered a clinical and commercial supply agreement with a CMO to manufacture ZYNTEGLO and SKYSONA vector products. The Company concluded this agreement contained an embedded finance lease. The Company and the CMO originally agreed to wind down manufacturing activities in December 2021. In December 2022, the Company reestablished this manufacturing agreement and concluded the revised arrangement contains an embedded finance lease as the Company is using the entire capacity of a manufacturing suite at the facility. The original term of the agreement was three years and required the Company to pay suite reservation fees of $ 13.5 million in 2023 and $ 18.0 million per year in 2024 and 2025, in addition to the cost of any services provided. In August 2024, the Company provided notice to this CMO of its intention to wind down adherent LVV manufacturing for ZYNTEGLO and SKYSONA, as the Company pursues alternative manufacturing methods and plans for LVV for these products. The CMO will continue to manufacture LVV for approximately twelve months (through August 2025) pursuant to the notice period under the applicable work order and the Clinical and Commercial Supply Agreement remains in place. Additionally, the terms were modified to reduce the suite reservation fees to $ 12.0 million in 2025.
 Quality Testing
 Embedded Lease No. 5:
 In 2018, the Company entered a 2-year MCSA with a CTO to provide clinical development services (other than manufacturing services). The original MCSA expired in June 2020 but was reinstated through December 2024 under the amendment of the MCSA effective April 2021. The Company concluded this agreement contained an embedded finance lease as the Company had certain lab suites implicitly dedicated to it for various clinical testing procedures. The Company is required to pay the fixed price outlined in each of the various service contracts covering quality, stability, and other services. The lease has been subsequently modified based on changes in the delivery of non-lease component services, which have been combined with lease components under our accounting policy. In December 2024, the MCSA was extended to June 2025. However, the lease term ends December 2026 due to reserved capacity commitments.

 Summary of all lease costs recognized under ASC 842
 The following table contains a summary of the lease costs recognized under ASC 842 and other information pertaining to the Company's operating and finance leases for the years ended December 31, 2024 and 2023 (in thousands):

 For the year ended December 31,

 2024
 2023

 Finance leases

 $
 11,163
 $
 16,350

 Amortization expense
 56,685
 24,653

 Total fixed finance lease cost
 $
 67,848
 $
 41,003

 Operating leases

 Fixed lease cost
 37,949
 43,272

 Total fixed operating lease cost
 37,949
 43,272

 Variable lease cost
 28,823
 22,960

 Short-term lease cost

 Total lease cost
 $
 134,930
 $
 107,473

 Operating sublease income
 $
 40,260
 $
 41,165

 Cash paid in the measurement of lease liabilities

 Operating cash flows used for operating leases
 $
 21,202
 $
 28,887

 Operating cash flows used for finance leases
 1,411
 12,924

 Financing cash flows for finance leases
 85,950
 54,367

 Other information:

 Weighted average remaining lease term - finance leases (in years)
 1.9 years
 1.6 years

 Weighted average discount rate - finance leases
 11.5
 %
 13.9
 %

 Weighted average remaining lease term - operating leases (in years)
 6.1 years
 7.0 years

 Weighted average discount rate - operating leases
 7.0
 %
 7.0
 %

 For finance leases embedded in CMO arrangements, interest expense is recognized using the effective interest method, applying the Company's incremental borrowing rate as required by ASC 842, and amortization expense is recognized on a straight-line basis over the shorter of the life of the asset or the term of the lease. Rather than amortizing the finance lease right-of-use assets that did not have alternative future use, those amounts were recognized as research and development expense at lease commencement or lease modification and were $ 0.0 million and $ 21.2 million for the years ended December 31, 2024 and December 31, 2023, respectively.

 As of December 31, 2024, future minimum commitments under ASC 842 under the Company's leases were as follows (in thousands):

 Operating Leases

 Financing Leases

 Remaining Lease Payments

 2025
 37,084
 91,248

 2026
 35,719
 6,129

 2027
 36,742
 1,664

 2028
 37,795

 2029
 37,235
 —

 2030 and thereafter
 44,752
 —

 Total
 229,327
 99,721

 Less: Imputed Interest
 ( 42,639)
 ( 3,048)

 Present Value of Lease Liabilities
 $
 186,688
 $
 96,673

 12. Commitments and contingencies
 Lease commitments
 The Company leases certain office and laboratory space and has embedded leases at CMOs and a CTO. As of December 31, 2024, the Company has commitments arising from forward starting leases that have not commenced as of December 31, 2024 related to embedded equipment leases with a CMO. These leases are expected to commence in the first and second quarters of 2025. Both leases have an initial lease term of three years. Fixed commitments under this contract approximate $ 60.3 million. The following table presents the non-cancelable contractual obligations arising from this arrangement (in thousands):

 Years ended December 31,
 Future
commitment

 2025
 $
 15,101

 2026
 18,742

 2027
 18,742

 2028
 7,673

 2029
 —

 2030 and thereafter
 —

 Total purchase commitments
 $
 60,258

 Refer to Note 11, Leases, for further information on the terms of these lease agreements.
 Litigation
 From time to time, the Company is party to various claims and complaints arising in the ordinary course of business, including securities class action litigation and intellectual property litigation. The Company enters into standard indemnification agreements in the ordinary course of business. Pursuant to the agreements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified party for losses suffered or incurred by the indemnified party, generally the Company's business partners. The term of these indemnification agreements is generally perpetual any time after execution of the agreement. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is generally unlimited. Accruals for loss contingencies are recognized when a loss is probable, and the amount of such loss can be reasonably estimated. The Company has not accrued for a loss for any matter described below as a loss is not probable and a loss, or a range of loss, is not reasonably estimable.
 On October 21, 2021, San Rocco Therapeutics, LLC, formerly known as Errant Gene Therapeutics, LLC, filed a complaint against the Company in the United States District Court for the District of Delaware for alleged infringement of U.S. Patent Nos. 7,541,179 and 8,058,061. The term of U.S. Patent No. 8,058,061 already expired on November 25, 2022, and U.S.

