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, 2023

 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: 001-37465

 le

 Seres Therapeutics, Inc.

 (Exact Name of Registrant as Specified in Its Charter)

 Delaware

 27-4326290

 (State or Other Jurisdiction of
 Incorporation or Organization)

 (IRS Employer
 Identification No.)

 101 Cambridgepark Drive
 Cambridge, Massachusetts

 02140

 (Address of Principal Executive Offices)

 (Zip Code)

 ( 617) 945-9626

 (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, par value $0.001 per share

 MCRB

 The Nasdaq Global Select Market

 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, a smaller reporting company, or an emerging growth company. See the definitions of the "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 the voting and non-voting 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 30, 2023, was $ 463,030,964. Solely for purposes of this disclosure, shares of common stock held by executive officers, directors and certain stockholders of the registrant as of such date have been excluded because such holders may be deemed to be affiliates.

 As of March 1, 2024 there were 151,009,462 shares of the registrant's common stock, par value $0.001 per share, outstanding.

 DOCUMENTS INCORPORATED BY REFERENCE

 Portions of the registrant's definitive Proxy Statement relating to its 2024 Annual Meeting of Stockholders to be filed with the SEC within 120 days after the end of the fiscal year ended December 31, 2023 are incorporated herein by reference in Part III.

 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 Risk

 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.

 Disclosure 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. We intend such forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. All statements other than statements of historical facts contained in this Annual Report on Form 10-K, including without limitation statements regarding our future results of operations and financial position, business strategy, prospective products, product approvals, research and development costs, timing and likelihood of success, manufacturing activities and related timing, expected benefits of our restructuring initiative and cost saving measures, commercialization efforts and related timing, our ability to continue as a going concern, plans and objectives of management for future operations and future results of anticipated products, are forward-looking statements. These statements involve known and unknown risks, uncertainties and other important 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 the forward-looking statements.

 In some cases, you can identify forward-looking statements by terms such as "may," "will," "should," "expect," "plan," "anticipate," "could," "intend," "target," "project," "contemplate," "believe," "estimate," "predict," "potential" or "continue" or the negative of these terms or other similar expressions. The forward-looking statements in this Annual Report on Form 10-K are only predictions. We have based these forward-looking statements largely on our current expectations and projections about future events and financial trends that we believe may affect our business, financial condition and results of operations. These forward-looking statements speak only as of the date of this report and are subject to a number of important factors that could cause actual results to differ materially from those in the forward-looking statements, including the risks, uncertainties and assumptions described under the sections in this report titled "Summary Risk Factors," "Risk Factors" and "Management's Discussion and Analysis of Financial Condition and Results of Operations" and elsewhere in this Annual Report on Form 10-K.

 Moreover, we operate in an evolving environment. New risk factors and uncertainties may emerge from time to time, and it is not possible for management to predict all risk factors and uncertainties.

 You should read this Annual Report on Form 10-K and the documents that we reference in this Annual Report on Form 10-K completely and with the understanding that our actual future results may be materially different from what we expect. We qualify all of our forward-looking statements by these cautionary statements. Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise.

 TRADEMARKS, SERVICE MARKS AND TRADENAMES

 We have proprietary rights to trademarks used in this Annual Report on Form 10-K, which are important to our business and many of which are registered under applicable intellectual property laws. Solely for convenience, the trademarks, service marks, logos and trade names referred to in this Annual Report on Form 10-K are without the and ™ symbols, but such references are not intended to indicate, in any way, that we will not assert, to the fullest extent under applicable law, our rights to these trademarks, service marks and trade names. This Annual Report on Form 10-K contains additional trademarks, service marks and trade names of others, which are the property of their respective owners. All trademarks, service marks and trade names appearing in this Annual Report on Form 10-K are, to our knowledge, the property of their respective owners. We do not intend our use or display of other companies' trademarks, service marks, copyrights or trade names to imply a relationship with, or endorsement or sponsorship of us by, any other companies.

 SUMMARY RISK FACTORS

 Our business is subject to numerous risks and uncertainties, including those described in Part I, Item 1A. "Risk Factors" in this Annual Report on Form 10-K. You should carefully consider these risks and uncertainties when investing in our common stock. The principal risks and uncertainties affecting our business include the following:

 • We may be unable to realize the expected benefits from our restructuring and other cost reduction efforts.

 • We are a commercial-stage company and have incurred significant losses since our inception. We expect to incur losses for the foreseeable future and may never achieve or maintain profitability.

 • We have identified conditions and events that raise substantial doubt regarding our ability to continue as a going concern.

 • We will need additional funding in order to complete development of our product candidates and commercialize VOWST and our product candidates, if approved. If we are unable to raise capital when needed, we could be forced to delay, reduce or eliminate our product development programs or commercialization efforts.

 • We depend heavily on the commercial success of VOWST, which was only recently approved for marketing by the FDA and launched in the United States. There is no assurance that our commercialization efforts or those of our collaborators will be successful or that we will be able to generate collaboration profit at the levels or within the timing we expect.

 • Our limited operating history may make it difficult to evaluate the success of our business to date and to assess our future viability.

 • Other than VOWST, we are early in our development efforts of our product candidates and may not be successful in our efforts to use our microbiome therapeutics platform to build a pipeline of product candidates and develop additional marketable drugs.

 • VOWST and our product candidates are based on microbiome therapeutics, which is a novel approach to therapeutic intervention.

 • Clinical drug development involves a risky, 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 product candidates.

 • Delays or difficulties in the enrollment of patients in clinical trials, could result in our receipt of necessary regulatory approvals being delayed or prevented.

 • If we are not able to obtain, or if there are delays in obtaining, required regulatory approvals, we or our collaborators will not be able to commercialize our product candidates or will not be able to do so as soon as anticipated, and our ability to generate revenue will be materially impaired. Additionally, failure to obtain marketing approval in international jurisdictions would prevent our product candidates from being marketed abroad.

 • The collaboration and license agreements with Soci t des Produits Nestl S.A., successor in interest to Nestec Ltd., and NHSc Rx License GmbH, successor in interest to NHSc Pharma Partners (collectively, and together with their affiliates and subsidiaries, Nestl) are important to our business. If we or Nestl fail to adequately perform under these agreements, or if we or Nestl terminate the agreements, the development and commercialization of our CDI and IBD product candidates could be delayed or terminated and our business would be adversely affected.

 • We rely, and expect to continue to rely, on third parties to conduct our clinical trials, and those third parties may not perform satisfactorily, including failing to meet deadlines for the completion of such trials.

 • We rely on third parties for certain aspects of the manufacture of our product and product candidates and expect to continue to do so for the foreseeable future. This reliance on third parties increases the risk that we will not have sufficient quantities of our product and product candidates or that such quantities may not be available at an acceptable cost, which could delay, prevent or impair our development or commercialization efforts.

 • Even though VOWST has received FDA approval and even if any of our product candidates receive marketing approval, VOWST and such product candidates may fail to achieve the degree of market acceptance by physicians, patients, hospitals, third-party payors and others in the medical community necessary for commercial success.

 • We face substantial competition, which may result in others discovering, developing or commercializing competing products before or more successfully than we do.

 • If we are unable to adequately protect our proprietary technology or obtain and maintain issued patents that are sufficient to protect our product or product candidates, others could compete against us more directly, which would have a material adverse impact on our business, results of operations, financial condition and prospects.

 • Our future success depends on our ability to retain key executives and to attract, retain and motivate qualified personnel.

 Item 1. Business

 Overview

 We are a commercial-stage microbiome therapeutics company focused on the development and commercialization of a novel class of biological drugs, which are designed to treat disease by modulating the microbiome to restore health by repairing the function of a disrupted microbiome to a non-disease state. Our first drug, VOWST™ (fecal microbiota spores, live-brpk), formerly called SER-109, was approved by the U.S. Food and Drug Administration, or FDA, on April 26, 2023, to prevent recurrence of Clostridioides difficile infection, or CDI, in patients 18 or older following antibacterial treatment for recurrent CDI. Our drug discovery and development pipeline includes other pre-clinical and clinical-stage assets. VOWST and our microbiome therapeutic candidates are consortia of bacteria designed to optimize specific, targeted pharmacological properties, and are formulated for oral delivery. We maintain a differentiated microbiome therapeutics drug discovery and development platform that includes good manufacturing practices, or GMP, manufacturing capabilities for this novel drug modality.

 Our highest priority is the commercialization of VOWST in the United States, the first orally administered microbiome therapeutic approved by the FDA. We launched VOWST in the United States with our collaborator, Nestl Health Science, or Nestl, in June 2023.

 We are also designing microbiome therapeutics optimized to decolonize pathogens and to modulate host function to both reduce and prevent infections and induce immune tolerance. We believe that the scientific and clinical data from our SER-109 program validate this novel approach, which we refer to as Infection Protection. We believe the Infection Protection approach may be replicable across different bacterial pathogens to develop microbiome therapeutics with the potential to protect a range of medically compromised patients from infections, including pathogens that harbor antimicrobial resistance, or AMR.

 In addition, we are evaluating SER-155 in a Phase 1b study in patients undergoing allogeneic hematopoietic stem cell transplantation, or allo-HSCT, to prevent enteric-derived infections and resulting blood stream infections, as well as induce immune tolerance responses to reduce the incidence of graft-versus-host disease, or GvHD. In May 2023, we announced the Phase 1b cohort 1 results. Gastrointestinal microbiome data from the first 100 days of SER-155 Phase 1b open-label study cohort 1 showed the successful engraftment of SER-155 bacterial strains, and a substantial reduction in the cumulative incidence of pathogen domination as compared to a reference cohort of patients, a biomarker associated with the risk of serious enteric infections and resulting bloodstream infections, as well as GvHD in this patient population. The tolerability profile observed was favorable, with no serious adverse events attributed to SER-155 administration. In December 2023, we received Fast Track Designation for SER-155 to reduce the risk of infection and GvHD in patients undergoing allo-HSCT. Enrollment in the placebo-controlled cohort 2 portion of the study is ongoing, and the cohort 2 data readout is anticipated in the third quarter of 2024.

 We have progressed additional preclinical stage programs to evaluate whether microbiome therapeutics may reduce the incidence of infection in indications such as chronic liver disease, cancer neutropenia, solid organ transplant, and AMR infections more broadly in high-risk settings such as intensive care units. Additional efforts in the early-stage portfolio are focused on the SER-301 program in irritable bowel disease, or IBD, and programmatic objectives that are supported through a partnership with the Crohn's and Colitis Foundation, or CCF. These efforts aim to (i) confirm the functional phenotype and inflammatory state of patient subpopulations observed in our prior ulcerative colitis, or UC, clinical trials, and (ii) prioritize inflammatory targets and evaluate the potential to utilize biomarker-based patient selection and stratification for future studies. In addition, we continue to leverage microbiome pharmacokinetic and pharmacodynamic data from across our clinical and preclinical portfolios, using our reverse translational microbiome therapeutic development platform to prioritize future drug targets and to identify opportunities for combination therapies across various indications, including inflammatory and immune diseases, cancer, and metabolic diseases.

 We have built and deploy a reverse translational platform and knowledge base for the discovery and development of microbiome therapeutics, and maintain extensive proprietary know-how that may be used to support future research and development efforts. This platform incorporates high-resolution analysis of human clinical data to identify microbiome biomarkers associated with disease and non-disease states; preclinical screening using human cell-based assays and in vitro/ex vivo and in vivo disease models customized for microbiome therapeutics; and microbiological capabilities and a strain library that spans broad biological and functional breadth. This platform and knowledge base enables both identification of specific microbes and microbial metabolites/peptides that are associated with disease and the design of therapeutic consortia of bacteria optimized for specific pharmacological properties. In addition, we own a valuable intellectual property estate related to the development and manufacture of microbiome therapeutics.

 In November 2023, we announced a restructuring plan, or the Restructuring Plan, to prioritize the commercialization of VOWST and the completion of the SER-155 Phase 1b study, while reducing costs and supporting longer-term business sustainability. The Restructuring Plan included (i) a reduction of our workforce by approximately 41% across the organization, resulting in the elimination of approximately 160 positions; (ii) significantly scaling back all non-partnered research and development activities other than the completion of the SER-155 Phase 1b study; and (iii) reducing general and administrative expenses, including consolidating office space. The Restructuring Plan was substantially implemented around the end of fiscal 2023. In connection with the Restructuring Plan, for the year ended December 31, 2023, we incurred approximately $5.6 million in restructuring costs, primarily related to the workforce reduction, of which $5.3 million are expected to result in cash expenditures, and the remaining $0.3 million relates to stock-based compensation expense associated with the acceleration of unvested equity awards. These costs were incurred in the fourth quarter of 2023. See Note 13, Restructuring, to our audited consolidated financial statements included elsewhere in this Annual Report. We expect to achieve annual cash savings of approximately $75.0 million to $85.0 million in 2024, of which approximately $35.0 million is expected to result from the reduction in workforce, and which excludes any one-time charges primarily associated with the workforce reduction.

 We have assembled a world class group of scientists, clinicians, directors and investors, who have established our leadership in the field of microbiome therapeutics. We were co-founded by Drs. Noubar Afeyan, David Berry and Geoffrey von Maltzahn of Flagship Pioneering. Through Flagship Pioneering's contribution of foundational scientific concepts and intellectual property, assembly of our management team and critical early-stage support, we launched as the first company focused on the ecological nature of the microbiome. Led by Eric Shaff, our President and Chief Executive Officer, our experienced management team possesses core capabilities and know-how in microbiome therapeutics, drug development, commercialization, chemistry, manufacturing and controls, or CMC, public company management and finance.

 Our Strategy

 Our goal is to remain the leading biopharmaceutical company developing and commercializing microbiome therapeutics to address significant unmet medical needs. We intend to focus in the near term on the commercialization of VOWST in the United States and the completion of the SER-155 Phase 1b study. Additionally, we continue to advance our differentiated microbiome drug discovery, development and manufacturing platforms and capabilities.

 Advancing our Programs

 • Supporting the commercialization of VOWST in the United States. VOWST was approved by the FDA in April 2023 and is the first and only orally administered microbiome therapeutic to prevent the recurrence of CDI in patients 18 or older following antibacterial treatment for recurrent CDI. In close collaboration with Nestl, we have scaled our healthcare provider education efforts, worked to create a positive customer experience with faster and higher conversion of enrollments to new patient starts, and continued to establish payer coverage. Since the FDA approval of VOWST, Nestl commercial customer facing field teams have been promoting VOWST and generating healthcare provider demand, including significant presence at both IDWeek and the American College of Gastroenterology, or ACG, meetings in October 2023. Nestl 's 170 field sales representatives promoting VOWST are divided into two teams, comprised of 150 gastroenterology representatives and 20 hospital/infectious disease representatives. In addition, the production of VOWST commercial supply enabled a strong commercial launch within weeks of FDA approval and we continue to make progress expanding commercial-scale production of VOWST to prepare for anticipated future market demand.

 • Completing the SER-155 Phase 1b study and maximizing the opportunity in Infection Protection. We believe that the scientific and clinical data from our SER-109 program validate our Infection Protection approach of using microbiome therapeutics to decolonize pathogens and modulate host function to reduce and prevent infections. Infection Protection may be replicable across different bacterial pathogens to develop microbiome therapeutics with the potential to protect a range of medically compromised patients from infections. We are evaluating SER-155 in a Phase 1b study in patients receiving allo-HSCT in an effort to reduce incidences of gastrointestinal infections, resulting bloodstream infections and GvHD. In December 2023, we received Fast Track Designation for SER-155 to reduce the risk of infection and GvHD in patients undergoing allo-HSCT. Enrollment in the placebo-controlled cohort 2 portion of the study is ongoing, and the cohort 2 data readout is anticipated in the third quarter of 2024.

 • Advance research and development activities supported by partnerships. Data from our SER-287 Phase 2b study and the first cohort of subjects from our SER-301 Phase 1b study in patients with mild-to-moderate UC suggest that the pharmacodynamic effects observed for SER-287 and SER-301 were greater in a subset of patients with IBD. Based on these results, we continue to advance research and development activities supported by partnerships to evaluate the potential to utilize biomarker-based patient selection and stratification in future clinical development efforts in IBD. In October 2023, we were awarded a $500,000 grant from the Crohn's & Colitis Foundation to leverage our clinical results and biological mechanism insights to functionally characterize subpopulations and to define associated biomarkers for IBD patient selection and stratification of patients where the gastrointestinal microbiome plays an active role in

 inflammation and could be modified to reduce colitis. Our preclinical studies conducted to date, have recapitulated the patient subpopulation observations from the previously run trials and progressed associated biomarker delineation.

 Advancing Our Capabilities

 • Leveraging our leading reverse translational microbiome therapeutics platform to develop additional innovative and novel microbiome therapeutics across a range of serious medical conditions with high unmet need including infectious and inflammatory disease and disease associated with modulation of host immunity. We believe that the combination of experience, proprietary data and proprietary know-how related to the microbiome, the functional properties of microbial species and strains, microbe-host interactions, the cultivation of microbial strains, and microbiome-specific functional screens and analytics provides us a competitive advantage in the design and development of microbiome therapeutics. Our platform enables us to build upon our existing and growing clinical experience to rationally design treatments for acute and complex chronic diseases. We intend to leverage this advantage to develop additional innovative microbiome therapeutics.

 • Developing manufacturing capabilities sufficient to support commercialization of any approved microbiome therapeutic candidates. Microbiome therapeutic manufacturing requires capabilities that are distinct from other biologic drugs. We have made strategic investments in manufacturing capabilities to help ensure that we maintain control of our know-how and also because we believe these capabilities will be necessary and highly advantageous for the development of future microbiome therapeutic candidates. Our bioprocess and manufacturing personnel are focused on creating a platform of manufacturing expertise that will set the stage for further advances in the emerging field of microbiome therapeutics.

 Our Microbiome Therapeutics Platform

 We have developed the leading reverse translational microbiome therapeutics platform and knowledge base which we believe enables us to apply our capabilities to efficiently identify, manufacture and develop novel microbiome therapeutics for serious human diseases. We use a reverse translational discovery platform that incorporates analysis of microbiome biomarkers from human clinical data and preclinical assessments using human cell-based assays and in vitro/ex vivo and in vivo disease models. Specifically, we start with data sets from healthy subjects and subjects with disease, or being treated for a disease, to delineate at high-resolution the profile of the microbiome (composition and function) and the physiological state of subjects to identify specific microbiome and host signatures that associate with disease or the onset of disease. These in-human insights on how different microbe species and strains and microbe-associated metabolites, genes, or peptides are associated with disease along with how these microbes and metabolites directly or indirectly modulate disease-relevant functional pathways in the host are leveraged in preclinical drug design and development.

 Our discovery process begins with human data derived from clinical trials and cohort studies, which we use as a basis for target identification and the design of our microbiome therapeutic candidates. We compare healthy, normal colonic microbiomes to those in an unhealthy disrupted or disease state, revealing the ecological, compositional and functional differences between various states of disease and during the transition from health to disease or vice versa. Specifically, we utilize clinical data sets combined with advanced data sciences and microbiome analytics to identify microbiome signatures of disease at the resolution of specific species and strains, metabolites, or genes that are associated with disease states. These microbiome biomarkers are associated with host signatures and biomarkers of disease to identify drug targets for our microbiome therapeutics. Our clinical data from the VOWST (developed as SER-109), SER-301, and SER-155 programs, and microbiome data generated with external collaborators, serve to instruct us on how the introduction of certain keystone microbes have the potential to restructure the microbiome and modulate the metabolic state of the gut to shift it to a non-disease state.

 We have developed a proprietary functionally characterized strain library and a suite of assays and screens, bioinformatics and computational tools, and databases, which facilitate our insights into the human microbiome. We have established proprietary, curated, reference databases and algorithms that: (i) integrate high-resolution genomic, metagenomic, metabolomic, and transcriptomic data sets, and data from in vitro and human cell-based assays, and in vitro/ex vivo and in vivo disease models, and (ii) enable us to track changes in the microbiome at the level of microbial species and individual strains and associate these changes with changes in the metabolic state of the gut and host physiology. Our analytics can integrate gene profiling and metabolomics data (the small molecules made by the microbiome) with genomic data (the collection of microbes defined by sequencing) to delineate microbiome biomarkers (the specific species or strains and functional pathways) that contribute to the state of disease or health. Further, we have established de novo analytics for pharmacokinetic and pharmacodynamic assessments of microbiome therapeutics. Additionally, leveraging all of these data we have curated and continue to build a database that links and associates: (i) functional properties of microbial species/strains, (ii) functional pathways in hosts that can be modulated by the microbiome, (iii) the association of functional pathways to disease, and (iv) the association of existing non-microbiome drugs to the functional pathways. This continually growing database can be mined to inform drug design and disease area and patient population prioritization.

 Our proprietary strain library of bacterial isolates from healthy donors and patients enables us to translate microbiome biomarker insights into defined consortia of bacteria. The strain library contains bacterial species isolated from individuals that are either healthy or that have a disease. We have developed extensive isolation and cultivation know-how. The strain library contains a majority of the Human Microbiome Project's "most wanted" and many novel species we do not believe are described in other databases or the scientific literature. The functional properties of strains are characterized using proprietary in vitro and ex vivo human cell-based assays as well as full-genome sequences and genome functional annotation. Functional characterization of target strains includes properties such as how the bacteria interact with human colonic epithelial cells and human immune cells. We also seek to understand how these microbes improve the health of barrier cells in the gut and how they may impact immune responses.

 We select bacteria from our library with specific predicted properties using novel algorithms for in silico functional design and optimization and grow the compositions in the lab to be tested both in vitro/ex vivo models as delineated above and in in vivo animal models. Our animal models include conventional mice, germ-free mice, and "humanized avatar" mice that possess only bacteria derived from humans; these models were developed to minimize confounding variables presented by model organism microbes. Data from our in vitro/ex vivo and in vivo screens are analyzed and used to optimize compositional designs; introducing new bacterial strains and optimizing existing strains until we identify a lead composition with the desired profile and that is suitable for clinical testing.

 Finally, we manufacture the bacterial composition under current Good Manufacturing Practices, or cGMP, or similar foreign requirements, which are required by FDA and European regulators. We believe our unique manufacturing capacities position us to exploit the insights of our proprietary human data and the novel biology of species and strains that have not previously been used for therapeutics. We have optimized fermentation conditions to generate spores and enhance bacterial yields in anaerobic fermentation and have in-house capabilities to formulate both spores and live non-spore bacteria. Our manufacturing facility in Cambridge, Massachusetts was designed to be fit-for-purpose and is highly differentiated compared to the offerings of commercial contract research organizations. We have secured additional capacity, designed to our specifications, via contract manufacturing organizations, or CMOs, to ensure adequate supply for VOWST and other potential commercial products. We addressed quality control requirements for VOWST using proprietary microbiological assays to assess the identity, potency, and purity of the final product.

 Taken together, we believe our platform, spanning drug discovery, preclinical translation, and novel manufacturing and quality control approaches, has enabled a field leading pipeline across a range of therapeutics areas.

 Disease Overview and Our Product Pipeline

 We believe our microbiome therapeutic product and product candidates represent a novel approach with potential application across a broad range of human diseases. Our first drug, VOWST, was approved by the FDA on April 26, 2023, to prevent recurrence of CDI in patients 18 or older following antibacterial treatment for recurrent CDI. VOWST is the first orally administered microbiome therapeutic approved by the FDA. We launched VOWST in the United States with our collaborator, Nestl, in June 2023. Building upon VOWST, we are developing novel microbiome therapeutics, such as SER-155, to specifically target infections and antimicrobial resistance. We are evaluating SER-155 in a Phase 1b study in allo-HSCT recipients in an effort to reduce incidences of gastrointestinal infections, resulting bloodstream infections and GvHD. SER-155, an oral microbiome therapeutic candidate consisting of a consortium of cultivated bacteria, is designed to prevent enteric-derived infections and resulting blood stream infections, as well as induce immune tolerance responses to reduce the incidence of GvHD in patients undergoing allo-HSCT. In December 2023, we received Fast Track Designation for SER-155 to reduce the risk of infection and GvHD in patients undergoing allo-HSCT. Enrollment in the placebo-controlled cohort 2 portion of the study is ongoing, and the cohort 2 data readout is anticipated in the third quarter of 2024.

 We have progressed additional preclinical stage programs to evaluate whether microbiome therapeutics may reduce the incidence of infection in indications such as chronic liver disease, cancer neutropenia, solid organ transplant, and AMR infections more broadly in high-risk settings such as intensive care units. Additional efforts in the early-stage portfolio are focused on the SER-301 program in IBD and programmatic objectives that are supported through a partnership with CCF. These efforts aim to leverage our clinical results and biological mechanism insights to functionally characterize patient subpopulations and to define associated biomarkers for IBD patient selection and stratification of patients where the gastrointestinal microbiome plays an active role in inflammation and could be modified to reduce colitis. In addition, we continue to leverage microbiome pharmacokinetic and pharmacodynamic data from across our clinical and preclinical portfolios, using our reverse translational microbiome therapeutic development platform to prioritize future drug targets and opportunities for combination therapies across various indications, including inflammatory and immune diseases, cancer, and metabolic diseases.

 CDI Overview and VOWST

 Clostridioides difficile Infection

 C. difficile is a Gram-positive, toxin-producing, spore forming bacterium that may cause debilitating diarrhea in infected individuals, but can also lead to more severe outcomes, such as inflammation of the colon, or colitis, toxic megacolon and death. C. difficile bacteria express toxins that disrupt the structural architecture of cells causing leakage of fluids through the gastrointestinal, or

 GI, epithelium. The cells disrupted by these toxins eventually undergo apoptosis and die, disrupting the epithelial barrier and exposing the immune system to inflammatory stimuli, severe and persistent diarrhea and, in the most serious cases, death.

 CDI is most often associated with the prior use of antibiotics, although age and poor immune status are important risk factors as well. Antibiotics are thought to decrease colonization resistance to CDI by disrupting the microbiome. Since C. difficile spores are able to survive for long periods of time outside the body, and because healthcare settings are often sites of significant antibiotic use, CDI is a leading cause of healthcare-associated infections in the United States. CDI is also a cause of morbidity and mortality among hospitalized cancer patients and bone marrow transplant patients as their immune systems are suppressed by cytotoxic drugs, which inhibit or prevent the functioning of cells, and they may be heavily treated with antibiotics to prevent or treat infections. More recently, the rise of community-acquired CDI has been recognized as a growing problem.

 The Centers for Disease Control and Prevention, or CDC, has identified C. difficile as one of the top three most urgent antibiotic-resistant bacterial threats in the United States. It is the most common cause of hospital acquired infection in the United States, having overtaken MRSA. CDI is responsible for the deaths of over 20,000 Americans each year. During 2023, we estimated that there would be approximately 459,000 cases of primary CDI and 156,000 incidences of recurrent CDI within the United States. CDI is also costly to the healthcare system. According to a study published in Clinical Infectious Diseases, the economic burden of CDI in 2008 in U.S. acute care facilities alone was estimated to be as much as $4.8 billion. In addition, the average recurrent CDI treatment cost in the U.S. is estimated to be $34 thousand per patient, comprising mostly (88%) hospital-related costs (Rodrigues Infect Control Hosp Epidemiol 2017). The national incidence of CDI remains high despite declining from 476,000 in 2011 to 462,000 in 2017 (Guh, New England Journal of Medicine 2020). Further, according to a 2014 article in the American Journal of Infection Control, from 2001 to 2010, incidence of CDI per 1,000 patients discharged increased from 4.5 to 8.2 with an average hospital stay of eight days. Due to suboptimal approaches to treatment, patients with primary CDI have an approximate 20% - 25% change of recurrent infection increasing to greater than 40% after the first recurrence (Gerding, CID 2018; Lashner ACG 2020; Dubberke CID 2018).

 Current and developing treatment alternatives and their limitations

 Antibiotics. According to the Infectious Disease Society of America, or IDSA, guidelines, the current standard of care for primary CDI is to treat with antibiotics, such as fidaxomicin or vancomycin. While fidaxomicin is indicated for the treatment of C. difficile-associated diarrhea, it does not have a label claim to reduce or prevent CDI recurrence. No antibiotic therapeutics are currently approved for the prevention of recurrent CDI.

 Prevention of recurrent CDI, defined as the presence of diarrhea and a positive C. difficile stool assay within two to eight weeks following the initial episode, is not well addressed by any of the available antibiotics. The risk of recurrent CDI increases to greater than 40% after the first recurrence. In extreme cases, patients may be treated continuously for years with vancomycin.

 Antibiotics have two major limitations: they have no effect on the spores that germinate in a disrupted microbiome and their use can exacerbate microbiome disruption, resulting in increased risk of future CDI. Research in animal models has shown that antibiotic use not only eliminates many healthy bacteria in the GI tract, but also leads to the release of nutrients that facilitate the growth of C. difficile. Antibiotics have also been shown to change the ratio of primary versus secondary bile acids in the colon by killing bacteria required to metabolize bile acids. This shift to a predominance of primary bile acids further facilitates the growth of C. difficile, as it requires primary bile acids for germination of its spores. As a result, antibiotic use may induce a lasting microbiome disruption that makes it possible for C. difficile to colonize a person and then cause, or further perpetuate, disease.

 Fecal microbiota transplantation. FMT, also known as a stool transplantation, is a procedure during which donated stool, including fecal microbes, is typically instilled via colonoscopy into a patient with recurrent CDI. FMT presents several challenges for effective treatment of the disease. FMT has the potential to transmit infectious or allergenic agents between hosts, involves the transmission of hundreds of unknown strains of bacteria, fungi, viruses and potentially parasites from donor to subject, and is difficult to perform on a mass scale. In November 2019 the FDA held a public hearing to obtain input on the use of FMT to treat CDI not responsive to standard therapies. Presentations were made by the academic community and development companies regarding the current and future use of FMT. In January 2020, we submitted comments to the docket for the meeting that recommended: 1) increased scrutiny and regulation of unapproved, commercially available FMT that does not comply with IND requirements; 2) implementation of guidance for establishing safety of source materials for all microbiome products; and 3) safety and efficacy of all microbiome products to reduce recurrent CDI must be based on adequate and well controlled clinical trials including accurate assurance of diagnosis of the disease state – specifically toxin testing.

 Fecal microbiota therapy. In November 2022, the FDA approved Rebyota, the first fecal microbiota product approved by the FDA, for the prevention of recurrence of CDI in individuals 18 years of age and older following antibiotic treatment for recurrent CDI. Rebyota is administered rectally and is prepared from stool sourced from qualified donors. The stool is tested for a panel of transmissible pathogens. We believe our CMC process is differentiated by additional processes to inactivate and clear potential adventitious agents to help ensure product safety.

 Antibodies. Bezlotoxumab a fully human monoclonal antibody directed against C. difficile toxin B was approved in the United States in October 2016 and in Europe in 2017 for the treatment of CDI. According to Phase 3 studies, the antibody demonstrated 10% absolute risk reduction in preventing recurrence of CDI. Antibodies bind toxins to alleviate the symptoms of CDI, but they do not address the underlying disruption of the microbiome, which we believe is the cause of recurrent CDI. Bezlotoxumab requires intravenous infusion.

 VOWST

 VOWST (developed as SER-109) was approved by the FDA on April 26, 2023, to prevent recurrence of CDI in individuals 18 years of age or older following antibacterial treatment for recurrent CDI. VOWST is the first FDA-approved orally administered microbiome therapeutic, and consists of a consortium of purified Firmicutes spores designed to prevent recurrent CDI in patients with a history of CDI by modulating the microbiome to a state that resists C. difficile germination and growth. The VOWST manufacturing purification process is designed to remove unwanted microbes in an effort to reduce the risk of pathogen transmission beyond donor screening alone. We estimated that there were approximately 156,000 recurrent CDI cases in the United States during 2023.

 Phase 1b/2 clinical study

 The Phase 1b/2 clinical study was an open-label, single arm, descending-dose study that enrolled 30 patients with recurrent CDI. All enrolled patients received standard-of-care antibiotic treatment, followed by oral administration of SER-109. Of the 30 study patients, 26 (87%) achieved the primary endpoint of absence of CDI (defined in this study as more than three unformed bowel movements in a 24-hour period with laboratory confirmation of a positive C. difficile stool test) up to eight weeks following dosing. Three of the four patients who did not meet the primary endpoint were determined by their primary investigator to be recovering from CDI, and all symptoms resolved without further therapeutic intervention or antibiotics. In total, 29 of 30 patients (97%) achieved the clinical cure rate, which we defined as the absence of CDI requiring antibiotic treatment during the eight-week period after SER-109 dosing. SER-109 was well tolerated in the study, with the most common adverse events being mild to moderate gastrointestinal symptoms. No drug related serious adverse events were observed.

 Phase 2 clinical study

 The Phase 2 clinical study was a randomized, double-blinded, placebo-controlled, parallel-group two arm trial that enrolled a total of 89 patients with a history of multiply-recurrent CDI, defined as 3 or more CDI episodes within 9 months. SER-109 was administered orally following the completion of antibiotic treatment for CDI. The predefined study primary efficacy endpoint was the relative risk of CDI recurrence up to 8 weeks after treatment with SER-109 compared to treatment with placebo. CDI recurrence was defined as diarrhea for 2 or more consecutive days, a positive CDI test, and the requirement for antibiotic treatment. Based on 8-week data, CDI recurrence occurred in 44% of subjects (26 of 59) who received SER-109, compared to 53% of subjects (16 of 30) who received placebo. The relative risk of CDI recurrence for the placebo population compared to the SER-109 population was not statistically significant. The most commonly reported AEs in both the SER-109 and placebo arms were in the GI category, and were diarrhea, abdominal pain, flatulence, and nausea. No drug-related SAEs were observed.

 Analysis of Phase 1b/2 and Phase 2 clinical study results

 In our Phase 2 clinical study, the study's primary endpoint of reducing the relative risk of CDI recurrence at up to 8 weeks after treatment was not achieved. In order to understand the difference in outcome between Phase 1b/2 and Phase 2 clinical studies, we conducted an analysis of the available clinical, microbiome and CMC data. We identified key factors that potentially explain the Phase 2 clinical study results, including issues related to both the accurate diagnosis of C. difficile recurrent infection, and potential suboptimal dosing of subjects in the trial.

 The key factors include:

 • The diagnostic test for entry may not have differentiated subjects with active CDI disease from those with other disease but who had C. difficile carriage (e.g., irritable bowel disease);

 • The diagnostic test for CDI recurrence during the study (the primary endpoint) overestimated recurrences, as PCR was the most common test performed;

 • The safety profile of SER-109, which may include diarrhea in the first week following dosing, led to SER-109 subjects presenting for evaluation of recurrence at a time when they were likely to be colonized with C. difficile leading to mistaken diagnosis of recurrent CDI; and

 • The dose and dosing regimen used in the study may not have been optimal in the Phase 2 clinical study based upon an assessment of the microbiome response using whole metagenomics shotgun sequencing.

 From our reanalysis of the phase 1b/2 and 2 trials, we learned that there is a dose-dependent response governing early SER-109 pharmacokinetics, with increased engraftment associated with successful CDI resolution through 8 weeks. In the Phase 2 trial, SER-109 was dosed at 1 108 spores based on equivalent clinical outcomes and week 8 engraftment measures observed between the phase 1 dosing cohorts. However, our integrated analysis of both trials revealed that (1) engraftment kinetics at week 1 were of greater

 importance for reducing rCDI than later time points, (2) week 1 engraftment was highly variable in Phase 2 subjects, and (3) rapid engraftment was dependent on dose, which was clearly suboptimal in the Phase 2 trial (McGovern, 2020; Young, 2020). We hypothesized that rapid engraftment of a microbiome therapeutic may be critical to efficacy since CDI recurrence usually occurs within 1–3 weeks of antibiotic discontinuation, the "window of vulnerability"; consistent with this hypothesis, in the Phase 2 trial, greater engraftment of SER-109 species at week 1 was correlated with reduced CDI rates. This correlation was not previously appreciated due to the use of lower resolution 16S rRNA gene amplicon–based methods used in the Phase 1b/2 study for determining drug engraftment (Khanna, 2016).

 Phase 3 clinical study design

 In the Phase 3 ECOSPOR III clinical study of SER-109, patients with multiply recurrent CDI were randomized 1:1 between SER-109 and placebo. Diagnosis of CDI for both study entry and for endpoint analysis utilized a C. difficile cytotoxin assay, compared to the Phase 2 clinical study, where most patients were diagnosed by PCR. Patients in the SER-109 arm received a total SER-109 dose, administered over three days, approximately 10-fold higher than the dose used in the Phase 2 clinical study to drive rapid engraftment of SER-109 bacteria in treated patients. The study evaluated patients for 24 weeks and the primary endpoint was to compare the C. difficile recurrence rate in subjects who receive SER-109 verses placebo at up to eight weeks after dosing. CDI recurrence is defined as diarrhea (>3 unformed bowel movements/day for 2 or more consecutive days), a positive CDI toxin test, and the decision by the primary investigator that antibiotic treatment is warranted. The study was conducted at approximately 100 sites in the United States and Canada.

 Phase 3 clinical study results

 The study enrolled 182 patients with multiply recurrent CDI. ECOSPOR III data demonstrated that the study achieved its primary endpoint where SER-109 was superior to placebo in reducing CDI recurrence at eight weeks, reflecting a recurrence-free rate of approximately 88% at eight weeks post-treatment. SER-109 resulted in a 27% absolute reduction of recurrence of CDI compared to placebo at eight weeks post-treatment, which is a relative risk reduction of 68%. The rate of recurrence at 12 weeks in the SER-109 arm was 18.0%, compared to a rate of 46.2% in the placebo arm, representing an absolute risk reduction of 28% (relative risk 0.40; 95% CI 0.24-0.65), and thereby consistent with the results seen at eight weeks. The efficacy results remained durable through 24 weeks of follow-up, as SER-109 was observed to significantly reduced recurrence rates compared to placebo over 24 weeks, 21.3% vs. 47.3%, respectively. These data were published in the New England Journal of Medicine in January 2022 and in the Journal of the American Medical Association in October 2022.

 Overall incidence of patients who experienced treatment-emergent adverse events, or TEAEs, was 92.2% for SER-109 and 91.3% for placebo. SER-109 had no serious treatment-related adverse events. The most commonly observed TEAEs were gastrointestinal disorders, the majority of which were mild to moderate in nature.

 The study also examined the pharmacokinetics (i.e., drug bacterial species engraftment) and pharmacodynamics (i.e., metabolic changes) following SER-109 dosing. The data demonstrate that SER-109 administration resulted in the rapid and durable engraftment of SER-109-derived bacterial species into the gastrointestinal tract as soon as one week following dosing, and that this engraftment was maintained at subsequent timepoints evaluated, including at the eight-week timepoint corresponding to the study's primary endpoint and the 24-week safety follow-up timepoint. The presence of SER-109 bacterial species was significantly greater (p<0.001) in SER-109 treated patients than in placebo patients at all timepoints evaluated. Significant differences were maintained in predefined subpopulation analyses of age and antibiotic use. We utilized advanced microbiome biomarker analytics and proprietary genomic reference datasets to identify, at a resolution of bacterial species, the gastrointestinal microbiome signatures associated with SER-109 engraftment.

 SER-109 administration also resulted in modulation of the gastrointestinal metabolic landscape. Notably, data demonstrated a significant decrease in primary bile acids (p=0.038) and an increase in secondary bile acids (p<0.001) by one-week post-dosing; significant differences were maintained through week eight for secondary bile acids. Notably, SER-109 subjects had less variance across subjects in bile acid response than placebo subjects. Observations for both primary and secondary bile acids were maintained in predefined subpopulation analyses of age and antibiotic use. All microbiome analyses were conducted according to the treatment subjects actually received. Published research as well as preclinical studies have demonstrated that primary bile acids support germination of C. difficile spores that are the source of disease recurrence. In contrast, secondary bile acids have been reported to inhibit germination and the growth of C. difficile (Theriot and Young, Annu. Rev. Microbiol. 2015).

 ECOSPOR IV was an open-label single-arm study evaluating SER-109 in 263 adult subjects with recurrent CDI. The safety results observed in ECOSPOR IV through 24 weeks showed that SER-109 was well tolerated, consistent with the safety profile observed in the prior completed Phase 3 study, ECOSPOR III. The ECOSPOR IV study results contributed to the SER-109 safety database and supported product approval. These data were published in the JAMA Network Open in February 2023.

 Sales and Marketing

 In July 2021, we entered into an agreement with NHSc Pharma Partners, succeeded by NHSc Rx License GmbH, or, together with Soci t des Produits Nestl S.A, Nestl, to jointly commercialize VOWST in the United States and Canada. Under the terms of

 the agreement, Nestl assumed the role of lead commercialization party. We received an upfront license payment of $175 million in July 2021 and an additional $125 million in May 2023 following FDA approval of VOWST. The agreement also includes sales target milestones which, if achieved, could total up to $225 million. We were responsible for development and pre-commercialization costs in the United States. Following first commercial sale of VOWST, which occurred on June 2, 2023, we are entitled to share equally in its commercial profits and losses.