 Patent No. 7,541,179 expired on May 13, 2024. The allegations relate to the Company's use of the BB305 lentiviral vector, including in connection with the beti-cel program and seeks injunctive relief and money damages. On February 21, 2022, the parties stipulated to amend the case caption, in light of the plaintiff's name change, from Errant Gene Therapeutics, LLC to San Rocco Therapeutics, LLC ("SRT"). The Court granted this stipulation and, accordingly, the case is now captioned, San Rocco Therapeutics, LLC v. bluebird bio, Inc. and Third Rock Ventures, LLC, C.A. No. 21-1478-RGA. On April 6, 2022, the Company—along with Third Rock Ventures, LLC—filed a motion seeking various relief including to stay the proceedings and compel arbitration on two threshold issues, which the Company argued warranted complete dismissal of the action as a matter of law, regardless of the merits of SRT's underlying infringement claims. On July 26, 2022, the Court granted the Company's request to stay the proceedings and issued an Order compelling the parties to arbitrate the threshold issues the Company raised. On February 7, 2023, the Arbitrator issued a final award finding in favor of SRT on both threshold issues, thereby enabling SRT to pursue its claims for alleged infringement. On March 1, 2023, the parties jointly stipulated, subject to the approval of the United States District Court for the District of Delaware, to lift the stay. The Court lifted the stay on March 2, 2023, and on March 31, 2023, the Company filed its answer to SRT's complaint with counterclaims asserting that it did not infringe the patents-in-suit and that the patents-in-suit are invalid. Also, on April 22, 2024, the Patent Trial & Appeal Board of the U.S. PTO found that the Company's two petitions for inter partes review did not show by a preponderance of the evidence that the challenged claims of the patents-in-suit are unpatentable, and the Company filed notices of appeal with the U.S. Court of Appeals for the Federal Circuit on June 21, 2024. The Company's opening brief was filed on December 20, 2024, SRT's responsive brief is due March 28, 2025, and the Company's reply brief is due May 19, 2025. On June 17, 2024, the Court entered a claim construction order in bluebird's favor. On July 17, 2024, the Court granted the Company's request for leave to file a case-dispositive motion for summary judgment of noninfringement, and on July 25, 2024, the Court ordered a stay of discovery pending a decision on the summary judgment motion. On August 1, 2024, the Company filed its motion for summary judgment of noninfringement, SRT filed an opposition on September 3, 2024 and the Company filed its reply on September 17, 2024. Briefing is now complete, and oral argument is scheduled for April 23, 2025. The Company plans to vigorously defend against SRT's claims in this action.

 On March 28, 2024, a class action lawsuit captioned Garry Gill v. bluebird bio, Inc. et al., Case No. 1:24-cv-10803-PBS (the "Gill Action"), was filed against the Company in the United States District Court for the District of Massachusetts. An amended complaint was filed on August 15, 2024. The amended complaint purports to assert claims against the Company and certain of its current and former officers pursuant to Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and Rule 10b-5 promulgated thereunder, on behalf of a putative class of investors who purchased or otherwise acquired the Company's shares between April 24, 2023 and December 8, 2023 (the "class period"). Plaintiff seeks to recover damages allegedly caused by purported misstatements and omissions regarding (i) whether the Company could obtain FDA approval for the lovo-cel BLA without a black box warning for hematologic malignancies; and (ii) whether the Company would be granted a priority review voucher by the FDA in connection with the BLA, which it could sell in order to strengthen its financial position. The amended complaint claims these alleged statements and omissions operated to artificially inflate the price paid for our common stock during the class period. On September 2, 2024, the Court entered the parties' stipulated schedule for briefing a motion to dismiss the amended complaint. The Company's opening brief in support of a motion to dismiss was filed on October 11, 2024; Plaintiff filed an opposition on December 5, 2024; and the Company filed its reply brief on December 20, 2024. The Court held oral argument on our motion to dismiss on January 14, 2025 and took the Company's motion under advisement. The Company intends to vigorously defend against the claims in this action.

 On June 27, 2024, a shareholder derivative lawsuit captioned imaitis v. Obenshain et al., Case No. 1:24-cv-11674-PBS, was filed nominally on the Company's behalf against certain current and former members of Company management and the Board of Directors in the United States District Court for the District of Massachusetts. The complaint purports to assert derivative claims pursuant to Sections 10(b), 14(a), and 21D of the Securities Exchange Act of 1934, as well as for breach of fiduciary duties, unjust enrichment, waste of corporate assets, gross mismanagement, and abuse of control. Plaintiff seeks to recover damages on the Company's behalf allegedly caused by purported materially false and misleading public statements and omissions, including in the April 28, 2023 proxy statement, regarding (i) whether the Company could obtain FDA approval for the lovo-cel BLA without a black box warning for hematologic malignancies; and (ii) whether the Company would be granted a priority review voucher by the FDA in connection with the BLA, which it could sell in order to strengthen its financial position. The complaint claims these allegedly misleading statements and omissions operated to artificially inflate the Company's common stock price during the relevant time period. To support its derivative claims, the complaint alleges that a legally required pre-suit demand on the Board would be futile and should be excused. On July 25, 2024, the case was consolidated with Syracuse v. Obenshain et al., Case No. 1:24-cv-11752 (D. Mass. July 8, 2024). The consolidated actions were recaptioned In re bluebird bio, Inc. Stockholder Derivative Litigation, Case No. 1:24-cv-11674-PBS. On September 19, 2024, the consolidated case was stayed pending resolution of the motion to dismiss filed in the Gill Action.

 On July 8, 2024, a shareholder derivative lawsuit captioned Syracuse v. Obenshain et al., Case No. 1:24-cv-11752-PBS, was filed nominally on the Company's behalf against certain current and former members of Company management and the Board of Directors in the United States District Court for the District of Massachusetts. The complaint purports to assert

 derivative claims against pursuant to Section 14(a) of the Securities Exchange Act of 1934, as well as for breach of fiduciary duties, gross mismanagement, waste of corporate assets, and unjust enrichment. Plaintiff seeks to recover damages on our behalf allegedly caused by purported materially false and misleading public statements and omissions, including in the April 28, 2023 proxy statement, regarding (i) whether the Company could obtain FDA approval for the lovo-cel BLA without a black box warning for hematologic malignancies; and (ii) whether the Company would be granted a priority review voucher by the FDA in connection with the BLA, which it could sell in order to strengthen its financial position. The complaint claims these allegedly misleading statements and omissions operated to artificially inflate the Company's common stock price during the relevant time period. To support its derivative claims, the complaint alleges that a legally required pre-suit demand on the Board would be futile and should be excused. On July 25, 2024, the case was consolidated with imaitis v. Obenshain et al., Case No. 24-cv-11674 (D. Mass. July 27, 2024). The consolidated actions were recaptioned In re bluebird bio, Inc. Stockholder Derivative Litigation, Case No. 1:24-cv-11674-PBS. On September 19, 2024, the consolidated case was stayed pending resolution of the motion to dismiss filed in the Gill Action.
 Four purported stockholders have filed lawsuits relating to the Merger Transaction (the "Lawsuits"): one on March 10, 2025, captioned Laughlin et al. v. bluebird bio, Inc., et al., No. 1:25-cv-02497 (N.D. Ill.); one on March 13, 2025, captioned Jones v. bluebird bio, Inc., et al., No. 651420/2025 (Sup. Ct. N.Y. Cnty.); two on March 17, 2025, captioned Kent v. bluebird bio, Inc., et al., No. 651424/2025 (Sup. Ct. N.Y. Cnty.), and Smith v. bluebird bio, Inc., et al., No. 1:25-cv-02802 (N.D. Ill.). Additionally, fifteen purported stockholders of bluebird have sent demand letters to the Company related to the Merger Transaction (the "Demand Letters"). Collectively, the Lawsuits and Demand Letters are referred to herein as the "Actions".
 The Lawsuits assert violations of Sections 14(d) and 14(e) of the Securities Exchange Act of 1934 and Rule 14d-9 promulgated thereunder, as well as claims under New York law for negligence and negligent misrepresentation and concealment. The Lawsuits seek injunctive relief to enjoin the merger, rescission or rescissory damages if the merger is consummated, an order directing compliance with federal securities laws, and awards of attorneys' and experts' fees.
 The Actions additionally allege that the tender offer statement and recommendation statement filed by the Company with the U.S. Securities and Exchange Commission ("SEC") are materially incomplete and misleading due to alleged omissions relating to, among other things: (i) the Company's historical price data and stock trading history; (ii) the Company's financial projections, including net revenue forecasts and standalone business plans; (iii) financial analyses underlying the fairness opinion provided by the Company's financial advisor, Leerink Partners LLC ("Leerink Partners"); (iv) potential conflicts of interest involving Company insiders and Leerink Partners; (v) discussions regarding employment or retention of Company management; (vi) the sales process and background of the proposed transaction; and (vii) details concerning the Company's Transaction Committee.
 The Company intends to vigorously defend against them.