 During the year ended December 31, 2023, Nestl reported 1,284 VOWST units sold and $19.6 million in net sales, reflecting an estimated gross-to-net reduction of 13%, primarily due to returns reserve, prompt payment discounts, statutory discounts and rebates, and commercial rebates. The total collaboration loss for the year ended December 31, 2023 was $37.7 million. We record our 50% share of the collaboration loss, which includes commercial and medical affairs expenses incurred by us, on a net basis. Accordingly for the year ended December 31, 2023, our share of the VOWST net loss was $18.9 million.

 As part of the commercialization of VOWST, we are closely monitoring the launch and focusing on a number of quantitative metrics. VOWST became commercially available in early June 2023. Broad demand for VOWST has been observed across both recurrent patients and healthcare providers since June 2023 (metrics noted below are based on data provided by Nestl through December 31, 2023):

 • Fourth quarter completed prescription enrollment forms received for VOWST were 1,322; of those 1,082 resulted in new patient starts by year-end 2023;

 • From launch through year-end 2023, there were 2,833 completed prescription enrollment forms received for VOWST; of those 2,015 resulted in new patient starts by year-end 2023;

 • In 2023, prescription enrollment forms were submitted by approximately 1,330 unique healthcare providers, or HCPs, since launch, with approximately 65% from gastroenterology and the remainder from other specialties; approximately 340 HCPs have prescribed VOWST to more than one patient; and

 • VOWST demand has been observed across the recurrent CDI patient pool, including first recurrence, which is the largest recurrent CDI patient segment.

 In close collaboration with Nestl, we have scaled our HCP education efforts, worked to create a positive customer experience with faster and higher conversion of enrollments to new patient starts, and continued to establish payer coverage. Since the FDA approval of VOWST, Nestl commercial customer facing field teams have been promoting VOWST and generating healthcare provider demand, including significant presence at both IDWeek and the American College of Gastroenterology, or ACG, meetings in October 2023. IDWeek and ACG are two of the largest infectious disease and gastroenterology conferences. Nestl 's 170 field sales representatives promoting VOWST are divided into two teams, comprised of 150 gastroenterology representatives and 20 hospital/infectious disease representatives.

 The VOWST Voyage Support Program, or VOWST Voyage, was launched upon VOWST FDA approval to provide treatment and financial support for eligible patients. The VOWST Voyage staff work with healthcare providers and patients to convert patient enrollments into new patient starts and provide a robust high-touch customer experience.

 Nestl 's payer field team continues to engage payers to build coverage, which would enable eligible patients to have access to VOWST as quickly and efficiently as possible. The team has been reinforcing what we believe to be a compelling value proposition for VOWST and is actively engaged with the three largest pharmacy benefit managers. In 2023, payers issued policies for VOWST coverage across plans representing 80% commercial and 54% Medicare Part D covered lives. Approximately 56% of the 1,082 fourth quarter new patient starts are being reimbursed through the patient's drug benefit.

 We are investing in patient financial assistance to increase access to VOWST for patients with affordability challenges due to co-pays or other cost sharing requirements imposed on them by their insurer after the prescription has been approved. We believe that providing this type of patient access early on will contribute to a positive patient and provider experience, thus increasing demand over time. In terms of free drug utilization, we saw approximately 46% of 2023 new patient starts dispensed via our free drug programs, mostly for Medicare patients. We expect utilization of these programs to drop when the benefit design changes contained in the Inflation Reduction Act, which address patient cost sharing requirements in Medicare Part D plans, go into effect in 2025.

 Infection Protection and SER-155

 We believe that the scientific and clinical data from our SER-109 program validate our novel approach of using microbiome therapeutics to decolonize pathogens, with the potential to reduce the rate of infections in medically compromised patients. Data from the SER-109 ECOSPOR III and ECOSPOR IV Phase 3 trial published in the New England Journal of Medicine (Feuerstadt et al., 2022) and Journal of the American Medical Association (Sims et al., 2023) suggest that microbiome therapeutics have the potential to restructure the gut microbiome and shift the gut metabolic landscape. Additional data show that SER-109 rapidly reduced the abundance of bacteria associated with common antibiotic resistance genes, or ARGs, and reduced ARG abundance in the gut (Straub et al., 2023). Collectively, we believe these data suggest the potential for microbiome therapeutics to restore colonization resistance and ultimately to reduce infections and antimicrobial resistance. We believe this Infection Protection approach may be replicable in

 protecting a range of medically compromised patients from infections seeded by the gut microbiome and resulting downstream clinical sequelae. We believe this approach may also enable us to reduce antimicrobial resistant infections, which the World Health Organization declared as a top ten global public health threat facing humanity.

 We are evaluating SER-155 in a Phase 1b study in allo-HSCT recipients in an effort to reduce incidences of gastrointestinal infections, resulting bloodstream infections and GvHD. SER-155, an oral microbiome therapeutic candidate consisting of a consortium of cultivated bacteria, is designed to prevent enteric-derived infections and resulting blood stream infections, as well as induce immune tolerance responses to reduce the incidence of GvHD in patients undergoing allo-HSCT. SER-155 was designed using our reverse translational microbiome therapeutics development platform and the rationale for this program is based in part on published clinical evidence from our collaborators at Memorial Sloan Kettering Cancer Center showing that allo-HSCT patients with decreased diversity of commensal microbes and pathogen domination in the gastrointestinal tract were significantly more likely to die due to infection and/or lethal GvHD (Peled et al., 2020). In December 2023, we received Fast Track Designation for SER-155 to reduce the risk of infection and GvHD in patients undergoing allo-HSCT.

 The SER-155 Phase 1b study is designed to include approximately 70 patients in both an open-label (cohort 1) and a randomized, double-blind, placebo-controlled cohort (cohort 2) that will evaluate safety and tolerability before and after HSCT. Additionally, the engraftment of SER-155 bacteria (a measure of pharmacokinetics) and gastrointestinal pathogen domination, as well as the rates of enteric-derived infections and resulting blood stream infections, and GvHD will be evaluated.

 Cohort 1 included 13 subjects who received any dosing of the SER-155 regimen, with 11 of these subjects subsequently receiving an allo-HSCT. Nine subjects had evaluable samples for microbiome data analysis. Gastrointestinal microbiome data from the first 100 days of cohort 1 showed the successful engraftment of SER-155 bacterial strains, and a substantial reduction in the cumulative incidence of pathogen domination as compared to a reference cohort of patients, a biomarker associated with the risk of serious enteric infections and resulting bloodstream infections as well as GvHD. The tolerability profile observed was favorable, with no serious adverse events attributed to SER-155 administration. We believe these initial SER-155 Phase 1b study results provide encouraging evidence to support further development of SER-155 to potentially reduce enteric-derived infections, resulting bloodstream infections, and GvHD in individuals undergoing allo-HSCT for cancers and other serious conditions. Study data from cohort 1 suggest that SER-155 administration results in significantly lower incidence rates of gastrointestinal dominations with pathogens of clinical concern, such as Enterococcaceae, Enterobacteriaceae, Streptococcaceae, and Staphylococcaceae.

 Enrollment of cohort 2 is ongoing, incorporating a randomized, double-blinded placebo-controlled design to further evaluate safety, engraftment, and incidence of gastrointestinal ESKAPE microbiome pathogen domination, as well as the incidence of enteric infections, enteric driven blood stream infections, and GvHD. Cohort 2 subjects are administered either SER-155 or placebo at a 1:1 ratio. The study is being conducted at a number of leading cancer centers across the U.S. The cohort 2 data readout is anticipated in the third quarter of 2024.

 Irritable Bowel Disease and Ulcerative Colitis

 UC, a form of IBD, is a relapsing-remitting chronic inflammatory disorder affecting the mucosal surface of the colon, leading to episodes of bloody diarrhea, urgency and mucosal inflammation (Danese and Fiocchi, 2011), which generally begins in young adulthood and endures for life. The incidence of UC is rising worldwide, and the prevalence of the disease is highest in the United States, Canada, and Europe. In the United States alone, the prevalence of UC is estimated to be 378 per 100,000, or approximately 1.25 million Americans (Lewis et al., 2023). The severity, extent, and duration of disease are also risk factors for developing colon cancer, which occurs at a rate as high as 0.5-1.0% per year, an important complication given the young age at which the disease strikes. Patients with UC also experience increased risk of CDI and primary sclerosing cholangitis, compared to the general population (Dlalal & Allegretti, 2022).

 Currently, patients with UC require life-long therapy. Current medical therapies for the treatment of UC suppress the immune system rather than target reducing the triggers of immune activation and promoting immune tolerance. We believe there remains an unmet need for safer agents with novel non-immunosuppressive mechanisms of action. Moreover, alternative therapy is needed for patients with UC who experience frequent flares, are intolerant to the aminosalicylate class of medication, or where there are safety concerns relating to the use of immunomodulator or steroid therapy.

 Current therapeutic approaches in IBD do not address the potential role of microbiome disruption in causing or aggravating disease in IBD. However, not all patients with IBD present with microbiome disruption; many patients with IBD demonstrate comparable taxonomic and functional microbiome diversity to healthy subjects (Lloyd-Price 2019). Similarly, pre-clinical models have shown that microbiomes from patients with IBD drive variable immune responses, with only a subset of microbiomes resulting in inflammation (Hart et al. 2017; Britton et al. 2019). These data suggest that the microbiome may play a role in a subset of subjects with IBD.

 Data from our SER-287 Phase 2b study and the first cohort of subjects from our SER-301 Phase 1b study in patients with mild-to-moderate UC suggest that the pharmacodynamic effects observed for SER-287 and SER-301 were greater in a subset of patients with IBD. Based on these results, we continue to advance research and development activities supported by partnerships to evaluate

 the potential to utilize biomarker-based patient selection and stratification in future clinical development efforts in IBD. In October 2023, we were awarded a $500,000 grant from the Crohn's & Colitis Foundation, or CCF, to leverage our clinical results and biological mechanism insights to functionally characterize subpopulations and to define associated biomarkers for IBD patient selection and stratification of patients where the gastrointestinal microbiome plays an active role in inflammation and could be modified to reduce colitis. Our preclinical studies conducted to date, have recapitulated the patient subpopulation observations from the previously run trials and progressed associated biomarker delineation.

 Manufacturing

 Donor-derived product candidates

 VOWST is a purified consortium of Firmicutes spores produced through a process of separation and purification from a natural human stool source, obtained from qualified, highly screened donors. The donor raw material is collected in a controlled setting, under a protocol that is designed to ensure that donors meet appropriate qualification criteria.

 We operate two in-house stool donation centers in Irvine, California and Tempe, Arizona. Donors are required to be in good health, and to possess a medical history that minimizes the risk of exposure to and transmission of an infectious disease. Donors are tested for infectious agents and screened for GI and other relevant health factors. We have also established an internal Clinical Laboratory Improvement Amendments, or CLIA, and College of American Pathologists, or CAP, certified medical laboratory to support this screening, including high-throughput automated testing systems. Donors are monitored for health status changes on an ongoing basis throughout the donation period. At periodic intervals, and at the end of the donation period, the qualification assessment is repeated to help ensure the donor has maintained their health status. After successful completion of a periodic or exit screening, donations are released for use in manufacturing.

 We initially process the donor material in our in-house Cambridge manufacturing facility, and then transfer the process intermediate to our partner CMO, GenIbet BioPharmaceuticals, SA, or GenIbet (acquired by Recipharm in February 2022), to further isolate and concentrate VOWST for finishing to the oral capsule dosage form. The manufacturing process includes processes to inactivate and clear potential adventitious agents, to help ensure product safety. The purified drug substance is tested for identity and potency, and subsequently formulated into drug product where it is tested for identity, potency, purity, and pharmaceutical properties. The final drug product oral dosage form is four capsules daily for 3-days. Steps are specifically built into the process to remove and kill non-spore microbes. We have conducted validation studies demonstrating the ability of the process to inactivate and clear any potential extraneous pathogens of concern. We have validated the commercial manufacturing process and successfully completed pre-approval inspections conducted by the FDA. We believe we will be able to produce sufficient commercial supply of VOWST to meet estimated demand in the United States using donations from a modest number of donors.

 Commercial product supply for the initial phase of U.S. commercial launch is being produced at our Cambridge manufacturing facility and further processed at GenIbet. In November 2021, we entered into a collaboration with Bacthera to manufacture VOWST to expand upon our existing capabilities for commercial product supply to meet anticipated demand in later years. Under the terms of the agreement, Bacthera is constructing a dedicated full-scale production suite for us at Bacthera's Microbiome Center of Excellence in Visp, Switzerland, which is substantially complete, and is intended to provide manufacturing services for VOWST. Following final completion of the facility, we will initiate technology transfer and certain process qualification and validation activities prior to commencement of commercial manufacturing.

 Cultivated product candidates

 The production of live bacterial products is highly specialized. Owing to their hardiness and environmental persistence, production of aerobic and anaerobic vegetative bacteria, as well as spore-forming organisms, poses unique considerations for product, personnel, and facility design, operation, quality assurance and quality control. Manufacturing activities with spores are subject to specialized regulations. We expect that a typical commercial fermentation will yield on the order of hundreds or thousands of doses per liter depending on the product and its composition. Additionally, because a given total dose contains multiple strains, the per-strain requirements for production may be even lower. As a result, we believe the relatively high productivity of our manufacturing processes relative to the dose level will enable production scales for both clinical and commercial supply to be modest by traditional industry standards for biologics and vaccine manufacturing.

 We have developed supply chains for producing and testing materials to ensure the availability of future clinical trial supplies. Our development processes are designed to ensure that the raw materials, process technologies and analytical tests we use are scalable and transferable to a cGMP manufacturing environment. These include the following core elements:

 • Fermentation. We are using microscale screening to optimize culture of the bacterial strains of interest in our current and foreseeable fermentation-based product candidates. These screens are designed to identify the fermentation platform that is best-suited for optimization and scale-up of the strains. Small-scale fermentation systems (0.1 L to 50 L) enable the optimization of a wide variety of culture conditions and have been demonstrated to be scalable to larger fermentation processes and enable technology transfer to clinical and final manufacturing sites. We employ platform fermentation processes as starting points for cGMP production processes and develop strain specific processes as required. To develop master cell banks, working cell banks, and bulk drug substance for commercial product, we are using bacterial strains that each originate from a unique research cell bank precursor, so we expect the research cell banks and final drug product should be genetically and physiologically similar.

 • Purification. Similar to fermentation, we believe small-scale purification operations are available for assessing large-scale cGMP manufacturing of live cells, and to quickly assess downstream process yield, quality and robustness. Our products in development are predominantly oral dosage forms containing live bacteria, hence purification is typically less complex than for parenteral biologics such as monoclonal antibodies that must separate highly similar components from the culturing process. Separation of viable microbes from soluble fermentation broth components is typically much simpler by comparison.

 • Formulation. Our microbiome therapeutic candidates are combinations of bacteria and can be administered by a number of methods and by different routes. Where possible, our product formulation development is focused on oral delivery for patient convenience. The primary goal in developing a formulation is to deliver bacteria to the intended location in a condition where they are able to replicate and modulate the microbiome. Formulation development generally uses approved excipients and preservatives with pharmaceutical industry precedent, and will include screening of liquid, solid, and suspension formulations to maximize the opportunity for extended stability with minimal cold-chain requirements. Dosage forms for oral products may be liquid- or powder-filled capsules, tablets, sachets, or liquid containers.

 • Analytical. We are addressing quality control requirements for our microbiome therapeutic candidates using proprietary microbiological, chemical, biochemical, and molecular sequence-based testing schemes. We have available and are further developing quality control, environmental monitoring and in-process analytical tools that can quantitatively measure the composition of spore, vegetative microbe and spore/vegetative combinations, which we believe enable a wide variety of drug products to be manufactured. Throughout the bioprocess and formulation development platform we use and will expand on quantitative analytics to assess the identity, potency and purity of the final product.

 We currently have a 10,000 square foot cGMP manufacturing facility at one of our Cambridge, Massachusetts locations where we conduct cGMP manufacture of therapeutic candidates to support drug substance and drug product for early phase and small-scale clinical supplies and with the ability to perform both drug substance and drug product manufacturing for early and late-phase clinical development and at larger scales of operation. We may establish further manufacturing facilities that will serve late-phase clinical and commercial supply for our product candidates. We may do this by expanding our current facilities, or by purchasing or building additional facilities. We also use contract manufacturing and testing organizations to supplement our internal capacity.

 Material Agreements

 Collaboration and Manufacturing Agreements

 Collaboration and License Agreement with Soci t des Produits Nestl S.A. (Nestl)

 In January 2016, we entered into the Collaboration and License Agreement, or the 2016 License Agreement, with Nestec, Ltd., as succeeded by Soci t des Produits Nestl S.A., or, together with NHSc Pharma Partners, succeeded by NHSc Rx License GmbH, their affiliates, and their subsidiaries, Nestl, for the development and commercialization of certain of our product candidates in development for the treatment and management of CDI and IBD, including UC and Crohn's disease. The 2016 License Agreement will support the development of our portfolio of products for CDI and IBD in markets outside of the United States and Canada, or the 2016 Licensed Territory.

 License Agreement with NHSc Rx License GmbH (Nestl)

 In July 2021, we entered into a License Agreement, or the 2021 License Agreement, with NHSc Pharma Partners, succeeded by NHSc Rx License GmbH, or, together with Soci t des Produits Nestl S.A., their affiliates and their subsidiaries, Nestl. Pursuant to the 2021 License Agreement, we granted to Nestl, under certain of our patent rights and know how, a co-exclusive, sublicensable (under certain circumstances) license to develop, commercialize and conduct medical affairs activities for (i) therapeutic products based on our microbiome technology (including VOWST) that are developed by us or on our behalf for the treatment of CDI and recurrent CDI, as well as any other indications pursued for the products upon mutual agreement of the parties, or the 2021 Field in the United States and Canada, or the 2021 Licensed Territory, and (ii) VOWST and any improvements and modifications thereto developed pursuant to the terms of the 2021 License Agreement, or the 2021 Collaboration Products, for any indications in the 2021 Licensed Territory.

 Long Term Manufacturing Agreement with Bacthera

 In November 2021, we entered into a Long Term Manufacturing Agreement with BacThera AG, or Bacthera, a joint venture between Chr. Hansen and a Lonza Group affiliate, which was amended on December 14, 2022, or the Bacthera Agreement. The Bacthera Agreement governs the general terms under which Bacthera, or one of its affiliates, will (i) construct a dedicated full-scale production suite for us at Bacthera's Microbiome Center of Excellence in Visp, Switzerland, which is substantially complete; and (ii) provide manufacturing services to us for our VOWST product and other products, as agreed to by both parties.

 GenIbet Supply Agreement

 In September 2015, we entered into a Supply Agreement, or the Supply Agreement, with GenIbet BioPharmaceuticals, SA (acquired by Recipharm in February 2022) to provide certain manufacturing and supply services to us for our product candidates for purposes of conducting clinical trials and supporting commercial supply. In March 2023, the term of the Supply Agreement was extended through June 30, 2024.

 Indebtedness

 Loan and Security Agreement with Hercules

 In October 2019, we entered into a loan and security agreement, or the Hercules Loan Agreement, with Hercules Capital, Inc., or Hercules, pursuant to which a term loan facility in an aggregate principal amount of up to $50.0 million, or the Original Credit Facility, was available to us in three tranches, subject to certain terms and conditions. We received the first tranche of $25.0 million upon signing the agreement on October 29, 2019, but did not borrow either of the second two tranches, which were available at different times upon Hercules' approval until June 30, 2021.

 In April 2020, we entered into an amendment to the Hercules Loan Agreement, or the First Amendment, permitting us to enter into a promissory note under the Paycheck Protection Program of the Coronavirus Aid, Relief and Economic Stability Act. In February 2022, we entered into a Second Amendment to the Original Credit Facility (as amended by the First Amendment), or the Hercules Credit Facility, pursuant to which a term loan facility in the amount of $100.0 million became available to us in five tranches including the first tranche of $25.0 million previously drawn under the Original Credit Facility, subject to certain terms and conditions. The Hercules Credit Facility was repaid on the Oaktree Closing Date (as defined below).

 Oaktree Credit Agreement

 On April 27, 2023, or the Oaktree Closing Date, we entered into the Oaktree Credit Agreement, among the Company, the subsidiary guarantors from time to time party thereto, the Oaktree Lenders, and Oaktree Fund Administration, LLC, in its capacity as administrative agent for the Oaktree Lenders (in such capacity, the "Agent"). The Oaktree Credit Agreement establishes a term loan facility of $250.0 million, consisting of (i) $110.0 million, or the Tranche A Loan, funded on the Oaktree Closing Date, (ii) $45.0 million, or the Tranche B Loan, that the Company may borrow subject to certain conditions, (iii) $45.0 million, or the Tranche C Loan, that the Company may borrow subject to certain conditions, and (iv) $50.0 million, or the Tranche D Loan, available in Oaktree's sole discretion. The Tranche B Loan may be drawn by the Company until September 30, 2024, if VOWST net sales for the trailing six consecutive months are at least $35 million and at least 4.5% greater in the calendar quarter prior to the Applicable Funding Date (as defined in the Oaktree Credit Agreement) over the calendar quarter immediately preceding it. The Tranche C Loan may be drawn until September 30, 2025, if VOWST net sales for the trailing 12 consecutive months are at least $120 million and at least 4.5% greater in each of the two calendar quarters prior to the Applicable Funding Date relative, in each case, to the calendar quarter immediately preceding it. The Oaktree Term Loan has a maturity date of April 27, 2029, or the Oaktree Maturity Date. Of the $110.0 million Tranche A Loan advanced by the Lenders at closing, approximately $53.4 million repaid our existing credit facility with Hercules. After deducting other transaction expenses and fees, we received net proceeds of approximately $50.4 million.

 For a further description of our material agreements, see "Management's Discussion and Analysis of Financial Condition and Results of Operations – Liquidity and Capital Resources" in Part II, Item 7 of this Annual Report on Form 10-K.

 Intellectual Property

 We strive to protect the proprietary technology that is important to our business, including seeking and, if granted, maintaining patents intended to cover our product candidates and compositions, their methods of use and processes for their manufacture and any other aspects of inventions that are commercially important to the development of our business. We also utilize regulatory exclusivity as well as trade secrets to protect aspects of our business.

 We plan to continue to expand our intellectual property estate by filing patent applications directed to compositions, methods of treatment, methods of manufacture and methods for patient selection created or identified from our ongoing development of our product candidates. Our success will depend 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 any patents that we may obtain, preserve the confidentiality of our trade secrets and operate without infringing the valid and enforceable patents and proprietary rights of third parties. We also rely on know-how and continuing technological innovation to develop and maintain our proprietary position and, in the future, may rely on or leverage in-licensing opportunities. We seek to obtain domestic and international patent protection, and endeavor to promptly file patent applications for new commercially valuable inventions.

 The patent positions of biopharmaceutical companies like us are generally uncertain and involve complex legal, scientific and factual questions. In addition, the coverage claimed in a patent may be challenged in courts after issuance. Moreover, many jurisdictions permit third parties to challenge issued patents in administrative proceedings, which may result in further narrowing or even cancellation of patent claims. We cannot predict whether the patent applications we are currently pursuing will issue as patents in any particular jurisdiction or at all, whether the claims of any patent applications, should they issue, will cover our product candidates, or whether the claims of any issued patents will provide sufficient protection from competitors or otherwise provide any competitive advantage.

 Because patent applications in the United States and certain other jurisdictions are maintained in secrecy for 18 months or potentially even longer, and because publication of discoveries in the scientific or patent literature often lags behind actual discoveries and patent application filings, we cannot be certain of the priority of inventions covered by pending patent applications. Accordingly, we may not have been the first to invent the subject matter disclosed in some of our patent applications or the first to file patent applications covering such subject matter, and we may have to participate in interference proceedings or derivation proceedings declared by the United States Patent and Trademark Office, or USPTO, to determine priority of invention.

 Our patent portfolio includes issued U.S. patents and patent applications in various stages of prosecution, including ex-U.S. international counterparts. We believe that issued claims will provide protection for our microbiome therapeutic candidates.

 Patent Term

 The base term of a U.S. patent is 20 years from the filing date of the earliest-filed non-provisional, patent application from which the patent claims priority. The term of a U.S. patent can be lengthened by patent term adjustment, which compensates the owner of the patent for administrative delays at the USPTO. In some cases, the term of a U.S. patent is shortened by terminal disclaimer that reduces its term to that of an earlier-expiring patent.

 The term of a U.S. patent may be eligible for patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, referred to as the Hatch-Waxman Act, to account for at least some of the time the drug is under development and regulatory review after the patent is granted. With regard to a drug for which FDA approval is the first permitted marketing of the active ingredient, the Hatch-Waxman Act allows for extension of the term of one U.S. patent that includes at least one claim covering the composition of matter of such an FDA-approved drug, an FDA- approved method of treatment using the drug and/or a method of manufacturing the FDA-approved drug. The extended patent term cannot exceed the shorter of five years beyond the non-extended expiration of the patent or fourteen years from the date of the FDA approval of the drug, and a patent cannot be extended more than once or for more than a single product. During the period of extension, if granted, the scope of exclusivity is limited to the approved product for approved uses. Some foreign jurisdictions, including Europe and Japan, have analogous patent term extension provisions, which allow for extension of the term of a patent that covers a drug approved by the applicable foreign regulatory agency. In the future, if and when our product candidates receive FDA approval, we expect to apply, if appropriate, for patent term extension on patents covering those product candidates, their methods of use and/or methods of manufacture.

 Trade Secrets

 In addition to patents, we rely on trade secrets and know-how to develop and maintain our competitive position. We typically utilize trade secrets to protect aspects of our business. We protect trade secrets and know-how by establishing confidentiality agreements and invention assignment agreements with our employees, consultants, scientific advisors, contractors and collaborators. These agreements provide that all confidential information developed or made known during the course of an individual or entities' relationship with us must be kept confidential during and after the relationship. These agreements also provide that all inventions resulting from work performed for us or relating to our business and conceived or completed during the period of employment or assignment, as applicable, shall be our exclusive property. In addition, we take other appropriate precautions, such as physical and technological security measures, to guard against misappropriation of our proprietary information by third parties.

 Competition

 The development and commercialization of new drug and biologic products is highly competitive and is characterized by rapid and substantial technological development and product innovations. We face competition with respect to VOWST and our current product candidates and will face competition with respect to any product candidates that we may seek to develop or commercialize in the future from major pharmaceutical companies, specialty pharmaceutical companies and biotechnology companies worldwide. We are aware of a number of large pharmaceutical and biotechnology companies, as well as smaller, early-stage companies, that are pursuing the development of products, including microbiome therapeutics, and disease indications we are targeting. Potential competitors also include academic institutions, government agencies and other public and private research organizations that conduct research, seek patent protection and establish collaborative arrangements for research, development, manufacturing and commercialization.

 Many of the companies against which we are competing or against which we may compete in the future have significantly greater financial resources, established presence in the market and expertise in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approvals and marketing approved products than we do. Mergers and acquisitions in the pharmaceutical and biotechnology industries may result in even more resources being concentrated among a smaller number of our competitors.

 These third parties compete with us in recruiting and retaining qualified scientific, clinical, manufacturing sales and marketing and management personnel, establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs.

 The key competitive factors affecting the success of VOWST and the product candidates that we develop, if approved, are likely to be their efficacy, safety, convenience, price, the level of competition and the availability of reimbursement from government and other third-party payors.

 Our commercial opportunity could be reduced or eliminated if our competitors develop and commercialize products that are more effective, have fewer or less severe side effects, are more convenient or are less expensive than any products that we may develop. Our competitors also may obtain FDA or other regulatory approval for their products more rapidly than we may obtain approval for ours, which could result in our competitors establishing a strong market position before we are able to enter the market, especially for any competitor developing a microbiome therapeutic which will likely share our same regulatory approval requirements. In addition, our ability to compete may be affected in many cases by insurers or other third-party payors seeking to encourage the use of lower cost products.

 Government Regulation

 The FDA and other regulatory authorities at federal, state and local levels, as well as in foreign countries, extensively regulate, among other things, the research, development, testing, manufacture, quality control, import, export, safety, effectiveness, labeling, packaging, storage, distribution, record keeping, approval, advertising, promotion, marketing, post-approval monitoring and post-approval reporting of drugs and biologics such as those we are developing. We, along with our contract manufacturers, will be required to navigate the various preclinical, clinical and commercial approval requirements of the governing regulatory authorities of the countries in which we wish to conduct studies or seek approval for our product candidates. The process of obtaining regulatory approvals and ensuring subsequent compliance with appropriate federal, state, local and foreign statutes and regulations requires the expenditure of substantial time and financial resources.

 In the United States, the FDA regulates drug and biologic products under the Federal Food, Drug and Cosmetic Act, its implementing regulations and other laws, including, in the case of biologics, the Public Health Service Act. Our product candidates are subject to regulation by the FDA as biologics. Biologics require the submission of a BLA and approval by the FDA before being marketed in the United States.

 The process required by the FDA before our biologic product candidates may be marketed in the United States generally involves the following:

 • completion of preclinical laboratory tests and animal studies performed in accordance with the FDA's good laboratory practice, or GLP, regulations;

 • submission to the FDA of an IND, which must become effective before clinical trials in the United States may begin;

 • approval by an institutional review board, or IRB, or ethics committee at each clinical site before a trial is commenced;

 • performance of adequate and well-controlled human clinical trials to establish the safety, purity and potency of the product candidate for each proposed indication, conducted in accordance with the FDA's good clinical practice, or GCP, regulations;

 • preparation and submission to the FDA of a BLA after completion of all pivotal trials;

 • satisfactory completion of an FDA Advisory Committee review, if applicable;

 • determination by the FDA within 60 days of its receipt of a BLA to file the application for review;

 • satisfactory completion of an FDA inspection of the manufacturing facility or facilities at which the product is produced to assess compliance with cGMP regulations, and to assure that the facilities, methods and controls are adequate to preserve the biological product's continued safety, purity and potency, and potential inspection of selected clinical investigation sites to assess compliance with GCPs; and

 • FDA review and approval of the BLA prior to any commercial marketing, sale or shipment of the product.

 Preclinical and Clinical Trials

 Once a product candidate is identified for development, it enters the preclinical testing stage. Preclinical studies include laboratory evaluations of drug chemistry, formulation and stability, as well as studies to evaluate toxicity in animals, certain of which must be conducted in accordance with GLP requirements. The results of the preclinical studies, together with manufacturing information and analytical data, are submitted to the FDA as part of an IND. An IND is a request for authorization from the FDA to administer an investigational drug to humans. An IND must become effective before human clinical trials may begin. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA, within the 30-day time period, raises concerns or questions about the conduct of the clinical trial, including concerns that human research subjects will be exposed to unreasonable health risks. In such a case, the IND sponsor and the FDA must resolve any outstanding concerns before the clinical trial can begin. Submission of an IND may result in the FDA not allowing clinical trials to commence or not allowing clinical trials to commence on the terms originally specified in the IND. A separate submission to an existing IND must also be made for each successive clinical trial conducted during product development, and the FDA allows the trial to proceed, either explicitly or implicitly by not objecting, before each clinical trial can begin.

 Clinical trials involve the administration of the product candidate to human subjects under the supervision of qualified investigators in accordance with GCPs, which include among other things, the requirement that all research subjects provide their informed consent for their participation in any clinical study. Clinical trials are conducted under protocols detailing, among other things, the objectives of the clinical trial and the parameters and criteria to be used in monitoring safety and evaluating effectiveness. Each protocol must be submitted to the FDA as part of the IND. While the IND is active, progress reports summarizing the results of the clinical trials and nonclinical studies performed since the last progress report, among other information, must be submitted at least annually to the FDA, and written IND safety reports must be submitted to the FDA and investigators for serious and unexpected suspected adverse events, findings from other studies suggesting a significant risk to humans exposed to the drug, findings from animal or in vitro testing suggesting a significant risk to humans exposed to the drug, and any clinically important increased rate of a serious suspected adverse reaction compared to that listed in the protocol or investigator brochure.

 An independent institutional review board, or IRB, for each investigator site proposing to participate in a clinical trial must also review and approve the clinical trial before it can begin at that site, and the IRB must monitor the clinical trial until it is completed. Some studies also include oversight by an independent group of qualified experts organized by the clinical study sponsor, known as a data safety monitoring board, which provides authorization for whether or not a study may move forward at designated check points based on access to certain data from the study and may halt the clinical trial if it determines that there is an unacceptable safety risk for subjects or other grounds, such as no demonstration of efficacy. The FDA, the IRB, or the sponsor may suspend or discontinue a clinical trial at any time on various grounds, including a finding that the subjects are being exposed to an unacceptable health risk. There are also requirements governing the reporting of ongoing clinical studies and clinical study results to public registries.

 For purposes of BLA approval, clinical trials are typically conducted in three sequential phases, which may overlap or be combined.

 • Phase 1 — The investigational product is initially introduced into healthy human subjects or patients with the target disease or condition. These studies are typically designed to test 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 investigational product is typically administered to a limited patient population with a specified disease or condition to evaluate the preliminary efficacy, optimal dosages and dosing schedule and to identify possible adverse side effects and safety risks.

 • Phase 3 — The investigational 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 multiple geographically dispersed clinical trial sites. These clinical trials are intended to establish the overall risk/benefit ratio of the investigational product and to provide an adequate basis for product labeling.

 In some cases, the FDA may condition approval of a BLA on the sponsor's agreement to conduct additional clinical trials to further assess the biologic's safety and effectiveness after BLA approval. Such post-approval clinical trials are typically referred to as Phase 4 clinical trials.

 Concurrent with clinical trials, companies usually complete additional animal studies and must also develop additional information about the chemistry and physical characteristics of the biologic and finalize a process for manufacturing the biologic in commercial quantities in accordance with cGMP requirements. The manufacturing process must be capable of consistently producing quality batches of the product candidate and manufacturers must develop, among other things, methods for testing the identity, strength, quality and purity of the final biological product. Additionally, appropriate packaging must be selected and tested, and stability studies must be conducted to demonstrate that the product candidate does not undergo unacceptable deterioration over its shelf life.

 BLA Submission and FDA Review

 The results of preclinical studies and clinical trials, together with other detailed information, including extensive manufacturing information and information on the composition of the biologic, are submitted to the FDA in the form of a BLA requesting approval to market the biologic for one or more specified indications. The BLA must include all relevant data available from preclinical and clinical studies, including negative or ambiguous results as well as positive findings, together with detailed information relating to the product's chemistry, manufacturing, controls, and proposed labeling, among other things. 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. The submission of a BLA requires payment of a substantial user fee unless a waiver is granted or exemption applies.

 In addition, the Pediatric Research Equity Act, or PREA, requires a sponsor to conduct pediatric clinical trials for most drugs and biologics, for a new active ingredient, new indication, new dosage form, new dosing regimen or new route of administration. Under PREA, original BLAs and certain supplements must contain a pediatric assessment unless the sponsor has received a deferral or waiver. The required assessment must evaluate the safety and effectiveness of the product for the claimed indications in all relevant pediatric subpopulations and support dosing and administration for each pediatric subpopulation for which the product is deemed safe and effective. The sponsor or FDA may request a deferral of pediatric clinical trials for some or all of the pediatric subpopulations. A deferral may be granted for several reasons, including a finding that the candidate is ready for approval for use in adults before pediatric clinical trials are complete or that additional safety or effectiveness data needs to be collected before the pediatric clinical trials begin. The FDA must send a non-compliance letter to any sponsor that fails to submit the required assessment, keep a deferral current or fails to submit a request for approval of a pediatric formulation.

 Each BLA submitted to the FDA is reviewed for administrative completeness and reviewability within 60 days of the FDA's receipt of the application. If the BLA is found to be complete, the FDA will file the BLA, triggering a full review of the application. The FDA may refuse to file any BLA that it deems incomplete or not properly reviewable at the time of submission. In this event, the BLA must be resubmitted with the additional information.

 Once a BLA has been accepted for review, 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, but the overall timeframe is often extended by FDA requests for additional information or clarification. The FDA reviews a BLA to determine, among other things, whether the biological product is safe, pure and potent and whether the facility or facilities in which it is manufactured meet standards designed to assure the product's continued safety, purity and potency.

 The FDA may also refer the application to an Advisory Committee for review, evaluation, and recommendation as to whether the application should be approved. The FDA is not bound by the recommendation of an advisory committee, but it generally follows such recommendations.

 Before approving a BLA, the FDA will typically inspect the facility or the facilities at which the biologic product is manufactured and will not approve the product unless it determines that the manufacturing processes and facilities are in compliance with cGMP and adequate to assure consistent production of the product within required specifications. Additionally, before approving a BLA, the FDA may inspect one or more clinical sites to assure that such trials were conducted in compliance with GCP. If the FDA determines that the application, manufacturing process or manufacturing facilities are not acceptable, it will outline the deficiencies in the submission and often will request additional testing or information. Notwithstanding the submission of any requested additional information, the FDA ultimately may decide that the application does not satisfy the regulatory criteria for approval.

 After the FDA evaluates a BLA and conducts any inspections of manufacturing facilities where the investigational product and/or its drug substance will be produced, the FDA may issue an approval letter or a Complete Response Letter, or CRL. An approval letter authorizes commercial marketing of the product with specific prescribing information for specific indications. A CRL indicates that the review cycle of the application is complete, and the application will not be approved in its present form. A CRL usually describes the specific deficiencies in the BLA identified by the FDA and may require additional clinical data, including additional clinical trials, or other significant and time-consuming requirements related to clinical trials, nonclinical studies or

 manufacturing. If a CRL is issued, the sponsor must resubmit the BLA, addressing all of the deficiencies identified in the letter, or withdraw the application. Even if such data and information are submitted, the FDA may decide that the BLA does not satisfy the criteria for approval.

 If regulatory approval of a product is granted, such approval will be granted for particular indications and may entail limitations on the indicated uses for which such product may be marketed. For example, the FDA may approve the BLA with a Risk Evaluation and Mitigation Strategy, or REMS, to ensure the benefits of the product outweigh its risks. A REMS is a safety strategy implemented to manage a known or potential serious risk associated with a product and to enable patients to have continued access to such medicines by managing their safe use, and could include medication guides, physician communication plans, or elements to assure safe use, such as restricted distribution methods, patient registries and other risk minimization tools. The FDA also may condition approval on, among other things, changes to proposed labeling or the development of adequate controls and specifications. The FDA may require one or more Phase 4 post-market studies and surveillance to further assess and monitor the product's safety and effectiveness after commercialization and may limit further marketing of the product based on the results of these post-marketing studies.

 Expedited Development and Review Programs

 The FDA maintains several programs intended to facilitate and expedite development and review of new biologics designed to address unmet medical needs in the treatment of serious or life- threatening diseases or conditions. These programs include Fast Track designation, Breakthrough Therapy designation, Priority Review designation and Accelerated Approval, and the purpose of these programs is to expedite the development and review of qualifying product candidates.

 A biologic is eligible for Fast Track designation if it is intended to treat a serious or life- threatening disease or condition and demonstrates the potential to address unmet medical needs for such disease or condition. Fast Track designation provides increased opportunities for sponsor meetings with the FDA during preclinical and clinical development, in addition to the potential for rolling review, meaning that the agency may review portions of the marketing application before the sponsor submits the complete application, if the sponsor provides a schedule for the submission of the sections of the BLA, the FDA agrees to accept sections of the BLA and determines that the schedule is acceptable, and the sponsor pays any required user fees upon submission of the first section of the BLA. Product candidates receiving Fast Track status may also be eligible for Priority Review, if the relevant criteria are met.

 In addition, a biologic product candidate may be eligible for Breakthrough Therapy designation if it is intended to treat a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the product candidate may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. Breakthrough Therapy designation provides all the features of Fast Track designation in addition to intensive guidance on an efficient development program beginning as early as Phase 1, and FDA organizational commitment to expedited development, including involvement of senior managers and experienced review staff in a cross-disciplinary review, where appropriate.

 Any product candidate submitted to the FDA for approval, including a product candidate with Fast Track or Breakthrough Therapy designation, may also be eligible for additional FDA programs intended to expedite the review process, including Priority Review designation. A BLA is eligible for Priority Review if the product candidate has the potential to provide a significant improvement in safety or effectiveness in the treatment, diagnosis or prevention of a serious disease or condition. For original BLAs, priority review designation means the FDA's goal is to take action on the marketing application within six months of the 60-day filing date (as compared to ten months under standard review).

 Additionally, depending on the design of the applicable clinical trials, product candidates are eligible for accelerated approval if they can be shown to have an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit, or an effect on a clinical endpoint that can be measured earlier than an effect on irreversible morbidity or mortality which 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. Accelerated approval is usually contingent on a sponsor's agreement to conduct confirmatory studies to verify and describe the product's clinical benefit, and the FDA may require that such studies be underway before granting any accelerated approval. Products receiving accelerated approval may be subject to expedited withdrawal procedures if the sponsor fails to conduct the required confirmatory studies in a timely manner or if such studies fail to verify the predicted clinical benefit. In addition, the FDA currently requires as a condition for accelerated approval pre-approval of promotional materials, which could adversely impact the timing of the commercial launch of the product.

 Fast Track designation, Breakthrough Therapy designation, Priority Review designation and Accelerated Approval do not change the standards for approval but may expedite the development or review process.

 Post-Approval Requirements

 Approved biologics that are manufactured or distributed in the United States are subject to pervasive and continuing regulation by the FDA, including, among other things, requirements relating to recordkeeping, periodic reporting, product distribution,

 advertising and promotion and reporting of adverse experiences with the product. There also are continuing, annual user fee requirements for products marketed pursuant to approved applications.