 13. Equity
 The Company is authorized to issue 250.0 million shares of common stock. Holders of common stock are entitled to one vote per share. Holders of common stock are entitled to receive dividends, if and when declared by the Company's board of directors, and to share ratably in the Company's assets legally available for distribution to the Company's shareholders in the event of liquidation. Holders of common stock have no preemptive, subscription, redemption or conversion rights. As of December 31, 2024 and 2023, the Company had 9.7 million and 9.6 million shares of common stock issued and outstanding, respectively.
 In September 2021, the Company entered into an equity purchase agreement with certain investors, pursuant to which the Company agreed to sell and issue, in a private placement offering of securities, an aggregate of (i) 0.1 million shares of the Company's common stock at a purchase price per share of $ 330.00 and (ii) pre-funded warrants to purchase up to 0.1 million shares of common stock (the "Pre-Funded Warrants") at an effective price of $ 329.80 per share ($ 329.80 paid to the Company upon the closing of the offering and $ 0.20 to be paid upon exercise of such Pre-Funded Warrants). This resulted in aggregate gross proceeds to the Company of approximately $ 75.0 million. In October 2023, the investors opted to exercise their warrant. Pursuant to the terms of the warrant agreement, the company issued 0.1 million shares of common stock to the investor. As of December 31, 2024, there are no outstanding Pre-Funded Warrants.
 In June 2022, the Company entered into the Equity Distribution Agreement with Goldman to sell shares of the Company's common stock, with aggregate gross sales proceeds of up to $ 75.0 million, from time to time, through an "at the market" equity offering program under which Goldman will act as manager. The Company terminated the Equity Distribution Agreement in August 2023.

 On January 18, 2023, the Company entered into an underwriting agreement (the "January Underwriting Agreement") with Goldman and J.P. Morgan Securities LLC in connection with the public offering, issuance, and sale by the Company of 1.0 million shares of the Company's common stock at a public offering price of $ 120.00 per share, less underwriting discounts and commissions, pursuant to an effective shelf registration statement on Form S-3 and a related prospectus supplement filed with the Securities and Exchange Commission. Under the terms of the January Underwriting Agreement, the Company also granted the underwriters an option exercisable for 30 days to purchase up to an additional 0.2 million shares of common stock at the public offering price, less underwriting discounts and commissions, which option the underwriters exercised in full. The offering closed on January 23, 2023. The Company received aggregate net proceeds of $ 130.5 million.
 In August 2023, the Company entered into an Open Market Sales Agreement (the "Sales Agreement") with Jefferies LLC ("Jefferies") to sell shares of the Company's common stock up to $ 125.0 million, from time to time, through an "at the market" equity offering program under which Jefferies will act as sales agent. As of December 31, 2024, the Company has made no sales pursuant to the Sales Agreement.
 On December 19, 2023, the Company entered into an underwriting agreement (the "December Underwriting Agreement") with Goldman and J.P. Morgan Securities LLC, in connection with the public offering, issuance, and sale by the Company of 4.2 million shares of the Company's common stock at a public offering price of $ 30.00 per share, less underwriting discounts and commissions, pursuant to an effective shelf registration statement on Form S-3 and a related prospectus supplement filed with the Securities and Exchange Commission. Under the terms of the December Underwriting Agreement, the Company also granted the underwriters an option exercisable for 30 days to purchase up to an additional 0.6 million shares of common stock at the public offering price, less underwriting discounts and commissions, which option was not exercised. The offering closed on December 22, 2023. The Company received aggregate net proceeds of $ 118.1 million.
 The Company is authorized to issue 5.0 million shares of preferred stock in one or more series and to fix the powers, designations, preferences and relative participating option or other rights thereof, including dividend rights, conversion rights, voting rights, redemption terms, liquidation preferences and the number of shares constituting any series, without any further vote or action by the Company's shareholders. As of December 31, 2024 and 2023, the Company had no shares of preferred stock issued or outstanding.
 On December 12, 2024, the Company filed a Certificate of Amendment to its Amended and Restated Certificate of Incorporation, as amended, with the Secretary of State of the State of Delaware to effect the Reverse Stock Split, effective December 12, 2024 at 5:00 p.m. Additionally, all share and per-share amounts have been retroactively adjusted to reflect the Reverse Stock Split in these consolidated financial statements.

 14. Sale of Priority Review Vouchers
 On January 5, 2023, the Company entered into an asset purchase agreement with Bristol-Myers Squibb Company ("BMS"), pursuant to which the Company agreed to sell a PRV to BMS. The Company was awarded the voucher under the FDA program described above. The Company received the PRV when ZYNTEGLO was approved by the FDA for the treatment of -thalassemia in adult and pediatric patients who require regular red blood cell transfusions. Pursuant to the agreement, BMS agreed to pay the Company $ 95.0 million, payable in cash, upon the closing of the sale, which occurred simultaneously with the parties entering into the agreement. The Company received cash of $ 95.0 million and recognized $ 2.1 million in transaction costs.

 15. Intangible assets
 Intangible assets, net of accumulated amortization, are summarized as follows (in thousands):
 As of December 31, 2024

 Cost
 Accumulated amortization
 Impairment
 Net

 In-licensed rights
 11,136
 ( 1,589)
 —
 9,547

 Total
 $
 11,136
 $
 ( 1,589)
 $
 —
 $
 9,547

 As of December 31, 2023

 Cost
 Accumulated amortization
 Impairment
 Net

 In-licensed rights
 11,089
 ( 651)
 —
 10,438

 Total
 $
 11,089
 $
 ( 651)
 $
 —
 $
 10,438

 Amortization expense for intangible assets was $ 0.9 million and $ 0.5 million for the years ended December 31, 2024 and 2023, respectively.
 In-licensed rights
 In-licensed rights consist of capitalized milestone payments made to third parties upon receiving regulatory approval of ZYNTEGLO, SKYSONA, and LYFGENIA in the U.S. The in-licensed rights are being amortized on a straight-line basis over the remaining life of the product exclusivity period in the U.S. of approximately twelve years per product, as the life of the product exclusivity reflects the expected time period that the Company will benefit from the in-licensed rights.
 The following table summarizes the estimated future amortization for intangible assets for the next five years and thereafter (in thousands):