 Any biologics manufactured or distributed pursuant to FDA approvals remain subject to continuing regulation by the FDA, including recordkeeping requirements and reporting of adverse experiences associated with the product. Manufacturers and their subcontractors 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 ongoing regulatory requirements, including cGMP, which impose certain procedural and documentation requirements upon manufacturers and contract manufacturers. Changes to the manufacturing process are strictly regulated, and, depending on the significance of the change, may require prior FDA approval before being implemented. FDA regulations also require investigation and correction of any deviations from cGMP and impose reporting requirements. Accordingly, manufacturers must continue to expend time, money and effort in the area of production and quality control to maintain compliance with cGMP and other aspects of regulatory compliance.

 The FDA may withdraw approval if compliance with regulatory requirements and standards is not maintained or if problems occur after the product reaches the market. Later discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, or with manufacturing processes, or failure to comply with regulatory requirements, may result in revisions to the approved labeling to add new safety information, requirements for post-market studies or clinical trials to assess new safety risks, or imposition of distribution or other restrictions under a REMS programs. Other potential consequences include, among other things:

 • restrictions on the marketing or manufacturing of the product, complete withdrawal of the product from the market or product recalls;

 • fines, warning letters, untitled lets, or holds on clinical trials;

 • refusal of the FDA to approve pending applications or supplements to approved applications, or suspension or revocation of product approvals;

 • product seizure or detention, or refusal to permit the import or export of products;

 • consent decrees, corporate integrity agreements, debarment or exclusion from federal healthcare programs;

 • mandated modification of promotional materials and labeling and the issuance of corrective information;

 • the issuance of safety alerts, Dear Healthcare Provider letters, press releases and other communications containing warnings or other safety information about the product; or

 • injunctions or the imposition of civil or criminal penalties.

 The FDA closely regulates the post-approval marketing and promotion of biologics, including standards and regulations for direct-to-consumer advertising, off-label promotion, industry-sponsored scientific and educational activities, and promotional activities involving the internet and social media. A company can make only those claims relating to safety and efficacy that are approved by the FDA. Physicians may prescribe legally available biologics for uses that are not described in the product's labeling and that differ from those tested by us and approved by the FDA. The FDA does not regulate the behavior of physicians in their choice of treatments. The FDA does, however, impose stringent restrictions on manufacturers' communications regarding off-label use. Failure to comply with these requirements can result in adverse publicity, warning letters, corrective advertising and potential civil and criminal penalties.

 Biosimilars and Regulatory Exclusivity

 The Affordable Care Act, signed into law in 2010, includes a subtitle called the Biologics Price Competition and Innovation Act, or BPCIA, which created an abbreviated approval pathway for biological products that are biosimilar to or interchangeable with an FDA-licensed reference biological product. 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 in any given patient and, for products that are administered multiple times to an individual, the biologic and the reference biologic may be alternated or 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 that applicant's own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the

 safety, purity and potency of its 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.

 A biological product can also obtain pediatric market exclusivity in the United States. Pediatric exclusivity, if granted, adds six months to existing exclusivity periods and patent terms. This six-month exclusivity, which runs from the end of existing periods of regulatory exclusivity protection or patent terms, may be granted based on the voluntary completion of a pediatric study in accordance with an FDA-issued "Written Request" for such a study.

 Orphan Drug Designation

 Under the Orphan Drug Act, the FDA may grant orphan designation to a drug or biologic intended to treat a rare disease or condition, which is a disease or condition that affects fewer than 200,000 individuals in the United States, or if it affects more than 200,000 individuals in the United States, there is no reasonable expectation that the cost of developing and making the product available in the United States for the disease or condition will be recovered from sales of the product. Orphan designation must be requested before submitting a BLA. Orphan designation does not convey any advantage in or shorten the duration of the regulatory review and approval process, though companies developing orphan products are eligible for certain incentives, including tax credits for qualified clinical testing and waiver of application fees.

 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 a seven-year period of marketing exclusivity during which the FDA may not approve any other applications to market the same therapeutic agent for the same disease or condition, except in limited circumstances, such as a subsequent product's showing of clinical superiority over the product with orphan exclusivity or where the original applicant cannot produce sufficient quantities of product for the applicable disease or condition. Competitors, however, may receive approval of different therapeutic agents for the disease or condition for which the orphan product has exclusivity or obtain approval for the same therapeutic agent for a different disease or condition than that for which the orphan product has exclusivity. Further, if a designated orphan product receives marketing approval for a disease or condition broader than the rare disease or condition for which it received orphan designation, it may not be entitled to orphan exclusivity.

 Government Regulation Outside of the United States

 To market any product outside of the United States, we would need to comply with numerous and varying regulatory requirements of other countries regarding safety and efficacy and governing, among other things, clinical trials, marketing authorization, manufacturing, commercial sales and distribution of our products. Because biologically sourced raw materials are subject to unique contamination risks, their use may be restricted in some countries. Whether or not we obtain FDA approval of a product, we must obtain the requisite approvals from regulatory authorities in foreign countries prior to the commencement of clinical studies or marketing of the product in those countries. The requirements and process governing the conduct of clinical studies, product licensing, pricing and reimbursement vary from country to country. Failure to comply with applicable foreign regulatory requirements, may be subject to, among other things, fines, suspension or withdrawal of regulatory approvals, product recalls, seizure of products, operating restrictions and criminal prosecution.

 Non-clinical studies and clinical trials

 Similar to the United States, the various phases of non-clinical and clinical research in the EU are subject to significant regulatory controls.

 Non-clinical studies are performed to demonstrate the health or environmental safety of new biological substances. Non-clinical (pharmaco-toxicological) studies must be conducted in compliance with the principles of good laboratory practice, or GLP, as set forth in EU Directive 2004/10/EC (unless otherwise justified for certain particular medicinal products, e.g., radio-pharmaceutical precursors for radio-labeling purposes). In particular, non-clinical studies, both in vitro and in vivo, must be planned, performed, monitored, recorded, reported and archived in accordance with the GLP principles, which define a set of rules and criteria for a quality system for the organizational process and the conditions for non-clinical studies. These GLP standards reflect the Organization for Economic Co-operation and Development requirements.

 Clinical trials of medicinal products in the EU must be conducted in accordance with EU and national regulations and the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use, or ICH, guidelines on Good Clinical Practices, or GCP, as well as the applicable regulatory requirements and the ethical principles that have their origin in the Declaration of Helsinki. Additional GCP guidelines from the European Commission, focusing in particular on traceability, apply to clinical trials of advanced therapy medicinal products, or ATMPs. If the sponsor of the clinical trial is not established within the EU, it must appoint an EU entity to act as its legal representative. The sponsor must take out a clinical trial insurance policy, and in most EU member states, the sponsor is liable to provide 'no fault' compensation to any study subject injured in the clinical trial.

 The regulatory landscape related to clinical trials in the EU has been subject to recent changes. The EU Clinical Trials Regulation, or CTR, which was adopted in April 2014 and repeals the EU Clinical Trials Directive, became applicable on January 31,

 2022. Unlike directives, the CTR is directly applicable in all EU member states without the need for member states to further implement it into national law. The CTR notably harmonizes the assessment and supervision processes for clinical trials throughout the EU via a Clinical Trials Information System, which contains a centralized EU portal and database.

 While the EU Clinical Trials Directive required a separate clinical trial application, or CTA, to be submitted in each member state in which the clinical trial takes place, to both the competent national health authority and an independent ethics committee, much like the FDA and IRB respectively, the CTR introduces a centralized process and only requires the submission of a single application for multi-center trials. The CTR allows sponsors to make a single submission to both the competent authority and an ethics committee in each member state, leading to a single decision per member state. The CTA must include, among other things, a copy of the trial protocol and an investigational medicinal product dossier containing information about the manufacture and quality of the medicinal product under investigation. The assessment procedure of the CTA has been harmonized as well, including a joint assessment by all member states concerned, and a separate assessment by each member state with respect to specific requirements related to its own territory, including ethics rules. Each member state's decision is communicated to the sponsor via the centralized EU portal. Once the CTA is approved, clinical study development may proceed.

 The CTR foresees a three-year transition period. The extent to which ongoing and new clinical trials will be governed by the CTR varies. Clinical trials for which an application was submitted (i) prior to January 31, 2022 under the EU Clinical Trials Directive, or (ii) between January 31, 2022 and January 31, 2023 and for which the sponsor has opted for the application of the EU Clinical Trials Directive remain governed by said Directive until January 31, 2025. After this date, all clinical trials (including those which are ongoing) will become subject to the provisions of the CTR.

 Medicines used in clinical trials must be manufactured in accordance with Good Manufacturing Practice, or GMP. Other national and EU-wide regulatory requirements may also apply.

 During the development of a medicinal product, the EMA and national regulators provide the opportunity for dialogue and guidance on the development program. At the EMA level, this is usually done in the form of scientific advice, which is given by the Scientific Advice Working Party of the Committee for Medicinal Products for Human Use, or CHMP. A fee is incurred with each scientific advice procedure. Advice from the EMA is typically provided based on questions concerning, for example, quality (chemistry, manufacturing and controls testing), nonclinical testing and clinical trials, and pharmacovigilance plans and risk-management programs. Advice is not legally binding with regard to any future marketing authorization application of the product concerned.

 Marketing Authorizations

 In the EU, medicinal products can only be placed on the market after obtaining a marketing authorization, or MA. To obtain regulatory approval of an investigational biological product in the EU, we must submit a MA application, or MAA. The process for doing this depends, among other things, on the nature of the medicinal product.

 Centralized procedure—Under the centralized procedure, following the opining of the EMA's CHMP the European Commission issues a single MA valid throughout the EU. The centralized procedure is compulsory for certain types of products, such as (i) medicinal products derived from biotechnology processes, such as genetic engineering, (ii) designated orphan medicinal products, (iii) advanced therapy medicinal products, or ATMPs, such as gene therapy, somatic cell therapy and tissue engineered products, and (iv) medicinal products that contain a new active substance indicated for the treatment of certain diseases, such as HIV/AIDS, cancer, neurodegenerative diseases, diabetes, autoimmune diseases and other immune dysfunctions, and viral diseases. The centralized procedure is optional for any products containing a new active substance not yet authorized in the EU, or for products that constitute a significant therapeutic, scientific or technical innovation or for which the granting of a MA would be in the interest of public health in the EU.

 Under the centralized procedure the maximum timeframe for the evaluation of an MAA by the EMA's CHMP is 210 days, excluding clock stops, when additional written or oral information is to be provided by the applicant in response to questions asked by the CHMP. At the end of the review period, the CHMP provides an opinion to the European Commission. If this opinion is favorable, the Commission may then adopt a decision to grant an MA. In exceptional cases, the CHMP might perform an accelerated review of a MAA in no more than 150 days (excluding clock stops), when a medicinal product targets an unmet medical need and is expected to be of a major public health interest, particularly from the point of view of therapeutic innovation. The timeframe for the evaluation of an MAA under the accelerated assessment procedure is 150 days, excluding clock stops.

 Innovative products that target an unmet medical need and are expected to be of major public health interest may be eligible for a number of expedited development and review programs, such as the PRIME scheme, which provides incentives similar to the breakthrough therapy designation in the U.S. In March 2016, the EMA launched an initiative, the Priority Medicines, or PRIME, scheme, a voluntary scheme aimed at enhancing the EMA's support for the development of medicines that target unmet medical needs. It is based on increased interaction and early dialogue with companies developing promising medicines, to optimize their product development plans and speed up their evaluation to help them reach patients earlier. Product developers that benefit from PRIME designation can expect to be eligible for accelerated assessment but this is not guaranteed. Many benefits accrue to sponsors of product candidates with PRIME designation, including but not limited to, early and proactive regulatory dialogue with the EMA, frequent discussions on clinical trial designs and other development program elements, and accelerated MAA assessment once a dossier has been submitted. Importantly, a dedicated contact and rapporteur from the CHMP is appointed early in the PRIME scheme facilitating increased understanding of the product at EMA's committee level. An initial meeting initiates these relationships and includes a team of multidisciplinary experts at the EMA to provide guidance on the overall development and regulatory strategies.

 National authorization procedures—There are also two other possible routes to authorize medicinal products in several member states, which are available for products that fall outside the scope of the centralized procedure:

 • Decentralized procedure. Using the decentralized procedure, an applicant may apply for simultaneous authorizations in more than one EU member states of medicinal products that have not yet been authorized in any EU member states and that do not fall within the mandatory scope of the centralized procedure. Under the decentralized procedure an identical dossier is submitted to the national competent authority of each of the member states in which the MA is sought, one of which is selected by the applicant as the reference member state. National MAs are issued by competent authorities of the EU member states for their respective territory.

 • Mutual recognition procedure. In the mutual recognition procedure, a medicine is first authorized in one EU member state, in accordance with the national procedures of that member state. Following this, further MAs can be sought from other EU member states in a procedure whereby the countries concerned recognize the validity of the original national MA.

 MAs have an initial duration of five years. After these five years, the authorization may be renewed on the basis of a reevaluation of the risk-benefit balance. Once renewed, the MA is valid for an unlimited period unless the European Commission or the national competent authority decides, on justified grounds relating to pharmacovigilance, to proceed with one additional five-year renewal.

 Data and Marketing Exclusivity

 In the EU, upon receiving a MA, reference medicinal products generally receive eight years of data exclusivity and an additional two years of market exclusivity. If granted, data exclusivity period prevents generic or biosimilar applicants from relying on the preclinical and clinical trial data contained in the dossier of the reference product when applying for a generic or biosimilar MA in the EU during a period of eight years from the date on which the reference product was first authorized in the EU. During the additional two-year period of the market exclusivity period a generic or biosimilar MA can be submitted, and the innovator's data may be referenced but no generic or biosimilar can be marketed in the EU until ten years have elapsed from the initial authorization of the reference product in the EU. The overall ten-year market exclusivity period can be extended to a maximum of eleven years if, during the first eight years of those ten years, the MA holder obtains an authorization for one or more new therapeutic indications which, during the scientific evaluation prior to their authorization, are held to bring a significant clinical benefit in comparison with existing

 therapies. However, there is no guarantee that a product will be considered by the EU's regulatory authorities to be a new chemical or biological entity, and products may not qualify for data exclusivity.

 There is a special regime for biosimilars, or biological medicinal products that are similar to a reference medicinal product but that do not meet the definition of a generic medicinal product, for example, because of differences in raw materials or manufacturing processes. For such products, the results of appropriate preclinical or clinical trials must be provided, and guidelines from the EMA detail the type of quantity of supplementary data to be provided for different types of biological product. There are no such guidelines for complex biological products, such as gene or cell therapy medicinal products, and so it is unlikely that biosimilars of those products will currently be approved in the EU. However, guidance from the EMA states that they will be considered in the future in light of the scientific knowledge and regulatory experience gained at the time.

 Orphan Medicinal Products

 The criteria for designating an "orphan medicinal product" in the EU are similar in principle to those in the United States. A medicinal product may be designated as orphan if (1) it is intended for the diagnosis, prevention or treatment of a life-threatening or chronically debilitating condition; (2) either (a) such condition affects no more than five in 10,000 persons in the EU when the application is made, or (b) the product, without the benefits derived from orphan status, would not generate sufficient return in the EU to justify investment; and (3) there exists no satisfactory method of diagnosis, prevention or treatment of such condition authorized for marketing in the EU, or if such a method exists, the product will be of significant benefit to those affected by the condition. The application for orphan drug designation must be submitted before the MAA. Orphan medicinal products are eligible for financial incentives such as reduction of fees or fee waivers, protocol assistance, access to the centralized procedure, and are, upon grant of a MA, entitled to ten years of market exclusivity for the approved therapeutic indication. During this ten-year orphan market exclusivity period, the competent authorities cannot accept another MAA, or grant a MA, or accept an application to extend a MA for a similar product for the same indication. The period of market exclusivity is extended by two years for orphan medicinal products that have also complied with an agreed pediatric investigation plan, or PIP. No extension to any supplementary protection certificate can be granted on the basis of pediatric studies for orphan indications. Orphan drug designation does not convey any advantage in, or shorten the duration of, the regulatory review and approval process.

 The ten-year market exclusivity may be reduced to six years if, at the end of the fifth year, it is established that the product no longer meets the criteria for orphan designation, for example, if the product is sufficiently profitable not to justify maintenance of market exclusivity or where the prevalence of the condition has increased above the threshold. Additionally, a MA may be granted to a similar product for the same indication at any time if (i) the second applicant can establish that its product, although similar, is safer, more effective or otherwise clinically superior; (ii) the applicant consents to a second orphan medicinal product application; or (iii) the applicant cannot supply enough orphan medicinal product.

 Pediatric Development

 In the EU, MAAs for new medicinal products have to include the results of trials conducted in the pediatric population, in compliance with a pediatric investigation plan, or PIP, agreed with the EMA's Pediatric Committee, or PDCO. The PIP sets out the timing and measures proposed to generate data to support a pediatric indication of the drug for which an MA is being sought. The PDCO can grant a deferral of the obligation to implement some or all of the measures of the PIP until there are sufficient data to demonstrate the efficacy and safety of the product in adults. Further, the obligation to provide pediatric clinical trial data can be waived by the PDCO when these data are not needed or appropriate because the product is likely to be ineffective or unsafe in children, the disease or condition for which the product is intended occurs only in adult populations, or when the product does not represent a significant therapeutic benefit over existing treatments for pediatric patients. Once the MA is obtained in all member states and study results are included in the product information, even when negative, the product is eligible for a six-months supplementary protection certificate extension (if any is in effect at the time of approval) or, in the case of orphan pharmaceutical products, a two year extension of the orphan market exclusivity is granted.

 Post-Approval Requirements

 Similar to the United States, both MA holders and manufacturers of medicinal products are subject to comprehensive regulatory oversight by the EMA, the European Commission and/or the competent regulatory authorities of the member states. The holder of a MA must establish and maintain a pharmacovigilance system and appoint an individual qualified person for pharmacovigilance, or QPPV, who is responsible for the establishment and maintenance of that system, and oversees the safety profiles of medicinal products and any emerging safety concerns. Key obligations include expedited reporting of suspected serious adverse reactions and submission of periodic safety update reports, or PSURs.

 All new MAAs must include a risk management plan, or RMP, describing the risk management system that the company will put in place and documenting measures to prevent or minimize the risks associated with the product. The regulatory authorities may also impose specific obligations as a condition of the MA. Such risk-minimization measures or post-authorization obligations may include additional safety monitoring, more frequent submission of PSURs, or the conduct of additional clinical trials or post-authorization safety studies.

 The advertising and promotion of medicinal products is also subject to laws concerning promotion of medicinal products, interactions with physicians, misleading and comparative advertising and unfair commercial practices. All advertising and promotional activities for the product must be consistent with the approved summary of product characteristics, and therefore all off-label promotion is prohibited. Direct-to-consumer advertising of prescription medicines is also prohibited in the EU. Although general requirements for advertising and promotion of medicinal products are established under EU directives, the details are governed by regulations in each member state and can differ from one country to another.

 Failure to comply with EU and member state laws that apply to the conduct of clinical trials, manufacturing approval, MA of medicinal products and marketing of such products, both before and after grant of the MA, manufacturing of pharmaceutical products, statutory health insurance, bribery and anti-corruption or with other applicable regulatory requirements may result in administrative, civil or criminal penalties. These penalties could include delays or refusal to authorize the conduct of clinical trials, or to grant MA, product withdrawals and recalls, product seizures, suspension, withdrawal or variation of the MA, total or partial suspension of production, distribution, manufacturing or clinical trials, operating restrictions, injunctions, suspension of licenses, fines and criminal penalties.

 The aforementioned EU rules are generally applicable in the European Economic Area, or EEA (comprised of the 27 EU member states plus Iceland, Liechtenstein and Norway).

 Brexit and the Regulatory Framework in the United Kingdom

 Since the end of the Brexit transition period on January 1, 2021, Great Britain (England, Scotland and Wales) has not been directly subject to EU laws, however under the terms of the Ireland/Northern Ireland Protocol, EU laws generally apply to Northern Ireland. The EU laws that have been transposed into United Kingdom, or UK, law through secondary legislation remain applicable in Great Britain. However, new legislation such as the CTR or in relation to orphan medicines is not applicable in Great Britain. The UK government has passed the Medicines and Medical Devices Act 2021, which introduces delegated powers in favor of the Secretary of State or an 'appropriate authority' to amend or supplement existing regulations in the area of medicinal products and medical devices. This allows new rules to be introduced in the future by way of secondary legislation, which aims to allow flexibility in addressing regulatory gaps and future changes in the fields of human medicines, clinical trials and medical devices.

 As of January 1, 2021, the Medicines and Healthcare products Regulatory Agency, or MHRA, is the UK's standalone medicines and medical devices regulator. Whilst Northern Ireland will continue to follow the EU regulatory regime, but its national competent authority will remain the MHRA.

 The MHRA has introduced changes to national licensing procedures, including procedures to prioritize access to new medicines that will benefit patients, including a 150-day assessment and a rolling review procedure. All existing EU MAs for centrally authorized products were automatically converted or grandfathered into UK MAs, effective in GB (only), free of charge on January 1, 2021, unless the MA holder chooses to opt-out. After Brexit, companies established in the UK cannot use the centralized procedure and instead must follow one of the UK national authorization procedures or one of the remaining post-Brexit international cooperation procedures to obtain an MA to commercialize products in the UK. A new international recognition framework has been in place from January 1, 2024, whereby the MHRA will have regard to decisions on the approval of MAs made by the EMA and certain other regulators when determining an application for a new GB MA.

 Other Healthcare Laws

 In addition to FDA restrictions on marketing of pharmaceutical and biological products, other healthcare regulatory laws restrict business practices in the biotechnology industry, which include, but are not limited to, anti-kickback, false claims, and transparency laws regarding drug pricing and payments and other transfers of value made to physicians and other healthcare providers. The federal Anti-Kickback Statute prohibits the offer, receipt, or payment of remuneration in exchange for or to induce the referral of patients or the use of products or services that would be paid for in whole or part by Medicare, Medicaid or other federal healthcare programs. Remuneration has been broadly interpreted to include anything of value, including cash, improper discounts and free or reduced-price items and services. Further, a person or entity does not need to have actual knowledge of the statute or specific intent to violate it to have committed a violation. Many states have similar laws that apply to their state healthcare programs as well as private payors.

 The False Claims Act, or FCA, imposes liability on persons who, among other things, knowingly present or cause to be presented, a false, fictitious or fraudulent claim for payment to, or approval by, the federal government, knowingly make, use, or cause to be made or used a false record or statement material to a false or fraudulent claim to the federal government, or knowingly make a false statement to avoid, decrease or conceal an obligation to pay money to the U.S. federal government. The FCA has been used to prosecute persons submitting claims for payment that are inaccurate or fraudulent, that are for services not provided as claimed, or for services that are not medically necessary. In addition, the government may assert that a claim including items or services resulting from a violation of the Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the False Claims Act. Actions under the FCA may be brought by the Attorney General or as a qui tam action by a private individual in the name of the government. The federal government is using the FCA, and the accompanying threat of significant liability, in its investigation and prosecution of pharmaceutical and biotechnology companies throughout the country, and has obtained multi-million and multi–billion-dollar

 settlements under the FCA in addition to individual criminal convictions under applicable criminal statutes. In addition, companies have been forced to implement extensive corrective action plans and have often become subject to consent decrees or corporate integrity agreements, severely restricting the manner in which they conduct their business. Given the significant size of actual and potential settlements, it is expected that the government authorities will continue to devote substantial resources to investigating healthcare providers' and manufacturers' compliance with applicable fraud and abuse laws.

 In addition, a person who offers or transfers to a Medicare or Medicaid beneficiary any remuneration, including waivers of co-payments and deductible amounts (or any part thereof), that the person knows or should know is likely to influence the beneficiary's selection of a particular provider, practitioner or supplier of Medicare or Medicaid payable items or services may be liable for civil monetary penalties for each wrongful act. Moreover, in certain cases, providers who routinely waive copayments and deductibles for Medicare and Medicaid beneficiaries can also be held liable under the Anti-Kickback Statute and civil False Claims Act, which can impose additional penalties associated with the wrongful act. One of the statutory exceptions to the prohibition is non-routine, unadvertised waivers of copayments or deductible amounts based on individualized determinations of financial need or exhaustion of reasonable collection efforts. The Office of Inspector General of the Department of Health and Human Services emphasizes, however, that this exception should only be used occasionally to address special financial needs of a particular patient. Although this prohibition applies only to federal healthcare program beneficiaries, the routine waivers of copayments and deductibles offered to patients covered by commercial payers may implicate applicable state laws related to, among other things, unlawful schemes to defraud, excessive fees for services, tortious interference with patient contracts and statutory or common law fraud.

 The federal Health Insurance Portability and Accountability Act of 1996, or HIPAA, created additional federal criminal statutes that prohibit, among other actions, knowingly and willfully executing, or attempting to execute, a scheme to defraud any healthcare benefit program, including private third-party payors, knowingly and willfully embezzling or stealing from a healthcare benefit program, willfully obstructing a criminal investigation of a healthcare offense, and 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.

 In addition, there has been a recent trend of increased federal and state regulation of payments made to physicians and other healthcare providers. The ACA, among other things, imposed new reporting requirements through the Physician Payments Sunshine Act on certain manufacturers of drugs covered by a federal healthcare program for payments made by them to physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors), certain non-physician practitioners (physician assistants, nurse practitioners, clinical nurse specialists, certified registered nurse anesthetists, anesthesiology assistants, and certified nurse midwives) and teaching hospitals, as well as ownership and investment interests held by physicians and their immediate family members. Failure to submit required information may result in civil monetary penalties for all payments, transfers of value or ownership or investment interests that are not timely, accurately and completely reported in an annual submission. Manufacturers must submit reports by the 90th day of each calendar year. Certain states also mandate implementation of compliance programs, impose restrictions on drug manufacturer marketing practices and/or require the tracking and reporting of gifts, compensation and other remuneration to physicians, and pricing information and marketing expenditures.

 To the extent that VOWST or any of our product candidates, once approved, are sold in a foreign country, we may be subject to similar foreign laws and regulations, which may include, for instance, applicable post-marketing requirements, including safety surveillance, anti-fraud and abuse laws, and implementation of corporate compliance programs and reporting of payments or other transfers of value to healthcare professionals.

 The shifting commercial compliance environment and the need to build and maintain robust systems to comply with different compliance and/or reporting requirements in multiple jurisdictions increase the possibility that a healthcare company may violate one or more of the requirements. Violations of any of such laws or any other governmental regulations that apply to drug manufacturers may result in significant penalties, including, without limitation, administrative, civil and criminal penalties, damages, fines, disgorgement, the curtailment or restructuring of operations, exclusion from participation in federal and state healthcare programs, reporting obligations and integrity oversight, and imprisonment.

 Coverage and Reimbursement

 Significant uncertainty exists as to the coverage and reimbursement status of any product candidates for which we obtain regulatory approval. In both domestic and foreign markets, sales and reimbursement of any approved products will depend, in part, on the extent to which third-party payors, such as government health programs, commercial insurance and managed healthcare organizations provide coverage, and establish adequate reimbursement levels for, such products. Third-party payors are increasingly challenging the prices charged for medical products and services and imposing controls to manage costs. Third-party payors may limit, or hinder, coverage to specific products on an approved list, also known as a formulary, which might not include all of the FDA-approved products for a particular indication. Additionally, we may need to conduct expensive pharmacoeconomic studies in order to demonstrate the cost-effectiveness of our products, as well as provide rebates and discounts which may impact the net selling price of our products. If third-party payors do not consider our products to be cost-effective compared to other therapies, the payors may not cover our products as a benefit under their plans or, if they do, the level of reimbursement may not be sufficient to allow us to sell our products on a profitable basis.

 The containment of healthcare costs also has become a priority of federal and state governments and the prices of pharmaceutical and biological products have been a focus in this effort. Governments have shown significant interest in implementing cost-containment programs, including price controls, restrictions on reimbursement and requirements for substitution of generic products. Adoption of price controls and cost-containment measures, and adoption of more restrictive policies in jurisdictions with existing controls and measures, could further limit our net revenue and results.

 Outside the United States, ensuring adequate coverage and payment for our products will face challenges. Pricing of prescription pharmaceuticals is subject to governmental control in many countries. Pricing negotiations with governmental authorities can extend well beyond the receipt of regulatory marketing approval for a product and may require us to conduct a clinical trial that compares the cost effectiveness of our product candidates or products to other available therapies. Conducting such a clinical trial could be expensive and result in delays in our commercialization efforts. Third-party payors are challenging the prices charged for medical products and services, and many third-party payors limit reimbursement for newly approved healthcare products. Recent budgetary pressures in many countries are also causing governments to consider or implement various cost-containment measures, such as price freezes, increased price cuts and rebates. If budget pressures continue, governments may implement additional cost-containment measures. Cost-control initiatives could decrease the price we might establish for products that we may develop or sell, which would result in lower product revenues or royalties payable to us. There can be no assurance that any country that has price controls or reimbursement limitations for pharmaceutical products will allow favorable reimbursement and pricing arrangements for any of our products. The downward pressure on healthcare costs in general, particularly prescription products, has become very intense. As a result, increasingly high barriers are being erected to the entry of new products. In addition, in some countries, cross border imports from low priced markets exert a commercial pressure on pricing within a country.

 Healthcare Reform

 In the United States, there have been a number of federal and state proposals during the last few years regarding the pricing of pharmaceutical and biological products, government control and other changes to the healthcare system. It is uncertain what legislative proposals will be adopted or what actions federal, state or private payors for medical goods and services may take in response to any healthcare reform proposals or legislation. We cannot predict the effect medical or healthcare reforms may have on our business, and no assurance can be given that any such reforms will not have a material adverse effect.

 By way of example, in March 2010, the ACA was signed into law, which, among other things, includes changes to the coverage and payment for pharmaceutical and biological products under government health care programs. Among other things, the ACA:

 • expanded manufacturers' rebate liability under the Medicaid Drug Rebate Program by increasing the minimum rebate for both branded and generic drugs and revising the definition of ''average manufacturer price,'' or AMP, for calculating and reporting Medicaid drug rebates on outpatient prescription drug prices;

 • extended Medicaid drug rebates, previously due only on fee-for-service utilization, to Medicaid managed care utilization, and created an alternate rebate formula for new formulations of certain existing products that is intended to increase the amount of rebates due on those drugs;

 • expanded the types of entities eligible for the 340B drug discount program that mandates discounts to certain hospitals, community centers and other qualifying providers. With the exception of children's hospitals, these newly eligible entities will not be eligible to receive discounted 340B pricing on orphan drugs. In addition, because 340B pricing is determined based on AMP and Medicaid drug rebate data, the revisions to the Medicaid rebate formula and AMP definition described above could cause the required 340B discounts to increase; and

 • established the Medicare Part D coverage gap discount program by requiring manufacturers to provide a 70% point-of-sale-discount off the negotiated price of applicable brand drugs to eligible beneficiaries during their coverage gap period as a condition for the manufacturers' outpatient drugs to be covered under Medicare Part D.

 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. Thus, the ACA will remain in effect in its current form. Further, prior to the U.S. Supreme Court ruling, President Biden issued an executive order to initiate a special enrollment period from February 15, 2021, through August 15, 2021, for purposes of obtaining health insurance coverage through the ACA marketplace. The executive order also instructed certain governmental agencies to review and reconsider their existing policies and rules that limit access to healthcare, including among others, reexamining Medicaid demonstration projects and waiver programs that include work requirements, and policies that create unnecessary barriers to obtaining access to health insurance coverage through Medicaid or the ACA.

 Other legislative changes have been proposed and adopted in the United States since the ACA was enacted. In For example, the Budget Control Act of 2011, enacted in August 2011, among other things, included reductions of Medicare payments to providers, which went into effect in April 2013 and, due to subsequent legislative amendments, will remain in effect through 2032, with the exception of a temporary suspension from May 1, 2020 through March 31, 2022, unless additional Congressional action is taken. In January 2013, the American Taxpayer Relief Act of 2012 was signed into law, which, among other things, further reduced Medicare payments to several types of providers, including hospitals, and increased the statute of limitations period for the government to recover overpayments to providers from three to five years. In addition, the American Rescue Plan Act of 2021 as signed into law, which eliminated the statutory Medicaid drug rebate cap, beginning January 1, 2024. The rebate was previously capped at 100% of a drug's AMP.

 More recently, there has been heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products, which have resulted in several Congressional inquiries and proposed and enacted legislation designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for pharmaceutical and biological products. Most recently, on August 16, 2022 the Inflation Reduction Act of 2022 ("IRA") was signed into law. Among other things, the IRA requires manufacturers of certain drugs to engage in price negotiations with Medicare (beginning in 2026), with prices that can be negotiated subject to a cap; imposes rebates under Medicare Part B and Medicare Part D to penalize price increases that outpace inflation (first due in 2023); and replaces the Part D coverage gap discount program with a new discounting program (beginning in 2025). 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. On August 29, 2023, HHS announced the list of the first ten drugs that will be subject to price negotiations, although the drug price negotiation program is currently subject to legal challenges. For that and other reasons, it is currently unclear how the IRA will be effectuated, and the impact of the IRA on the pharmaceutical industry cannot yet be fully determined. Individual states in the United States have also become increasingly active in passing legislation and implementing regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing. Adoption of other new legislation at the federal, state, or foreign level could further limit reimbursement for pharmaceuticals, including our product candidates if approved.

 Data Privacy and Security

 We may also be subject to U.S. federal, state and foreign laws, regulations and standards governing the collection, use, access to, confidentiality, and security of health-related and other personal information, that could apply now or in the future to our operations or the operations of our partners. 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.

 Human Capital

 Employees

 In November 2023, we announced the Restructuring Plan, which included a reduction in workforce of approximately 160 employees, or approximately 41% of our workforce. As of January 1, 2024, after the substantial implementation of the reduction in workforce in 2023, we had 233 full-time permanent employees. Thirty-nine employees work in administration, operations, and commercial and 194 work in research and development. None of our employees in the U.S. are currently represented by a labor union or covered by collective bargaining agreements, and we believe our relationship with our employees is good.

 Talent Acquisition and Development

 We consider the intellectual capital, skills and experience of our employees to be an essential driver of our business and key to our future prospects. We face intense competition for qualified individuals from numerous pharmaceutical and biotechnology

 companies, universities, governmental entities and other research institutions, and we believe that our future success will depend in large part on our continued ability to attract and retain highly skilled employees. To attract qualified applicants to our company and retain our employees, we offer a total rewards package consisting of base salary and cash target bonus targeting the 50th percentile of the market based on geography, a comprehensive benefit package and equity compensation for every employee. Annual cash bonus opportunity and equity compensation increase as a percentage of total compensation based on level of responsibility. Any actual bonus payout is based on a combination of individual performance and corporate performance.

 Diversity, Inclusion, and Belonging

 As a microbiome therapeutics company developing a novel class of live biotherapeutic drugs, we believe that our long-term success and ability to deliver innovative, safe and effective medicines to patients requires a diverse and inclusive workforce. We value diversity at all levels of the organization and continue to focus on extending our diversity, equity and inclusion initiatives across our entire workforce, from: working with managers to develop strategies for fostering high performing teams from all backgrounds; to ensuring that we attract, develop and retain diverse talent from all backgrounds; to increasing awareness within our company of unconscious biases, and supporting all employees, including those who may be underrepresented in our company, industry or society, such as women, members of the LGBTQ community and people of color. In addition, we pride ourselves on an open culture that respects co-workers, values employees' health and well-being and fosters professional development. We support employee growth and development in a variety of ways including with group training, individual mentoring and coaching, conference attendance and tuition reimbursement. Our management conducts annual employee engagement surveys and reports to our board of directors on human capital management topics, including corporate culture, diversity, equity and inclusion, employee development and retention, and compensation and benefits. Similarly, our board of directors regularly provides input on important decisions relating to these matters, including with respect to employee compensation and benefits, talent retention and development.

 Our Corporate Information

 We were incorporated in the State of Delaware in 2010 under the name Newco LS21, Inc. In October 2011, we changed our name to Seres Health, Inc., and in May 2015, we changed our name to Seres Therapeutics, Inc. Our principal executive offices are located at 101 Cambridgepark Drive, Cambridge, Massachusetts 02140 and our telephone number is (617) 945-9626. Our website address is www.serestherapeutics.com. The information contained in, or accessible through, our website does not constitute a part of this Annual Report on Form 10-K.

 We are subject to the informational requirements of the Securities Exchange Act of 1934, as amended, or the Exchange Act, and, accordingly, file reports, proxy statements and other information with the Securities and Exchange Commission, or SEC. The SEC maintains a web site ( that contains material regarding issuers that file electronically, such as ourselves, with the SEC.

 We make available free of charge on our website our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, 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, as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC.

 Item 1A. Risk Factors

 Our business faces significant risks and uncertainties. Accordingly, in evaluating our business, you should carefully consider the risk factors discussed below, as well as the other information included or incorporated by reference in this Annual Report on Form 10-K, including our consolidated financial statements and the related notes and "Management's Discussion and Analysis of Financial Condition and Results of Operations." The occurrence of any of the events or developments described below or elsewhere in this report could harm our business, financial condition, results of operations or growth prospects.

 Risks Related to Our Financial Position and Need for Additional Capital

 We are a commercial-stage company and have incurred significant losses since our inception. We expect to incur losses for the foreseeable future and may never achieve or maintain profitability.

 Since inception, we have incurred significant operating losses. Our net loss was $113.7 million for the year ended December 31, 2023, and $250.2 million for the year ended December 31, 2022. As of December 31, 2023, we had an accumulated deficit of $978.2 million. As noted elsewhere in this Annual Report on Form 10-K, we have identified conditions and events that raise substantial doubt about our ability to continue as a going concern. To date, we have financed our operations through the public offerings of our common stock, private placements of our common stock and preferred stock, payments under our collaboration agreements, and loan facility. We have devoted substantially all of our financial resources and efforts to developing our microbiome therapeutics platform, identifying potential product candidates and conducting preclinical studies and clinical trials. We have only had one product, VOWST, which was approved for marketing in the United States to prevent the recurrence of CDI in individuals 18 years of age and older following antibacterial treatment for recurrent CDI on April 26, 2023, and launched in June 2023. We have not completed development of any of our other product candidates, which we call microbiome therapeutic candidates, or other drugs or biologics. We expect to continue to incur significant expenses and operating losses for the foreseeable future. While we plan to focus our investment on supporting commercialization of VOWST and on our SER-155 Phase 1b study in the near-term, our expenses may increase substantially in connection with our ongoing and future activities, particularly if and as we:

 • commercialize and manufacture VOWST for adult patients with recurrent CDI with our collaborator Nestl;

 • continue the clinical development of SER-155 to potentially reduce incidences of gastrointestinal infections, resulting bloodstream infections, and GvHD in patients receiving allo-HSCT;

 • advance research and development activities supported by partnerships;

 • make strategic investments in manufacturing capabilities;

 • maintain and augment our extensive proprietary microbiome therapeutic drug development know-how that may be used to support future research and development efforts, including our intellectual property portfolio and intellectual property that we may opportunistically acquire;

 • establish a sales and distribution infrastructure and scale-up manufacturing capabilities to commercialize any products for which we have obtained and in the future may obtain regulatory approval;

 • perform our obligations under our agreements with our collaborators;

 • seek to obtain regulatory approvals for our product candidates; and

 • experience any delays or encounter any issues with any of the above, including but not limited to failed studies, complex results, safety issues or other regulatory challenges.

 To become and remain profitable, we must succeed in developing and commercializing products that generate significant revenue. This will require us to be successful in a range of challenging activities, including completing preclinical testing and clinical trials of our product candidates, discovering additional product candidates, obtaining regulatory approval for these product candidates and manufacturing, marketing and selling any products for which we have already obtained and may in the future obtain regulatory approval. We are in the preliminary stages of many of these activities. We may never succeed in these activities and, even if we do, may never generate revenue that is significant enough to achieve profitability.

 Because of the numerous risks and uncertainties associated with pharmaceutical product and biological development, we are unable to accurately predict the timing or amount of increased expenses or when, or if, we will be able to achieve profitability.

 Even if we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain profitable would depress our value and could impair our ability to raise capital, expand our business, maintain our research and development and commercialization efforts, diversify our product offerings or even continue our operations.

 We have identified conditions and events that raise substantial doubt regarding our ability to continue as a going concern.

 Based on our currently available cash resources and our current level of operations and cash flows for the 12-month period subsequent to the date of issuance of the consolidated financial statements included elsewhere in this Annual Report on Form 10-K, we will require additional funding prior to the end of 2024. Because the ability to obtain sufficient additional equity or debt financing with terms favorable or acceptable to us cannot be considered probable according to the applicable accounting standards because they are outside our control, there is substantial doubt about our ability to continue as a going concern for at least 12 months from the date that our consolidated financial statements for the year ended December 31, 2023 were issued.

 Substantial doubt about our ability to continue as a going concern may materially and adversely affect the price per share of our common stock, and it may be more difficult for us to obtain financing. If potential collaborators decline to do business with us or potential investors decline to participate in any future financings due to such concerns, our ability to increase our cash position may be limited. The perception that we may not be able to continue as a going concern may cause others to choose not to deal with us due to concerns about our ability to meet our contractual obligations.