 As of December 31, 2024

 2025
 $

 2026

 2027

 2028

 2029

 2030 and thereafter
 $
 4,897

 Total
 $
 9,547

 16. Stock-based compensation
 2023 Incentive Award Plan
 In June 2023, the Company's stockholders approved the bluebird bio, Inc. 2023 Incentive Award Plan ("2023 Plan"), which became effective on June 16, 2023. The 2023 Plan replaced the 2013 Stock Option and Incentive Plan ("2013 Plan").
 The 2023 Plan allows for the granting of incentive stock options, non-qualified stock options, restricted stock units, and restricted stock awards to the Company's employees, members of the board of directors, and consultants of the Company. The 2023 Plan initially authorized the issuance of up to 0.3 million shares of common stock.
 On November 6, 2024, the Company's stockholders approved a proposal to amend and restate the Company's 2023 Plan to (i) increase the aggregate number of shares authorized for issuance under the 2023 Plan by 0.8 million shares to 1.0 million shares, (ii) include minimum vesting requirements for certain awards granted thereunder, (iii) clarify the treatment of performance-based awards in the event of a change in control and (iv) extend the date following which incentive stock options

 can no longer be granted to September 12, 2034, the tenth anniversary of the date the Company's board of directors approved the amended and restated 2023 Plan.
 Any awards outstanding under the Company's 2013 Plan at the time of adoption of the 2023 Plan remained outstanding and effective. The shares of common stock underlying any awards that are forfeited, canceled, repurchased, expired or are otherwise terminated (other than by exercise) under the 2013 Plan are added to the shares of common stock available for issuance under the 2023 Plan. The 2023 Plan will expire in 2033. As of December 31, 2024, the total number of available shares of common stock that may be issued under the 2023 Plan is 0.8 million.
 2021 Inducement Plan
 On May 18, 2021, the Company's board of directors adopted the bluebird bio, Inc. 2021 Inducement Plan (the "Inducement Plan") pursuant to the Nasdaq Stock Market LLC listing rules ("Rule 5635(c)(4)"). In accordance with Rule 5635(c)(4), equity-based incentive awards under the Inducement Plan may only be made to a newly hired employee who has not previously been a member of the Company's board of directors, or an employee who is being rehired following a bona fide period of non-employment by the Company as a material inducement to the employee's entering into employment with the Company. The Inducement Plan initially reserved less than 0.1 million shares, which was later increased to an aggregate of 0.1 million shares in January 2022.
 The exercise price of stock options granted under the Inducement Plan will not be less than the fair market value of a share of the Company's common stock on the grant date. Other terms of awards, including vesting requirements, are determined by the Company's board of directors or compensation committee and are subject to the provisions of the Inducement Plan. Stock options granted to employees under the Inducement Plan generally vest over a four-year period but may be granted with different vesting terms. Certain options may provide for accelerated vesting in the event of a change in control. Stock options granted under the Inducement Plan expire no more than 10 years from the date of grant. As of December 31, 2024, less than 0.1 million shares of common stock are available for future grant under the Inducement Plan.
 2013 Stock Option and Incentive Plan
 In June 2013, the Company's board of directors adopted the 2013 Plan, which was subsequently approved by the Company's stockholders and became effective upon the closing of the Company's IPO. The 2013 Plan expired in June 2023.
 The 2013 Plan allowed for the granting of incentive stock options, non-qualified stock options, restricted stock units and restricted stock awards to the Company's employees, members of the board of directors, and consultants of the Company. The Company initially reserved less than 0.1 million shares of its common stock for the issuance of awards under the 2013 Plan. The 2013 Plan provided that the number of shares reserved and available for issuance would automatically increase each January 1, beginning on January 1, 2014, by four percent of the outstanding number of shares of common stock on the immediately preceding December 31 or such lesser number of shares as determined by the Company's compensation committee. In January 2023, the number of common stock available for issuance under the 2013 Plan was increased by approximately 0.1 million shares as a result of this automatic increase provision.
 Conversion and modification of equity awards outstanding at the Separation
 In connection with the Separation on November 4, 2021, under the provisions of the existing plans, the Company adjusted its outstanding equity awards in accordance with the terms of the Employee Matters Agreement (an equitable adjustment) to preserve the intrinsic value of the awards immediately before and after the distribution of all of the outstanding shares of 2seventy bio common stock to our stockholders. Upon the distribution, employees holding stock options, restricted stock units ("RSUs") and performance restricted stock units ("PRSUs") denominated in pre-distribution bluebird stock received a number of otherwise-similar awards either in post-Distribution bluebird stock or in a combination of post-distribution bluebird stock and 2seventy bio stock based on conversion ratios outlined for each group of employees in the Employee Matters Agreement that the Company entered into in connection with the distribution. The equity awards that were granted prior to 2021 were converted under the shareholder method, wherein employees holding outstanding equity awards received equity awards in both bluebird and 2seventy bio. The conversion ratio for the shareholder method took into consideration a distribution ratio of one share of 2seventy bio common stock for every three shares of bluebird common stock. For equity awards granted in 2021, the number of awards that were outstanding at the Separation were proportionately adjusted to maintain the aggregate intrinsic value of the awards at the date of the Separation. The conversion ratio was determined based on the volume weighted-average trading price for bluebird common stock for the five trading days before and after the Separation. These modified awards otherwise retained substantially the same terms and conditions, including term and vesting provisions.

 Additionally, bluebird will not incur any future compensation cost related to equity awards held by 2seventy bio employees and directors. The Company will incur future compensation cost related to 2seventy bio equity awards held by bluebird employees.
 The Company recognized stock-based compensation expense totaling $ 13.7 million and $ 19.4 million during the years ended December 31, 2024 and 2023, respectively. Stock-based compensation expense recognized by award type is as follows (in thousands):

 2024
 2023

 Stock options
 $
 4,805
 $
 6,478

 Restricted stock units
 8,812
 12,619

 Employee stock purchase plan and other

 $
 13,736
 $
 19,429

 Stock-based compensation expense by classification included within the consolidated statements of operations and comprehensive loss was as follows (in thousands):

 2024
 2023

 $
 1,339
 $

 Selling, general and administrative
 8,147
 9,548

 Research and development
 3,982
 9,000

 Restructuring expenses
 —

 $
 13,736
 $
 19,429

 As of December 31, 2024 and 2023, the Company had $ 0.5 million and $ 1.7 million of stock-based compensation expense that was capitalized into inventory, respectively.
 As of December 31, 2024, the Company had $ 6.7 million and $ 9.3 million of unrecognized compensation expense related to unvested stock options and restricted stock units, respectively, that is expected to be recognized over a weighted-average period of 2.27 years and 2.83 years, respectively.
 Stock options
 The fair value of each option issued to employees was estimated at the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions:

 2024
 2023

 Expected volatility
 84.6
 %
 70.9
 %

 Expected term (in years)
 6.10
 6.10

 Risk-free interest rate
 4.2
 %
 4.1
 %

 Expected dividend yield
 0.0
 %
 0.0
 %

 The following table summarizes the stock option activity under the Company's equity awards plans excluding awards held by employees of 2seventy bio:
 Shares
 Weighted-
average
exercise price
per share
 Weighted-
average
contractual
life
(in years)
 Aggregate
intrinsic
value (a)

 Outstanding at December 31, 2023
 $
 283.20

 Granted
 $
 26.95

 Exercised
 —
 $
 —

 Canceled or forfeited
 ( 53)
 $
 231.67

 Outstanding at December 31, 2024
 $
 157.66
 8.14
 $
 —

 Exercisable at December 31, 2024
 $
 320.66
 6.91
 $
 —

 Vested and expected to vest at December 31, 2024
 $
 157.66
 8.14
 $
 —

 (a) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of the common stock for the options that were in the money at December 31, 2024.
 The weighted-average fair values of options granted during the years ended December 31, 2024 and 2023 was $ 19.99 and $ 64.80, respectively. There was no intrinsic value of options exercised during the years ended December 31, 2024 and 2023, respectively.
 Restricted stock units
 The following table summarizes the restricted stock unit activity under the Company's equity award plans excluding awards held by employees of 2seventy bio:
 Shares
 Weighted-average
grant date
fair value

 Unvested balance at December 31, 2023
 $
 121.60

 Granted
 23.00

 Vested
 ( 81)
 122.99

 Forfeited
 ( 73)
 70.06

 Unvested balance at December 31, 2024
 $
 60.48

 The intrinsic value of restricted stock units, including shares held by employees of 2seventy bio, vested during the years ended December 31, 2024 and 2023 was $ 1.7 million and $ 5.4 million, respectively. The total grant date fair value of restricted stock units vested during the years ended December 31, 2024 and December 31, 2023 was $ 9.9 million and $ 15.2 million, respectively.
 Employee Stock Purchase Plan
 In June 2013, the Company's board of directors adopted the Company's 2013 Employee Stock Purchase Plan ("2013 ESPP"), which was subsequently approved by its stockholders and became effective upon the closing of the Company's IPO. The 2013 ESPP authorizes the initial issuance of up to a total of 10,000 shares of the Company's common stock to participating employees. In June 2021, the Company amended the 2013 ESPP to authorize an additional approximately 0.1 million shares of the Company's common stock available to participating employees. During each of the years ended December 31, 2024 and 2023, less than 0.1 million shares of common stock were issued under the 2013 ESPP. As of December 31, 2024, less than 0.1 million shares of common stock are available for future grant under the 2013 ESPP.

 17. 401(k) Savings plan
 In 1997, the Company established a defined-contribution savings plan under Section 401(k) of the Internal Revenue Code (the "401(k) Plan"). The 401(k) Plan covers all employees who meet defined minimum age and service requirements, and allows participants to defer a portion of their annual compensation on a pretax basis. Expense related to the 401(k) Plan from continuing operations totaled $ 2.7 million and $ 3.1 million for the years ended December 31, 2024 and 2023, respectively.

 18. Income taxes
 The components of loss before income taxes were as follows (in thousands):

 2024
 2023

 U.S.
 $
 ( 241,440)
 $
 ( 213,306)

 Foreign
 1,267

 Total
 $
 ( 240,645)
 $
 ( 212,039)

 The provision for (benefit from) income taxes were as follows (in thousands):

 2024
 2023

 Current:

 Federal
 $
 —
 $
 —

 State
 —
 —

 Foreign
 ( 126)

 Deferred:

 Federal
 —
 —

 State
 —
 —

 Foreign
 —
 —

 Total income tax expense (benefit)
 $
 $
 ( 126)

 A reconciliation of income tax expense (benefit) computed at the statutory federal income tax rate to the Company's effective income tax rate as reflected in the financial statements is as follows:

 2024
 2023

 Federal income tax expense at statutory rate
 21.0
 %
 21.0
 %

 State income tax, net of federal benefit
 1.0
 %
 7.3
 %

 Permanent differences
 ( 0.1)
 %
 0.6
 %

 Stock-based compensation
 ( 2.2)
 %
 ( 3.6)
 %

 Research and development credit
 —
 %
 5.8
 %

 Leases
 0.6
 %
 5.4
 %

 Fixed assets
 —
 %
 ( 2.7)
 %

 Other
 ( 0.3)
 %
 0.9
 %

 Change in valuation allowance
 ( 20.0)
 %
 ( 34.6)
 %

 Effective income tax rate (expense) benefit
 —
 %
 0.1
 %

 For the years ended December 31, 2024 and 2023, the Company recognized an income tax expense (benefit) of $ 0.1 million or 0.0 % and $( 0.1) million or 0.1 %, respectively. The Company did not recognize any significant tax expense for the years ended December 31, 2024 or 2023 as the Company was subject to a full valuation allowance. Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes.
 The significant components of the Company's deferred tax assets and liabilities are composed of the following (in thousands):

 2024
 2023

 Deferred tax assets:

 U.S. net operating loss carryforwards (federal and state)
 $
 781,085
 $
 726,021

 Tax credit carryforwards (federal and state)
 313,972
 313,963

 Capitalized license fees and research and development expenses
 1,654
 2,079

 Capitalized research and development expenses under Section 174
 99,905
 91,306

 Stock-based compensation
 6,628
 9,847

 Lease liabilities
 73,587
 100,288

 Accruals and other
 24,046
 20,336

 Total deferred tax assets
 1,300,877
 1,263,840

 Right-of-use assets
 ( 45,935)
 ( 54,976)

 Fixed assets
 ( 14,570)
 ( 16,701)

 Less valuation allowance
 ( 1,240,372)
 ( 1,192,163)

 Net deferred taxes
 $
 —
 $
 —

 A valuation allowance is recorded against deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be realized. Due to the uncertainty surrounding the realization of the favorable tax attributes in future tax returns, the Company has recorded a full valuation allowance against the Company's otherwise recognizable net deferred tax assets. The valuation allowance increased on a net basis by approximately $ 48.2 million during the year ended December 31, 2024 due primarily to the capitalization of research and development expenses, net operating losses, and tax credit carryforwards.
 As of December 31, 2024 and 2023, the Company had U.S. federal net operating loss carryforwards of approximately $ 2.9 billion and $ 2.7 billion, respectively, which may be available to offset future income tax liabilities. Of the amount as of December 31, 2024, $ 2.2 billion will carryforward indefinitely while $ 0.7 billion will expire at various dates through 2037. As of December 31, 2024 and 2023, the Company also had U.S. state net operating loss carryforwards of approximately $ 2.7 billion and $ 2.5 billion, respectively, which may be available to offset future income tax liabilities and expire at various dates through 2044.
 As of December 31, 2024 and 2023, the Company had federal research and development and orphan drug tax credit carryforwards of approximately $ 299.5 million and $ 299.5 million, respectively, available to reduce future tax liabilities which expire at various dates through 2044. As of December 31, 2024 and 2023, the Company had state credit carryforwards of approximately $ 18.3 million and $ 18.3 million, respectively, available to reduce future tax liabilities which expire at various dates through 2037. During the fourth quarter of 2018, the Company completed an analysis of prior year estimates of U.S. research and development and orphan drug tax credits for the years 2013 through 2017. The analysis resulted in an immaterial adjustment to the Company's income tax benefit, which was offset by an adjustment to the valuation allowance. An analysis of the U.S. research and development and orphan drug credits has not yet been completed for years 2018 through 2024. As of December 31, 2024 and 2023, the Company had capital loss carryforwards of approximately $ 4.2 million and $ 4.2 million, respectively, which may be available to offset future capital gains and will begin to expire in 2027.
 Under the provisions of the Internal Revenue Code, the net operating loss and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50 percent, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has completed several financings since its inception and prior to its initial public offering in 2013, which it believes has resulted in a change in control as defined by Sections 382 and 383 of the Internal Revenue Code. The Company completed a study through December 2023 confirming no ownership changes have occurred since the Company's initial public offering in 2013; any ownership shifts occurring after December 2023 could result in an ownership change under Section 382. There is a significant likelihood that the Company may experience an ownership change

 as a result of future equity offerings, although whether the Company experiences an ownership change will depend on the specific facts that apply at the time of any offering.
 The Company files Federal income tax returns in the United States, and various state and foreign jurisdictions. The federal, state and foreign income tax returns are generally subject to tax examinations for the tax years ended December 31, 2021 through December 31, 2024. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the Internal Revenue Service, or state or foreign tax authorities to the extent utilized in a future period.
 A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):
 Unrecognized tax benefits