 We have prepared our consolidated financial statements on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities and commitments in the normal course of business. Our audited consolidated financial statements included in this Annual Report on Form 10-K do not include any adjustments to reflect the possible inability of the Company to continue as a going concern within 12 months after the issuance of such financial statements.

 We will need additional funding in order to complete development of our product candidates and commercialize VOWST and our product candidates, if approved. If we are unable to raise capital when needed, we could be forced to delay, reduce or eliminate our product development programs or commercialization efforts.

 Our expenses may increase in connection with our ongoing activities, particularly if and as we scale up manufacturing operations and continue the commercialization of VOWST, continue the SER-155 Phase 1b study, and research, develop and initiate clinical trials of our product candidates. In addition, if we obtain marketing approval for any of our product candidates, we expect to incur costs related to product manufacturing and commercialization, including marketing, sales and distribution, and may not generate meaningful product revenues or collaboration profit in the near future. Furthermore, we have incurred and expect to continue to incur additional costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding in connection with our continuing operations. If we are unable to raise capital when needed or on attractive terms, we could be forced to delay, reduce or eliminate our research and development programs or any current or future commercialization efforts.

 As noted above, we have identified conditions and events that raise substantial doubt about our ability to continue as a going concern. Our future capital requirements will depend on many factors, including:

 • the impact of a continued increase in inflation rates or interest rates;

 • the progress and results of our clinical studies;

 • the cost of manufacturing VOWST and our product candidates;

 • the scope, progress, results and costs of preclinical development, laboratory testing and clinical trials for our product candidates;

 • our share of the profits and losses from commercial sales of VOWST pursuant to the 2021 License Agreement;

 • the revenue, if any, received from commercial sales of any of our product candidates for which we receive marketing approval;

 • the costs and timing of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property rights and defending any intellectual property-related claims;

 • the effect of competing technological and market developments;

 • the success of our Restructuring Plan announced in November 2023, which has been substantially implemented; and

 • the extent to which we acquire or invest in businesses, products and technologies, including entering into licensing or collaboration arrangements for product candidates.

 Any additional fundraising efforts may divert our management from their day-to-day activities, which may adversely affect our ability to develop and commercialize our products or product candidates. In addition, we cannot guarantee that future financing will be available in sufficient amounts or on terms acceptable to us, if at all. Additionally, market volatility resulting from current macroeconomic conditions, the COVID-19 pandemic, the conflicts involving Ukraine and Russia and Israel and its surrounding regions, or other factors could also adversely impact our ability to access capital as and when needed. 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 or debt, 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 and may decrease our stock price. The incurrence of indebtedness could

 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. We could also be required to seek funds through arrangements with collaborators or others at an earlier stage than otherwise would be desirable and we may be required to relinquish rights to some of our technologies or product candidates or otherwise agree to terms unfavorable to us, any of which may have a material adverse effect on our business, operating results and prospects.

 If we are unable to obtain funding on a timely basis, we may be required to significantly curtail, delay, or discontinue one or more of our research or development programs or the commercialization of VOWST or any product candidates, or be unable to expand our operations or otherwise capitalize on our business opportunities, as desired, which could materially adversely affect our business, financial condition and results of operations.

 Our limited operating history may make it difficult to evaluate the success of our business to date and to assess our future viability.

 Since our inception in October 2010, we have devoted substantially all of our resources to developing our clinical and preclinical program, building our intellectual property portfolio, developing our supply chain, planning our business, raising capital and providing general and administrative support for these operations. Other than with respect to VOWST, which was approved by the FDA in April 2023, we have not yet demonstrated our ability to obtain regulatory approvals. Moreover, with the recent approval of VOWST, we have limited experience in demonstrating our ability to manufacture a commercial-scale product, or arrange for a third party to do so on our behalf, or conduct sales and marketing activities necessary for successful product commercialization. Additionally, we expect our financial condition and operating results to continue to fluctuate significantly from quarter to quarter and year to year due to a variety of factors, including for example, the impact of our Restructuring Plan announced in November 2023 and substantially implemented by December 31, 2023, many of which are beyond our control. Consequently, any predictions made about our future success or viability may not be as accurate as they could be if we had a longer operating history.

 Risks Related to the Discovery, Development and Regulatory Approval of Our Product Candidates

 Other than VOWST, we are early in our development efforts of our product candidates and may not be successful in our efforts to use our reverse translational microbiome therapeutics platform to build a pipeline of product candidates and develop additional marketable drugs.

 We are using our reverse translational microbiome therapeutics platform to develop microbiome therapeutic candidates. Other than VOWST, which launched in the United States in June 2023, we are at an early stage of development of our product candidates and our platform has not yet, and may never, lead to other approvable or marketable drugs. We are developing additional product candidates that we intend to develop to reduce infection and treat diseases where the microbiome is implicated. We may have problems applying our technologies to these areas, and our product candidates may not be effective in reducing infection and disease. Our product candidates may not be suitable for clinical development, including as a result of their harmful side effects, limited efficacy or other characteristics that indicate that they are unlikely to be products that will receive marketing approval and, if approved, achieve market acceptance.

 The success of our product and product candidates will depend on several factors, including the following:

 • completion of preclinical studies and clinical trials with positive results;

 • receipt of marketing approvals from applicable regulatory authorities;

 • obtaining and maintaining patent and trade secret protection and regulatory exclusivity for our product candidates;

 • making arrangements with third-party manufacturers for, or establishing our own, commercial manufacturing capabilities;

 • launching commercial sales of our products, if and when approved, whether alone or in collaboration with others;

 • entering into new collaborations throughout the development process as appropriate, from preclinical studies through to commercialization;

 • acceptance of our products and our product candidates, if and when approved, by patients, the medical community and third-party payors;

 • effectively competing with other therapies;

 • obtaining and maintaining coverage and adequate reimbursement by third-party payors, including government payors, for our products, if approved;

 • protecting our rights in our intellectual property portfolio;

 • operating without infringing or violating the valid and enforceable patents or other intellectual property of third parties;

 • maintaining a continued acceptable safety profile of our products following approval; and

 • maintaining and growing an organization of scientists and business people who can develop and commercialize our products and technology.

 If we or our collaborators do not successfully develop and commercialize our products or product candidates we will not be able to obtain product revenue or collaboration profit in future periods, which likely would result in significant harm to our financial position and adversely affect our stock price.

 VOWST and our product candidates are based on microbiome therapeutics, which is a novel approach to therapeutic intervention.

 VOWST and our product candidates are based on microbiome therapeutics, a novel class of biological drugs, which are designed to treat disease by modulating the microbiome to restore health by repairing the function of a disrupted microbiome to a non-disease state. To our knowledge, VOWST is the first oral product based on this approach to receive FDA approval. We cannot be certain that our approach will lead to the development of additional approvable or marketable products or that we will be able to manufacture at commercial scale. Finally, the FDA or other regulatory authorities may lack experience in evaluating the safety and efficacy of novel product candidates based on microbiome therapeutics, which could result in a longer than expected regulatory review process, increase our expected development costs and delay or prevent commercialization of our product candidates.

 Our reverse translational microbiome therapeutics platform relies on third parties for biological materials, including human stool. Some biological materials have not always met our expectations or requirements, and any disruption in the supply of these biological materials could materially adversely affect our business. For example, if any supplied biological materials are contaminated with disease organisms, we would not be able to use such biological materials. Although we have control processes and screening procedures, biological materials are susceptible to damage and contamination and may contain active pathogens. Improper storage of these materials, by us or any third-party suppliers, may require us to destroy some of our materials or products, which could delay the development or commercialization of VOWST or our product candidates.

 Clinical drug development involves a risky, 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 product candidates.

 Other than VOWST, which received FDA approval in April 2023 to prevent the recurrence of CDI in individuals 18 years of age and older following antibacterial treatment for recurrent CDI, it is difficult to predict when or if any of our product candidates will prove effective and safe in humans or will receive regulatory approval, and the risk of failure through the development process is high. Before obtaining marketing approval from regulatory authorities for the sale of any product candidate, we must complete preclinical development and then conduct extensive clinical trials to demonstrate the safety and efficacy of our product candidates in humans. Clinical testing is expensive, difficult to design and implement, can take many years to complete and is uncertain as to outcome. A failure of one or more clinical trials can occur at any stage of testing, and our clinical trials may not be successful. The outcome of preclinical testing and early clinical trials may not be predictive of the success of later clinical trials, and interim or preliminary results of a clinical trial, that we may from time to time announce, do not necessarily predict final results. A number of companies in the pharmaceutical and biotechnology industries have suffered significant setbacks in advanced clinical trials due to lack of efficacy or adverse safety profiles, notwithstanding promising results in earlier studies, and we cannot be certain that we will not face similar setbacks.

 In addition, we cannot be certain as to what type and how many clinical trials the FDA, or other regulatory authorities, will require us to conduct before we may successfully gain approval to market any of our product candidates. Prior to approving a new therapeutic product, the FDA (or other regulatory authorities) generally requires that safety and efficacy, or with respect to biological products such as our microbiome therapeutic candidates, safety, purity and potency, be demonstrated in two adequate and well-controlled clinical trials. In some situations, evidence from a Phase 2 trial and a Phase 3 trial or from a single Phase 3 trial can be sufficient for FDA approval, such as in cases where the trial or trials provide highly reliable and statistically strong evidence of an important clinical benefit.

 We may experience numerous unforeseen events during, or as a result of, clinical trials that could delay or prevent our ability to receive marketing approval or commercialize our product candidates, including:

 • inability to generate sufficient preclinical, toxicology, or other in vivo or in vitro data to support the initiation or continuation of clinical trials;

 • regulatory authorities or institutional review boards or ethics committees may not authorize us or our investigators to commence a clinical trial or conduct a clinical trial at a prospective trial site;

 • failures or delays in reaching agreement on acceptable clinical trial contracts or clinical trial protocols with prospective trial sites;

 • clinical trials of our product candidates may demonstrate undesirable side effects or produce negative or inconclusive results, and we may decide, or regulators may require us, to conduct additional clinical trials or abandon product development programs;

 • the number of patients required for clinical trials of our product candidates may be larger than we anticipate, enrollment in these clinical trials may be slower than we anticipate or participants may drop out of these clinical trials at a higher rate than we anticipate;

 • our third-party contractors may fail to comply with regulatory requirements or meet their contractual obligations to us in a timely manner, or at all;

 • we may have to suspend or terminate clinical trials of our product candidates for various reasons, including a finding that the participants are being exposed to unacceptable health risks;

 • regulatory authorities or institutional review boards or ethics committees may require that we or our investigators suspend or terminate clinical research for various reasons, including noncompliance with regulatory requirements or a finding that the participants are being exposed to unacceptable health risks;

 • the cost of clinical trials of our product candidates may be greater than we anticipate;

 • the supply or quality of our product candidates or other materials necessary to conduct clinical trials of our product candidates may be insufficient or inadequate;

 • regulatory authorities may revise the requirements for approving our product candidates, or such requirements may not be as we anticipate; and

 • regarding trials managed by any current or future collaborators, our collaborators may face any of the above issues, and may conduct clinical trials in ways they view as advantageous to them but potentially suboptimal for us.

 If we are required to conduct additional clinical trials or other testing of our product candidates beyond those that we currently contemplate, if we are unable to successfully complete clinical trials of our product candidates or other testing, if the results of these trials or tests are not positive or are only modestly positive or if there are safety concerns, we may:

 • be delayed in obtaining marketing approval for our product candidates;

 • lose the support of current or any future collaborators, requiring us to bear more of the burden of development of certain compounds;

 • not obtain marketing approval at all;

 • obtain marketing approval in some countries and not in others;

 • obtain approval for indications or patient populations that are not as broad as we intend or desire;

 • obtain approval with labeling that includes significant use or distribution restrictions or safety warnings;

 • be subject to additional post-marketing testing requirements;

 • be subject to increased pricing pressure; or

 • have the product removed from the market after obtaining marketing approval.

 Clinical trials must be conducted in accordance with the FDA and other applicable regulatory authorities' legal requirements, regulations and guidelines, and remain subject to oversight by these governmental agencies and ethics committees or IRBs at the medical institutions where such clinical trials are conducted. We could also encounter delays if a clinical trial is suspended or terminated by us, by the IRBs of the institutions in which such trials are being conducted, by a Data Safety Monitoring Board for such trial or by the FDA or comparable foreign regulatory authorities. These authorities may impose such a suspension or termination due to a number of factors, including failure to conduct the clinical trial in accordance with regulatory requirements or applicable clinical trial protocols, adverse findings from inspections of clinical trial sites by the FDA or comparable foreign regulatory authorities, unforeseen safety issues or adverse side effects, failure to demonstrate a benefit from using a product candidate, changes in governmental regulations or administrative actions or lack of adequate funding to continue the clinical trial. In addition, changes in regulatory requirements and policies may occur, and we may need to amend clinical trial protocols to comply with these changes. Amendments may require us to resubmit our clinical trial protocols to regulators, IRBs or ethics committees for reexamination, which may impact the costs, timing or successful completion of a clinical trial. Additional clinical trials or changes in our development plans could cause us to incur significant development costs, delay or prevent the commercialization of our product candidates or otherwise adversely affect our business.

 In addition, many of the factors that cause, or lead to, the termination suspension of, or a delay in the commencement or completion of, clinical trials may also ultimately lead to the denial of regulatory approval of a product candidate. We do not know whether any of our preclinical studies or clinical trials will begin as planned, will need to be restructured or will be completed on schedule, or at all. Significant preclinical or clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize our product candidates or allow our competitors to bring products to market before we do, potentially impairing our ability to successfully commercialize our product candidates and harming our business and results of operations.

 In addition, the FDA's and other regulatory authorities' policies may change and additional government regulations may be enacted with respect to clinical trials. For instance, the regulatory landscape related to clinical trials in the European Union, or EU, recently evolved. The EU Clinical Trials Regulation, or CTR, which was adopted in April 2014 and repeals the EU Clinical Trials Directive, became applicable on January 31, 2022. While the EU Clinical Trials Directive required a separate clinical trial application, or CTA, to be submitted in each member state in which the clinical trial takes place, to both the competent national health authority and an independent ethics committee, the CTR introduces a centralized process and only requires the submission of a single application for multi-center trials. The CTR allows sponsors to make a single submission to both the competent authority and an ethics committee in each member state, leading to a single decision per member state. The assessment procedure of the CTA has been harmonized as well, including a joint assessment by all member states concerned, and a separate assessment by each member state with respect to specific requirements related to its own territory, including ethics rules. Each member state's decision is communicated to the sponsor via the centralized EU portal. Once the CTA is approved, clinical study development may proceed. The CTR foresees a three-year transition period. The extent to which ongoing and new clinical trials will be governed by the CTR varies. Clinical trials for which an application was submitted (i) prior to January 31, 2022 under the EU Clinical Trials Directive, or (ii) between January 31, 2022 and January 31, 2023 and for which the sponsor has opted for the application of the EU Clinical Trials Directive remain governed by said Directive until January 31, 2025. After this date, all clinical trials (including those which are ongoing) will become subject to the provisions of the CTR. Compliance with the CTR requirements by us and our third-party service providers, such as contract research organizations, or CROs, may impact our developments plans.

 It is currently unclear to what extent the United Kingdom, or UK, will seek to align its regulations with the EU. The UK regulatory framework in relation to clinical trials is derived from existing EU legislation (as implemented into UK law, through secondary legislation). On January 17, 2022, the UK Medicines and Healthcare products Regulatory Agency, or MHRA, launched an eight-week consultation on reframing the UK legislation for clinical trials with the aim to streamline clinical trials approvals, enable innovation, enhance clinical trials transparency, enable greater risk proportionality, and promote patient and public involvement in clinical trials. The UK Government published its response to the consultation on March 21, 2023 confirming that it would bring forward changes to the legislation. These resulting legislative amendments will be closely watched and will determine how closely the UK regulations are aligned with the CTR. Under the terms of the Protocol on Ireland/Northern Ireland, provisions of the CTR which relate to the manufacture and import of investigational medicinal products and auxiliary medicinal products apply in Northern Ireland. On February 27, 2023, the UK Government and the European Commission reached a political agreement on the "Windsor Agreement" which will revise the Protocol on Ireland/Northern Ireland in order to address some of the perceived shortcomings in its operation. Once implemented, this may have further impact on the application of the CTR in Northern Ireland. A decision by the UK Government not to closely align any new legislation with the new approach that has been adopted in the EU may have an effect on the cost of conducting clinical trials in the UK as opposed to other countries.

 If we are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies governing clinical trials, our business may be impacted.

 Delays or difficulties in the enrollment of patients in clinical trials, could result in our receipt of necessary regulatory approvals being delayed or prevented.

 Successful and timely completion of clinical trials will require that we enroll a sufficient number of patient candidates. These trials and other trials we 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 trial or halt further development.

 Our clinical trials will compete with other clinical trials that are in the same therapeutic areas as our product candidates, and this competition reduces the number and types of patients available to us, as some patients who might have opted to enroll in our trials 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 is limited, we expect to conduct some of our 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 our clinical studies will further limit the pool of available study participants as we will 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 is also affected by other factors including:

 • the severity of the disease under investigation;

 • the patient eligibility criteria for the study in question;

 • the perceived risks and benefits of the product candidate under study;

 • the availability of other treatments for the disease under investigation;

 • the existence of competing clinical trials;

 • the efforts to facilitate timely enrollment in clinical trials;

 • our payments for conducting clinical trials;

 • the patient referral practices of physicians;

 • the burden, or perceived burden, of the clinical study;

 • the ability to monitor patients adequately during and after treatment; and

 • the proximity and availability of clinical trial sites for prospective patients.

 Our inability to enroll a sufficient number of patients for our clinical trials or a delayed rate of enrollment would result in significant delays and could require us to abandon one or more clinical trials altogether.

 Interim "top-line" and preliminary data from our clinical trials that we announce or publish from time to time may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data.

 From time to time, we may publicly disclose interim, top-line or preliminary data from our preclinical studies and clinical trials, which is 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. As a result, the top-line 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. Top-line or preliminary data also remain subject to audit and verification procedures that may result in the final data being materially different from the top-line or preliminary data we previously published. As a result, top-line and preliminary data should be viewed with caution until the final data are available. Adverse differences between interim data and final data could significantly harm our business prospects. Further, disclosure of interim data by us or by our competitors could result in volatility in the price of our common stock.

 Further, others, including regulatory authorities, 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 the interim, top-line or preliminary data that we report differ from actual results, or if others, including regulatory authorities, disagree with the conclusions reached, our ability to obtain approval for, and commercialize, our product candidates may be harmed, which could harm our business, operating results, prospects or financial condition.

 If we are not able to obtain, or if there are delays in obtaining, required regulatory approvals, we or our collaborators will not be able to commercialize our product candidates or will not be able to do so as soon as anticipated, and our ability to generate revenue will be materially impaired.

 Our product candidates and the activities associated with their development and commercialization, including their design, testing, manufacture, safety, efficacy, recordkeeping, labeling, storage, approval, advertising, promotion, sale and distribution, are subject to comprehensive regulation by the FDA and other regulatory agencies in the United States and similar regulatory authorities outside the United States. Failure to obtain marketing approval for a product candidate in any jurisdiction will prevent us and our collaborators from commercializing the product candidate in that jurisdiction and may affect our plans for commercialization in other jurisdictions as well. Other than FDA approval for VOWST in the United States to prevent the recurrence of CDI in individuals 18 years of age and older following antibacterial treatment for recurrent CDI, we have not received approval to market any of our product candidates from regulatory authorities in any jurisdiction. We have only limited experience in filing and supporting the applications necessary to gain marketing approvals and expect to rely on third parties to assist us in this process. Securing marketing approval requires the submission of extensive preclinical and clinical data and supporting information to regulatory authorities for each therapeutic indication to establish the product candidate's safety and efficacy, or with respect to biologics such as our microbiome

 therapeutic candidates, safety, purity and potency. Securing marketing approval also requires the submission of information about the product manufacturing process to, and inspection of manufacturing facilities by, the regulatory authorities. Our product candidates may not be effective, may be only moderately effective or may prove to have undesirable or unintended side effects, toxicities or other characteristics that may preclude our obtaining marketing approval or prevent or limit commercial use.

 The process of obtaining marketing approvals, both in the United States and abroad, is expensive, risky and may take many years. The scope and amount of clinical data required to obtain marketing approvals can vary substantially from jurisdiction to jurisdiction, and it may be difficult to predict whether a particular regulatory body will require additional or different studies than those conducted by a sponsor, especially for novel product candidates such as our microbiome therapeutic candidates. The FDA or foreign regulatory authorities may delay, limit, or deny approval to market our product candidates for many reasons, including: our inability to demonstrate that the clinical benefits of our product candidates outweigh any safety or other perceived risks; the regulatory authority's disagreement with the interpretation of data from nonclinical or clinical studies; the regulatory authority's requirement that we conduct additional preclinical studies and clinical trials; changes in marketing approval policies during the development period; changes in or the enactment of additional statutes or regulations, or changes in regulatory review process for each submitted product application; or the regulatory authority's failure to approve the manufacturing processes or third-party manufacturers with which we contract. For instance, the EU pharmaceutical legislation is currently undergoing a complete review process, in the context of the Pharmaceutical Strategy for Europe initiative, launched by the European Commission in November 2020. The European Commission's proposal for revision of several legislative instruments related to medicinal products (potentially reducing the duration of regulatory data protection, revising the eligibility for expedited pathways, etc.) was published on April 26, 2023. The proposed revisions remain to be agreed and adopted by the European Parliament and European Council (not expected before early 2026) and may have a significant impact on the biopharmaceutical industry in the long term.

 Additionally, regulatory authorities have substantial discretion in the approval process and may refuse to accept or file a marketing application if deficient. In addition, varying interpretations of the data obtained from preclinical and clinical testing could delay, limit or prevent marketing approval of a product candidate. Any marketing approval we ultimately obtain may be limited or subject to restrictions or post-approval commitments that render the approved product not commercially viable. Of the large number of drugs in development, only a small percentage successfully complete the FDA or other regulatory approval processes and are commercialized.

 Furthermore, our product candidates may not receive marketing approval even if they achieve their specified endpoints in clinical trials. Clinical data are often susceptible to varying interpretations and many companies that have believed that their products performed satisfactorily in clinical trials have nonetheless failed to obtain regulatory authority approval for their products. The FDA or foreign regulatory authorities may disagree with our trial design and our interpretation of data from nonclinical and clinical studies, or they may require additional confirmatory or safety evidence beyond our existing clinical studies. Upon the FDA's review of data from any pivotal trial, it may request that the sponsor conduct additional analyses of the data or gather more data and, if it believes the data are not satisfactory, could advise the sponsor to delay submitting a marketing application.

 Even if we eventually complete clinical testing and receive approval of a biologics license application, or BLA, or foreign marketing authorization for one of our product candidates, the FDA or the applicable foreign regulatory authority may grant approval contingent on the performance of costly additional clinical trials, which may be required after approval. The FDA or the applicable foreign regulatory authority may also approve our product candidates for a more limited indication and/or a narrower patient population than we originally request, and the FDA, or applicable foreign regulatory authority, may not approve the labeling that we believe is necessary or desirable for the successful commercialization of our product candidates. Any delay in obtaining, or inability to obtain, applicable regulatory approval would delay or prevent commercialization of our product candidates and would materially adversely impact our business and prospects.

 The development of therapeutic products targeting the underlying biology of the human microbiome is an emerging field, and it is possible that the FDA and other regulatory authorities could issue regulations or new policies in the future that could adversely affect our microbiome therapeutic candidates.

 If we experience delays in obtaining approval or if we fail to obtain approval of our product candidates, the commercial prospects for our product candidates may be harmed and our ability to generate revenues will be materially impaired.

 A Fast Track designation by the FDA may not actually lead to a faster development or regulatory review or approval process.

 We have and may in the future seek Fast Track designation for some of our product candidates. If a drug or biologic is intended for the treatment of a serious or life-threatening condition and nonclinical or clinical data demonstrate the potential to address unmet medical needs for this condition, the drug or biologic sponsor may apply for Fast Track designation. In December 2023, we received Fast Track designation for SER-155 to reduce the risk of infection and GvHD in patients undergoing allo-HSCT, and for SER-287 for the induction and maintenance of clinical remission in adults with mild-to-moderate UC. Fast Track designation applies to the combination of the product candidate and the specific indication for which it is being studied. Once granted, Fast Track designation provides increased opportunities for sponsor meetings with the FDA during preclinical and clinical development, and a BLA submitted for a Fast Track product candidate may also be eligible for rolling review, where the FDA may consider for review sections

 of the BLA on a rolling basis before the complete application is submitted, if the sponsor provides a schedule for the submission of the sections of the BLA, the FDA agrees to accept sections of the BLA and determines that the schedule is acceptable, and the sponsor pays any required user fees upon submission of the first section of the application.

 The FDA has broad discretion whether or not to grant this designation, and even if we believe another particular product candidate is eligible for this designation, we cannot be certain that the FDA would decide to grant it. Even with Fast Track designation, we may not experience a faster development process, review or approval compared to conventional FDA procedures. Fast Track designation does not assure ultimate approval by the FDA. The FDA may withdraw Fast Track designation if it believes that the designation is no longer supported by data from our clinical development program.

 A Breakthrough Therapy designation by the FDA for our product candidates may not lead to a faster development, regulatory review or approval process, and it does not increase the likelihood that our product candidates will receive marketing approval.

 Prior to receiving FDA approval for VOWST, we received Breakthrough Therapy designation for SER-109 for treatment of CDI, and we may seek a Breakthrough Therapy designation for other product candidates. A Breakthrough Therapy is defined as a drug or biologic that is intended to treat a serious or life-threatening disease or condition, and preliminary clinical evidence indicates that the drug or biologic may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed in early clinical development. For drugs or biologics that have been designated as breakthrough therapies, interaction and communication between the FDA and the sponsor can help to identify the most efficient path for clinical development. Drugs designated as breakthrough therapies by the FDA also receive all of the Fast Track program features, including eligibility for rolling review of the associated marketing application.

 Designation as a Breakthrough Therapy is within the discretion of the FDA. Accordingly, even if we believe one of our product candidates meets the criteria for designation as a Breakthrough Therapy, the FDA may disagree and instead determine not to make such designation. The receipt of a Breakthrough Therapy designation for a product candidate may not result in a faster development process, review or approval compared to conventional FDA procedures and does not assure ultimate approval by the FDA. In addition, not all products designated as breakthrough therapies ultimately will be shown to have the substantial improvement over available therapies suggested by the preliminary clinical evidence at the time of designation. As a result, if a Breakthrough Therapy designation for any future designation we receive is no longer supported by subsequent data, the FDA may rescind the designation.

 We may seek PRIME designation by EMA or other designations, schemes or tools in the EU for one or more of our product candidates, which we may not receive. Such designations may not lead to a faster development or regulatory review or approval process and do not increase the likelihood that our product candidates will receive marketing authorization.

 We may seek EMA PRIME (Priority Medicines) designation or other designations, schemes or tools for one or more of our product candidates. In the EU, innovative products that target an unmet medical need and are expected to be of major public health interest may be eligible for a number of expedited development and review programs, such as the PRIME scheme, which provides incentives similar to the Breakthrough Therapy designation in the United States. PRIME is a voluntary scheme aimed at enhancing the European Medicines Agency's, or EMA, support for the development of medicines that target unmet medical needs. It is based on increased interaction and early dialogue with companies developing promising medicines, to optimize their product development plans and speed up their evaluation to help them reach patients earlier. The benefits of a PRIME designation include the appointment of a rapporteur before submission of a marketing authorization application, early dialogue and scientific advice at key development milestones, and the potential to qualify products for accelerated review earlier in the application process.

 Even if we believe one of our product candidates is eligible for PRIME, the EMA may disagree and instead determine not to make such designation. The EMA PRIME scheme or other schemes, designations, or tools, even if obtained or used for any of our product candidates may not lead to a faster development, regulatory review or approval process compared to therapies considered for approval under conventional procedures and do not assure ultimate approval. In addition, even if one or more of our product candidates is eligible to the PRIME scheme, the EMA may later decide that such product candidates no longer meet the conditions for qualification or decide that the time period for review or approval will not be shortened.

 Product developers that benefit from PRIME designation may be eligible for accelerated assessment (in 150 days instead of 210 days), which may be granted for medicinal products of major interest from a public health perspective or that target an unmet medical need, but this is not guaranteed.

 The competent regulatory authorities in the EU have broad discretion whether to grant such an accelerated assessment, and, even if such assessment is granted, we may not experience a faster development process, review or authorization compared to conventional procedures. Moreover, the removal or threat of removal of such an accelerated assessment may create uncertainty or delay in the clinical development of our product candidates and threaten the commercialization prospects of our products and product candidates, if approved. Such an occurrence could materially impact our business, financial condition and results of operations.

 We may seek orphan drug designation for some of our product candidates but may not be able to obtain it.

 We previously obtained orphan drug designation from the FDA for SER-109 for recurrent CDI and SER-287 for pediatric UC and may seek orphan drug designation and exclusivity for some of our future product candidates. Regulatory authorities in some jurisdictions, including the United States and Europe, may designate drugs and biologics for relatively small patient populations as orphan drugs. In the United States, the FDA may designate a drug or biologic as an orphan drug if it is intended to treat a rare disease or condition, which is defined as a disease or condition that affects fewer than 200,000 individuals 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 and application fee waivers. After the FDA grants orphan drug designation, the generic identity of the drug and its potential orphan use are disclosed publicly by the FDA.

 In addition, if a product with an orphan drug designation subsequently receives the first marketing approval for the disease or condition for which it has such designation, the product is entitled to a period of marketing exclusivity, which precludes the FDA or other regulatory authorities from approving another marketing application for the same drug and same disease or condition during that time period, 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. The applicable period is seven years in the United States and ten years in the EU. The European exclusivity period can be reduced to six years if, at the end of the fifth year, it is established that a product no longer meets the criteria for orphan designation, if the product is sufficiently profitable so that market exclusivity is no longer justified, or the prevalence of the condition has increased above the orphan designation threshold. Orphan drug exclusivity may be lost if the FDA or other regulatory authorities determine that the request for designation was materially defective or if the manufacturer is unable to assure a sufficient quantity of the drug or biologic to meet the needs of patients with the rare disease or condition. Exclusive marketing rights in the United States may also be unavailable if we or our collaborators seek approval for an indication broader than the orphan designated indication and may be lost if the FDA later determines that the request for designation was materially defective. In connection with VOWST's approval, we received a seven year period of exclusivity to prevent the recurrence of CDI in individuals 18 years of age and older following antibacterial treatment for recurrent CDI, which period began on April 26, 2023.

 Even if we obtain orphan drug designation, we may not be the first to obtain marketing approval for any particular orphan indication due to the uncertainties associated with developing pharmaceutical products. Further, even if we obtain orphan drug exclusivity for a product candidate, that exclusivity for a product may not effectively protect the product from competition because different drugs and biologics can be approved for the same disease or condition. Even after an orphan drug or biologic is approved, the FDA or other regulatory authorities can subsequently approve the same drug or biologic for the same disease or condition if the FDA or other regulatory authorities conclude that the later drug is clinically superior in that it is shown to be safer, more effective or makes a major contribution to patient care. Orphan drug designation neither shortens the development time or regulatory review time nor gives the drug any advantage in the regulatory review or approval process.

 Disruptions at the FDA and other government agencies caused by funding shortages or global health concerns could hinder their ability to hire, retain or deploy key leadership and other personnel, or otherwise prevent new or modified products from being developed, approved or commercialized in a timely manner or at all, which could negatively impact our business.

 The ability of the FDA and other regulatory authorities to review and or approve new products can be affected by a variety of factors, including government budget and funding levels, statutory, regulatory, and policy changes, the FDA's and other 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 and other regulatory authorities' ability to perform routine functions. Average review times at the FDA 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 and other regulatory authorities, such as the EMA, following its relocation to Amsterdam and resulting staff changes, may also slow the time necessary for new drugs and biologics to be reviewed and/or approved by necessary regulatory authorities, 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 authorities, such as the FDA, have had to furlough critical FDA employees and stop critical activities.

 Separately, in response to the 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 further inspectional or administrative delays. If a prolonged government shutdown occurs, or if global health concerns continue to delay or 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.

 Risks Related to our Dependence on Third Parties and Manufacturing

 The collaboration and license agreements with Soci t des Produits Nestl S.A. and NHSc Rx License GmbH (collectively, and together with their affiliates and subsidiaries, Nestl) are important to our business. If we or Nestl fail to adequately perform under these agreements, or if we or Nestl terminate the agreements, the development and commercialization of our CDI and IBD product candidates and/or VOWST could be adversely affected, delayed or terminated and our business would be adversely affected.

 In January 2016, we entered into a Collaboration and License Agreement with Nestl, or the 2016 License Agreement. The 2016 License Agreement may be terminated:

 • by Nestl in the event of serious safety issues related to VOWST, SER-287, SER-301 or other specific products added under the 2016 License Agreement, or, collectively, the 2016 Collaboration Products;

 • by us if Nestl challenges the validity or enforceability of any of our licensed patents; and

 • by either Nestl or us in the event of the other party's uncured material breach or insolvency.

 Upon termination of the 2016 License Agreement, all licenses granted to Nestl by us will terminate, and all rights in and to the 2016 Collaboration Products held by Nestl will revert to us. If we commit a material breach of the 2016 License Agreement, Nestl may elect not to terminate the 2016 License Agreement but instead apply specified adjustments to its payment obligations and other terms and conditions of the 2016 License Agreement. If Nestl were to make such adjustments, the funding from and benefits of the 2016 License Agreement could be diminished, which could adversely affect our financial condition. Unless the 2016 License Agreement is terminated by us for Nestl 's uncured material breach, upon termination of the 2016 License Agreement, Nestl will be eligible to receive post-termination royalties from us until Nestl has recouped certain development costs related to the 2016 Collaboration Products and specified percentages of any milestone payments paid to us under the 2016 License Agreement prior to termination, which could have a material adverse effect on our business.

 In July 2021, we entered into a License Agreement with Nestl, or the 2021 License Agreement. The 2021 License Agreement may be terminated:

 • by Nestl with twelve months' prior written notice, effective only on or after the third anniversary of first commercial sale of VOWST and any improvements and modifications thereto developed pursuant to the terms of the 2021 License Agreement, or the 2021 Collaboration Products;

 • by us if Nestl challenges the validity or enforceability of any of our licensed patents; and

 • by either Nestl or us in the event of the other party's uncured material breach or insolvency.

 Upon termination of the 2021 License Agreement, all licenses granted to Nestl by us will terminate. If we commit a material breach of the 2021 License Agreement, Nestl may elect not to terminate the 2021 License Agreement but instead apply specified adjustments to the payment terms and other terms and conditions of the agreement. If Nestl were to make such adjustments, the funding from and benefits of the 2021 License Agreement could be diminished, which could adversely affect our financial condition. In the event we materially breach the 2021 License Agreement or file for bankruptcy, the share of profits and milestones due to us will be reduced by a specified percentage until Nestl has recouped twice the losses caused by our material breach or bankruptcy.

 Termination of these agreements could cause significant delays in our product development and commercialization efforts that could prevent us from commercializing our CDI and IBD products and product candidates without first expanding our internal capabilities or entering into another agreement with a third party. Any alternative collaboration or license could also be on less favorable terms to us. In addition, under the agreements, Nestl agreed to provide funding for certain clinical development activities. If either of the agreements were terminated, we may need to refund those payments and seek additional financing to support the research and development or commercialization of any terminated products or discontinue any terminated products or product candidates, which could have a material adverse effect on our business.

 Under the collaboration and license agreements, we are dependent upon Nestl to successfully commercialize any applicable collaboration products both outside and within the United States and Canada, as applicable. For example, we must work closely with Nestl to supply VOWST to them and coordinate scientific messaging. To optimize the commercial potential of VOWST, we must execute these plans effectively and collaboratively. We cannot directly control Nestl 's commercialization activities or the resources it allocates to our product candidates. Our interests and Nestl 's interests may differ or conflict from time to time, or we may disagree with Nestl 's level of effort or resource allocation. Nestl may internally prioritize our product candidates differently than we do or it may not allocate sufficient resources to effectively or optimally commercialize them. If these events were to occur, our business would be adversely affected.

 We rely on Nestl to provide information related to the commercialization of VOWST so that we can make strategic decisions and projections, and we may provide this data, or statements based upon this data, to investors. If the data Nestl provides us is inaccurate or incomplete, it may adversely affect our financial statements, business operations, the commercial success of VOWST or our stock price.

 Under the 2021 License Agreement, VOWST net sales are recorded by Nestl and include gross sales net of discounts, rebates, allowances, and other applicable deductions. We rely on Nestl to provide reporting related to net sales of VOWST in accordance with U.S. generally accepted accounting principles in order to calculate and record collaboration profit or loss. We also rely on Nestl to provide timely, accurate and complete information related to the commercialization of VOWST, including data on prescribers, prescriptions and new patient starts. We use the information provided to us by Nestl to report our results of operations, to plan for our future operations, and to make strategic decisions and projections, which may prove to be inaccurate or suboptimal. We base some of our strategic decisions and projections on the data Nestl provides and we may provide this information to investors and analysts who may make their own predictions and estimates, all of which may prove to be inaccurate. Any failure by Nestl to provide accurate and complete information related to the commercialization of VOWST, or to provide it on a timely basis, could adversely impact our financial statements, business operations, the commercial success of VOWST or our stock price.

 We rely, and expect to continue to rely, on third parties to conduct our clinical trials, and those third parties may not perform satisfactorily, including failing to meet deadlines for the completion of such trials.

 We expect to continue to rely on third parties, such as CROs, clinical data management organizations, medical institutions and clinical investigators, to conduct and manage our clinical trials.

 Our reliance on these third parties for research and development activities will reduce our control over these activities but does not relieve us of our responsibilities. For example, we remain responsible for ensuring that each of our clinical trials is conducted in accordance with the general investigational plan and protocols for the trial. Moreover, the FDA requires us to comply with regulatory standards, commonly referred to as good clinical practices, or GCPs, for conducting, recording and reporting the results of clinical trials to assure that data and reported results are credible and accurate and that the rights, safety and welfare of trial participants are protected. Regulatory authorities enforce these GCPs through periodic inspections of trial sponsors, principal investigators and trial sites. If we or any of these third parties or our CROs fail to comply with applicable GCPs, the clinical data generated in our clinical trials may be deemed unreliable and the FDA or comparable foreign regulatory authorities may require us to perform additional clinical trials before approving our marketing applications. We cannot assure you that upon inspection by a given regulatory authority, such regulatory authority will determine that any of our clinical trials comply with GCP regulations. In addition, our clinical trials must be conducted with product produced under cGMP regulations or similar regulatory requirements outside the United States. Our failure to comply with these regulations may require us to repeat clinical trials, which would delay the regulatory approval process. Moreover, our business may be adversely affected if any of these third parties violates federal or state fraud and abuse or false claims laws and regulations or data privacy and security laws. Other countries' regulatory authorities also have requirements for clinical trials with which we must comply. We also are required to register ongoing clinical trials and post the results of completed clinical trials on a government-sponsored database, ClinicalTrials.gov, within specified timeframes. Failure to do so can result in fines, adverse publicity and civil and criminal sanctions.

 Furthermore, these third parties may also have relationships with other entities, some of which may be our competitors. If these third parties do not successfully carry out their contractual duties, do not meet expected deadlines, experience work stoppages, terminate their agreements with us or need to be replaced, or do not conduct our clinical trials in accordance with regulatory requirements or our stated protocols, we may need to enter into new arrangements with alternative third parties, which could be difficult, costly or impossible, and our clinical trials may be extended, delayed, or terminated or may need to be repeated. If any of the foregoing occur, we may not be able to obtain, or may be delayed in obtaining, marketing approvals for our product candidates and may not be able to, or may be delayed in our efforts to, successfully commercialize our product candidates.

 We also expect to rely on other third parties to store and distribute drug supplies for our clinical trials. Any performance failure on the part of our distributors could delay clinical development or marketing approval of our product candidates or commercialization of our products, producing additional losses and depriving us of potential product revenue.

 We rely on third parties for certain aspects of the manufacture of our product and product candidates, and we expect to continue to do so for the foreseeable future. This reliance on third parties increases the risk that we will not have sufficient quantities of our product and product candidates or that such quantities may not be available at an acceptable cost, which could delay, prevent or impair our development or commercialization efforts.

 We rely, and expect to continue to rely, on third parties, including GenIbet and Bacthera, for certain aspects of materials supply for our product candidates in preclinical and clinical testing, as well as for commercial manufacture of VOWST and if any of our product candidates receive marketing approval. This reliance on third parties increases the risk that we will not have sufficient quantities of our product candidates on a timely basis or at all, or that such quantities will be available at an acceptable cost or quality, which could delay, prevent or impair our development or commercialization efforts. For example, VOWST and certain of our product candidates rely on human stool from third-party donors. If we do not obtain an adequate supply of donor-derived material to meet clinical or commercial demand, our ability to manufacture VOWST and our product candidates may be delayed or adversely impacted.

 We rely on third-party manufacturers, which entails additional risks, including:

 • failure of third-party manufacturers to comply with regulatory requirements and maintain quality assurance;

 • failure of third-party manufacturers to perform the manufacturing process adequately;

 • breach of supply agreements by the third-party manufacturers;

 • failure to supply components, intermediates, services, or product according to our specifications;

 • failure to supply components, intermediates, services, or product according to our schedule or at all;

 • misappropriation or disclosure of our proprietary information, including our trade secrets and know-how; and

 • termination or nonrenewal of agreements by third-party manufacturers at times that are costly or inconvenient for us.

 Third-party manufacturers may not be able to comply with current good manufacturing processes, or cGMP, regulations or similar regulatory requirements inside or outside the United States. Our failure, or the failure of our third-party manufacturers, to comply with applicable regulations could result in sanctions being imposed on us, including clinical holds, fines, injunctions, civil penalties, delays, suspension or withdrawal of approvals, license revocations, seizures or recalls of product candidates or products, operating restrictions and criminal prosecutions, any of which could significantly and adversely affect supplies of our products. Some of the contract manufacturers we rely on to produce VOWST or our product candidates have never produced any other FDA-approved therapeutic. One of the contract manufacturers on which we rely is constructing a building, which is substantially complete but remains under construction, to manufacture VOWST and our product candidates, however, upon completion, it may not be approved by the FDA for the manufacture of VOWST. If our manufacturers are unable to comply with cGMP regulation or similar regulatory requirements outside the United States or if the FDA or other regulatory authorities do not approve their facility upon a pre-approval inspection, our therapeutic candidates may not be approved or may be delayed in obtaining approval. In addition, there are a limited number of manufacturers that operate under cGMP regulations and similar regulatory requirements outside the United States that might be capable of manufacturing our products. Therefore, our product candidates and any future products that we may develop may compete with other products for access to manufacturing facilities. Any failure to gain access to these limited manufacturing facilities could severely impact the clinical development, marketing approval and commercialization of our product candidates.

 Any performance failure on the part of our existing or future manufacturers could delay clinical development or marketing approval. We do not currently have a second source for certain required materials used for the manufacture of finished product. If our current manufacturers cannot perform as agreed, we may be required to replace such manufacturers and we may be unable to replace them on a timely basis or at all. Our current and anticipated future dependence upon others for the manufacture of our product candidates or products could delay, prevent or impair our development and commercialization efforts.

 Other than the manufacture of VOWST after its recent FDA approval, we have very little experience manufacturing our product candidates commercially, and we cannot assure you that we can manufacture our product candidates in compliance with regulations at a cost or in quantities necessary to make them commercially viable.

 We have manufacturing facilities at our Cambridge and Waltham, Massachusetts locations where we conduct process development, scale-up activities and a portion of the manufacture of microbiome therapeutics as well as conduct quality control. The FDA and other comparable foreign regulatory authorities must, pursuant to inspections that are conducted after submitting a BLA or relevant foreign marketing submission, confirm that the manufacturing processes for the product meet cGMP or similar regulatory requirements outside the United States. The FDA inspected our Cambridge and Waltham facilities in December 2022 and closed the inspections without issue. We currently intend to rely in part on third-party manufacturers for portions of the commercial manufacturing of VOWST and may establish a manufacturing facility for VOWST or any of our product candidates for production at a commercial scale. We have no experience in manufacturing, without reliance on third-party manufacturers, sufficient volume of our product candidates to meet potential market demands. We may not be able to develop commercial-scale manufacturing facilities that are adequate to produce materials for commercial use.

 The equipment and facilities employed in the manufacture of pharmaceuticals are subject to stringent qualification requirements by regulatory agencies, including validation of facility, equipment, systems, processes and analytics. We may be subject to lengthy delays and expense in conducting validation studies, if we can meet the requirements at all.

 In addition, some of our product candidates require donor material, of which we may not be able to collect sufficient quantities for commercial-scale or other manufacturing.

 Risks Related to Commercialization of Our Products, Product Candidates and

 Other Legal Matters

 We depend heavily on the commercial success of VOWST, which was approved for marketing by the FDA in April 2023 and launched in the United States in June 2023. There is no assurance that our commercialization efforts, or those of our collaborators, in the United States with respect to VOWST will be successful or that we will be able to generate collaboration profit at the levels or within the timing we expect, or at the levels or within the timing necessary to support our goals for VOWST.

 Our business currently depends heavily on our ability to successfully commercialize VOWST in the United States in its approved indication with our collaborator, Nestl. We may never be able to successfully commercialize VOWST or meet our expectations with respect to collaboration profit. There is no guarantee that the infrastructure, systems, processes, policies, personnel, relationships and materials we have built in preparation for the launch and commercialization of VOWST in the United States will be sufficient for us to achieve success at the levels we expect. Additionally, healthcare providers may not accept a new treatment paradigm for patients with recurrent CDI. We may also encounter challenges related to reimbursement of VOWST, even if we have positive early indications from payors, including potential limitations in the scope, breadth, availability, or amount of reimbursement covering VOWST. Similarly, healthcare settings or patients may determine that the financial burdens of treatment are not acceptable. Our results may also be negatively impacted if we encounter deficiencies or inefficiencies in our infrastructure or processes. Any of these issues could impair our ability to successfully commercialize VOWST or to generate substantial collaboration profit or to meet our expectations with respect to the amount or timing of collaboration profit. Any issues or hurdles related to our commercialization efforts may materially adversely affect our business, results of operations, financial condition and prospects. There is no guarantee that we will be successful in our commercialization efforts with respect to VOWST, or that we will generate significant collaboration profit from VOWST or any product candidate or become profitable.

 Even though VOWST has received FDA approval and even if any of our product candidates receive marketing approval, VOWST and such product candidates may fail to achieve the degree of market acceptance by physicians, patients, hospitals, third-party payors and others in the medical community necessary for commercial success.

 Even though VOWST has received FDA approval to prevent the recurrence of CDI in individuals 18 years of age and older following antibacterial treatment for recurrent CDI, and even if any of our product candidates receive marketing approval, VOWST or our product candidates may nonetheless fail to gain sufficient market acceptance by physicians, patients, third-party payors and others in the medical community. For example, current CDI treatment involves the use of antibiotics alone, which are well established in the medical community or the use of FMT, and physicians may continue to rely on these treatments or the treatments of our competitors. If VOWST or our product candidates (if and when they are approved) do not achieve an adequate level of acceptance, we or our collaborators may not generate significant collaboration profit and we may not become profitable. The degree of market acceptance of VOWST or any of our product candidates, if approved, will depend on a number of factors, including:

 • their efficacy, safety and other potential advantages compared to alternative treatments;

 • the clinical indications for which such products are approved;

 • our ability to offer them for sale at competitive prices;

 • their convenience and ease of administration compared to alternative treatments;

 • the willingness of the target patient population to try new therapies and of physicians to prescribe these therapies;

 • the strength of marketing and distribution support;

 • the availability of third-party coverage and adequate reimbursement for our product candidates;

 • the prevalence and severity of their side effects and their overall safety profiles;

 • any restrictions on the use of our products together with other medications;

 • interactions of our products with other medicines patients are taking; and

 • the ability of patients to take our products.

 If we or our collaborators are unable to establish effective sales, marketing and distribution capabilities or enter into agreements with third parties with such capabilities, we or our collaborators may not be successful in commercializing VOWST or any of our product candidates if and when they are approved.

 We have employees with experience in sales and marketing, but we have limited sales or marketing infrastructure and, as a company, have little experience in the sale, marketing, and distribution of pharmaceutical products. To achieve commercial success for VOWST or for any other product for which we obtain marketing approval, we will need to establish a sales and marketing organization and/or we will need our collaborator Nestl to perform sales and marketing functions and they may not be successful in doing so.

 In July 2021, we entered into the 2021 License Agreement with Nestl, pursuant to which we granted Nestl, under certain of our patent rights and know how, a co-exclusive, sublicensable (under certain conditions) license to develop, commercialize and conduct medical affairs activities for the 2021 Collaboration Products, including VOWST, in the United States and Canada. Under the 2021 License Agreement, Nestl has the sole right to commercialize VOWST in the 2021 Licensed Territory in accordance with a commercialization plan, subject to our right to elect to provide up to a specified percentage of all promotional details for a certain target audience. Each party will use commercially reasonable efforts to commercialize VOWST in the 2021 Licensed Territory in

 accordance with the commercialization plan. Both parties will perform medical affairs activities for VOWST in the 2021 Licensed Territory in accordance with a medical affairs plan. We were responsible for commercialization and medical affairs activities costs incurred by the parties until first commercial sale of the first 2021 Collaboration Product, or VOWST, in the 2021 Licensed Territory and in accordance with a pre-launch plan, up to a specified cap. Since the first commercial sale of VOWST in June 2023, we are entitled to share equally in its commercial profits and losses.

 In the future, we expect to build a focused sales and marketing infrastructure, or certain components of such infrastructure, if we were to market or co-promote VOWST and our product candidates, if and when they are approved in the United States and potentially elsewhere. There are risks involved with establishing our own sales, marketing and distribution capabilities. For example, recruiting and training a sales force is expensive and time-consuming and could delay any product launch. If the commercial launch of a product candidate for which we recruit a sales force and establish marketing capabilities is delayed or does not occur for any reason, we would have prematurely or unnecessarily incurred these commercialization expenses. This may be costly, and our investment would be lost if we or our collaborators cannot retain or reposition sales and marketing personnel.

 Factors that may inhibit efforts to commercialize our products include:

 • inability to recruit, train and retain adequate numbers of effective sales and marketing personnel;

 • the inability of sales personnel to obtain access to or educate physicians on the benefits of our products;

 • the lack of complementary products to be offered by sales personnel, which may put us at a competitive disadvantage relative to companies with more extensive product lines;

 • unforeseen costs and expenses associated with creating an independent sales and marketing organization; and

 • inability to obtain sufficient coverage and reimbursement from third-party payors and governmental agencies.

 Outside the United States, we intend to rely and may increasingly rely on third parties, including Nestl, to sell, market and distribute VOWST and our product candidates, if and when approved. We may not be successful in entering into arrangements with such third parties or may be unable to do so on terms that are favorable to us. In addition, our product revenue or collaboration profit and our profitability, if any, may be lower if we rely on third parties for these functions than if we were to market, sell and distribute any products that we develop ourselves. We likely will have little control over such third parties, and any of them may fail to devote the necessary resources and attention to sell and market our products effectively. If we do not establish sales, marketing and distribution capabilities successfully, either on our own or in collaboration with third parties, we will not be successful in commercializing our product candidates.

 We face substantial competition, which may result in others discovering, developing or commercializing competing products before or more successfully than we do.

 The development and commercialization of new drug and biologic products is highly competitive and is characterized by rapid and substantial technological development and product innovations. We and our collaborators face competition with respect to VOWST and our other current product candidates and will face competition with respect to any product candidates that we may seek to develop or commercialize in the future, from major pharmaceutical companies, specialty pharmaceutical companies and biotechnology companies worldwide. We are aware of a number of large pharmaceutical and biotechnology companies, as well as smaller, early-stage companies, that are pursuing the development or commercialization of products, including microbiome therapeutics, for reducing CDI and other disease indications we are targeting. Some of these competitive products and therapies are based on scientific approaches that are the same as or similar to our approach, and others may be based on entirely different approaches. For example, FMT is a procedure that has resulted in reports of high success rates for recurrent CDI. Potential competitors also include academic institutions, government agencies, not-for-profits, and other public and private research organizations that conduct research, seek patent protection and establish collaborative arrangements for research, development, manufacturing and commercialization.

 Many of the companies against which we are competing or against which we may compete in the future have significantly greater financial resources, established presence in the market and expertise in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approvals and reimbursement and marketing approved products than we do. Mergers and acquisitions in the pharmaceutical and biotechnology industries may result in even more resources being concentrated among a smaller number of our competitors.

 These third parties compete with us in recruiting and retaining qualified scientific, sales and marketing and management personnel, establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs.

 Our commercial opportunity could be reduced or eliminated if our competitors develop and commercialize products that are more effective, have fewer or less severe side effects, are more convenient or are less expensive than any products that we have or may in the future develop. Our competitors also may obtain FDA or other regulatory approval for their product candidates more rapidly than we may obtain approval for ours, which could result in our competitors establishing a strong market position before we are able to enter the market, especially for any competitor developing a microbiome therapeutic which will likely share our same regulatory approval requirements. In addition, our ability to compete may be affected in many cases by insurers or other third-party payors seeking to encourage the use of generic or biosimilar products.

 Even if we are able to commercialize VOWST or any of our product candidates, if approved, the products may become subject to unfavorable pricing regulations or third-party coverage and reimbursement policies, any of which would harm our business.

 Our ability to continue to commercialize VOWST or any of our product candidates successfully will depend, in part, on the extent to which coverage and reimbursement for these products and related treatments will be available from government health administration authorities, private health insurers and other organizations. Government authorities and third-party payors, such as private health insurers and health maintenance organizations, decide which medications they will pay for and impact reimbursement levels.

 Obtaining and maintaining adequate reimbursement for our products may be difficult. We cannot be certain if and when we will obtain an adequate level of reimbursement for our products by third-party payors. Even if we do obtain adequate levels of reimbursement, third-party payors, such as government or private healthcare insurers, carefully review, and increasingly question the coverage of, and challenge the prices charged for, drugs. Reimbursement rates from private health insurance companies vary depending on the company, the insurance plan and other factors. A primary trend in the U.S. healthcare industry and elsewhere is cost containment. Government authorities and third-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular medications. Increasingly, third-party payors are requiring that drug companies provide them with predetermined discounts from list prices and are challenging the prices charged for drugs. We may also be required to conduct expensive pharmacoeconomic studies to justify coverage and reimbursement or the level of reimbursement relative to other therapies. If coverage and reimbursement are not available or reimbursement is available only to limited levels, we may not be able to successfully commercialize VOWST or any product candidate for which we obtain marketing approval, and the royalties resulting from the sales of those products may also be adversely impacted.

 There may be significant delays in obtaining reimbursement for newly approved drugs, and coverage may be more limited than the purposes for which the drug is approved by the FDA or similar regulatory authorities outside the United States. Moreover, eligibility for reimbursement does not imply that a drug will be paid for in all cases or at a rate that covers our costs, including research, development, manufacture, sale and distribution. Interim reimbursement levels for new drugs, if applicable, may also not be sufficient to cover our costs and may not be made permanent. Reimbursement rates may vary according to the use of the drug and the clinical setting in which it is used, may be based on reimbursement levels already set for lower cost treatment approaches and may be incorporated into existing payments for other services. Net prices for drugs may be reduced by mandatory discounts or rebates required by government healthcare programs or private payors and by any future relaxation of laws that presently restrict imports of drugs from countries where they may be sold at lower prices than in the United States. Our inability to promptly obtain coverage and adequate reimbursement rates from both government-funded and private payors for any approved products that we develop could have a material adverse effect on our operating results, our ability to raise capital needed to commercialize products and our overall financial condition.

 The regulations that govern marketing approvals, pricing, coverage and reimbursement for new drug products vary widely from country to country. Current and future legislation may significantly change the approval requirements in ways that could involve additional costs and cause delays in obtaining approvals. Some countries require approval of the sale price of a drug before it can be reimbursed. In many countries, the pricing review period begins after marketing or product licensing approval is granted. In some foreign markets, prescription pharmaceutical pricing remains subject to continuing governmental control, including possible price reductions, even after initial approval is granted. As a result, we might obtain marketing approval for a product in a particular country, but then be subject to price regulations that delay our commercial launch of the product, possibly for lengthy time periods, and negatively impact the revenues we are able to generate from the sale of the product in that country. Adverse pricing limitations may hinder our ability to recoup our investment in one or more product candidates, even if our product candidates obtain marketing approval. There can be no assurance that our product candidates, if they are approved for sale in the United States or in other countries, will be considered medically necessary for a specific indication or cost-effective, or that coverage or an adequate level of reimbursement will be available.

 Product liability lawsuits against us could cause us to incur substantial liabilities and limit commercialization of VOWST or any other products that we may develop.

 We face an inherent risk of product liability exposure related to the testing of our product candidates in clinical trials and an even greater risk with the commercial sale of VOWST or any other products that we may develop. If we cannot successfully defend ourselves against claims that our product candidates or products caused injuries, we will incur substantial liabilities. Regardless of merit or eventual outcome, liability claims may result in:

 • regulatory investigations, product recalls or withdrawals, or labeling, marketing or promotional restrictions;

 • decreased demand for any product candidates or products;

 • injury to our reputation and significant negative media attention;

 • withdrawal of clinical trial participants;

 • significant costs to defend the related litigation;

 • substantial monetary awards to trial participants or patients;

 • loss of revenue;

 • reduced resources of our management to pursue our business strategy; and

 • the inability to commercialize any products that we develop.

 We currently hold $10.0 million in product liability insurance coverage in the aggregate, with a per occurrence limit of $10.0 million, which may not be adequate to cover all liabilities that we may incur. We may need to increase our insurance coverage as we expand our clinical trials, increase commercialization of VOWST, or if we commence commercialization of our product candidates. Insurance coverage is increasingly expensive. We may not be able to maintain insurance coverage at a reasonable cost or in an amount adequate to satisfy any liability that may arise.

 We may face competition from biosimilars, which may have a material adverse impact on the future commercial prospects of VOWST or our product candidates.

 Because we have received FDA approval of VOWST to prevent the recurrence of CDI in individuals 18 years of age and older following antibacterial treatment for recurrent CDI, and if we obtain approval or any of our product candidates, we may face competition from biosimilars. In the United States, the Biologics Price Competition and Innovation Act, or BPCIA, enacted in 2010 as part of the Patient Protection and Affordable Care Act, created an abbreviated approval pathway for biological products that are demonstrated to be "highly similar," or biosimilar, to or "interchangeable" with an FDA-approved biological product. 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 four 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. This pathway could allow competitors to reference data from innovative biological products 12 years after the time of approval of the innovative biological product, though the FDA may not approve an application relying on such data for a further eight years. This data exclusivity does not prevent another company from developing a product that is highly similar to the innovative product, generating its own data and seeking approval. Data exclusivity only assures that another company cannot rely upon the data within the innovator's application to support the biosimilar product's approval.

 VOWST qualified, and we believe that any of our product candidates approved as a biological product under a BLA should also qualify, for the 12-year period of reference product exclusivity. However, there is a risk that this exclusivity could be shortened due to congressional action or otherwise, or that the FDA will not consider our product candidates to be reference products for competing products, potentially creating the opportunity for generic competition sooner than anticipated.

 In the EU, the European Commission has granted marketing authorizations for several biosimilars pursuant to a set of general and product class-specific guidelines for biosimilar approvals issued over the past few years. In Europe, a competitor may reference data supporting approval of an innovative biological product but will not be able to get on the market until 10 years after the time of approval of the innovative product. This 10-year marketing exclusivity period can be extended to 11 years if, during the first eight of those 10 years, the marketing authorization holder obtains an approval for one or more new therapeutic indications that bring significant clinical benefits compared with existing therapies. In addition, companies may be developing biosimilars in other countries that could compete with our products. If competitors are able to obtain marketing approval for biosimilars referencing our products, our products may become subject to competition from such biosimilars, with the attendant competitive pressure and consequences.

 Failure to obtain marketing approval in international jurisdictions would prevent our product candidates from being marketed abroad.

 In order to market and sell our products in the EU and many other jurisdictions, we or our collaborators must obtain separate marketing approvals and comply with numerous and varying regulatory requirements. The approval procedure varies among countries and can involve additional testing. The time required to obtain approval in foreign countries may differ substantially from that required to obtain FDA approval. Clinical trials conducted in one country may not be accepted by regulatory authorities in other countries. The regulatory approval process outside the United States generally includes all of the risks associated with obtaining FDA approval. In addition, in many countries outside the United States, it is required that the product be approved for reimbursement before the product can be approved for sale in that country. We or our collaborators may not obtain approvals for VOWST or our product candidates from regulatory authorities outside the United States on a timely basis, if at all. Approval by the FDA does not ensure approval by regulatory authorities in other countries or jurisdictions, and approval by one regulatory authority outside the United States does not ensure approval by regulatory authorities in other countries or jurisdictions or by the FDA. However, a failure or delay in obtaining regulatory approval in one country may have a negative effect on the regulatory process in others. We may not be able to file for marketing approvals and may not receive necessary approvals to commercialize our products in any market.

 VOWST and any product candidate for which we obtain marketing approval will remain subject to significant post-marketing regulatory requirements and oversight.

 VOWST and any product candidate for which we obtain marketing approval, along with the manufacturing processes, post-approval clinical data, labeling, advertising and promotional activities for such product, will be subject to the continual requirements of and review by the FDA and other regulatory authorities. These requirements include submissions of safety and other post-marketing information and reports, registration and listing requirements, cGMP and similar foreign requirements relating to manufacturing, quality control, quality assurance and corresponding maintenance of records and documents, requirements regarding the distribution of samples to physicians and recordkeeping. We and our contract manufacturers will also be subject to continual review and periodic inspections to assess compliance with cGMP and similar foreign requirements. Accordingly, we, and our collaborators and others with whom we work, must continue to expend time, money and effort in all areas of regulatory compliance, including manufacturing, production and quality control. For example, the FDA-approved label for VOWST includes certain warnings and precautions regarding transmissible infectious agents and the potential presence of food allergens.

 Even if marketing approval of a product candidate is granted, the approval may be subject to limitations on the indicated uses for which the product may be marketed or to specific conditions of approval, including a requirement to implement a risk evaluation and mitigation strategy, which could include requirements for a medication guide, communication plan, or restricted distribution system. If any of our product candidates receives marketing approval, the accompanying label may limit the approved use of our drug, which could limit sales of the product. For example, the FDA-approved label for VOWST includes a limitation of use that VOWST is not indicated for the treatment of CDI.

 The FDA or other regulatory authorities may also impose requirements for costly post-marketing studies or clinical trials and surveillance to monitor the safety or efficacy of our approved products. The FDA or other regulatory authorities closely regulates the post-approval marketing and promotion of drugs and biologics to ensure they are marketed only for the approved indications and in accordance with the provisions of the approved labeling. Violations of the FDA's and other regulatory authorities' restrictions relating to the promotion of prescription drugs by us or our collaborators may also lead to investigations alleging violations of federal and state health care fraud and abuse laws, as well as state consumer protection laws.

 In addition, if a regulatory authority, we or our collaborators later discover previously unknown problems with our products, such as adverse events of unanticipated severity or frequency, problems with manufacturers or manufacturing processes, or failure to comply with regulatory requirements, the regulatory authority may impose restrictions on the products or us and our collaborators, including requiring withdrawal of the product from the market. Any failure by us or our collaborators to comply with applicable regulatory requirements may yield various results, including:

 • litigation involving patients taking our products;

 • restrictions on such products, manufacturers or manufacturing processes;

 • restrictions on the labeling or marketing of a product;

 • restrictions on product distribution or use;

 • requirements to conduct post-marketing studies or clinical trials;

 • warning letters;

 • withdrawal of products from the market;

 • suspension or termination of ongoing clinical trials;

 • refusal to approve pending applications or supplements to approved applications that we submit;

 • recall of products;

 • fines, restitution or disgorgement of profits or revenues;

 • suspension or withdrawal of marketing approvals;

 • damage to relationships with potential collaborators;

 • unfavorable press coverage and damage to our reputation;

 • refusal to permit the import or export of our products;

 • product seizure or detention;

 • injunctions; or

 • imposition of civil or criminal penalties.

 Noncompliance with similar EU requirements regarding safety monitoring or pharmacovigilance can also result in significant financial penalties. Similarly, failure to comply with U.S. and foreign regulatory requirements regarding the development of products for pediatric populations and the protection of personal health information can also lead to significant penalties and sanctions.

 Any government investigation of alleged violations of law could require us to expend significant time and resources in response and could generate negative publicity.

 In addition, the FDA's and other regulatory authorities' policies may change and additional government regulations may be enacted that could prevent, limit or delay regulatory approval of our product candidates. 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 authorities actively enforce the laws and regulations prohibiting the promotion of off-label uses.

 If we or our collaborators are found to have improperly promoted off-label uses of approved products, including VOWST or any of our product candidates that may be approved in the future, we may become subject to significant liability. The FDA and other regulatory authorities strictly regulate the promotional claims that may be made about prescription products, such as VOWST and our product candidates, if approved. In particular, a product may not be promoted for uses that are not approved by the FDA or such other regulatory authorities as reflected in the product's approved labeling. The current FDA-approved indication for VOWST is limited to prevent the recurrence of CDI in individuals 18 years of age and older following antibacterial treatment for recurrent CDI. Physicians may nevertheless prescribe VOWST or a product candidate that is approved in future, if any, to their patients in a manner that is inconsistent with the approved label. If we or our collaborators are found to have 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 VOWST or of our product candidates, if approved, we could become subject to significant liability, which would materially adversely affect our business and financial condition.

 Our relationships and any collaborators' relationships with customers, physicians and third-party payors are and will be subject to applicable anti-kickback, fraud and abuse and other healthcare laws and regulations, which could expose us or our collaborators to criminal sanctions, civil penalties, exclusion from governmental healthcare programs, contractual damages, reputational harm and diminished profits and future earnings.

 Healthcare providers, physicians and third-party payors will play a primary role in the recommendation and prescription of VOWST and any product candidates for which we obtain marketing approval. Our and our collaborators' current and future arrangements with third-party payors, physicians and customers expose us to broadly applicable fraud and abuse and other healthcare laws and regulations that may restrict the business or financial arrangements and relationships through which we market, sell and distribute VOWST and any other products for which we may in the future obtain marketing approval. Restrictions under applicable federal and state healthcare laws and regulations include the following:

 • the federal Anti-Kickback Statute prohibits, among other things, persons from knowingly and willfully soliciting, offering, receiving or providing remuneration, directly or indirectly, in cash or in kind, to induce or reward, or in return for, either the referral of an individual for, or the purchase, order or recommendation of, any good or service, for which payment may be made under a federal healthcare program, such as Medicare and Medicaid; a person or entity does not need to have actual knowledge of the statute or specific intent to violate it to have committed a violation;

 • the False Claims Act, imposes, among other things, impose criminal and civil penalties, including through civil whistleblower or qui tam actions, against individuals or entities for knowingly presenting, or causing to be presented, to the

 federal government, claims for payment that are false or fraudulent, knowingly making, using or causing to be made or used, a false record or statement material to a false or fraudulent claim or from knowingly making a false statement to avoid, decrease or conceal an obligation to pay money 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 federal False Claims Act;

 • the federal Civil Monetary Penalties law, which prohibits, among other things, offering or transferring remuneration to a federal healthcare beneficiary that a person knows or should know is likely to influence the beneficiary's decision to order or receive items or services reimbursable by the government from a particular provider or supplier. To the extent our patient assistance programs are found to be inconsistent with applicable laws, we may be required to restructure or discontinue such programs, or be subject to other significant penalties;

 • HIPAA, imposes criminal and civil liability for executing a scheme to defraud any healthcare benefit program or making false statements relating to healthcare matters; similar to the federal Anti-Kickback Statute, a person or entity does not need to have actual knowledge of these statutes or specific intent to violate them to have committed a violation;

 • the federal Physician Payment Sunshine Act requires applicable manufacturers of covered drugs to report payments and other transfers of value to physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors), certain non-physician practitioners (physician assistants, nurse practitioners, clinical nurse specialists, certified registered nurse anesthetists, anesthesiology assistants, and certified nurse midwives), and teaching hospitals, and ownership and investment interests held by physicians and their immediate family members; manufacturers are required to submit reports to the government by the 90th day of each calendar year; and

 • analogous state and foreign laws and regulations, such as state anti-kickback and false claims laws, may apply to our business practices, including but not limited to, research, distribution, sales or marketing arrangements and claims involving healthcare items or services reimbursed by non-governmental third-party payors, 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 foreign governments) and may require drug manufacturers to report information related to payments and other transfers of value to physicians and other healthcare providers, pricing information or marketing expenditures.

 The risk of our or our collaborators being found in violation of these laws is increased by the fact that many of them have not been fully interpreted by the regulatory authorities or the courts, and their provisions are open to a variety of interpretations. Any action against us or our collaborators for violation of these laws, even if we successfully defend against it, could cause us to incur significant legal expenses and divert our management's attention from the operation of our business. The shifting compliance environment and the need to build and maintain a robust system to comply with multiple jurisdictions with different compliance and reporting requirements increases the possibility that we may violate one or more of the requirements.

 Efforts to ensure that our business arrangements with third parties will comply with applicable healthcare laws and regulations will involve substantial costs. It is possible that governmental authorities will conclude that our business practices may not comply with current or future statutes, regulations or case law involving applicable fraud and abuse or other healthcare laws and regulations. If our operations are found to be in violation of any of these laws or any other governmental laws and regulations that may apply to us, we may be subject to significant civil, criminal and administrative penalties, damages, fines, imprisonment, exclusion from government funded healthcare programs, such as Medicare and Medicaid, reporting obligations and oversight if we become subject to a corporate integrity agreement or other agreement, and the curtailment or restructuring of our operations.

 Recently enacted and future legislation may increase the difficulty and cost for us to obtain marketing approval of and commercialize our products and product candidates and affect the prices we may obtain.

 In the United States and some foreign jurisdictions, there have been a number of legislative and regulatory changes and proposed changes regarding the healthcare system that could prevent or delay marketing approval of our product candidates, restrict or regulate post-approval activities and affect our ability to profitably sell any product candidates for which we obtain marketing approval.

 In the United States, the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Affordability Reconciliation Act, or collectively the ACA, is a sweeping law intended to broaden access to health insurance, reduce or constrain the growth of healthcare spending, enhance remedies against fraud and abuse, add new transparency requirements for the healthcare and health insurance industries, impose new taxes and fees on the health industry and impose additional health policy reforms.

 Among the provisions of the ACA of importance to VOWST and our other potential product candidates are the following:

 • establishment of a new pathway for approval of lower-cost biosimilars to compete with biologic products, such as those we are developing or commercializing;

 • an annual, nondeductible fee payable by any entity that manufactures or imports specified branded prescription drugs and biologic agents;

 • an increase in the statutory minimum rebates a manufacturer must pay under the Medicaid Drug Rebate Program;

 • a new Medicare Part D coverage gap discount program, in which manufacturers must agree to offer point-of-sale discounts off negotiated prices;

 • extension of manufacturers' Medicaid rebate liability;

 • expansion of eligibility criteria for Medicaid programs;

 • expansion of the entities eligible for discounts under the Public Health Service pharmaceutical pricing program;

 • a new requirement to annually report drug samples that manufacturers and distributors provide to physicians; and

 • a new Patient-Centered Outcomes Research Institute to oversee, identify priorities in and conduct comparative clinical effectiveness research, along with funding for such research.

 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 since the ACA was enacted. For example, the Budget Control Act of 2011, enacted in August 2011, required sequestration that included aggregate reductions of Medicare payments to providers, which went into effect on April 1, 2013 and, due to subsequent legislative amendments, will remain in effect through 2032, unless additional Congressional action is taken. Under current legislation, the actual reduction in Medicare payments will increase in future years of the sequester. On January 2, 2013, the American Taxpayer Relief Act of 2012 was signed into law, which, among other things, reduced Medicare payments to several providers, including hospitals, and an increase in the statute of limitations period for the government to recover overpayments to providers from three to five years.

 Further, in March 2021, the American Rescue Plan Act of 2021 was signed into law, which, among other things, eliminated the statutory cap on drug manufacturers' Medicaid Drug Rebate Program rebate liability, effective January 1, 2024. Drug manufacturers' Medicaid Drug Rebate Program rebate liability was previously capped at 100% of the average manufacturer price for a covered outpatient drug. We expect that other healthcare reform measures that may be adopted in the future may result in additional reductions in Medicare and other healthcare funding, more rigorous coverage criteria, new payment methodologies and in additional downward pressure on the price that we receive for any approved product. Any reduction in reimbursement from Medicare or other government programs may result in a similar reduction in payments from private payors. The implementation of cost containment measures or other healthcare reforms may prevent us from being able to price our products at what we consider to be a fair or competitive price, generate revenue, attain profitability, or commercialize VOWST or our product candidates, if approved.

 Moreover, there has recently been heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products. Individual states in the United States have become increasingly active in implementing regulations designed to contain pharmaceutical and biological product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures. Most significantly, on August 16, 2022, President Biden signed the Inflation Reduction Act of 2022, or the 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 (beginning in 2026), with prices that can be negotiated subject to a cap; imposes rebates under Medicare Part B and Medicare Part D to penalize price increases that outpace inflation (first due in 2023); and replaces the Part D coverage gap discount program with a new discounting program (beginning in 2025). The IRA permits the Secretary of the Department of Health and Human Services, or 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. On August 29, 2023, HHS announced the list of the first ten drugs that will be subject to price negotiations, although the Medicare drug price negotiation program is currently subject to legal challenges. Legally mandated price controls on payment amounts by third-party payors or other restrictions could harm our ability to price our products appropriately, which could negatively impact our business, results of operations, financial condition and prospects. In addition, regional healthcare authorities and individual hospitals are increasingly using bidding procedures to determine what pharmaceutical products and which suppliers will be included in their prescription drug and other healthcare programs. This could reduce the ultimate demand for VOWST or our product candidates, if approved, or put pressure on our product pricing, which could negatively affect our business, results of operations, financial condition and prospects.

 Legislative and regulatory proposals have been made to expand post-approval requirements and restrict sales and promotional activities for pharmaceutical products. We cannot be sure whether additional legislative changes will be enacted, or whether the FDA or foreign regulations, guidance or interpretations will be changed, or what the impact of such changes on the marketing approvals of

 our product candidates, if any, may be. In addition, increased scrutiny by Congress of the FDA's approval process may significantly delay or prevent marketing approval, as well as subject us to more stringent product labeling and post-marketing testing and other requirements.

 Governments outside the United States tend to impose strict price controls, which may adversely affect our revenues, if any.

 In some countries, particularly the EU member states, the pricing of certain pharmaceuticals is subject to governmental control. In these countries, pricing negotiations with governmental authorities can take considerable time after the receipt of marketing approval for a product. In addition, there can be considerable pressure by governments and other stakeholders on prices and reimbursement levels, including as part of cost containment measures. Political, economic and regulatory developments may further complicate pricing negotiations, and pricing negotiations may continue after coverage and reimbursement have been obtained. Reference pricing used by various EU member states and parallel distribution or arbitrage between low-priced and high-priced member states, can further reduce prices. To obtain reimbursement or pricing approval in some countries, we may be required to conduct a clinical trial that compares the cost-effectiveness of our product candidate to other available therapies. Other member states allow companies to fix their own prices for medicines but monitor and control company profits. Even if a pharmaceutical product obtains a marketing authorization in the EU, there can be no assurance that reimbursement for such product will be secured on a timely basis or at all. If coverage and reimbursement of our products are unavailable or limited in scope or amount, or if pricing is set at unsatisfactory levels that impacts our ability to compete with other products or our ability to recoup our costs of developing our products, our business could be harmed, possibly materially.

 Risks Related to Our Intellectual Property

 If we are unable to adequately protect our proprietary technology or obtain and maintain issued patents that are sufficient to protect our product candidates, others could compete against us more directly, which would have a material adverse impact on our business, results of operations, financial condition and prospects.

 Our success depends in large part on our ability to obtain and maintain patent and other intellectual property protection in the United States and other countries with respect to our proprietary technology and products. We seek to protect our proprietary position by filing patent applications in the United States and abroad related to our novel technologies and product candidates. We also rely on trade secrets to protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection.

 The patent prosecution process is expensive and time-consuming, and we may not be able to file and prosecute all necessary or desirable patent applications at a reasonable cost, in a timely manner, or in all jurisdictions. Prosecution of our patent portfolio is at various stages. We have successfully obtained multiple patents (both U.S. and foreign) in some patent families. In others, prosecution is at an early stage (e.g., provisional or PCT stage). For many patent applications in our portfolio, we have filed national stage applications based on our Patent Cooperation Treaty, or PCT, applications, thereby limiting the jurisdictions in which we can pursue patent protection for the various inventions claimed in those applications. It is also possible that we will fail to identify patentable aspects of our research and development output before it is too late to obtain patent protection. It is possible that defects of form in the preparation or filing of our patents or patent applications may exist, or may arise in the future, such as, with respect to proper priority claims, inventorship, claim scope or patent term adjustments. If there are material defects in the form or preparation of our patents or patent applications, such patents or applications may be invalid and unenforceable. Moreover, our competitors may independently develop equivalent knowledge, methods and know-how. Any of these outcomes could impair our ability to prevent competition from third parties, which may have an adverse impact on our business, financial condition and operating results.

 We have obtained licenses and options to obtain licenses from third parties and may obtain additional licenses and options in the future. In some circumstances, we may not have the right to control the preparation, filing and prosecution of patent applications, or to maintain the patents, covering technology that we license from third parties. We may also require the cooperation of our licensors to enforce any licensed patent rights, and such cooperation may not be provided. Therefore, these patents and applications may not be prosecuted and enforced in a manner consistent with the best interests of our business. Moreover, if we do obtain necessary licenses, we will likely have obligations under those licenses, and any failure to satisfy those obligations could give our licensor the right to terminate the license. Termination of a necessary license could have a material adverse impact on our business.

 We have had in the past, and may have in the future, certain funding arrangements. Such funding arrangements impose various obligations on us, including reporting obligations, and may subject certain of our intellectual property, such as intellectual property made using the applicable funding, to the rights of the U.S. government under the Bayh-Dole Act. Any failure to comply with our obligations under a funding arrangement may have an adverse effect on our rights under the applicable agreement or our rights in the applicable intellectual property. Compliance with our obligations or the exercise by the government or other funder of its rights, may limit certain opportunities or otherwise have an adverse effect on our business.

 Our patent portfolio currently includes 21 active patent application families (which includes exclusive licenses to certain IP from Memorial Sloan Kettering Cancer Center). Of these, 20 applications have been nationalized and one is at the PCT stage. While we have obtained 30 issued U.S. patents, we cannot provide any assurances that any of our pending patent applications will mature into issued patents and, if they do, that such patents or our current patents will include claims with a scope sufficient to protect our product candidates or otherwise provide any competitive advantage. For example, we are pursuing claims to therapeutic, binary compositions of certain bacterial populations. Any claims that may issue may provide coverage for such binary compositions and/or their use. However, there can be no assurance that an alternative composition that may fall outside the scope of such claims will not be equally effective. Further, given that VOWST is a complex composition with some variation from lot-to-lot and that, likewise, third-party compositions may have similar complexity and variability, it is possible that a patent claim may provide coverage for some but not all lots of a product, product candidate or third-party product. These and other factors may provide opportunities for our competitors to design around our patents, should they issue.

 Moreover, other parties have developed technologies that may be related or competitive to our approach and may have filed or may file patent applications and may have received or may receive patents that may overlap or conflict with our patent applications, either by claiming similar methods or by claiming subject matter that could dominate our patent position or cover one or more of our products or product candidates. In addition, given the on-going prosecution of our portfolio, we continue development of our understanding of how patent offices react to our patent claims and whether they identify prior art of relevance that we have not already considered.

 Publications of discoveries in the scientific literature often lag behind the actual discoveries, and patent applications in the United States and other jurisdictions are typically not published until 18 months after filing, or in some cases not at all. Therefore, we cannot know with certainty whether we were the first to make the inventions claimed in any owned patents or pending patent applications, or that we were the first to file for patent protection of such inventions, nor can we know whether those from whom we may license patents were the first to make the inventions claimed or were the first to file. For these and other reasons, the issuance, scope, validity, enforceability and commercial value of our patent rights are subject to a level of uncertainty. Our pending and future patent applications may not result in patents being issued which protect our technology or products, in whole or in part, or which effectively prevent others from commercializing competitive technologies and products. Changes in either the patent laws or interpretation of the patent laws in the United States and other countries may diminish the value of our patents or narrow the scope of our patent protection.

 We may be subject to third-party preissuance submissions of prior art to the United States Patent and Trademark Office, or USPTO, or in a foreign jurisdiction in which our applications are filed, or become involved in opposition, derivation, reexamination, inter partes review, post-grant review or interference proceedings challenging our patent rights or the patent rights of others. For example, on April 25, 2017, we filed a notice of opposition in the European Patent Office challenging the validity of a patent issued to The University of Tokyo. See "—Third parties may initiate legal proceedings alleging that we are infringing their intellectual property rights, the outcome of which would be uncertain and could have a material adverse effect on the success of our business." The oral proceedings were held at the European Patent Office on February 18, 2019 and the Opposition Division required The University of Tokyo to narrow the scope of the claims of the patent. The University of Tokyo appealed certain aspects of the Opposition Division's decision, as did we and other opponents. On November 18, 2022, The University of Tokyo requested termination of the appeal proceeding and revocation of its patent. On December 19, 2022, the Opposition Division officially terminated the appeal proceeding, and European Patent No. 2 575 835 B1 has been revoked in its entirety.