 Balance as of December 31, 2022 (As Restated)

 $
 23,493

 Increases (decreases) for tax positions related to current period

 Increases (decreases) for tax positions related to prior periods

 Balance as of Balance as of December 31, 2023
 24,538

 Increases (decreases) for tax positions related to current period

 Increases (decreases) for tax positions related to prior periods
 ( 5)

 Balance as of December 31, 2024
 24,538

 The unrecognized tax benefits at December 31, 2024, if recognized, would not affect the Company's effective tax rate due to its full valuation allowance position. The Company does not anticipate that the amount of existing unrecognized tax benefits will significantly increase or decrease within the next 12 months. The Company has elected to include interest and penalties related to uncertain tax positions as a component of its provision for income taxes. For the years ended December 31, 2024 and 2023, the Company's accrued interest and penalties related to uncertain tax positions were no t material.

 19. Reduction in workforce
 In September 2024, the Company's board of directors approved a restructuring action (the "Restructuring") following a comprehensive review of the Company's operations. The Restructuring includes a reduction of the Company's workforce by 92 employees, or approximately 25 % of employees.
 As a result of the Restructuring, the Company incurred aggregate charges of $ 2.8 million in restructuring costs, $ 2.5 million of which relates to cash expenditures for severance and employee termination-related costs to be paid out over multiple weeks through the second quarter of 2025, with the majority paid out by December 31, 2024, and $ 0.3 million in stock-based compensation expense associated with accelerated vesting of restricted stock units.
 The following table summarizes the accrued liabilities activity recorded in connection with the reduction in workforce for the year ended December 31, 2024:

 For the year ended December 31,

 2024

 Cash expenditure charges
 $
 2,494

 Amount paid through December 31, 2024
 ( 2,083)

 Amounts accrued at December 31, 2024
 $

 There were no restructuring expenses recorded as of December 31, 2023.

 20. Net loss per share
 The following common stock equivalents were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect (in thousands):

 2024
 2023

 Outstanding stock options (1)

 Restricted stock units (1)

 Warrants

 ESPP shares and other

 Total excluded common stock equivalents
 1,133

 (1) Outstanding stock options and restricted stock units include awards outstanding to employees of 2seventy bio.

 Net loss per share for the years ended December 31, 2024 and 2023 were $ 24.84 and $ 38.59, respectively.

 21. Subsequent events
 Termination of Lease

 On February 13, 2025, the Company executed a termination agreement (the "Termination Agreement") with its sublessor and sub-sublessee related to certain office space located at 50 Binney Street in Cambridge that the Company had subleased in 2019 and subsequently sub-subleased out in 2021 (refer to Note 11). Upon entering into the sublease, the Company had executed as a security deposit a $ 40.1 million cash-collateralized letter of credit. Under the Termination Agreement, the sublessor agreed to enter into a sublease agreement (the "New Sublease Agreement") directly with the sub-sublessee, thereby releasing the Company of all obligations as sublessee under the sublease and as sub-sublessor under the sub-sublease, including the release of $ 30.1 million of the security deposit, which was classified within restricted cash and other non-current on the Company's balance sheet as of December 31, 2024. The remaining $ 10.0 million of the security deposit, which was also classified within restricted cash and other non-current assets on the Company's balance sheet as of December 31, 2024, will remain in a cash-collateralized letter of credit until termination or expiration of the prime lease. During the first quarter of 2025, the Company will write off its right-of-use asset, operating lease liability, and the rent receivable due from the sub-sublease and recognize the difference within Other income, net on the consolidated statements of operations and comprehensive loss.

 Merger Agreement
 On February 21, 2025, we announced that we entered into an Agreement and Plan of Merger (the "Merger Agreement") with Beacon Parent Holdings, L.P., a Delaware limited partnership ("Parent"), and Beacon Merger Sub, Inc., a Delaware corporation ("Merger Sub"). Pursuant to the Merger Agreement, Merger Sub will conduct a cash tender offer (the "Offer") to acquire any and all of the outstanding shares of our common stock, for (i) $ 3.00 in cash per share, plus (ii) one contingent value right (each, a "CVR") per share, representing the right to receive a non-tradeable contingent payment of $ 6.84 in cash, in each case subject to any applicable withholding taxes and without interest thereon (the "Merger Transaction"). On March 7, 2025, Parent and Merger Sub commenced the Offer. The Company expects the Merger Transaction will be completed in the first half of 2025, and as such, it is not included in its going concern assessment.

 Fifth Amendment to Loan and Security Agreement

 On February 21, 2025, the Company and Hercules entered into an amendment to the LSA (the "Fifth Amendment"). Pursuant to the Fifth Amendment, the parties agreed to, among other things: (i) amendments to the required amount of the minimum cash covenant under the LSA, (ii) addition of an event of default that will be triggered if (a) the Merger Agreement is terminated (other than as a result of the consummation of the Merger Transaction) or amended in a manner materially adverse to the Lenders or (b) the change of control contemplated by the Merger Agreement does not occur on or prior to April 25, 2025, which may be extended to May 23, 2025 and further extended to June 20, 2025, in each case, in accordance with the terms thereof, and (iii) waiver of the Company's requirement to comply with the net product revenue covenant in the LSA, from the effective date of the Fifth Amendment until the termination of the Merger Agreement (other than as a result of the consummation of the Merger Transaction).

 Sixth Amendment to Loan and Security Agreement

 On February 21, 2025, the Company entered into the Sixth Amendment (the "Sixth Amendment") to the LSA (as amended by the Fifth Amendment, the "Amended LSA"), by and among the Company, the Lenders, and the Agent. Pursuant to the terms of the Sixth Amendment, the Agent and the Lenders, among other things: (i) consented to the Company's entry into the Merger

 Agreement and the consummation of the Merger Transaction and (ii) agreed, upon satisfaction of certain conditions therein (including the consummation of the Merger Transaction), to amend certain terms of the Amended LSA, as set forth therein. In addition, the Lenders acknowledged that the warrants previously issued to the Lenders in connection with the LSA will be cancelled and extinguished for no consideration at the effective time of the Merger Transaction.