 An adverse determination in any such submission, proceeding or litigation could reduce the scope of, or invalidate, our patent rights, allow third parties to commercialize our technology or products and compete directly with us, without payment to us, or result in our inability to manufacture or commercialize products without infringing third-party patent rights. In addition, if the breadth or strength of protection provided by our patents and patent applications is threatened, it could dissuade companies from collaborating with us to license, develop or commercialize current or future product candidates. Furthermore, an adverse decision in an interference proceeding can result in a third party receiving the patent right sought by us, which in turn could affect our ability to develop, market or otherwise commercialize our product candidates. The issuance, scope, validity, enforceability and commercial value of our patents are subject to a level of uncertainty.

 The patent position of biotechnology and pharmaceutical companies generally is highly uncertain, involves complex legal and factual questions and has in recent years been the subject of much litigation. Due to legal standards relating to patentability, validity, enforceability and claim scope of patents covering biotechnological and pharmaceutical inventions, our ability to obtain, maintain and enforce patents is uncertain and involves complex legal and factual questions. Even if issued, a patent's validity, inventorship, ownership or enforceability is not conclusive. Accordingly, rights under any existing patent or any patents we might obtain or license may not cover our product candidates, or may not provide us with sufficient protection for our product candidates to afford a commercial advantage against competitive products or processes, including those from branded and generic pharmaceutical companies.

 The degree of future protection for our proprietary rights is uncertain, and we cannot ensure that:

 • any of our pending patent applications, if issued, will include claims having a scope sufficient to protect any products or product candidates;

 • any of our pending patent applications will issue as patents at all;

 • we will be able to successfully commercialize VOWST or any of our product candidates, if approved, before our relevant patents expire;

 • we were the first to make the inventions covered by any existing patent and pending patent applications;

 • we were the first to file patent applications for these inventions;

 • others will not develop similar or alternative technologies that do not infringe or design around our patents;

 • others will not use pre-existing technology to effectively compete against us;

 • any of our patents, if issued, will be found to ultimately be valid and enforceable;

 • third parties will not compete with us in jurisdictions where we do not pursue and obtain patent protection;

 • we will be able to obtain and/or maintain necessary or useful licenses on reasonable terms or at all;

 • any patents issued to us will provide a basis for an exclusive market for our commercially viable products, will provide us with any competitive advantages or will not be challenged by third parties;

 • we will develop additional proprietary technologies or product candidates that are separately patentable; or

 • our commercial activities or products will not infringe upon the patents or proprietary rights of others.

 Any litigation to enforce or defend our patent rights, even if we were to prevail, could be costly and time-consuming and would divert the attention of our management and key personnel from our business operations. We may not prevail in any lawsuits that we initiate and the damages or other remedies awarded if we were to prevail may not be commercially meaningful. Even if we are successful, domestic or foreign litigation, or USPTO or foreign patent office proceedings, may result in substantial costs and distraction to our management. We may not be able, alone or with our licensors or potential collaborators, to prevent misappropriation of our proprietary rights, particularly in countries where the laws may not protect such rights as fully as in the United States. Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation or other proceedings, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation or other proceedings. In addition, during the course of this kind of litigation or proceedings, there could be public announcements of the results of hearings, motions or other interim proceedings or developments or public access to related documents. If investors perceive these results to be negative, the market price for our common stock could be significantly harmed.

 If we are unable to protect the confidentiality of our trade secrets and know-how, our business and competitive position may be harmed.

 In addition to seeking patents for some of our technology and product candidates, we also utilize our trade secrets, including unpatented know-how, technology and other proprietary information, to maintain our competitive position. We seek to protect these trade secrets, in part, by entering into non- disclosure and confidentiality agreements with parties who have access to them, such as our employees, corporate collaborators, outside scientific collaborators, contract manufacturers, consultants, advisors and other third parties. We also seek to enter into confidentiality and invention or patent assignment agreements with our employees, advisors and consultants. Despite these efforts, any of these parties may breach the agreements and disclose our proprietary information, including our trade secrets, and we may not be able to obtain adequate remedies for such breaches. Our trade secrets may also be obtained by third parties by other means, such as breaches of our physical or computer security systems. Enforcing a claim that a party illegally disclosed or misappropriated a trade secret is difficult, expensive and time-consuming, and the outcome is unpredictable. In addition, some courts inside and outside the United States are less willing or unwilling to protect trade secrets. Moreover, if any of our trade secrets were to be lawfully obtained or independently developed by a competitor, we would have no right to prevent them, or those to whom they communicate it, from using that technology or information to compete with us. If any of our trade secrets were to be disclosed to or independently developed by a competitor, our competitive position would be harmed.

 Changes in U.S. patent law could diminish the value of patents in general, thereby impairing our ability to protect our 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 involves both technological and legal complexity, and is therefore costly, time-consuming and inherently uncertain. In addition, patent reform legislation could further increase the uncertainties and costs surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents. On September 16, 2011, the Leahy-Smith America Invents Act, or the Leahy-Smith Act, was signed into law. The Leahy-Smith Act includes a number of significant changes to U.S. patent law. These include provisions that affect the way patent applications are prosecuted and may also affect patent litigation. The USPTO developed new regulations and procedures to govern administration of the Leahy-Smith Act, and many of the substantive changes to patent law associated with the Leahy-Smith Act, in particular the first to file provisions, became effective on March 16, 2013. A third party that files a patent application in the USPTO after that date but before us could therefore be awarded a patent covering an invention of ours even if we had made the invention before it was made by the third party. This will require us to be cognizant going forward of the time from invention to filing of a patent application. Thus, for our U.S. patent applications containing a priority claim after March 16, 2013, there is a greater level of uncertainty in the patent law. Moreover, some of the patent applications in our portfolio will be subject to examination under the pre-Leahy- Smith Act law and regulations, while other patent applications in our portfolio will be subject to examination under the law and regulations, as amended by the Leahy-Smith Act. This introduces additional complexities into the prosecution and management of our portfolio.

 In addition, the Leahy-Smith Act limits where a patentee may file a patent infringement suit and provides opportunities for third parties to challenge any issued patent in the USPTO. These provisions apply to all of our U.S. patents, even those filed before March 16, 2013. Because of a lower evidentiary standard in USPTO proceedings compared to the evidentiary standard in U.S. federal court necessary to invalidate a patent claim, a third party could potentially provide evidence in a USPTO proceeding sufficient for the USPTO to hold a claim invalid even though the same evidence would be insufficient to invalidate the claim if first presented in a federal court action. Accordingly, a third party may attempt to use the USPTO procedures to invalidate our patent claims because it may be easier for them to do so relative to challenging the patent in a federal court action. It is not clear what, if any, impact the Leahy-Smith Act will have on the operation of our business. However, the Leahy-Smith Act and its implementation could increase the uncertainties and costs surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents, all of which could have a material adverse effect on our business and financial condition.

 In addition, Supreme Court rulings have narrowed the scope of patent protection available in certain circumstances and weakened the rights of patent owners in certain situations. From time to time, the Supreme Court, other federal courts, Congress, or the USPTO, may change the standards of patentability and any such changes could have a negative impact on our business.

 A number of cases decided by the Supreme Court have involved questions of when claims reciting abstract ideas, laws of nature, natural phenomena and/or natural products are eligible for a patent, regardless of whether the claimed subject matter is otherwise novel and inventive. These cases include Association for Molecular Pathology v. Myriad Genetics, Inc., 569 U.S. 12-398 (2013); Alice Corp. v. CLS Bank International, 573 U.S. 13-298 (2014); and Mayo Collaborative Services v. Prometheus Laboratories, Inc., 566 U.S. 10-1150 (2012). In response to these cases, the USPTO has issued guidance to the examining corps.

 The USPTO first issued a memorandum reflecting the USPTO's interpretation of the cases related to patent eligibility of natural products on March 4, 2014, which it subsequently revised and expanded upon in several additional updates now incorporated into its Manual of Patent Examination Procedure. The USPTO's interpretation of the case law and new guidelines for examination may influence, possibly adversely, prosecution and defense of certain types of claims in our portfolio.

 In addition to increasing uncertainty with regard to our ability to obtain future patents, this combination of events has created uncertainty with respect to the value of patents, once obtained. Depending on these and other decisions by Congress, the federal courts and the USPTO, the laws and regulations governing patents could change or be interpreted in unpredictable ways that would weaken our ability to obtain new patents or to enforce any patents that may issue to us in the future. In addition, these events may adversely affect our ability to defend any patents that may issue in procedures in the USPTO or in courts.

 Third parties may initiate legal proceedings alleging that we are infringing their intellectual property rights, the outcome of which would be uncertain and could have a material adverse effect on the success of our business.

 Our commercial success depends upon our ability, and the ability of our collaborators, to develop, manufacture, market and sell VOWST and our product candidates, if approved, and use our proprietary technologies without infringing the proprietary rights of third parties. There is considerable intellectual property litigation in the biotechnology and pharmaceutical industries. While no such litigation has been brought against us and we have not been held by any court to have infringed a third party's intellectual property rights, we cannot guarantee that our technology, VOWST or our product candidates, or use of VOWST or our product candidates do not infringe third-party patents.

 We are aware of numerous patents and pending applications owned by third parties in the fields in which we are developing product candidates, both in the United States and elsewhere. However, we may have failed to identify relevant third-party patents or applications. For example, applications filed before November 29, 2000 and certain applications filed after that date that will not be filed outside the United States remain confidential until patents issue. Moreover, it is difficult for industry participants, including us, to identify all third-party patent rights that may be relevant to VOWST or our product candidates and technologies because patent

 searching is imperfect due to differences in terminology among patents, incomplete databases and the difficulty in assessing the meaning of patent claims. We may fail to identify relevant patents or patent applications or may identify pending patent applications of potential interest but incorrectly predict the likelihood that such patent applications may issue with claims of relevance to our technology, VOWST or our product candidates. In addition, we may be unaware of one or more issued patents that would be infringed by the manufacture, sale or use of VOWST or our product candidates, or we may incorrectly conclude that a third-party patent is invalid, unenforceable or not infringed by our activities. Additionally, pending patent applications that have been published can, subject to certain limitations, be later amended in a manner that could cover our technologies, VOWST or our product candidates or the use of VOWST or our product candidates. We are aware of several pending patent applications containing one or more claims that could be construed to cover VOWST, some of our product candidates or technology, should those claims issue in their original form or in the form presently being pursued. In addition, we are aware of third-party patent families that include issued and allowed patents, including in the United States, including claims that, if valid and enforceable, could be construed to cover VOWST, some of our product candidates or their methods of use. On April 25, 2017, we filed a notice of opposition in the European Patent Office challenging the validity of a patent issued to The University of Tokyo and requesting that it be revoked in its entirety for the reasons set forth in our opposition. The oral proceedings were held at the European Patent Office on February 18, 2019 and the Opposition Division required The University of Tokyo to narrow the scope of the claims of the patent. The University of Tokyo appealed certain aspects of the Oppositions Division's decision, as did we and other opponents. On November 18, 2022, The University of Tokyo requested termination of the appeal proceeding and revocation of its patent. On December 19, 2022, the Opposition Division officially terminated the appeal proceeding, and European Patent No. 2 575 835 B1 has been revoked in its entirety.

 The biotechnology and pharmaceutical industries are characterized by extensive litigation regarding patents and other intellectual property rights. Other parties may allege that VOWST, our product candidates, or the use of our technologies infringes patent claims or other intellectual property rights held by them or that we are employing their proprietary technology without authorization. We may become party to, or threatened with, future adversarial proceedings or litigation regarding intellectual property rights with respect to VOWST, our product candidates and technology, including interference or derivation proceedings before the USPTO and similar bodies in other countries. Third parties may assert infringement claims against us based on existing intellectual property rights and intellectual property rights that may be granted in the future. If we were to challenge the validity of an issued U.S. patent in court, such as an issued U.S. patent of potential relevance to some of VOWST, our product candidates or methods of use, we would need to overcome a statutory presumption of validity that attaches to every U.S. patent. This means that in order to prevail, we would have to present clear and convincing evidence as to the invalidity of the patent's claims. There is no assurance that a court would find in our favor on questions of infringement or validity.

 Patent and other types of intellectual property litigation can involve complex factual and legal questions, and their outcome is uncertain. If we are found or believe there is a risk we may be found, to infringe a third party's intellectual property rights, we could be required or may choose to obtain a license from such third party to continue developing and marketing VOWST, our product candidates and technology. However, we may not be able to obtain any such license on commercially reasonable terms or at all. Even if we were able to obtain a license, it could be non-exclusive, thereby giving our competitors access to the same technologies licensed to us. We could be forced, including by court order, to cease commercializing the infringing technology or product. In addition, we could be found liable for monetary damages, including treble damages and attorneys' fees if we are found to have willfully infringed a patent. A finding of infringement could prevent us from commercializing VOWST or our product candidates or force us to cease some of our business operations, which could materially harm our business. Claims that we have misappropriated the confidential information or trade secrets of third parties could have a similar negative impact on our business.

 Even if we are successful in these proceedings, we may incur substantial costs and divert management time and attention in pursuing these proceedings, which could have a material adverse effect on us. If we are unable to avoid infringing the patent rights of others, we may be required to seek a license, defend an infringement action or challenge the validity of the patents in court, or redesign VOWST or our product candidates. Patent litigation is costly and time-consuming. We may not have sufficient resources to bring these actions to a successful conclusion. In addition, intellectual property litigation or claims could force us to do one or more of the following:

 • cease developing, selling or otherwise commercializing VOWST or our product candidates;

 • pay substantial damages for past use of the asserted intellectual property;

 • obtain a license from the holder of the asserted intellectual property, which license may not be available on reasonable terms, if at all; and

 • in the case of trademark claims, redesign, or rename, some or all of our product candidates or other brands to avoid infringing the intellectual property rights of third parties, which may not be possible and, even if possible, could be costly and time-consuming.

 Any of these risks coming to fruition could have a material adverse effect on our business, results of operations, financial condition and prospects.

 Issued patents covering VOWST or our product candidates could be found invalid or unenforceable or could be interpreted narrowly if challenged in court.

 Competitors may infringe our intellectual property, including our patents or the patents of our licensors. As a result, we may be required to file infringement claims to stop third-party infringement or unauthorized use. This can be expensive, particularly for a company of our size, and time-consuming. If we initiated legal proceedings against a third party to enforce a patent, if and when issued, covering VOWST or one of our product candidates, the defendant could counterclaim that the patent covering VOWST or our product candidate is invalid and/or unenforceable. In patent litigation in the United States, defendant counterclaims alleging invalidity and/or unenforceability are commonplace. Grounds for a validity challenge include alleged failures to meet any of several statutory requirements, including lack of novelty, obviousness or non-enablement, or failure to claim patent eligible subject matter. Grounds for unenforceability assertions include allegations that someone connected with prosecution of the patent withheld relevant information from the USPTO, 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, such as opposition proceedings. Such proceedings could result in revocation or amendment of our patents in such a way that they no longer cover our product candidates or competitive products. The outcome following legal assertions of invalidity and unenforceability is unpredictable. With respect to validity, 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 VOWST or our product candidates. Moreover, even if not found invalid or unenforceable, the claims of our patents could be construed narrowly or in a manner that does not cover the allegedly infringing technology in question. Such a loss of patent protection would have a material adverse impact on our business.

 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 noncompliance with these requirements.

 Periodic maintenance fees on any issued patent are due to be paid to the USPTO and foreign patent agencies in several stages over the lifetime of the patent and, in some jurisdictions, during the pendency of a patent application. The USPTO and various foreign governmental patent agencies require compliance with a number of procedural, documentary, fee payment and other similar provisions during the patent application process. While an inadvertent lapse can in many cases be cured by payment of a late fee or by other means in accordance with the applicable rules, there are situations in which noncompliance 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. Noncompliance events that could result in abandonment or lapse of a patent or patent application include, but are not limited to, failure to respond to official actions within prescribed time limits, non-payment of fees and failure to properly legalize and submit formal documents. In such an event, our competitors might be able to enter the market, which would have a material adverse effect on our business.

 We may be subject to claims challenging the inventorship or ownership of our patents and other intellectual property.

 It is our policy to enter into confidentiality and intellectual property assignment agreements with our employees, consultants, contractors and advisors. These agreements generally provide that inventions conceived by the party in the course of rendering services to us will be our exclusive property. However, these agreements may not be honored and may not effectively assign intellectual property rights to us. For example, even if we have a consulting agreement in place with an academic advisor pursuant to which such academic advisor is required to assign any inventions developed in connection with providing services to us, such academic advisor may not have the right to assign such inventions to us, as it may conflict with his or her obligations to assign all such intellectual property to his or her employing institution.

 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.

 We may be subject to claims by third parties asserting that our employees or we have misappropriated their intellectual property, or claiming ownership of what we regard as our own intellectual property.

 Many of our employees were previously employed at universities or other biotechnology or pharmaceutical companies, including our competitors or potential competitors. We may also engage advisors and consultants who are concurrently employed at universities or other organizations or who perform services for other entities. Although we try to ensure that our employees, advisors and consultants 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, advisors or consultants have used or disclosed intellectual property, including trade secrets or other proprietary information, of any such party's former or current employer or in violation of an agreement with another party. Although we have no knowledge of any such claims being alleged to date, if such claims were to arise, litigation may be necessary to defend against any such claims.

 In addition, while it is our policy to require our employees, consultants, advisors and contractors who may be involved in the development of intellectual property to execute agreements assigning such intellectual property to us, we may be unsuccessful in executing such an agreement with each party who in fact develops intellectual property that we regard as our own. Our and their assignment agreements may not be self-executing or may be breached, and we may be forced to bring claims against third parties, or defend claims they may bring against us, to determine the ownership of what we regard as our intellectual property. Similarly, we may be subject to claims that an employee, advisor or consultant performed work for us that conflicts with that person's obligations to a third party, such as an employer, and thus, that the third party has an ownership interest in the intellectual property arising out of work performed for us. Litigation may be necessary to defend against these claims. Although we have no knowledge of any such claims being alleged to date, if such claims were to arise, litigation may be necessary to defend against any such claims.

 If we fail in prosecuting or defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights or personnel. Even if we are successful in prosecuting or defending against such claims, litigation could result in substantial costs and be a distraction to management.

 If our trademarks and trade names are not adequately protected, then we may not be able to build name recognition in our markets of interest and our business may be adversely affected.

 Our registered or unregistered trademarks or trade names may be challenged, infringed, circumvented or declared generic or determined to be infringing on other marks. We may not be able to protect our rights to these trademarks and trade names, which we need to build name recognition among potential collaborators or customers in our markets of interest. At times, competitors may adopt trade names or trademarks similar to ours, thereby impeding our ability to build brand identity and possibly leading to market confusion. In addition, there could be potential trade name or trademark infringement claims brought by owners of other registered trademarks or trademarks that incorporate variations of our registered or unregistered trademarks or trade names. Over the long term, if we are unable to establish name recognition based on our trademarks and trade names, then we may not be able to compete effectively and our business may be adversely affected. Our efforts to enforce or protect our proprietary rights related to trademarks, trade secrets, domain names, copyrights or other intellectual property may be ineffective and could result in substantial costs and diversion of resources and could adversely impact our financial condition or results of operations.

 We will not seek to protect our intellectual property rights in all jurisdictions throughout the world and we may not be able to adequately enforce our intellectual property rights even in the jurisdictions where we seek protection.

 Filing, prosecuting and defending patents on product candidates in all countries and jurisdictions throughout the world would be prohibitively expensive, and our intellectual property rights in some countries outside the United States could be less extensive than in the United States, assuming that rights are obtained in the United States and assuming that rights are pursued outside the United States. The statutory deadlines for pursuing patent protection in individual foreign jurisdictions are based on the priority date of each of our patent applications. For each of the patent families that we believe provide coverage for our product candidates, we decide whether and where to pursue protection outside 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, even if we do elect to pursue patent rights outside the United States, we may not be able to obtain relevant claims and/or 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.

 Additionally, Europe's Unified Patent Court, or UPC, may present uncertainties for our ability to protect and enforce our patent rights against competitors in Europe. Although this new court has been implemented to provide more certainty and efficiency to patent enforcement throughout Europe, it will also provide our competitors with a new forum to use to centrally challenge our patents if opted into the UPC, rather than having to seek invalidity or non-infringement decisions on a country-by-country basis. It will be several years before the scope of patent rights that will be recognized and the strength of patent remedies that will be provided is known.

 Competitors may use our technologies in jurisdictions where we do not pursue and obtain 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. Even if we pursue and obtain issued patents in particular jurisdictions, our patent claims or other intellectual property rights may not be effective or sufficient to prevent third parties from so competing.

 The laws of some foreign countries do not protect intellectual property rights to the same extent as the laws of the United States. Many companies have encountered significant problems in protecting and defending intellectual property rights in certain foreign jurisdictions. The legal systems of some countries, particularly developing countries, do not favor the enforcement of patents and other intellectual property protection, especially those relating to biotechnology. This could make it difficult for us to stop the infringement of our patents, if obtained, or the misappropriation of our other intellectual property rights. For example, many foreign countries have compulsory licensing laws under which a patent owner must grant licenses to third parties. In addition, many countries limit the enforceability of patents against third parties, including government agencies or government contractors. In these countries, patents

 may provide limited or no benefit. Patent protection must ultimately be sought on a country-by-country basis, which is an expensive and time-consuming process with uncertain outcomes. Accordingly, we may choose not to seek patent protection in certain countries, and we will not have the benefit of patent protection in such countries.

 If our ability to obtain and, if obtained, enforce our patents to stop infringing activities is inadequate, third parties may compete with our products, and our patents or other intellectual property rights may not be effective or sufficient to prevent them from competing. Accordingly, our intellectual property rights around the world may be inadequate to obtain a significant commercial advantage from the intellectual property we develop or license.

 Risks Related to Our Operations

 We may be unable to realize the expected benefits from our Restructuring Plan and our business might be adversely affected.

 In November 2023, we announced that, based on a challenging macro environment and financial backdrop, a Restructuring Plan to focus our business operations to prioritize the commercialization of VOWST and the completion of the SER-155 Phase 1b study, while significantly reducing costs and supporting longer-term business sustainability. Under the Restructuring Plan, we reduced our workforce by approximately 41% and significantly scaled back all non-partnered research and development activities other than the completion of the SER-155 Phase 1b study. The Restructuring Plan has been substantially implemented.

 These types of restructuring and cost reduction activities are complex and may result in unintended consequences and costs, such as unforeseen delays in the implementation of our strategic initiatives, business and operational disruptions, decreased employee morale and retention, loss of institutional knowledge and expertise, and potential impacts on financial reporting. The significant reduction in our workforce under the Restructuring Plan 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. In addition, the decision to significantly scale back all non-partnered research and development activities other than the completion of the SER-155 Phase 1b study may negatively impact our growth, competitive positioning, business and results of operations. If we do not successfully manage the impact of the Restructuring Plan or any other similar activities that we may undertake in the future, we may not achieve the expected costs savings and other expected benefits in the expected timeframe or at all, and our business, financial condition, and results of operations may be materially adversely affected.

 Our future success depends on our ability to retain key executives and to attract, retain and motivate qualified personnel.

 We are highly dependent on Eric Shaff, our President and Chief Executive Officer, as well as the other principal members of our management, scientific and clinical team. Although we have entered into employment agreements with our executive officers, each of them may terminate their employment with us at any time. We do not maintain "key person" insurance for any of our executives or other employees.

 Recruiting and retaining qualified scientific, clinical, manufacturing and sales and marketing personnel will also be critical to our success. The loss of the services of our executive officers or other key employees could impede the achievement of our research, development and commercialization objectives and seriously harm our ability to successfully implement our business strategy. Furthermore, replacing executive officers and key employees may be difficult and may take an extended period of time because of the limited number of individuals in our industry with the breadth of skills and experience required to successfully develop, gain regulatory approval of and commercialize products. Competition to hire from this limited pool is intense, and we may be unable to hire, train, retain or motivate these key personnel on acceptable terms given the competition among numerous pharmaceutical and biotechnology companies for similar personnel. We also experience competition for the hiring of scientific and clinical personnel from universities and research institutions. Our Restructuring Plan may make it more difficult for us to hire qualified personnel. In addition, we rely on consultants and advisors, including scientific and clinical advisors, to assist us in formulating our research and development and commercialization strategy and execution. Our consultants and advisors may be employed by employers other than us and may have commitments under consulting or advisory contracts with other entities that may limit their availability to us. If we are unable to continue to attract and retain high quality personnel, our ability to pursue our growth strategy will be limited.

 A variety of risks associated with operating internationally could materially adversely affect our business.

 We currently have limited international operations, but our business strategy incorporates potentially expanding internationally with respect to VOWST and if any of our product candidates receive regulatory approval. We have conducted clinical studies in Australia and New Zealand in the past, and may in the future conduct clinical studies in other countries as well. We currently plan to rely on collaborators, including Nestl, to commercialize certain approved products outside of North America. Also, for certain manufacturing services for VOWST, we rely on GenIbet in Portugal, and Bacthera, which has substantially completed a dedicated full-scale production suite for us in Switzerland. Doing business internationally involves a number of risks, including but not limited to:

 • multiple, conflicting and changing laws and regulations, such as privacy regulations, tax laws, export and import restrictions, employment laws, regulatory requirements and other governmental approvals, permits and licenses;

 • failure by us to obtain and maintain regulatory approvals for the use of our products in various countries;

 • additional potentially relevant third-party patent rights;

 • complexities and difficulties in obtaining protection and enforcing our intellectual property;

 • difficulties in staffing and managing foreign operations;

 • complexities associated with managing multiple payor reimbursement regimes, government payors or patient self-pay systems;

 • limits in our ability to penetrate international markets;

 • global macroeconomic conditions, including a continued increase in inflation rates or interest rates, labor shortages, supply chain shortages, disruptions and instability in the banking industry and other parts of the financial services sector, or other economic, political or legal uncertainties or adverse developments;

 • financial risks, such as longer payment cycles, difficulty collecting accounts receivable, the impact of local and regional financial crises on demand and payment for our products and exposure to foreign currency exchange rate fluctuations;

 • terrorism and/or political instability, unrest and wars, such as the conflicts involving Ukraine and Russia or Israel and its surrounding regions, which could delay or disrupt our business, and if such political unrest escalates or spills over to or otherwise impacts additional regions it could heighten many of the other risk factors included in this Item 1A;

 • natural disasters (including as a result of climate change), which could cause significant damage to the infrastructure upon which our business operations rely, and the timing, nature or severity of which we may be unable to prepare for;

 • economic instability, outbreak of disease or epidemics such as the COVID-19 pandemic, boycotts, curtailment of trade and other business restrictions;

 • certain expenses including, among others, expenses for travel, translation and insurance; and

 • regulatory and compliance risks that relate to maintaining accurate information and control over sales and activities that may fall within the purview of the U.S. Foreign Corrupt Practices Act, its books and records provisions, or its anti-bribery provisions.

 Any of these factors could significantly harm our future international expansion and operations and, consequently, our results of operations.

 Our business and operations may suffer in the event of information technology system failures, cyberattacks or deficiencies in our cybersecurity.

 In the ordinary course of our business, we collect and store sensitive data, including personally identifiable information, intellectual property and proprietary business information owned or controlled by ourselves or our employees, customers and other third-parties. We manage and maintain our applications and data utilizing a combination of on-site systems and cloud-based data centers. We utilize external security and infrastructure vendors to manage parts of our data centers, and as a result a number of third-party vendors may or could have access to our confidential information. These applications and data encompass a wide variety of business-critical information, including research and development information, customer information, commercial information and business and financial information. We face a number of risks relative to protecting this critical information, including loss of access risk, inappropriate or unauthorized access, use, modification or disclosure, and the risk of our being unable to adequately monitor and audit and modify our controls over our confidential information. This risk extends to the third-party vendors and subcontractors we use to manage this sensitive data or otherwise process it on our behalf. The secure processing, storage, maintenance and transmission of this critical information are vital to our operations and business strategy, and we devote significant resources to protecting such information.

 Although we take reasonable measures to protect sensitive data from unauthorized access, use or disclosure, our information technology systems and those of our third-party service providers, strategic partners and other contractors or consultants are vulnerable to attack, damage and interruption from computer viruses and malware (e.g., ransomware), 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 organization, or persons with access to systems inside our organization.

 We may also face increased cybersecurity risks due to our reliance on internet technology and the number of our employees who continue to work 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.

 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 such an event were to occur and cause interruptions in our operations, it could result in a material disruption of our development programs and our business operations, whether due to a loss, corruption or unauthorized disclosure of our trade secrets, personal information or other proprietary or sensitive information or other similar disruptions. If we or our third-party vendors were to experience a significant cybersecurity breach of our or their information technology systems or data, the costs associated with the investigation and remediation could be material. Any such real or perceived unauthorized access or use, breach, or other loss of confidential information could also result in regulatory scrutiny, reputational harm, legal claims or proceedings, and liability under federal or state laws that protect the privacy of personal information, and regulatory enforcement, including penalties or fines. Notice of breaches may be required to affected individuals or state, federal or foreign regulators, and for extensive breaches, notice may need to be made to the media or State Attorneys General. Such notifications could be costly, harm our reputation and our ability to compete. Although we have implemented security measures to prevent unauthorized access, such data is currently accessible through multiple channels, and there is no guarantee that our cybersecurity risk management program and processes, including our policies, controls or procedures, will be fully implemented, complied with or effective in protecting our systems and data from breach.

 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 in the U.S. and abroad. 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 regulation, 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 results of operations, financial performance and business.

 In the U.S., HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act, and their implementing regulations, or collectively HIPAA, imposes privacy, security and breach notification obligations on certain healthcare providers, health plans, and healthcare clearinghouses, known as covered entities, as well as their business associates that perform certain services that involve creating, receiving, maintaining or transmitting individually identifiable health information for or on behalf of such covered entities, and their covered subcontractors. Most healthcare providers, including research institutions from which we obtain clinical trial information, are subject to privacy and security regulations promulgated under HIPAA. We do not believe that we are currently acting as a covered entity or business associate under HIPAA and thus are not regulated under HIPAA. However, any person may be prosecuted under HIPAA's criminal provisions either directly or under aiding-and-abetting or conspiracy principles. Consequently, depending on the facts and circumstances, we could face substantial criminal penalties if we knowingly receive individually identifiable health information from a HIPAA-covered healthcare provider or research institution that has not satisfied HIPAA's requirements for disclosure of individually identifiable health information.

 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. Such laws and regulations will be subject to interpretation by various courts and other governmental authorities, thus creating potentially complex compliance issues for us and our future customers and strategic partners. For example, the California Consumer Privacy Act, as amended by the California Privacy Rights Act or collectively, CCPA, requires certain businesses that process personal information of California residents to, among other things: provide certain disclosures to California residents regarding the business's collection, use, and disclosure of their personal information; 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 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 also be required. Similar laws have passed in other states, and continue 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, or 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. 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.

 Our operations abroad may also be subject to increased scrutiny or attention from data protection authorities. For example, in Europe, the European Union General Data Protection Regulation, or the GDPR, went into effect in May 2018 and imposes strict requirements for processing the personal data of individuals within the European Economic Area, or EEA, or in the context of our activities within the 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 undertaking, whichever is greater. In addition to fines, a breach of the GDPR may result in regulatory investigations, reputational damage, orders to cease/ change our data processing activities, enforcement notices, assessment notices (for a compulsory audit) and/ or civil claims (including class actions). 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 EU states that reliance on the standard contractual clauses, or 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-U.S. Data Privacy Framework, or 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 UK's departure from the European Union, we are also subject to the UK General Data Protection Regulation and Data Protection Act 2018, or collectively, the UK GDPR, 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 undertaking's global annual revenue for the preceding financial year, whichever is greater. On October 12, 2023, the UK Extension to the DPF came into effect (as approved by the UK Government), as a data transfer mechanism from the UK 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.

 Although we work to comply with applicable laws, regulations and standards, our contractual obligations and other legal obligations, these requirements are evolving and may be modified, interpreted and applied in an inconsistent manner from one jurisdiction to another, and may conflict with one another or other legal obligations with which we must comply. Any failure or perceived failure by us or our employees, representatives, contractors, consultants, collaborators, or other third parties to comply with such requirements or adequately address privacy and security concerns, even if unfounded, could result in additional cost and liability to us, damage our reputation, and adversely affect our business and results of operations.

 Acquisitions or joint ventures could disrupt our business, cause dilution to our stockholders and otherwise harm our business.

 We may acquire other businesses, products or technologies as well as pursue strategic alliances, joint ventures, technology licenses or investments in complementary businesses. We have not made any acquisitions to date, and our ability to do so successfully is unproven. Any of these transactions could be material to our financial condition and operating results and expose us to many risks, including:

 • disruption in our relationships with future customers or with current or future distributors or suppliers as a result of such a transaction;

 • unanticipated liabilities related to acquired companies;

 • additional exposure to cybersecurity risks and vulnerabilities from any newly acquired information technology infrastructure;

 • difficulties integrating acquired personnel, technologies and operations into our existing business;

 • diversion of management time and focus from operating our business to acquisition integration challenges;

 • increases in our expenses and reductions in our cash available for operations and other uses;

 • possible write-offs or impairment charges relating to acquired businesses; and

 • inability to develop a sales force for any additional product candidates.

 Foreign acquisitions involve unique risks in addition to those mentioned above, including those related to integration of operations across different cultures and languages, currency risks and the particular economic, political and regulatory risks associated with specific countries.

 Also, the anticipated benefit of any acquisition may not materialize. Future acquisitions or dispositions could result in potentially dilutive issuances of our equity securities, the incurrence of debt, contingent liabilities or amortization expenses or write-offs of goodwill, any of which could harm our financial condition. We cannot predict the number, timing or size of future joint ventures or acquisitions, or the effect that any such transactions might have on our operating results.

 We have in the past been subject to securities class action litigation and may be subject to similar or other litigation in the future, which may harm our business.

 Securities class action litigation has often been brought against a company following a decline in the market price of its securities. This risk is especially relevant for us because biopharmaceutical companies have experienced significant stock price volatility in recent years. On September 28, 2016, a purported stockholder filed a putative class action lawsuit in the U.S. District Court for the District of Massachusetts against us entitled Mariusz Mazurek v. Seres Therapeutics, Inc., et.al. alleging false and misleading statements and omissions about our clinical trials for our then product candidate SER-109 in our public disclosures between June 25, 2015 and July 29, 2016. Although this lawsuit has been dismissed by the court, should we face similar or other litigation again, it could result in substantial costs and a diversion of management's attention and resources, which could harm our business. In addition, the uncertainty of a pending lawsuit or potential filing of additional lawsuits could lead to more volatility and a reduction in our stock price.

 If we fail to comply with environmental, health and safety laws and regulations, we could become subject to fines or penalties or incur costs that could harm our business.

 We are subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the handling, use, storage, treatment and disposal of hazardous materials and wastes. Our operations involve the use of hazardous and flammable materials, including chemicals and biological materials such as human stool. Our operations also produce hazardous waste products. We generally contract with third parties for the disposal of these materials and wastes. We cannot eliminate the risk of contamination or injury, including from the novel coronavirus SARS-CoV-2, which causes the COVID-19 disease, from these materials. In the event of contamination or injury resulting from our use of hazardous materials, we could be held liable for any resulting damages, and any liability could exceed our resources. We also could incur significant costs associated with civil or criminal fines and penalties for failure to comply with such laws and regulations.

 Although we maintain workers' compensation insurance to cover us for costs and expenses we may incur due to injuries to our employees resulting from the use of hazardous materials, this insurance may not provide adequate coverage against potential liabilities. We do not maintain insurance for environmental liability or toxic tort claims that may be asserted against us in connection with our storage or disposal of biological, hazardous or radioactive materials.

 In addition, we may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations. These current or future laws and regulations may impair our research, development or production efforts. Our failure to comply with these laws and regulations also may result in substantial fines, penalties or other sanctions.

 Our ability to use our net operating loss carryforwards and research and development credits to offset future taxable income or income tax liabilities may be subject to certain limitations.

 As of December 31, 2023, we had net operating loss carryforwards, or NOLs, of $527.1 million for federal income tax purposes and $504.2 million for state income tax purposes, which may be available to offset our future taxable income, if any. Our federal NOLs subject to expiration begin to expire in various amounts in 2035. Our federal NOLs generated in taxable years beginning after December 31, 2017 are not subject to expiration, but may generally only be used to offset 80% of taxable income in years beginning after December 31, 2020. Our state NOLs also begin to expire in various amounts in 2035. As of December 31, 2023, we also had federal and state research and development and other tax credit carryforwards of approximately $45.1 million and $7.7 million, respectively, net of uncertain tax position reserves, available to reduce future income tax liabilities, if any. Our federal and state tax credit carryforwards begin to expire in various amounts in 2031 and 2028, respectively. The federal research and development tax credit carryforwards include an orphan drug credit carryforward of $25.9 million. These NOLs and tax credit carryforwards could expire unused, to the extent subject to expiration, and be unavailable to offset future taxable income or income tax liabilities.

 In addition, in general, under Sections 382 and 383 of the U.S. Internal Revenue Code of 1986, as amended (the "Code"), a corporation that undergoes an "ownership change" is subject to limitations on its ability to use its pre-change NOLs and tax credit carryforwards to offset future taxable income and income taxes. For these purposes, an ownership change generally occurs where the aggregate change in stock ownership of one or more stockholders or groups of stockholders owning at least 5% of a corporation's

 stock exceeds 50 percentage points over a rolling three-year period. Similar rules may apply under state tax laws. We have experienced ownership changes in the past, per a Section 382 study performed through December 31, 2020. We believe that none of our existing tax assets will expire unused as a result of the calculated limitations resulting from such ownership changes. However, we may have experienced additional ownership changes since December 31, 2020, and we may experience ownership changes in the future as a result of future transactions in our stock, some of which may be outside our control. If we have undergone additional ownership changes, or if we undergo ownership changes in the future, our ability to use our NOLs and tax credit carryforwards could be further limited. For these reasons, we may not be able to use a material portion of our NOLs or tax credit carryforwards, even if we attain profitability. We have recorded a full valuation allowance related to our NOLs and other deferred tax assets due to the uncertainty of the ultimate realization of the future tax benefits of such assets.

 The terms of the Oaktree Credit Agreement place restrictions on our operating and financial flexibility. If we raise additional capital through debt financing, the terms of any new debt could further restrict our ability to operate our business.

 On April 27, 2023, we entered into the Oaktree Credit Agreement, which establishes a term loan facility of $250.0 million, consisting of (i) the Tranche A Loan, funded on the Oaktree Closing Date, (ii) the Tranche B Loan, that we may borrow subject to certain conditions, (iii) the Tranche C Loan, that we may borrow subject to certain conditions, and (iv) the Tranche D Loan, available in Oaktree's sole discretion (collectively with the Tranche A Loan, the Tranche B Loan, the Tranche C Loan, and the Tranche D Loan, the "Oaktree Term Loan"). We may draw the Tranche B Loan until September 30, 2024, if VOWST net sales for the trailing six consecutive months are at least $35.0 million and at least 4.5% greater in the calendar quarter prior to the Applicable Funding Date (as defined in the Oaktree Credit Agreement) over the calendar quarter immediately preceding it. We may draw the Tranche C Loan until September 30, 2025, if VOWST net sales for the trailing 12 consecutive months are at least $120.0 million and at least 4.5% greater in each of the two calendar quarters prior to the Applicable Funding Date relative, in each case, to the calendar quarter immediately preceding it. The Oaktree Term Loan has a maturity date of April 27, 2029 (the "Oaktree Maturity Date").

 Our obligations under the Oaktree Credit Agreement and the other Loan Documents (as defined in the Oaktree Credit Agreement) will be guaranteed by any of our domestic subsidiaries that become Guarantors (as defined in the Oaktree Credit Agreement), subject to certain exceptions. Our and our Guarantors' (collectively, the "Loan Parties") respective obligations under the Oaktree Credit Agreement and the other Loan Documents are secured by first priority security interests in substantially all assets of the Loan Parties, including intellectual property, subject to certain customary thresholds and exceptions. As of December 31, 2023, there are no Guarantors.

 The Oaktree Credit Agreement contains customary representations, warranties and affirmative and negative covenants, including a financial covenant requiring us to maintain certain levels of cash and cash equivalents in accounts subject to a control agreement in favor of the Agent of at least $30.0 million at all times commencing from 30 days after the Oaktree Closing Date and decreasing to $25.0 million of cash and cash equivalents in such controlled accounts after we borrow any Tranche B Loan. As of December 31, 2023, we were in compliance with all financial covenants pursuant to the Oaktree Credit Agreement.

 In addition, the Oaktree Credit Agreement contains certain events of default that entitle the Agent to cause our indebtedness under the Oaktree Credit Agreement to become immediately due and payable, and to exercise remedies against the Loan Parties and the collateral securing the Oaktree Term Loan, including cash. Under the Oaktree Credit Agreement, an event of default will occur if, among other things, we fail to make payments under the Oaktree Credit Agreement (subject to specified cure periods with respect to certain payments), we or our subsidiaries breach any of the covenants under the Oaktree Credit Agreement (subject to specified cure periods with respect to certain breaches), a material adverse change occurs, we, our subsidiaries or our or their respective assets become subject to certain legal proceedings, such as bankruptcy proceedings, we and/or our subsidiaries are unable to pay our or their debts as they become due or default on contracts with third parties which would permit the holder of indebtedness in excess of a certain threshold to accelerate the maturity of such indebtedness or that could cause a material adverse change. Upon the occurrence and for the duration of an event of default, an additional default interest rate equal to 2.0% per annum may apply to all obligations owed under the Oaktree Credit Agreement.

 Any declaration by the Oaktree Lenders of an event of default could significantly harm our business and prospects and could cause the price of our common stock to decline. If we raise any additional debt financing, the terms of such additional debt could further restrict our operating and financial flexibility.

 Risks Related to Our Common Stock

 Our executive officers, directors and principal stockholders, if they choose to act together, have the ability to significantly influence all matters submitted to stockholders for approval.

 Our executive officers, directors and stockholders who owned more than 5% of our outstanding common stock and their respective affiliates, in the aggregate, hold shares representing approximately 43% of our outstanding voting stock as of December 31, 2023. As a result, if these stockholders were to choose to act together, they would be able to significantly influence all matters submitted to our stockholders for approval, as well as our management and affairs. For example, these persons, if they choose to act

 together, would significantly influence the election of directors and approval of any merger, consolidation or sale of all or substantially all of our assets. This concentration of ownership control may:

 • delay, defer or prevent a change in control;

 • entrench our management and the board of directors; or

 • impede a merger, consolidation, takeover or other business combination involving us that other stockholders may desire.

 A significant portion of our total outstanding shares are eligible to be sold into the market, which could cause the market price of our common stock to drop significantly, even if our business is doing well.

 Sales of a substantial number of shares of our common stock in the public market, or the perception in the market that the holders of a large number of shares intend to sell shares, could reduce the market price of our common stock. We have also registered and intend to continue to register all shares of common stock that we may issue under our equity compensation plans. Once we register these shares, they can be freely sold in the public market upon issuance, subject to volume limitations applicable to affiliates.

 We are a "smaller reporting company," and the reduced disclosure requirements applicable to smaller reporting companies may make our common stock less attractive to investors.

 We are a "smaller reporting company" as defined under the rules promulgated under the Exchange Act. We will remain a smaller reporting company until the fiscal year following the determination that both (i) the value of our voting and non-voting common shares held by non-affiliates is more than $250 million measured on the last business day of our second fiscal quarter and (ii) our annual revenues are more than $100 million during the most recently completed fiscal year and the value of our voting and non voting common shares held by non-affiliates is $700 million or more as measured on the last business day of our second fiscal quarter. Smaller reporting companies are able to provide simplified executive compensation disclosure and have certain other reduced disclosure obligations, including, among other things, being required to provide only two years of audited financial statements and not being required to provide selected financial data, or supplemental financial information.

 We have elected to take advantage of certain of the reduced reporting obligations, and may in the future take advantage of these or others. We cannot predict whether investors will find our common stock less attractive if we rely on these exemptions. If some investors find our common stock less attractive as a result, there may be a less active trading market for our common stock and our stock price may be reduced or more volatile.

 Provisions in our restated certificate of incorporation and amended and restated bylaws and under Delaware law could make an acquisition of our company, which may be beneficial to our stockholders, more difficult and may prevent attempts by our stockholders to replace or remove our current management.

 Provisions in our restated certificate of incorporation and our amended and restated bylaws may discourage, delay or prevent a merger, acquisition or other change in control of our company that stockholders may consider favorable, including transactions in which stockholders might otherwise receive a premium for their shares. These provisions could also limit the price that investors might be willing to pay in the future for shares of our common stock, thereby depressing the market price of our common stock. In addition, because our board of directors is responsible for appointing the members of our management team, these provisions may frustrate or prevent any attempts by our stockholders to replace or remove our current management by making it more difficult for stockholders to replace members of our board of directors. Among other things, these provisions include those establishing:

 • a classified board of directors with three-year staggered terms, which may delay the ability of stockholders to change the membership of a majority of our board of directors;

 • no cumulative voting in the election of directors, which limits the ability of minority stockholders to elect director candidates;

 • the exclusive right of our board of directors to elect a director to fill a vacancy created by the expansion of the board of directors or the resignation, death or removal of a director, which prevents stockholders from filling vacancies on our board of directors;

 • the ability of our board of directors to authorize the issuance of shares of preferred stock and to determine the terms of those shares, including preferences and voting rights, without stockholder approval, which could be used to significantly dilute the ownership of a hostile acquirer;

 • the ability of our board of directors to alter our bylaws without obtaining stockholder approval;

 • the required approval of the holders of at least two-thirds of the shares entitled to vote at an election of directors to adopt, amend or repeal our bylaws or repeal the provisions of our restated certificate of incorporation regarding the election and removal of directors;

 • a prohibition on stockholder action by written consent, which forces stockholder action to be taken at an annual or special meeting of our stockholders;

 • the requirement that a special meeting of stockholders may be called only by the chairman of the board of directors, the chief executive officer, the president or the board of directors, which may delay the ability of our stockholders to force consideration of a proposal or to take action, including the removal of directors; and

 • advance notice procedures that stockholders must comply with in order to nominate candidates to our board of directors or to propose matters to be acted upon at a stockholders' meeting, which may discourage or deter a potential acquirer from conducting a solicitation of proxies to elect the acquirer's own slate of directors or otherwise attempting to obtain control of us.

 Moreover, because we are incorporated in Delaware, we are governed by the provisions of Section 203 of the General Corporation Law of the State of Delaware, which prohibits a person who owns in excess of 15% of our outstanding voting stock from merging or combining with us for a period of three years after the date of the transaction in which the person acquired in excess of 15% of our outstanding voting stock, unless the merger or combination is approved in a prescribed manner.

 Our certificate of incorporation designates the Court of Chancery of the State of Delaware, subject to certain exceptions, as the sole and exclusive forum for certain types of actions and proceedings that may be initiated by our stockholders and our bylaws designate the federal district courts of the United States as the exclusive forum for actions arising under the Securities Act of 1933, as amended, which could limit our stockholders' ability to obtain a favorable judicial forum for disputes with us or our directors, officers or employees.

 Our restated certificate of incorporation specifies 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 actions brought against us by stockholders. In addition, our bylaws provide that the federal district courts of the United States are the exclusive forum for any complaint raising a cause of action arising under 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 restated certificate of incorporation and bylaws described above.

 We believe these choice of forum provisions benefit us by providing increased consistency in the application of Delaware law by chancellors particularly experienced in resolving corporate disputes and in the application of the Securities Act by federal judges, as applicable, efficient administration of cases on a more expedited schedule relative to other forums and protection against the burdens of multi-forum litigation. However, the provisions may have the effect of discouraging lawsuits against our directors and officers. The enforceability of similar choice of forum provisions in other companies' certificates of incorporation 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 restated certificate of incorporation or bylaws to be inapplicable or unenforceable in such action. If a court were to find the choice of forum provisions contained in our restated certificate of incorporation or bylaws 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.

 Because we do not anticipate paying any cash dividends on our capital stock in the foreseeable future, capital appreciation, if any, will be the sole source of gain for our stockholders.

 We have never declared or paid cash dividends on our capital stock. We currently intend to retain all of our future earnings, if any, to finance the growth and development of our business. In addition, the Oaktree Credit Agreement currently prohibits us from paying dividends on our equity securities, and any future debt agreements may likewise preclude us from paying dividends. As a result, capital appreciation, if any, of our common stock will be our stockholders' sole source of gain for the foreseeable future.

 General Risk Factors

 The price of our common stock may be volatile and fluctuate substantially, which could result in substantial losses for purchasers of our common stock.

 Our stock price is likely to be volatile. Furthermore, the stock market in general and the market for smaller biopharmaceutical companies in particular have experienced extreme volatility that has often been unrelated to the operating performance of particular companies. As a result of this volatility, our stockholders may not be able to sell their common stock at or above the price they paid for their common stock. The market price for our common stock may be influenced by many factors, including:

 • our ability to execute and realize the benefits of strategic plans, such as the Restructuring Plan we announced in November 2023;

 • the success of competitive products or technologies;

 • actual or anticipated changes in our growth rate relative to our competitors;

 • results of clinical trials of our product candidates or those of our competitors;

 • the success of our commercialization efforts;

 • developments related to any future collaborations;

 • regulatory or legal developments in the United States and other countries;

 • development of new product candidates that may address our markets and may make our product candidates less attractive;

 • changes in physician, hospital or healthcare provider practices that may make our product candidates less useful;

 • announcements by us, our collaborators or our competitors of significant acquisitions, strategic partnerships, joint ventures, collaborations or capital commitments;

 • developments or disputes concerning patent applications, issued patents or other proprietary rights;

 • the recruitment or departure of key personnel;

 • the level of expenses related to any of our product candidates or clinical development programs;

 • failure to meet or exceed financial estimates and projections of the investment community or that we provide to the public;

 • the results of our efforts to discover, develop, acquire or in-license additional product candidates or products;

 • actual or anticipated changes in estimates as to financial results, development timelines or recommendations by securities analysts;

 • variations in our financial results or those of companies that are perceived to be similar to us;

 • changes in the structure of healthcare payment systems;

 • market conditions in the pharmaceutical and biotechnology sectors;

 • general economic, industry and market conditions; and

 • the other factors described in this "Risk Factors" section.

 If securities or industry analysts issue an adverse or misleading opinion regarding our business, our common stock price and trading volume could decline.

 The trading market for our common stock is influenced by the research and reports that industry or securities analysts publish about us or our business. If any of the analysts who cover us issue an adverse or misleading opinion regarding us, our business model, our intellectual property or our stock performance, or if our clinical studies and operating results fail to meet the expectations of analysts, our stock price would likely decline. If one or more of these analysts cease coverage of us or fail to publish reports on us regularly, we could lose visibility in the financial markets, which in turn could cause our stock price or trading volume to decline.

 We will continue to incur costs as a result of being a public company, and our management will continue to devote substantial time to compliance initiatives and corporate governance practices.

 As a public company, we have incurred and will continue to incur significant legal, accounting and other expenses. The Sarbanes-Oxley Act of 2002, the Dodd-Frank Wall Street Reform and Consumer Protection Act, the listing requirements of The Nasdaq Global Select Market and other applicable securities rules and regulations impose various requirements on public companies, including establishment and maintenance of effective disclosure and financial controls and corporate governance practices. Our management and other personnel devote and will need to continue to devote a substantial amount of time to these compliance initiatives. Moreover, these rules and regulations have increased and will continue to increase our legal and financial compliance costs and make some activities more time-consuming and costly. For example, we expect that these rules and regulations will continue to make it more difficult and more expensive for us to maintain director and officer liability insurance, which in turn could make it more difficult for us to attract and retain qualified members of our board of directors.

 These rules and regulations are often subject to varying interpretations, in many cases due to their lack of specificity, and, as a result, their application in practice may evolve over time as new guidance is provided by regulatory and governing bodies. This could result in future uncertainty regarding compliance matters and higher costs necessitated by ongoing revisions to disclosure and governance practices.

 If we fail to maintain an effective system of internal control over financial reporting, we may not be able to accurately report our financial results or prevent fraud. As a result, stockholders could lose confidence in our financial and other public reporting, which would harm our business and the trading price of our common stock.

 Effective internal control over financial reporting is necessary for us to provide reliable financial reports and, together with adequate disclosure controls and procedures, is designed to prevent fraud. Any failure to implement required new or improved controls, or difficulties encountered in their implementation could cause us to fail to meet our reporting obligations.

 Pursuant to Section 404, we are required to furnish a report by our management on our internal control over financial reporting. However, while we remain a non-accelerated filer, we will not be required to include an attestation report on internal control over financial reporting issued by our independent registered public accounting firm. If we are unable to maintain effective internal control over financial reporting, we may not have adequate, accurate or timely financial information, and we may be unable to meet our reporting obligations as a public company or comply with the requirements of the Securities and Exchange Commission or Section 404. This could result in a restatement of our financial statements, the imposition of sanctions, including the inability of registered broker dealers to make a market in our common stock, or investigation by regulatory authorities. Any such action or other negative results caused by our inability to meet our reporting requirements or comply with legal and regulatory requirements or by disclosure of an accounting, reporting or control issue could adversely affect the trading price of our securities and our business. Material weaknesses in our internal control over financial reporting could also reduce our ability to obtain financing or could increase the cost of any financing we obtain. This could result in an adverse reaction in the financial markets due to a loss of confidence in the reliability of our financial statements.

 Failure to keep up with evolving laws, regulations, trends and stakeholder expectations relating to environmental, social and governance, or ESG, practices or reporting could adversely impact our reputation, share price and access to and cost of capital or otherwise adversely impact our business.

 Certain institutional investors, investor advocacy groups, investment funds, creditors and other influential financial market participants, as well as governments, regulators, customers, patients, employees and other stakeholders or third parties, have become increasingly focused on companies' ESG practices, including the impact of business on the environment and diversity, equity and inclusion matters. Certain organizations also provide ESG ratings, scores and benchmarking studies that assess companies' ESG practices. Although there are no universal standards for such ratings, scores or benchmarking studies, they are used by some investors to inform their investment and voting decisions. It is possible that our future stockholders or organizations that report on, rate or score ESG practices will not be satisfied with our ESG strategy or performance. Unfavorable press about or ratings or assessments of our ESG strategies or practices, regardless of whether or not we comply with applicable legal requirements, may lead to negative investor sentiment toward us, which may hinder the Company's access to capital.

 Our reputation could be damaged if we do not, or are perceived not to, meet evolving stakeholder demand with respect to ESG matters, which could adversely affect our business, financial condition, profitability and cash flows. We may be criticized for our lack of ESG initiatives or goals or perceived as not taking sufficient action in connection with any of these matters. In turn, we may take certain actions, including the establishment of ESG-related goals or targets, to improve our ESG profile and/or respond to stakeholder demand; however, such actions may be costly or be subject to numerous conditions that are outside our control, and we cannot guarantee that we will meet these goals or targets or that such actions will have the desired effect even if met.

 Additionally, we and/or other parties in our value chain are subject to, or are expected to be subject to additional climate and other ESG-related obligations arising from legislation and regulation in the United States, the European Union and other jurisdictions, including new reporting requirements, even as the availability and quality of the information that may be required to comply with such laws and regulations remains limited. We expect for our compliance costs with these laws and regulations to increase in future, and any failure, or perceived failure, by us to adhere to such laws and regulations, or meet evolving and varied stakeholder expectations and standards, could harm our business, reputation, financial condition, and operating results.

 Item 1B. Unresolved Staff Comments

 None.

 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 security incident response plan.

 We design and assess our program based on the National Institute of Standards and Technology Cybersecurity Framework, or 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.

 Our cybersecurity risk management program is integrated into our overall enterprise risk management program, and shares common methodologies, reporting channels and governance processes that apply across the enterprise risk management program to other legal, compliance, strategic, operational, and financial risk areas.

 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 IT 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;

 • a security incident response plan that includes procedures for responding to cybersecurity incidents; and

 • a third-party risk management process for service providers, suppliers, and vendors who 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, "Risk Factors— Risks Related to Our Operations—Our business and operations may suffer in the event of information technology system failures, cyberattacks or deficiencies in our cybersecurity."

 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 quarterly reports from our Chief Information Officer, or CIO, on our cybersecurity risks. In addition, our CIO 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.

 Our management team, including our CIO, is 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 CIO has over three decades of IT experience in life sciences organizations. Her cybersecurity work includes the development and implementation of cybersecurity policies, platforms, and robust end-user training curriculums. Our CIO and IT Information Security Group work together to monitor and report cybersecurity trends and threats to management. Additionally, we work with an external IT partner and external cybersecurity counsel to assess, identify, and manage risks from cybersecurity threats. The IT Information Security Group undertakes table-top business disruption, disaster recovery and related response strategies, and plans on a periodic basis, and aims to review, and if appropriate update, applicable policies and procedures annually.

 Our management team and IT Information Security Group 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 public or private sources, including external consultants engaged by us; and alerts and reports produced by security tools deployed in the IT environment.

 Item 2. Properties

 Research and Offices

 Our corporate headquarters is located in Cambridge, Massachusetts, where we lease approximately 82,714 square feet of office, research, development, warehouse and laboratory space under a lease that expires in March 2033.

 Clinical Manufacturing

 We currently conduct part of our manufacturing operations in our leased facilities in Cambridge, Massachusetts, which contain manufacturing facilities for clinical products. We believe our current laboratory facilities and contract relationships are sufficient to meet our current bioprocess development and manufacturing needs. Product candidates may be brought into the facilities for economies of operation, or may remain external with contract manufacturing organizations, depending on business dynamics and development needs.

 We plan to control the production of all products under current good manufacturing practices by making strategic investments in manufacturing, which may include collaborations with third parties, the design and renovation of existing facilities and the construction of additional new facilities for commercial supply.

 Item 3. Legal Proceedings

 None.

 Item 4. Mine Safety Disclosures

 Not applicable.

 Item 5. Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

 Market Information

 Our common stock has been publicly traded on the Nasdaq Global Select Market under the symbol "MCRB" since June 26, 2015. Prior to that time, there was no public market for our common stock.

 Holders

 As of March 1, 2024, there were approximately nine 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. The 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. See "Management's Discussion and Analysis of Financial Condition and Results of Operations – Liquidity and Capital Resources."

 Recent Sales of Unregistered Securities

 We did not make any sales of unregistered securities during the quarter ended December 31, 2023.

 Purchases of Equity Securities by the Issuer or Affiliated Purchasers

 There were no repurchases of shares of common stock made during the quarter ended December 31, 2023.

 Item 6. [Reserved]

 Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations

 You should read the following discussion and analysis of our financial condition and results of operations in conjunction with our consolidated financial statements and related notes appearing elsewhere in this Annual Report on Form 10-K. Some of the information contained in this discussion and analysis or set forth elsewhere in this Annual Report on Form 10-K, such as statements regarding our plans, objectives, expectations, intentions and projections, includes forward-looking statements that involve risks and uncertainties. As a result of many factors, including those factors set forth in the ''Risk Factors'' section of this Annual Report on Form 10-K, our actual results could differ materially from the results described in, or implied by, these forward-looking statements.

 A discussion regarding our financial condition and results of operations for the years ended December 31, 2023 and 2022, including a year-to-year comparison between 2023 and 2022, is presented below. For a discussion regarding our financial condition and results of operations for the year ended December 31, 2021, including a year-to-year comparison between 2022 and 2021, refer to Part II, Item 7. "Management's Discussion and Analysis of Financial Condition and Results of Operations" in our Annual Report on Form 10-K for the fiscal year ended December 31, 2022, filed with the SEC on March 7, 2023.

 Overview

 We are a commercial-stage microbiome therapeutics company focused on the development and commercialization of a novel class of biological drugs, which are designed to treat disease by modulating the microbiome to restore health by repairing the function of a disrupted microbiome to a non-disease state. Our first drug, VOWST (fecal microbiota spores, live-brpk), formerly called SER-109, was approved by the U.S. Food and Drug Administration, or FDA, on April 26, 2023, to prevent recurrence of Clostridioides difficile infection, or CDI, in patients 18 or older following antibacterial treatment for recurrent CDI. Our drug discovery and development pipeline includes other pre-clinical and clinical-stage assets. VOWST and our microbiome therapeutic candidates are consortia of bacteria designed to optimize specific, targeted pharmacological properties, and are formulated for oral delivery. We maintain a differentiated microbiome therapeutics drug discovery and development platform that includes good manufacturing practices, or GMP, manufacturing capabilities for this novel drug modality.

 Our highest priority is the commercialization of VOWST in the United States, the first orally administered microbiome therapeutic approved by the FDA. We launched VOWST in the United States with our collaborator, Nestl Health Science, or Nestl, in June 2023.

 We are also designing microbiome therapeutics optimized to decolonize pathogens and to modulate host function to both reduce and prevent infections and induce immune tolerance. We believe that the scientific and clinical data from our SER-109 program validate this novel approach, which we refer to as Infection Protection. We believe the Infection Protection approach may be replicable across different bacterial pathogens to develop microbiome therapeutics with the potential to protect a range of medically compromised patients from infections, including pathogens that harbor antimicrobial resistance, or AMR.

 In addition, we are evaluating SER-155 in a Phase 1b study in patients undergoing allogeneic hematopoietic stem cell transplantation, or allo-HSCT, to prevent enteric-derived infections and resulting blood stream infections, as well as induce immune tolerance responses to reduce the incidence of graft-versus-host disease, or GvHD. In May 2023, we announced the Phase 1b cohort 1 results. Gastrointestinal microbiome data from the first 100 days of SER-155 Phase 1b open-label study cohort 1 showed the successful engraftment of SER-155 bacterial strains, and a substantial reduction in the cumulative incidence of pathogen domination as compared to a reference cohort of patients, a biomarker associated with the risk of serious enteric infections and resulting bloodstream infections, as well as GvHD in this patient population. The tolerability profile observed was favorable, with no serious adverse events attributed to SER-155 administration. In December 2023, we received Fast Track Designation for SER-155 to reduce the risk of infection and GvHD in patients undergoing allo-HSCT. Enrollment in the placebo-controlled cohort 2 portion of the study is ongoing, and the cohort 2 data readout is anticipated in the third quarter of 2024.

 We have progressed additional preclinical stage programs to evaluate whether microbiome therapeutics may reduce the incidence of infection in indications such as chronic liver disease, cancer neutropenia, solid organ transplant, and AMR infections more broadly in high-risk settings such as intensive care units, or ICUs. Additional efforts in the early-stage portfolio are focused on the SER-301 program in irritable bowel disease, or IBD, and programmatic objectives that are supported through a partnership with the Crohn's and Colitis Foundation, or CCF. These efforts aim to (i) confirm the functional phenotype and inflammatory state of patient subpopulations observed in our prior ulcerative colitis, or UC clinical trials, and (ii) prioritize inflammatory targets and evaluate the potential to utilize biomarker-based patient selection and stratification for future studies. In addition, we continue to leverage microbiome pharmacokinetic and pharmacodynamic data from across our clinical and preclinical portfolios, using our reverse translational microbiome therapeutic development platform to prioritize future drug targets and to identify opportunities for combination therapies across various indications, including inflammatory and immune diseases, cancer, and metabolic diseases.

 We have built and deploy a reverse translational platform and knowledge base for the discovery and development of microbiome therapeutics, and maintain extensive proprietary know-how that may be used to support future research and development efforts. This platform incorporates high-resolution analysis of human clinical data to identify microbiome biomarkers associated with disease and non-disease states; preclinical screening using human cell-based assays and in vitro/ex vivo and in vivo disease models

 customized for microbiome therapeutics; and microbiological capabilities and a strain library that spans broad biological and functional breadth. This platform and knowledge base enables both identification of specific microbes and microbial metabolites/peptides that are associated with disease and the design of therapeutic consortia of bacteria optimized for specific pharmacological properties. In addition, we own a valuable intellectual property estate related to the development and manufacture of microbiome therapeutics.

 Since our inception in October 2010, we have devoted substantially all of our resources to developing our programs, platforms, and technologies, building our intellectual property portfolio, developing our supply chain, business planning, raising capital and providing general and administrative support for these operations.

 Other than VOWST, our product candidates are still in preclinical development or early-stage discovery. Our ability to generate collaboration profit or product revenue sufficient to achieve profitability will depend heavily on the commercial success of VOWST, as well as the successful development and eventual commercialization of one or more of our product candidates. Since our inception, we have incurred significant operating losses. Our net loss was $113.7 million for the year ended December 31, 2023 and as of December 31, 2023, we had an accumulated deficit of $978.2 million.

 In November 2023, we announced a restructuring plan, or the Restructuring Plan, to prioritize the commercialization of VOWST and the completion of the SER-155 Phase 1b study, while reducing costs and supporting longer-term business sustainability. The Restructuring Plan included (i) a reduction of our workforce by approximately 41% across the organization, resulting in the elimination of approximately 160 positions; (ii) significantly scaling back all non-partnered research and development activities other than the completion of the SER-155 Phase 1b study; and (iii) reducing general and administrative expenses, including consolidating office space. The Restructuring Plan was substantially implemented around the end of fiscal 2023. In connection with the Restructuring Plan, for the year ended December 31, 2023, we incurred approximately $5.6 million in restructuring costs, primarily related to the workforce reduction, of which $5.3 million are expected to result in cash expenditures, and the remaining $0.3 million relates to stock-based compensation expense associated with the acceleration of unvested equity awards. These costs were incurred in the fourth quarter of 2023. See Note 13, Restructuring, to our audited consolidated financial statements included elsewhere in this Annual Report.

 We expect to achieve annual cash savings of approximately $75.0 million to $85.0 million in 2024, of which approximately $35.0 million is expected to result from the reduction in workforce, and which excludes any one-time charges primarily associated with the workforce reduction.

 The foregoing estimates are based upon current assumptions and expectations but are subject to known and unknown risks and uncertainties. Accordingly, we may not be able to fully realize the cost savings and benefits initially anticipated from the Restructuring Plan, and the expected costs may over time be greater than initially expected. See "Risk Factors—Risks Related to Our Operations—We may be unable to realize the expected benefits from our Restructuring Plan and our business might be adversely affected."

 While we plan to focus our investment on supporting commercialization of VOWST and on our SER-155 Phase 1b study in the near-term, our expenses may increase in connection with future activities. See "Risk Factors—Risks Related to Our Financial Position and Need for Additional Capital—We are a commercial-stage company and have incurred significant losses since our inception. We expect to incur losses for the foreseeable future and may never achieve or maintain profitability."

 In addition, if we obtain marketing approval for any more of our product candidates, we expect to incur costs related to product manufacturing and commercialization, including marketing, sales and distribution. Furthermore, we expect to continue to incur additional costs associated with operating as a public company.

 As a result, we will need additional financing to support our continuing operations. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of public or private equity or debt financings or other sources, which may include collaborations with third parties. Adequate additional financing may not be available to us on acceptable terms, or at all. For example, the trading prices for our and other biopharmaceutical companies' stock have been highly volatile as a result of factors such as the impacts of pandemics, such as COVID-19, and increases in inflation rates or interest rates. As a result, we may face difficulties raising capital through sales of our common stock and any such sales may be on unfavorable terms. Our inability to raise capital as and when needed would have a negative impact on our financial condition and our ability to pursue our business strategy. We will need to generate significant revenue to achieve profitability, and we may never do so.

 As of December 31, 2023, we had cash and cash equivalents totaling $128.0 million. Based on our currently available cash resources and our current level of operations and cash flows for the 12-month period subsequent to the date of issuance of the consolidated financial statements included elsewhere in this Annual Report on Form 10-K we will require additional funding prior to the end of 2024. In accordance with applicable accounting standards, we evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about our ability to continue as a going concern within 12 months after the date of the issuance of the consolidated financial statements included elsewhere in this Annual Report on Form 10-K. In performing this analysis, we excluded certain elements of our operating plan that cannot be considered probable of occurring. Under the

 applicable accounting standards, the receipt of potential funding from future equity issuances cannot be considered probable, as these events are outside our control. Accordingly, management has concluded that substantial doubt exists about the Company's ability to continue as a going concern for 12 months from the date the consolidated financial statements included elsewhere in this Annual Report on Form 10-K, are issued. See "Risk Factors— Risks Related to Our Financial Position and Need for Additional Capital —We have identified conditions and events that raise substantial doubt regarding our ability to continue as a going concern."

 On February 22, 2024, our board of directors adopted a resolution to amend the Restated Certificate of Incorporation, subject to stockholder approval at our annual meeting of stockholders to be held in 2024, by increasing the number of authorized shares of our Common Stock from 240,000,000 shares to 360,000,000 shares, or the Share Increase Amendment.

 VOWST

 VOWST was approved by the FDA on April 26, 2023, to prevent recurrence of CDI in individuals 18 years of age or older following antibacterial treatment for recurrent CDI. VOWST is the first FDA-approved orally administered microbiome therapeutic, and consists of a consortium of purified Firmicutes spores designed to prevent recurrent CDI in patients with a history of CDI by modulating the microbiome to a state that resists C. difficile germination and growth. The VOWST manufacturing purification process is designed to remove unwanted microbes in an effort to reduce the risk of pathogen transmission beyond donor screening alone. We estimate that there will be approximately 156,000 recurrent CDI cases in the United States during 2023.

 We launched VOWST in the United States with our collaborator, Nestl, in June 2023. Under the terms of the 2021 License Agreement, Nestl is assuming the role of lead commercialization party. We received an upfront license payment of $175 million in July 2021 and an additional $125 million in May 2023 following FDA approval of VOWST. The agreement also includes sales target milestones which, if achieved, could total up to $225 million. We were responsible for development and pre-commercialization costs in the United States. Following first commercial sale of VOWST, which occurred on June 2, 2023, we are entitled to share equally in its commercial profits and losses.

 During the year ended December 31, 2023, Nestl reported 1,284 VOWST units sold and $19.6 million in net sales, reflecting an estimated gross-to-net reduction of 13%, primarily due to returns reserve, prompt payment discounts, statutory discounts and rebates, and commercial rebates. The total collaboration loss for the year ended December 31, 2023 was $37.7 million. We record our 50% share of the collaboration loss, which includes commercial and medical affairs expenses incurred by us, on a net basis. Accordingly for the year ended December 31, 2023, our share of the VOWST net loss was $18.9 million.

 As part of the commercialization of VOWST, we are closely monitoring the launch and focusing on a number of quantitative metrics. VOWST became commercially available in early June. Broad demand for VOWST has been observed across both recurrent patients and healthcare providers since June 2023 (metrics noted below are based on data provided by Nestl through December 31, 2023):

 • Fourth quarter completed prescription enrollment forms received for VOWST were 1,322; of those 1,082 resulted in new patient starts by year-end 2023;

 • From launch through year-end 2023, there were 2,833 completed prescription enrollment forms received for VOWST; of those 2,015 resulted in new patient starts by year-end 2023;

 • In 2023, prescription enrollment forms were submitted by approximately 1,330 unique healthcare providers, or HCPs, since launch, with approximately 65% from gastroenterology and the remainder from other specialties; approximately 340 HCPs have prescribed VOWST to more than one patient; and

 • VOWST demand has been observed across the recurrent CDI patient pool, including first recurrence, which is the largest recurrent CDI patient segment.

 In close collaboration with Nestl, we have scaled our HCP education efforts, worked to create a positive customer experience with faster and higher conversion of enrollments to new patient starts, and continued to establish payer coverage. Since the FDA approval of VOWST, Nestl commercial customer facing field teams have been promoting VOWST and generating healthcare provider demand, including significant presence at both IDWeek and the American College of Gastroenterology, or ACG, meetings in October 2023. IDWeek and ACG are two of the largest infectious disease and gastroenterology conferences. Nestl 's 170 field sales representatives promoting VOWST are divided into two teams, comprised of 150 gastroenterology representatives and 20 hospital/infectious disease representatives.

 The VOWST Voyage Support Program, or VOWST Voyage, was launched upon VOWST FDA approval to provide treatment and financial support for eligible patients. The VOWST Voyage staff work with healthcare providers and patients to convert patient enrollments into new patient starts and provide a robust high-touch customer experience.

 Nestl 's payer field team continues to engage payers to build coverage, which would enable eligible patients to have access to VOWST as quickly and efficiently as possible. The team has been reinforcing what we believe to be a compelling value proposition for VOWST and is actively engaged with the three largest pharmacy benefit managers. In 2023, payers issued policies for VOWST

 coverage across plans representing 80% commercial and 54% Medicare Part D covered lives. Approximately 56% of the 1,082 fourth quarter new patient starts are being reimbursed through the patient's drug benefit.

 We are investing in patient financial assistance to increase access to VOWST for patients with affordability challenges due to co-pays or other cost sharing requirements imposed on them by their insurer after the prescription has been approved. We believe that providing this type of patient access early on will contribute to a positive patient and provider experience, thus increasing demand over time. In terms of free drug utilization, we saw approximately 46% of 2023 new patient starts dispensed via our free drug programs, mostly for Medicare patients. We expect utilization of these programs to drop when the benefit design changes contained in the Inflation Reduction Act, which address patient cost sharing requirements in Medicare Part D plans, go into effect in 2025.

 VOWST was previously granted Breakthrough Therapy and Orphan Drug Designations by the FDA. In connection with the FDA approval of VOWST, we received seven years of orphan-drug exclusivity, which began on April 26, 2023. During that time, VOWST is entitled to a period of marketing exclusivity, which precludes the FDA or other regulatory authorities from approving another marketing application for the same drug or biologic for the same disease or condition during that time period, except under certain circumstances.

 The FDA approval of VOWST was supported by the Phase 3 development program that included the ECOSPOR III and ECOSPOR IV studies. ECOSPOR III was a multicenter, randomized, placebo-controlled study that enrolled 182 patients with multiply recurrent CDI. All patients who entered ECOSPOR III must have tested positive for C. difficile toxin. This inclusion criterion was implemented in an effort to ensure enrollment of only patients with active infection rather than simple colonization. The study was designed to evaluate patients for 24 weeks, with the primary endpoint comparing the C. difficile recurrence rate in subjects who received SER-109 verses placebo at up to eight weeks after dosing.

 ECOSPOR III data demonstrated that the study achieved its primary endpoint where SER-109 was superior to placebo in reducing CDI recurrence at eight weeks, reflecting a recurrence-free rate of approximately 88% at eight weeks post-treatment. SER-109 resulted in a 27% absolute reduction of recurrence of CDI compared to placebo at eight weeks post-treatment, which is a relative risk reduction of 68%. The rate of recurrence at 12 weeks in the SER-109 arm was 18.0%, compared to a rate of 46.2% in the placebo arm, representing an absolute risk reduction of 28% (relative risk 0.40; 95% CI 0.24-0.65), and thereby consistent with the results seen at eight weeks. The efficacy results remained durable through 24 weeks of follow-up, as SER-109 was observed to significantly reduced recurrence rates compared to placebo over 24 weeks, 21.3% vs. 47.3%, respectively. These data were published in the New England Journal of Medicine in January 2022 and in the Journal of the American Medical Association in October 2022.

 ECOSPOR IV was an open-label single-arm study evaluating SER-109 in 263 adult subjects with recurrent CDI. The overall safety profile observed in ECOSPOR IV through 24 weeks indicated that SER-109 was well tolerated, consistent with the safety profile observed in the prior completed Phase 3 study, ECOSPOR III. The ECOSPOR IV study results contributed to the SER-109 safety database and supported product approval. These data were published in the JAMA Network Open in February 2023.

 Infection Protection and SER-155

 We believe that the scientific and clinical data from our SER-109 program validate our novel approach of using microbiome therapeutics to decolonize pathogens, resulting in reduced rate of infections in medically compromised patients. Data from the SER-109 ECOSPOR III and ECOSPOR IV Phase 3 trial published in the New England Journal of Medicine (Feuerstadt et al., 2022) and Journal of the American Medical Association (Sims et al., 2023) suggest that microbiome therapeutics have the potential to restructure the gut microbiome and shift the gut metabolic landscape. Additional data show that SER-109 rapidly reduced the abundance of bacteria associated with common antibiotic resistance genes, or ARGs, and reduced ARG abundance in the gut (Straub et al., 2023). Collectively, we believe these data suggest the potential for microbiome therapeutics to restore colonization resistance and ultimately to reduce infections and antimicrobial resistance. We believe this Infection Protection approach may be replicable in protecting a range of medically compromised patients from infections seeded by the gut microbiome and resulting downstream clinical sequelae. We believe this approach may also enable us to reduce antimicrobial resistant infections, which the World Health Organization declared as a top ten global public health threat facing humanity.

 We are evaluating SER-155 in a Phase 1b study in allo-HSCT recipients in an effort to reduce incidences of gastrointestinal infections, resulting bloodstream infections and GvHD. SER-155, an oral microbiome therapeutic candidate consisting of a consortium of cultivated bacteria, is designed to prevent enteric-derived infections and resulting blood stream infections, as well as induce immune tolerance responses to reduce the incidence of GvHD in patients undergoing allo-HSCT. SER-155 was designed using our reverse translational microbiome therapeutics development platform and the rationale for this program is based in part on published clinical evidence from our collaborators at Memorial Sloan Kettering Cancer Center showing that allo-HSCT patients with decreased diversity of commensal microbes and pathogen domination in the gastrointestinal tract were significantly more likely to die due to infection and/or lethal GvHD (Peled et al., 2020). In December 2023, we received Fast Track Designation for SER-155 to reduce the risk of infection and GvHD in allo-HSCT patients.

 The SER-155 Phase 1b study is designed to include approximately 70 patients in both an open-label (cohort 1) and a randomized, double-blind, placebo-controlled cohort (cohort 2) that will evaluate safety and tolerability before and after HSCT.

 Additionally, the engraftment of SER-155 bacteria (a measure of pharmacokinetics) and gastrointestinal pathogen domination, as well as the rates of enteric-derived infections and resulting blood stream infections, and GvHD will be evaluated.

 Cohort 1 was designed to assess safety and drug pharmacology including the engraftment of drug bacteria in the gastrointestinal tract. Cohort 1 included 13 subjects who received any dosing of the SER-155 regimen, with 11 of these subjects subsequently receiving an allo-HSCT. Nine subjects had evaluable samples for microbiome data analysis. Gastrointestinal microbiome data from the first 100 days of cohort 1 showed the successful engraftment of SER-155 bacterial strains, and a substantial reduction in the cumulative incidence of pathogen domination as compared to a reference cohort of patients, a biomarker associated with the risk of serious enteric infections and resulting bloodstream infections as well as GvHD. The tolerability profile results were favorable, with no serious adverse events attributed to SER-155 administration. Stem cell engraftment was observed in all subjects. We believe these initial SER-155 Phase 1b study results provide encouraging evidence to support further development of SER-155 to potentially reduce enteric-derived infections, resulting bloodstream infections, and GvHD in individuals undergoing allo-HSCT for cancers and other serious conditions. We also believe the available study data from cohort 1 suggest that SER-155 administration results in significantly lower incidence rates of gastrointestinal dominations with pathogens of clinical concern, such as Enterococcaceae, Enterobacteriaceae, Streptococcaceae, and Staphylococcaceae.

 Enrollment of cohort 2 is ongoing, incorporating a randomized, double-blinded placebo-controlled design to further evaluate safety, engraftment, and incidence of gastrointestinal ESKAPE microbiome pathogen domination, as well as the incidence of enteric infections, enteric driven blood stream infections, and GvHD. Cohort 2 subjects are administered either SER-155 or placebo at a 1:1 ratio. The study is being conducted at a number of leading cancer centers across the U.S. The cohort 2 data readout is anticipated in the third quarter of 2024.

 Intellectual Property

 Patent Portfolio

 We have an extensive patent portfolio directed to rationally designed ecologies of spores and microbes. The portfolio includes both company-owned patents and applications, and those that we have rights to as licensee. For example, pursuant to an exclusive license to certain intellectual property from Memorial Sloan Kettering Cancer Center, with a patent term running until at least 2035, we are responsible for paying a 2.5% royalty on net sales of VOWST, minimum annual royalties, and milestone payments. The milestone payments are based on VOWST target sales milestones, the first being $1.0 million which was payable upon the first commercial sale of VOWST and paid in July 2023, the second being $2.5 million payable upon annual VOWST sales of $100.0 million, and the last being $10.0 million payable upon annual VOWST sales of $500.0 million. The patents and applications included in our portfolio cover both composition of matter and methods (e.g., method of treating). Our intellectual property rights related to VOWST extend through 2034, through 2041 for SER-155, and through 2040 for SER-301. We plan on continuing to broaden our patent portfolio. Currently, we have 21 active patent application families, which includes 20 nationalized applications and one at the PCT stage. To date, we have obtained 30 issued U.S. patents.

 Regulatory Exclusivity

 If we obtain marketing approval for any of our product candidates, we expect to receive reference product exclusivity against biosimilar products. For example, VOWST (which was recently approved by the FDA) has a 12-year period of exclusivity in the United States. In the European Union, new molecular entities generally receive eight years of data exclusivity and an additional two years of market exclusivity upon marketing authorization.

 Financial Operations Overview

 Revenue

 To date we have not generated any revenues from the sale of products. Our revenues have been derived primarily from our agreements with our collaborators. Under our 2021 License Agreement with Nestl, beginning with the first commercial sale of VOWST, which occurred in June 2023, net sales of VOWST are recorded by Nestl and include gross sales net of discounts, rebates, allowances, and other applicable deductions. We record our share of the net profits or losses from the sales of VOWST, including our commercial and medical affairs expenses, on a net basis, pursuant to the terms of the 2021 License Agreement. See Collaboration (Profit) Loss Sharing - related party below, and also "–Liquidity and Capital Resources."

 Operating Expenses

 Our operating expenses since inception have consisted primarily of research and development activities and general and administrative costs.

 Research and Development Expenses

 Research and development expenses consist primarily of costs incurred for our research activities, including our discovery efforts and the development of our product candidates, which include:

 • expenses incurred under agreements with third parties, including contract research organizations, or CROs, that conduct research, preclinical activities and clinical trials on our behalf as well as contract manufacturing organizations that manufacture drug products for use in our preclinical and clinical trials;

 • salaries, benefits and other related costs, including stock-based compensation expense, for personnel in our research and development functions;

 • costs of outside consultants, including their fees, stock-based compensation and related travel expenses;

 • the cost of laboratory supplies and acquiring, developing and manufacturing preclinical study and clinical trial materials;

 • costs related to compliance with regulatory requirements; and

 • facility-related expenses, which include direct depreciation costs and allocated expenses for rent and maintenance of facilities and other operating costs.