 Exhibit Index
 Incorporated by Reference

Number
 Exhibit Title
 Form
 File no.
 Filing Date

 2.1*
 Separation Agreement, dated as of November 3, 2021, by and between the Registrant and 2seventy bio, Inc.

 2.1

 2.2*

 Asset Purchase Agreement, dated as of November 29, 2022, by and between bluebird bio, Inc. and argenx BV

 2.1
 November 30, 2022

 2.3*

 Asset Purchase Agreement, dated as of January 5, 2023, by and between bluebird bio, Inc. and Bristol-Myers Squibb Company

 2.1
 January 6, 2023

 2.4*

 Asset Purchase Agreement, dated as of October 26, 2023, by and between bluebird bio, Inc. and Novartis Pharma AG

 2.1

 October 30, 2023

 2.5*
 Agreement and Plan of Merger, by and among Beacon Parent Holdings, L.P., Beacon Merger Sub, Inc., and bluebird bio, Inc.

 2.1

 February 21, 2025

 3.1
 Amended and Restated Certificate of Incorporation of the Registrant

 3.1
 June 24, 2013

 3.2

 Certificate of Amendment to the Amended and Restated Certificate of Incorporation of the Registrant

 3.1

 June 20, 2023

 3.3
 Certificate of Amendment to the Amended and Restated Certificate of Incorporation of the Registrant

 3.1
 December 13, 2024

 3.4
 Amended and Restated By-laws of the Registrant

 3.1

 December 18, 2023

 4.1
 Specimen Common Stock Certificate

 S-1/A
 4.1
 June 4, 2013

 4.2
 Description of the Registrant's Securities

 4.2

 4.3**

 Form of Warrant Agreement

 4.1

 August 14, 2024

 4.4

 Form of Warrant Agreement Amendment

 4.2

 August 14, 2024

 10.1#

 2013 Stock Option and Incentive Plan and forms of award agreement thereunder

 S-1/A
 10.3
 June 4, 2013

 10.2

 Form of Indemnification Agreement between the Registrant and each of its Executive Officers and Directors

 S-1
 10.4

 10.3

 Patent and Know-How License Agreement No. 07554F30, dated May 14, 2009, by and between the Registrant (formerly known as Genetix Pharmaceuticals Inc.) and INSERM-TRANSFERT, as amended

 S-1
 10.7

 10.4

 Amendment No. 3 to Patent and Know-How License Agreement No. 07554F33, dated October 29, 2014, by and between the Registrant (formerly known as Genetix, Inc.) and INSERM-TRANSFERT

 10.4

 10.5

 Amendment No. 4 to Patent and Know-How License Agreement No. 07554F33, dated December 16, 2015, by and between the Registrant (formerly known as Genetix, Inc.) and INSERM-TRANSFERT

 10.5

 10.6

 License Agreement, dated September 13, 2011, by and between the Registrant and Institut Pasteur, as amended

 S-1
 10.8

 10.7

 Amendment No. 3 to License Agreement, dated September 10, 2013, by and between the Registrant and Institut Pasteur

 10.2
 November 14, 2013

 10.8

 Amendment No. 4 to License Agreement, dated April 1, 2015, by and between the Registrant and Institut Pasteur

 10.10
 May 6, 2015

 10.9

 License Agreement, dated December 7, 2011, by and between the Registrant and Research Development Foundation

 S-1
 10.9

 10.10

 Novation Agreement, dated April 2, 2012, by and between the Registrant and The Board of Trustees of the Leland Stanford Junior University

 S-1
 10.10

 10.11

 License Agreement, dated December 23, 2015, by and between the Registrant and SIRION Biotech GmbH

 10.23
 February 21, 2019

 Incorporated by Reference

Number
 Exhibit Title
 Form
 File no.
 Filing Date

 10.12

 Clinical and Commercial Supply Agreement – Viral Vector Product, dated November 27, 2017, by and between the Registrant and SAFC Carlsbad, Inc., as amended

 10.25
 August 1, 2019

 10.13

 Amendment No. 2 to Clinical and Commercial Supply Agreement Viral Vector Product by and between the Registrant and SAFC Carlsbad, Inc.

 10.1
 January 21, 2020

 10.14

 Amendment No. 3 to Clinical and Commercial Supply Agreement Viral Vector Product by and between the Registrant and SAFC Carlsbad, Inc.

 10.28
 February 23, 2021

 10.15

 Amendment No. 4 to Clinical and Commercial Supply Agreement Viral Vector Product by and between the Registrant and SAFC Carlsbad, Inc.

 10.1
 August 4, 2022

 10.16

 Amendment No. 5 to Clinical and Commercial Supply Agreement Viral Vector Product by and between the Registrant and SAFC Carlsbad, Inc.

 10.1
 November 7, 2022

 10.17

 Amendment No. 6 to Clinical and Commercial Supply Agreement Viral Vector Product by and between the Registrant and SAFC Carlsbad, Inc.

 10.17

 10.18

 Master Manufacturing Services Agreement, dated June 3, 2016, by and between the Registrant and Lonza Houston, Inc.

 10.22

 March 29, 2023

 10.19

 Amendment to Master Manufacturing Services Agreement, dated October 23, 2017, by and between the Registrant and Lonza Houston, Inc.

 10.23

 March 29, 2023

 10.20

 Second Amendment to Master Manufacturing Services Agreement, dated September 21, 2023, by and between the Registrant and Lonza Houston, Inc.

 10.1

 November 7, 2023

 10.21

 Development and Manufacturing Services Agreement, dated February 28, 2012, by and between the Registrant and Minaris Regenerative Medicine, LLC (formerly known as Hitachi Advanced Therapeutic Solutions, LLC, PCT Cell Therapy Services, PCT, LLC, a Caladrius Company, and Progenitor Cell Therapy, LLC), as amended

 10.21

 10.22 **
 Master Services Agreement for Viral Vector Services, dated as of September 15, 2024, between the Registrant and Henogen SRL, as part of Thermo Fisher Scientific

 10.4
 November 14, 2024

 10.23#

 Consulting Agreement, dated May 26, 2022, by and between bluebird bio, Inc. and Danforth Advisors, LLC, as amended

 10.5
 November 7, 2022

 10.24#

 Employment Agreement, dated January 7, 2021, by and between the Registrant and Andrew Obenshain

 10.23
 March 4, 2022

 10.25#

 Employment Agreement, dated April 20, 2021, by and between the Registrant and Thomas Klima

 10.25
 March 4, 2022

 10.26#

 Employment Agreement, dated October 31, 2022, by and between the Registrant and Richard Colvin

 10.36

 March 29, 2023

 10.27#

 Employment Agreement, dated January 1, 2023, by and between the Registrant and Joseph Vittiglio

 10.37

 March 29, 2023

 10.28#

 Employment Agreement, dated May 28, 2024, by and between the Registrant and O. James Sterling

 10.1
 May 29, 2024

 10.29#

 2013 Employee Stock Purchase Plan

 S-1/A
 10.17
 June 4, 2013

 10.30#

 First Amendment of the Bluebird Bio, Inc. 2013 Employee Stock Purchase Plan

 10.38
 February 21, 2018

 10.31#

 Second Amendment of the Bluebird Bio, Inc. 2013 Employee Stock Purchase Plan

 S-8
 333-257135
 99.1
 June 15, 2021

 10.32#

 2021 Inducement Plan and forms of award agreements thereunder

 S-8
 333-257135
 99.2
 June 15, 2021

 10.33#

 First Amendment to the bluebird bio, Inc. 2021 Inducement Plan

 S-8
 333-257135
 99.3
 March 4, 2022

 Incorporated by Reference

Number
 Exhibit Title
 Form
 File no.
 Filing Date

 10.34#
 bluebird bio, Inc. 2023 Incentive Award Plan, as amended and restated, and forms of award agreements thereunder

 10.5
 November 14, 2024

 10.35#
 Executive Cash Incentive Bonus Plan

 S-1
 10.18

 10.36#
 Non-Employee Director Compensation Policy

 10.37

 10.37**
 Office Lease Agreement, dated November 2, 2021, by and between the Registrant and Assembly Row 5B, LLC

 10.30
 November 5, 2021

 10.38**
 Sub-sublease Agreement, by and between the Registrant and Meta Platforms, Inc.

 10.36
 March 4, 2022

 10.39**
 Sublease, dated October 31, 2022, by and between Finch Therapeutics, Inc. and bluebird bio, Inc.

 10.6
 November 7, 2022

 10.40 **
 Securities Purchase Agreement, dated September 7, 2021, by and among the Registrant and the institutional investors named therein

 10.1
 September 8, 2021

 10.41
 Registration Rights Agreement, dated September 7, 2021, by and among the Registrant and the persons listed on the attached Schedule A thereto

 10.2
 September 8, 2021

 10.42
 Tax Matters Agreement, dated as of November 3, 2021, by and between the Registrant and 2seventy bio, Inc.

 10.1

 10.43**
 Employee Matters Agreement, dated as of November 3, 2021, by and between the Registrant and 2seventy bio, Inc.

 10.2

 10.44**
 Intellectual Property License Agreement, dated as of November 3, 2021, by and between the Registrant and 2seventy bio, Inc.

 10.3

 10.45**
 Transition Services Agreement, dated as of November 3, 2021, by and between the Registrant and 2seventy bio, Inc.

 10.4

 10.46**
 Transition Services Agreement, dated as of November 3, 2021, by and between 2seventy bio, Inc. and the Registrant

 10.5

 10.47**
 Amendment to the Transition Services Agreement, by and between 2seventy bio, Inc. and the Registrant

 10.2
 August 4, 2022

 10.48 **
 Invoice Purchase and Sale Agreement, dated as of December 14, 2023, between the Registrant and Alterna Capital Solutions LLC

 10.1

 December 18, 2023

 10.49 **
 Loan and Security Agreement, dated as of March 15, 2024, between the Registrant, as Borrower, and Hercules Capital, Inc., as Lender

 10.1

 May 3, 2024

 10.50 **
 First Amendment to Loan and Security Agreement, dated April 30, 2024, between the Registrant, as Borrower, and Hercules Capital, Inc., as Lender

 10.2

 May 3, 2024

 10.51
 Second Amendment to Loan and Security Agreement, dated July 9, 2024, between the Registrant, as Borrower, and Hercules Capital, Inc., as Lender

 10.1

 July 11, 2024

 10.52
 Third Amendment to Loan and Security Agreement, dated August 13, 2024, between the Registrant, as Borrower, and Hercules Capital, Inc., as Lender

 10.1

 August 14, 2024

 10.53
 Fourth Amendment to Loan and Security Agreement, dated August 29, 2024, between the Registrant, as Borrower, and Hercules Capital, Inc., as Lender

 10.1

 August 30, 2024

 10.54
 Fifth Amendment to Loan and Security Agreement, dated February 21, 2025, between the Registrant, as Borrower, and Hercules Capital, Inc., as Lender

 10.1

 February 21, 2025

 19.1
 Policy and Procedures on Insider Trading and Disclosure

 —
 —
 —

 23.1
 Consent of Ernst & Young LLP

 —
 —
 —

 Incorporated by Reference

Number
 Exhibit Title
 Form
 File no.
 Filing Date

 31.1
 Certification of Principal Executive Officer pursuant to Rule 13a-14(a) or Rule 15d-14(a) of the Securities Exchange Act of 1934, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

 —
 —
 —

 31.2
 Certification of Principal Financial Officer pursuant to Rule 13a-14(a) or Rule 15d-14(a) of the Securities Exchange Act of 1934, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

 —
 —
 —

 32.1
 Certification of Principal Executive Officer and Principal Financial Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

 —
 —
 —
 Furnished herewith

 Policy for Recovery of Erroneously Awarded Compensation

 101.INS

 101.SCH
 —
 —
 —

 101.CAL
 —
 —
 —

 101.DEF
 —
 —
 —

 101.LAB
 —
 —
 —

 101.PRE
 —
 —
 —

 —
 —
 —

 ______________
 Portions of this exhibit (indicated by asterisks) have been omitted pursuant to a request for confidential treatment and this exhibit has been submitted separately to the SEC.
 Portions of this exhibit (indicated by asterisks) have been omitted in accordance with the rules of the SEC.
 # Indicates a management contract or any compensatory plan, contract or arrangement.
 * Schedules and exhibits have been omitted pursuant to Item 601(b)(2) of Regulation S-K. The Registrant will furnish copies of any such schedules and exhibits to the SEC upon request.
 ** Exhibits have been omitted pursuant to Item 601(a)(5) of Regulation S-K. The Registrant will furnish copies of any such exhibits to the SEC upon request.

 SIGNATURES
 Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

 By:
 /s/ Andrew Obenshain

 President, Chief Executive Officer and Director

 Date:

 SIGNATURES AND POWER OF ATTORNEY
 We, the undersigned directors and officers of bluebird bio, Inc. (the "Company"), hereby severally constitute and appoint Andrew Obenshain and O. James Sterling and each of them singly, our true and lawful attorneys, with full power to them, and to each of them singly, to sign for us and in our names in the capacities indicated below, any and all amendments to this Annual Report on Form 10-K, and to file or cause to be filed the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as each of us might or could do in person, and hereby ratifying and confirming all that said attorneys, and each of them, or their substitute or substitutes, shall do or cause to be done by virtue of this Power of Attorney.

 Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.
 Name
 Title
 Date

 /s/ Andrew Obenshain
 President, Chief Executive Officer and Director

 (Principal Executive Officer and Duly Authorized Officer)

 /s/ O. James Sterling

 Chief Financial Officer

 O. James Sterling
 Chief Financial Officer (Principal Financial Officer and Principal Accounting Officer)

 /s/ Mark Vachon

 Mark Vachon

 /s/ John O. Agwunobi, M.D.

 John O. Agwunobi, M.D.

 /s/ Michael Cloonan

 Michael Cloonan

 /s/ Charlotte Jones-Burton, M.D.

 Charlotte Jones-Burton, M.D.

 /s/ Lis Leiderman, M.D.

 Lis Leiderman, M.D.

 /s/ Nick Leschly

 Nick Leschly

 /s/ Richard Paulson

 Richard Paulson

 Najoh Tita-Reid