 We expense research and development costs as incurred. We recognize external development costs based on an evaluation of the progress to completion of specific tasks using information provided to us by our vendors and our clinical investigative sites. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred, and are reflected in our consolidated financial statements as prepaid or accrued research and development expenses.

 Our primary focus of research and development since inception has been on our reverse translational microbiome therapeutics platform and the subsequent development of our product candidates. Our direct research and development expenses are tracked on a program-by-program basis and consist primarily of external costs, such as fees paid to investigators, consultants, CROs in connection with our preclinical studies and clinical trials, lab supplies and consumables, and regulatory fees. We do not allocate employee-related costs and other indirect costs to specific research and development programs because these costs are deployed across multiple product programs under development.

 Research and development activities are central to our business model. Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. We anticipate an overall decrease in research and development expenses beginning in 2024, as we expect the Restructuring Plan to significantly reduce research and development activities other than the completion of the SER-155 Phase 1b study. Research and development expenses may increase in the future as we initiate technology transfer activities with Bacthera and prepare for qualification of the Bacthera manufacturing facility, and if and as we resume development of any clinical or preclinical programs.

 General and Administrative Expenses

 General and administrative expenses consist primarily of salaries and other related costs, including stock-based compensation for personnel in our executive, finance, commercial, business development and administrative functions. General and administrative expenses also include legal fees relating to patent and corporate matters; professional fees for accounting, auditing, tax and consulting services; insurance costs; travel expenses; and facility-related expenses, which include direct depreciation costs and allocated expenses for rent and maintenance of facilities and other operating costs. Prior to the commercial launch of VOWST, general and administrative expenses also included professional service fees for marketing and market access activities to commercialize VOWST.

 We expect that our general and administrative expenses will decrease starting in 2024 as the Restructuring Plan is expected to result in a reduction of personnel expenses due the workforce reduction and a reduction in external expenses including the elimination of non-essential expenses and consolidation of office space. General and administrative expenses may increase as we undertake efforts from time to time to raise additional capital. We may also continue to incur increased expenses associated with being a public company, including increased costs of accounting, audit, legal, regulatory and tax-related services associated with maintaining compliance with exchange listing rules and the requirements of the Securities and Exchange Commission, director and officer insurance costs and investor and public relations costs.

 Collaboration (Profit) Loss Sharing - related party

 Under the 2021 License Agreement with Nestl, VOWST net sales are recorded by Nestl and include gross sales net of discounts, rebates, allowances, and other applicable deductions. These amounts include the use of estimates and judgments, which could be adjusted based on actual results in the future. We record our share of the profits or losses from the sales of VOWST, including our commercial and medical affairs expenses, on a net basis, as collaboration (profit) loss sharing - related party. This treatment is in accordance with our revenue recognition and collaboration policy, given that Nestl and we are both active participants in commercialization activities and are exposed to significant risks and rewards that are dependent on the commercial success of the

 activities in the arrangement. Nestl provides us with reporting related to net sales of VOWST in accordance with U.S. generally accepted accounting principles in order to calculate and record collaboration profit or loss.

 The collaboration (profit) loss sharing - related party line item also includes our profit on the transfer of VOWST inventory to Nestl, which represents the excess of the supply price paid by Nestl over our cost to manufacture VOWST, subject to a supply price cap.

 The collaboration (profit) loss sharing - related party line item also includes collaboration loss related to pre-launch activities, which were completed prior to the first commercial sale of VOWST in June 2023.

 Other (Expense) Income, Net

 Interest Income, Net

 Interest income consists of interest earned on our cash, cash equivalents and investments.

 Interest Expense

 Interest expense consists of interest incurred under our loan and security agreement with Hercules Capital, Inc. and Oaktree, including the accretion of the discount on our Oaktree Term Loan.

 Other (Expense) Income

 Other (expense) income primarily consists of amortization of premiums or accretion of discounts on investments, and changes in the fair values of our warrant liabilities associated with our Oaktree Term Loan.

 Income Taxes

 Since our inception in 2010, we have not recorded any U.S. federal or state income tax benefits for the net losses we have incurred in each year or our earned research and development tax credits, due to our uncertainty of realizing a benefit from those items. As of December 31, 2023, we had federal and state net operating loss carryforwards of $527.1 million and $504.2 million, respectively, both of which begin to expire in 2035. As of December 31, 2023, we also had federal and state research and development tax credit carryforwards of $45.1 million and $7.7 million, respectively, net of uncertain tax position reserves, which begin to expire in 2031 and 2028, respectively. The federal research and development tax credits include an orphan drug credit carryforward of $25.9 million.

 Critical Accounting Policies and Significant Judgments and Estimates

 Our consolidated financial statements are prepared in accordance with generally accepted accounting principles in the United States, or GAAP. The preparation of our consolidated financial statements and related disclosures requires the application of appropriate technical accounting rules and guidance, as well as the use of estimates. The application of these policies necessarily involves judgments regarding future events. These estimates and judgments, in and of themselves, could materially impact the consolidated financial statements and disclosures based on varying assumptions. We believe that the estimates and assumptions involved in the accounting policies described below may have the greatest potential impact on our consolidated financial statements and, therefore, consider these to be our critical accounting policies. We evaluate our estimates and assumptions on an ongoing basis. Our actual results may differ from these estimates under different assumptions and conditions.

 Revenue Recognition

 We recognize revenue in accordance with the guidance under ASC 606, Revenue from Contracts with Customers. ASC 606 applies to all contracts with customers, except those contracts that are within the scope of other guidance, such as leases, insurance, and financial instruments. We enter into agreements that are within the scope of ASC 606, under which we license certain of our product candidates and perform research and development services in connection with such arrangements. The terms of these arrangements typically include payment of one or more of the following: nonrefundable up-front fees, reimbursement of research and development costs, development, clinical, regulatory and commercial sales milestone payments, and royalties on net sales of licensed products. Under ASC 606, we recognize revenue when our customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. When determining the timing and extent of revenue recognition for arrangements that we determine are within the scope of ASC 606, we perform the following five steps:

 (i) identify the contract(s) with a customer;

 (ii) identify the performance obligation(s) in the contract;

 (iii) determine the transaction price;

 (iv) allocate the transaction price to the performance obligation(s) 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 we will collect the consideration to which we are entitled in exchange for the goods or services transferred to our customer.

 At contract inception, once the contract is determined to be within the scope of ASC 606, we assess the goods or services promised within the contract to determine whether each promised good or service is a performance obligation. The promised goods or services in our arrangements typically consist of a license to our intellectual property and/or research and development services. We may provide options to additional items in such arrangements, which are accounted for as separate contracts when our customer elects to exercise such options, unless the option provides a material right to our customer. Performance obligations are promises in a contract to transfer a distinct good or service to our customer that (i) our customer can benefit from on its own or together with other readily available resources, and (ii) is separately identifiable from other promises in the contract. Goods or services that are not individually distinct performance obligations are combined with other promised goods or services until such combined group of promises meets the requirements of a performance obligation.

 We determine transaction price based on the amount of consideration we expect to receive for transferring the promised goods or services in the contract. Consideration may be fixed, variable, or a combination of both. At contract inception for arrangements that include variable consideration, we estimate the probability and extent of consideration we expect to receive under the contract utilizing either the most likely amount method or expected amount method, whichever best estimates the amount expected to be received. We then consider any constraints on the variable consideration and include in the transaction price variable consideration to the extent it is deemed probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved.

 We then allocate the transaction price to each performance obligation based on the relative standalone selling price and recognize as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) control is transferred to our customer and the performance obligation is satisfied. For performance obligations which consist of licenses and other promises, we utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of performance and related revenue recognition.

 We record amounts as accounts receivable when the right to consideration is deemed unconditional. When consideration is received, or such consideration is unconditionally due, from our customer prior to transferring goods or services to our customer under the terms of a contract, a contract liability is recorded for deferred revenue.

 We do not assess whether a contract has a significant financing component if the expectation at contract inception is that the period between payment by our customer and the transfer of the promised goods or services to our customer will be one year or less. Incremental costs of obtaining a contract are expensed as and when incurred if the expected period over which we would have amortized the asset is one year or less, or the amount is immaterial.

 Collaboration Revenue

 Arrangements with collaborators may include licenses to intellectual property, research and development services, manufacturing services for clinical and commercial supply, and participation on joint steering committees. We evaluate the promised goods or services to determine which promises, or group of promises, represent performance obligations. In contemplation of whether a promised good or service meets the criteria required of a performance obligation, we consider the stage of development of the underlying intellectual property, the capabilities and expertise of our customer relative to the underlying intellectual property, and whether the promised goods or services are integral to or dependent on other promises in the contract. When accounting for an arrangement that contains multiple performance obligations, we must develop judgmental assumptions, which may include market conditions, reimbursement rates for personnel costs, development timelines and probabilities of regulatory success to determine the stand-alone selling price for each performance obligation identified in the contract.

 When we conclude that a contract should be accounted for as a combined performance obligation and recognized over time, we must then determine the period over which revenue should be recognized and the method by which to measure revenue. We generally recognize revenue using a cost-based input method.

 Licenses of Intellectual Property

 If a license to our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenue allocated to the license when the license is transferred to our customer and our customer is able to use and benefit from the license. For licenses that are bundled with other promises, we utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue associated with the bundled performance obligation. We evaluate the measure of progress each reporting period and, if necessary, adjust the measure of progress and related revenue recognition.

 Milestone Payments

 At the inception of each arrangement that includes developmental and regulatory milestone payments, we evaluate whether the achievement of each milestone specifically relates to our efforts to satisfy a performance obligation or transfer a distinct good or service within a performance obligation. If the achievement of a milestone is considered a direct result of our efforts to satisfy a performance obligation or transfer a distinct good or service and the receipt of the payment is based upon the achievement of the milestone, the associated milestone value is allocated to that distinct good or service, otherwise it will be allocated to all performance obligations of the arrangement based on the initial allocation.

 We evaluate each milestone to determine when and how much of the milestone to include in the transaction price. We first estimate the amount of the milestone payment that we could receive using either the expected value or the most likely amount approach. We primarily use the most likely amount approach as that approach is generally most predictive for milestone payments with a binary outcome. Then, we consider whether any portion of that estimated amount is subject to the variable consideration constraint (that is, whether it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty). We update the estimate of variable consideration included in the transaction price at each reporting date which includes updating the assessment of the likely amount of consideration and the application of the constraint to reflect current facts and circumstances.

 Royalties

 For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, we have not recognized any revenue related to sales-based royalties or milestone payments based on the level of sales.

 Manufacturing Supply Services

 For arrangements that include a promise of supply of clinical or commercial product, we determine if the supply is a promise in the contract or a future obligation at our customer's option. If determined to be a promise at inception of the contract, we evaluate the promise to determine whether it is a separate performance obligation or a component of a bundled performance obligation. If determined to be an option, we determine if the option provides a material right to our customer and if so, account for the option as a separate performance obligation. If determined to be an option but not a material right, we account for the option as a separate contract when our customer elects to exercise the option.

 Application of the above guidance requires significant judgment and requires us to make determinations based on the facts and circumstances under each arrangement.

 Collaboration Profit and Loss

 We analyze our collaboration arrangements to assess whether they are within the scope of ASC 808, Collaborative Arrangements ("ASC 808"), which includes determining whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. For collaboration arrangements within the scope of ASC 808 that contain multiple elements, we first determine which elements of the collaboration are deemed to be within the scope of ASC 808 and those that are more reflective of a vendor-customer relationship and therefore within the scope of ASC 606. For those elements of the arrangement that are accounted for pursuant to ASC 606, we apply the five-step model prescribed in ASC 606, as described above. For elements of collaboration arrangements that are accounted for pursuant to ASC 808, an appropriate recognition method is determined and applied consistently, generally by analogy to ASC 606. We record our share of the profits or losses from the sales of VOWST on a net basis as collaboration (profit) loss sharing - related party because Nestl and we are both active participants in commercialization activities and are exposed to significant risks and rewards that are dependent on the commercial success of the activities in the arrangement. The collaboration (profit) loss sharing - related party line item also includes our profit on the transfer of VOWST inventory to Nestl, which represents the excess of the supply price paid by Nestl over our cost to manufacture VOWST.

 Accrued Research and Development Expenses

 As part of the process of preparing our consolidated financial statements, we are required to estimate our accrued research and development 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 costs incurred for the services when we have not yet been invoiced or otherwise notified of the actual costs. The majority of our service providers invoice us in arrears for services performed, on a pre-determined schedule or when contractual milestones are met; however, some require advanced payments. 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, which include information from our CROs and CMOs reported to us on a periodic basis. Examples of estimated accrued research and development expenses include fees paid to:

 • CROs in connection with performing research services on our behalf and clinical trials;

 • investigative sites or other providers in connection with clinical trials;

 • vendors in connection with preclinical and clinical development activities; and

 • vendors related to product manufacturing, development and distribution of preclinical and clinical supplies.

 We base our expenses related to preclinical studies and clinical trials on our estimates of the services received and efforts expended pursuant to quotes and contracts with multiple CROs that conduct and manage clinical trials 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 patients and the completion of clinical trial milestones. In accruing service fees, we estimate the time period over which services will be performed, enrollment of patients, number of sites activated and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrual or amount of prepaid expense accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in us reporting amounts that are too high or too low in any particular period. To date, we have not made any material adjustments to our prior estimates of accrued research and development expenses.

 Results of Operations

 Comparison of the Years Ended December 31, 2023 and 2022

 The following table summarizes our results of operations for the years ended December 31, 2023 and 2022.

 Year Ended

 2023

 2022

 Change

 (in thousands)

 Revenue:

 Collaboration revenue - related party

 $

 126,325

 $

 7,128

 $

 119,197

 Total revenue

 126,325

 7,128

 119,197

 Operating expenses:

 Research and development

 145,860

 172,920

 (27,060

)

 General and administrative

 87,744

 79,694

 8,050

 Collaboration (profit) loss sharing - related party

 1,004

 (300

)

 Total operating expenses

 234,308

 253,618

 (19,310

)

 Loss from operations

 (107,983

)

 (246,490

)

 138,507

 Other (expense) income:

 Interest income

 7,301

 3,058

 4,243

 Interest expense

 (13,176

)

 (6,020

)

 (7,156

)

 Other income (expense)

 (705

)

 Total other expense, net

 (5,741

)

 (3,667

)

 (2,074

)

 $

 (113,724

)

 $

 (250,157

)

 $

 136,433

 Revenue

 Total revenue was $126.3 million and $7.1 million for the years ended December 31, 2023 and 2022, respectively. The increase in total revenue of $119.2 million was primarily due to the milestone payment of $125.0 million received from our collaborator Nestl, upon FDA approval of VOWST. The increase was partially offset by a $3.7 million decrease in collaboration revenue

 attributable to the services performed pursuant to the 2016 License Agreement and a $2.1 million decrease in collaboration revenue attributable to the services performed pursuant to the 2021 License Agreement.

 Research and Development Expenses

 Year Ended

 2023

 2022

 Change

 (in thousands)

 Microbiome therapeutics platform

 $

 44,062

 $

 37,857

 $

 6,205

 VOWST

 17,871

 48,649

 (30,778

)

 SER-155

 7,759

 5,069

 2,690

 Early stage programs

 1,245

 1,759

 (514

)

 Total direct research and development expenses

 70,937

 93,334

 (22,397

)

 Personnel-related (including stock-based compensation)

 74,923

 79,586

 (4,663

)

 Total research and development expenses

 $

 145,860

 $

 172,920

 $

 (27,060

)

 Research and development expenses were $145.9 million for the year ended December 31, 2023, compared to $172.9 million for the year ended December 31, 2022. The decrease of $27.1 million was due primarily to the following:

 • a decrease in personnel-related costs of $4.7 million, primarily due to a decrease of $13.3 million resulting from the capitalization of certain labor costs into inventory beginning with the commercialization of VOWST, and a decrease of $2.0 million resulting from the receipt of payroll tax credits, partially offset by an increase of $2.5 million in salaries, bonus, and employee benefits expenses, a $5.9 million increase in stock-based compensation expense, which was primarily as a result of options and awards with performance conditions that were achieved during the year following the FDA approval of VOWST, and a $2.2 million increase in employee post-termination benefits due to the Restructuring Plan (see Note 13, Restructuring, to our audited consolidated financial statements included elsewhere in this Annual Report);

 • a decrease of $30.8 million in expenses related to our VOWST program, primarily due to a decrease in clinical trial costs of $12.6 million, and a decrease of $12.0 million in lab supplies and consumables and facility-related costs, as we have capitalized certain of these costs into inventory in conjunction with the commercialization of VOWST. The total decrease is also attributable to a decrease of $6.0 million in consulting and professional fees and a decrease of $0.2 million in analytical testing and other manufacturing costs;

 • a decrease of $0.5 million in expenses of our early stage programs, primarily driven by reduced clinical trial costs of $1.2 million, partially offset by an increase in analytical testing of $0.7 million;

 partially offset by:

 • an increase of $6.2 million in research expenses related to our microbiome therapeutics platforms, primarily due to an increase of $7.0 million in facilities costs, lab supplies, and consumables, driven primarily by our new and amended lease agreements for laboratory and office spaces in Massachusetts and Pennsylvania, and an increase of $1.6 million in consulting and professional fees, partially offset by a decrease of $2.2 million in analytical testing expenses, and a decrease of $0.2 million in clinical trial costs and other manufacturing costs;

 • an increase of $2.7 million in expenses related to our SER-155 program due to an increase in clinical trial and other manufacturing costs.

 General and Administrative Expenses

 Year Ended

 2023

 2022

 Change

 (in thousands)

 Personnel-related (including stock-based compensation)

 $

 36,629

 $

 31,277

 $

 5,352

 Professional fees

 28,446

 32,260

 (3,814

)

 Facility-related and other

 22,669

 16,157

 6,512

 Total general and administrative expenses

 $

 87,744

 $

 79,694

 $

 8,050

 General and administrative expenses were $87.7 million for the year ended December 31, 2023, compared to $79.7 million for the year ended December 31, 2022. The increase of $8.1 million was primarily due to the following:

 • an increase in personnel-related costs of $5.4 million, due to an increase of $1.0 million in salaries, bonus, payroll taxes and employee benefit expenses, a $1.7 million increase in employee post-termination benefits due to the Restructuring Plan (see Note 13, Restructuring, to our audited consolidated financial statements included elsewhere in this Annual Report), and a $2.7 million increase in stock-based compensation expense, which was primarily the result of options and awards with performance conditions that were achieved during the year ended December 31, 2023 upon FDA approval of VOWST, partially offset by the reversal of stock-based compensation expense associated with the forfeiture of unvested awards; and

 • an increase in facility-related and other costs of $6.5 million, due to increases in laboratory and office rent expenses of $3.8 million and an increase in information technology costs of $2.7 million; partially offset by

 • a decrease in professional fees of $3.8 million, due to a $9.8 million decrease in professional services, consulting and recruiting fees, offset by a $6.0 million increase in legal expenses primarily due to certain transaction and milestone payments due to third parties as a result of the FDA approval of VOWST.

 Collaboration (Profit) Loss Sharing - related party

 Collaboration (profit) loss sharing – related party resulted in $0.7 million of expense for the year ended December 31, 2023, compared to $1.0 million of expense for the year ended December 31, 2022. Beginning with the commercial launch of VOWST in June 2023, we record our share of the net profits and losses from the sales of VOWST, which are recorded by Nestl and include gross sales net of discounts, rebates, allowances, and other applicable deductions, as collaboration (profit) loss sharing - related party. Our share of VOWST net profits and losses also includes commercial and medical affairs expenses incurred by us. For the year ended December 31, 2023, our share of the VOWST net loss was $18.9 million. We also record as collaboration (profit) loss sharing - related party our net profit on the transfer of VOWST to Nestl, as well as our share of pre-launch expenses. For the year ended December 31, 2023, these amounts were $23.3 million in net profit and $5.1 million in net loss, respectively.

 For the year ended December 31, 2022, we incurred $15.1 million of pre-launch expenses which we recorded within research and development expense or general and administrative expense based on the nature of the underlying expense, and our collaborative partner incurred $17.1 million of pre-launch expenses. The $1.0 million of expense recorded for the year ended December 31, 2022 represent the sharing of 50% of the pre-launch expenses. These amounts represent expense to us in 2022 because our collaborative partner performed more of the pre-launch activities than us.

 The components of the collaboration (profit) loss sharing - related party are as follows (in thousands):

 For the Year Ended December 31,

 2023

 2022

 2021

 Share of VOWST net loss

 $

 18,873

 $

 —

 $

 —

 Profit on transfer of VOWST inventory to Nestl

 (23,327

)

 —

 —

 Collaboration (profit)/loss related to pre-launch activities

 5,158

 1,004

 (1,732

)

 Total collaboration (profit) loss sharing - related party

 $

 $

 1,004

 $

 (1,732

)

 Other (Expense) Income, Net

 Other (expense) income, net was $5.7 million of expense for the year ended December 31, 2023 compared to $3.7 million of expense for the year ended December 31, 2022. The increase in other expense, net was primarily due to an increase in interest expense of $7.1 million as a result of higher interest rates and a higher borrowing base with the Oaktree Term Loan. This increase was partially offset by an increase in other income of $0.8 million and an increase in interest income of $4.3 million.

 Liquidity and Capital Resources

 Since our inception, we have generated revenue only from collaborations and have incurred recurring net losses. We anticipate that we will continue to incur losses for at least the next several years. Our research and development and general and administrative expenses may continue to increase and, as a result, we will need additional capital to fund our operations, which we may obtain from additional financings, public offerings, research funding, additional collaborations, contract and grant revenue or other sources.

 On February 22, 2024, our board of directors adopted a resolution to amend the Restated Certificate of Incorporation, subject to stockholder approval at our annual meeting of stockholders to be held in 2024, by increasing the number of authorized shares of our common stock from 240,000,000 shares to 360,000,000 shares, or the Share Increase Amendment. Our board of directors believes it is in the best interests of us and our stockholders to increase our authorized shares of common stock in order to have additional shares available for use as our board of directors deems appropriate or necessary. As such, the primary purpose of the Share Increase Amendment is to provide us with greater flexibility with respect to managing our common stock in connection with such corporate purposes as may, from time to time, be considered advisable by our Board. These corporate purposes could include, without limitation, financing activities, public or private offerings of common stock, stock dividends or splits, conversions of convertible securities, issuance of options and other equity awards pursuant to our incentive plans, establishing a strategic relationship with a corporate collaborator and acquisition transactions.

 In May 2021, we entered into a Sales Agreement, or the 2021 Sales Agreement, with Cowen and Company, LLC, or Cowen, to sell shares of our common stock with aggregate gross sales proceeds of up to $150.0 million, from time to time, through an "at-the-market" equity offering program under which Cowen acts as sales agent. During the year ended December 31, 2023, we sold 7,711,199 shares of common stock under the 2021 Sales Agreement, at an average price of approximately $2.46 per share, raising aggregate net proceeds of approximately $18.2 million after deducting an aggregate commission of approximately 3% and other issuance costs. During the year ended December 31, 2022, we sold 655,000 shares of common stock under the 2021 Sales Agreement, at an average price of approximately $7.26 per share, raising aggregate net proceeds of approximately $4.4 million after deducting an aggregate commission of approximately 3%. Between December 31, 2023 and February 29, 2024, we sold 15,366,630 shares of common stock under the 2021 Sales Agreement, at an average price of approximately $1.23 per share, raising aggregate net proceeds of approximately $18.5 million after deducting an aggregate commission of approximately 3% and other issuance costs.

 As of December 31, 2023, we had cash and cash equivalents totaling $128.0 million and an accumulated deficit of $978.2 million. For the year ended December 31, 2023, we incurred a net loss of $113.7 million, and used cash in operations of $117.4 million. We expect that our operating losses and negative cash flows will continue for the foreseeable future.

 Under applicable accounting standards, we have the responsibility to evaluate whether conditions or events raise substantial doubt about our ability to meet our future financial obligations as they become due within 12 months after the date the consolidated financial statements are issued. The ability to obtain sufficient additional equity or debt financing with terms favorable or acceptable to us cannot be considered probable, as these events are outside of our control. Based on our currently available cash resources, we will require additional funding prior to the end of 2024. Accordingly, management has concluded that these circumstances raise substantial doubt about our ability to continue as a going concern. Substantial doubt about our ability to continue as a going concern may materially and adversely affect the price per share of our common stock, and it may be more difficult for us to obtain financing. If potential collaborators decline to do business with us or potential investors decline to participate in any future financings due to such concerns, our ability to increase our cash position may be limited. We will need to generate significant revenues to achieve profitability, and we may never do so. Because of the numerous risks and uncertainties associated with the development of our current and any future product candidates, the development of our platform and technology and because the extent to which we may enter into collaborations with third parties for development of any of our product candidates is unknown, we are unable to estimate the amounts of increased capital outlays and operating expenses required for completing the research and development of our product candidates.

 Restructuring Plan

 In November 2023, we announced the Restructuring Plan to prioritize the commercialization of VOWST and the completion of the SER-155 Phase 1b study, while reducing costs and supporting longer-term business sustainability. The Restructuring Plan included (i) a reduction of our workforce by approximately 41% across the organization, resulting in the elimination of approximately 160 positions; (ii) significantly scaling back all non-partnered research and development activities other than the completion of the SER-155 Phase 1b study; and (iii) reducing general and administrative expenses, including consolidating office space. The Restructuring Plan was substantially implemented around the end of fiscal 2023. In connection with the Restructuring Plan, for the year ended December 31, 2023, we incurred approximately $5.6 million in restructuring costs, primarily related to the workforce reduction, of which $5.3 million are expected to result in cash expenditures, and the remaining $0.3 million relates to stock-based compensation expense associated with the acceleration of unvested equity awards. These costs were incurred in the fourth quarter of 2023. See Note 13, Restructuring, to our audited consolidated financial statements included elsewhere in this Annual Report. We expect to achieve annual cash savings of approximately $75.0 million to $85.0 million in 2024, of which approximately $35.0 million is expected to result from the reduction in workforce, and which excludes any one-time charges primarily associated with the workforce reduction.

 Collaboration and Manufacturing Agreements

 License Agreement with Soci t des Produits Nestl S.A. (Nestl)

 In January 2016, we entered into the 2016 License Agreement with Nestec, Ltd., as succeeded by Soci t des Produits Nestl S.A., or, together with NHSc Rx License GmbH, their affiliates, and their subsidiaries, Nestl, for the development and commercialization of certain of our product candidates in development for the treatment and management of CDI and IBD, including

 UC and Crohn's disease. In exchange for the license, Nestl agreed to pay us an upfront cash payment of $120.0 million, which we received in February 2016. Nestl has also agreed to pay us tiered royalties, at percentages ranging from the high single digits to high teens, of net sales of certain products based on our microbiome technology that are being developed for the treatment of CDI and IBD, including VOWST, SER-262, SER-287 and SER-301, or collectively, the 2016 Collaboration Products, in markets outside of the United States and Canada, or the 2016 Licensed Territory. We are eligible to receive up to $285.0 million in development milestone payments, $375.0 million in regulatory payments and up to an aggregate of $1.1 billion for the achievement of certain commercial milestones related to the sales of 2016 Collaboration Products. The full potential value of the up-front payment and milestone payments payable by Nestl is over $1.9 billion, assuming all products receive regulatory approval and are successfully commercialized. In September 2016, we received a $10.0 million milestone payment associated with the initiation of the Phase 1b clinical study for SER-262 in CDI. In June 2017, we initiated a Phase 3 clinical study of VOWST (ECOSPOR III) in patients with multiply recurrent CDI. In July 2017, we received $20.0 million based on the achievement of this milestone under the 2016 License Agreement. In November 2018, we executed a letter agreement with Nestl, or the Letter Agreement, modifying certain terms of the 2016 License Agreement. Under the Letter Agreement, Nestl agreed to pay us the $20.0 million Phase 3 milestone payment upon commencement of the Phase 2b study for SER-287. In December 2018, we received $40.0 million in milestone payments in connection with the commencement of the Phase 2b study for SER-287. In August 2020, we received $10.0 million from Nestl in connection with the initiation of the Phase 1b SER-301 study. To date, we have received $80.0 million in development milestones under the 2016 License Agreement with Nestl.

 For the development of 2016 Collaboration Products for IBD under a global development plan, we agreed to pay the costs of clinical trials of such products up to and including Phase 2 clinical trials, and 67% of the costs for Phase 3 and other clinical trials of such products, with Nestl bearing the remaining 33% of such costs. For other clinical development of 2016 Collaboration Products for IBD, we agreed to pay the costs of such activities to support approval in the United States and Canada.

 With respect to development of 2016 Collaboration Products for CDI under a global development plan, we agreed to pay all costs of Phase 2 clinical trials for VOWST and for Phase 3 clinical trials for VOWST. We agreed to bear all costs of conducting any Phase 1 or Phase 2 clinical trials under a global development plan for 2016 Collaboration Products other than VOWST for CDI. We agreed to pay 67% and Nestl agreed to pay 33% of other costs of Phase 3 clinical trials conducted for 2016 Collaboration Products other than VOWST for CDI under a global development plan. For other clinical development of 2016 Collaboration Products for CDI, we agreed to pay costs of such development activities to support approval in the United States and Canada, and Nestl agreed to bear the cost of such activities to support approval of 2016 Collaboration Products in the 2016 Licensed Territory.

 The 2016 License Agreement continues in effect until terminated by either party on the following bases: (i) Nestl may terminate the 2016 License Agreement in the event of serious safety issues related to any of the 2016 Collaboration Products; (ii) we may terminate the 2016 License Agreement if Nestl challenges the validity or enforceability of any of our licensed patents; and (iii) either party may terminate the 2016 License Agreement in the event of the other party's uncured material breach or insolvency. Upon termination of the 2016 License Agreement, all licenses granted to Nestl by us will terminate, and all rights in and to the 2016 Collaboration Products in the 2016 Licensed Territory will revert to us. If we commit a material breach of the 2016 License Agreement, Nestl may elect not to terminate the 2016 License Agreement but instead apply specified adjustments to its payment obligations and other terms and conditions of the 2016 License Agreement.

 License Agreement with NHSc Rx License GmbH (Nestl)

 On July 1, 2021, we entered into a License Agreement, or the 2021 License Agreement, with NHSc Pharma Partners, succeeded by NHSc Rx License GmbH, or, together with Soci t des Produits Nestl S.A., their affiliates, and their subsidiaries, Nestl. Pursuant to the 2021 License Agreement, we granted to Nestl, under certain of our patent rights and know how, a co-exclusive, sublicensable (under certain circumstances) license to develop, commercialize and conduct medical affairs activities for (i) therapeutic products based on our microbiome technology (including VOWST) that are developed by us or on our behalf for the treatment of CDI and recurrent CDI, as well as any other indications pursued for the products upon mutual agreement of the parties, or the 2021 Field, in the United States and Canada, or the 2021 Licensed Territory, and (ii) VOWST and any improvements and modifications thereto developed pursuant to the terms of the 2021 License Agreement, or the 2021 Collaboration Products, for any indications in the 2021 Licensed Territory.

 The 2021 License Agreement sets forth the parties' respective obligations for development, regulatory, commercialization, medical affairs, and manufacturing and supply activities for the 2021 Collaboration Products with respect to the 2021 Field and the 2021 Licensed Territory. Pursuant to the 2021 License Agreement, we were responsible for, and used commercially reasonable efforts in, conducting development of VOWST in the 2021 Field in the United States until first regulatory approval for VOWST was obtained in the 2021 Field in the United States and in accordance with a development and regulatory activity plan, at our cost, subject to certain exceptions specified in the 2021 License Agreement. We are also responsible for all regulatory affairs related to the 2021 Collaboration Products in the 2021 Field in the 2021 Licensed Territory, at our cost, except that expenses incurred for regulatory activities approved by a joint steering committee pursuant to a life cycle management plan for the 2021 Collaboration Products are shared equally between the parties. We are now solely responsible for manufacturing and supplying VOWST for development in the 2021 Field in the 2021 Licensed Territory.

 Nestl has the sole right to commercialize VOWST in the 2021 Licensed Territory in accordance with a commercialization plan, subject to our right to elect to provide up to a specified percentage of all promotional details for a certain target audience. Each party will use commercially reasonable efforts to commercialize VOWST in the 2021 Licensed Territory in accordance with the commercialization plan. Both parties will perform medical affairs activities for VOWST in the 2021 Licensed Territory in accordance with a medical affairs plan. We are solely responsible for the manufacturing and supply of VOWST for commercialization under a supply agreement that has been executed between the parties. We were responsible for commercialization and medical affairs activities costs incurred by the parties until first commercial sale of the first 2021 Collaboration Product, or VOWST, in the 2021 Licensed Territory and in accordance with a pre-launch plan, up to a specified cap. Since the first commercial sale of VOWST in June 2023, we are entitled to share equally in its commercial profits and losses.

 In exchange for the grant of the licenses under the 2021 License Agreement, Nestl agreed to pay us a non-refundable, non-creditable and non-cancelable upfront payment of $175.0 million, which was received in July 2021. Nestl also agreed to pay us an additional $125.0 million due upon FDA approval of VOWST, which we received in May 2023, $10.0 million upon Canadian regulatory approval of VOWST, and sales target milestones payments totaling up to $225.0 million.

 The 2021 License Agreement continues in effect until all development and commercialization activities for VOWST in the 2021 Licensed Territory have permanently ceased. The 2021 License Agreement may be terminated by either party upon sixty days' written notice for the other party's material breach that remains uncured during such sixty-day period, or immediately upon written notice for the other party's insolvency. Nestl may also terminate the 2021 License Agreement at-will with twelve months' prior written notice, effective only on or after the third anniversary of first commercial sale of VOWST in the 2021 Licensed Territory. We may also terminate the 2021 License Agreement immediately upon written notice if Nestl challenges any licensed patent in the 2021 Licensed Territory.

 Upon termination of the 2021 License Agreement, all licenses granted to Nestl by us will terminate. If we commit a material breach of the 2021 License Agreement, Nestl may elect not to terminate the 2021 License Agreement but instead apply specified adjustments to the payment terms and other terms and conditions of the 2021 License Agreement. The 2021 License Agreement contains customary representations and warranties by the parties, intellectual property provisions including ownership, patent prosecution, enforcement and defense, certain indemnification rights in favor of each party, and customary confidentiality provisions and limitations of liability.

 Long Term Manufacturing Agreement with Bacthera

 In November 2021, we entered into a Long Term Manufacturing Agreement with BacThera AG, or Bacthera, a joint venture between Chr. Hansen and a Lonza Group affiliate, which was amended on December 14, 2022, or the Bacthera Agreement. The Bacthera Agreement governs the general terms under which Bacthera, or one of its affiliates, will (i) construct a dedicated full-scale production suite for us at Bacthera's Microbiome Center of Excellence in Visp, Switzerland, which is substantially complete; and (ii) provide manufacturing services to us for VOWST and other products, as agreed to by the parties.

 Under the terms of the Bacthera Agreement, we agreed to pay Bacthera a total of at least 256 million CHF (or approximately $301 million) for the initial term of the agreement, inclusive of the construction fees and annual operating fees. Bacthera is funding the majority of the construction costs and will own and control the manufacturing suite during construction. The construction fees that we are responsible for represent a small percentage of the overall construction costs and are payable upon the achievement of certain milestones related to the construction of the dedicated manufacturing suite. The annual operating fee includes the cost of a baseline annual batch production volume. We have also agreed to pay certain other ancillary fees and a per-batch fee in excess of the baseline batches. These fees are subject to adjustment during construction for certain items outside of Bacthera's control and annually against an agreed index. We will supply the active pharmaceutical ingredients to Bacthera to enable it to perform the services and pay for certain other raw materials and manufacturing components, which will be acquired by Bacthera.

 The Bacthera Agreement has an initial term that continues until the tenth anniversary of the earlier of (a) successful completion of construction and demonstration of Bacthera's readiness for commercial production or (b) the commencement of manufacturing. The initial term is subject to renewals, which could extend the term to 16 years, and additional three-year terms thereafter. Each party has the ability to terminate the Bacthera Agreement upon the occurrence of certain customary conditions. We may also terminate the Bacthera Agreement for convenience after a defined period. In the event of a termination, we have certain financial obligations that would apply, and Bacthera has agreed to grant a license to Bacthera-developed manufacturing know how, if any, and provide technical assistance to us, so that we could transfer the manufacturing operations to ourselves or a third party. The Bacthera Agreement also

 contains representations, warranties and indemnity obligations as well as limitations of liability that are customary for agreements of this type.

 Indebtedness

 Loan and Security Agreement with Hercules

 In October 2019, we entered into a loan and security agreement, or the Hercules Loan Agreement, with Hercules Capital, Inc., or Hercules, pursuant to which a term loan facility in an aggregate principal amount of up to $50.0 million, or the Original Credit Facility, was available to us in three tranches, subject to certain terms and conditions. We received the first tranche of $25.0 million upon signing the agreement on October 29, 2019, but did not borrow either of the second two tranches, which were available at different times upon Hercules' approval until June 30, 2021.

 On April 16, 2020, we entered into an amendment to the Hercules Loan Agreement, or the First Amendment, permitting us to enter into a promissory note under the Paycheck Protection Program of the Coronavirus Aid, Relief and Economic Stability Act. On April 17, 2020 we issued a Promissory Note to Bank of America, NA, or the Loan, pursuant to which we received loan proceeds of $2.9 million, however, based on updated guidance related to this program, we decided to repay the full amount of the Loan, and repaid the Loan on May 4, 2020.

 Effective as of February 24, 2022, we entered into a Second Amendment to the Original Credit Facility (as amended by the First Amendment), or the Hercules Credit Facility, pursuant to which a term loan facility in the amount of $100.0 million became available to us in five tranches including the first tranche of $25.0 million previously drawn under the Original Credit Facility, subject to certain terms and conditions.

 The Hercules Credit Facility was secured by substantially all of our assets, other than our intellectual property. We agreed to not pledge or secure our intellectual property to others.

 The Hercules Credit Facility was repaid on the Oaktree Closing Date (as defined below). For a further description of the Hercules Credit Facility, see Note 9 to our consolidated financial statements included elsewhere in this Annual Report on Form 10-K.

 Oaktree Credit Agreement

 On April 27, 2023, or the Oaktree Closing Date, we entered into the Oaktree Credit Agreement, among the Company, the subsidiary guarantors from time to time party thereto, the Oaktree Lenders, and the Agent. The Oaktree Credit Agreement establishes a term loan facility of $250.0 million, consisting of (i) $110.0 million, or the Tranche A Loan, funded on the Closing Date, (ii) $45.0 million, or the Tranche B Loan, that the Company may borrow subject to certain conditions, (iii) $45.0 million, or the Tranche C Loan, that the Company may borrow subject to certain conditions, and (iv) $50.0 million, or the Tranche D Loan, available in Oaktree's sole discretion. The Tranche B Loan may be drawn by the Company until September 30, 2024, if VOWST net sales for the trailing six consecutive months are at least $35 million and at least 4.5% greater in the calendar quarter prior to the Applicable Funding Date (as defined in the Oaktree Credit Agreement) over the calendar quarter immediately preceding it. The Tranche C Loan may be drawn until September 30, 2025, if VOWST net sales for the trailing 12 consecutive months are at least $120 million and at least 4.5% greater in each of the two calendar quarters prior to the Applicable Funding Date relative, in each case, to the calendar quarter immediately preceding it. The Oaktree Term Loan has a maturity date of April 27, 2029, or the Oaktree Maturity Date. Of the $110.0 million Tranche A Loan advanced by the Lenders at closing, approximately $53.4 million repaid the Company's then-existing credit facility with Hercules Capital, Inc. After deducting other transaction expenses and fees, the Company received net proceeds of approximately $50.4 million.

 Borrowings under the Oaktree Term Loan bear interest at a rate per annum equal to the three-month term Secured Overnight Financing Rate (subject to a 2.500% floor and a 5.000% cap), plus an applicable margin of 7.875%, payable quarterly in arrears. If certain VOWST net sales targets are met, the applicable margin will be reduced from 7.875% to 7.50% through the Oaktree Maturity Date. We are required to make quarterly interest-only payments on the Oaktree Term Loan for the first three years after the Oaktree Closing Date. Beginning on June 30, 2026, we will be required to make quarterly payments of interest, plus repay 7.5% of the outstanding principal of the Oaktree Term Loan in quarterly installments until the Oaktree Maturity Date, unless the interest only period is extended based upon the achievement of certain VOWST net sales targets.

 We are obligated to pay the Oaktree Lenders an exit fee equal to 1.50% of the aggregate amount of the Oaktree Term Loan funded, such exit fee to be due and payable upon the earliest to occur of (1) the Oaktree Maturity Date, (2) the acceleration of the outstanding Oaktree Term Loan, and (3) the prepayment of the outstanding Oaktree Term Loan. We may voluntarily prepay the outstanding Oaktree Term Loan, subject to a customary make-whole for the first two years following the Oaktree Closing Date plus 4.0% of the principal amount of the Oaktree Term Loan prepaid, and thereafter a prepayment premium equal to (i) 4.0% of the principal amount of the Oaktree Term Loan prepaid, if prepaid after the second anniversary of the Oaktree Closing Date through and including the third anniversary of the Oaktree Closing Date, (ii) 2.0% of the principal amount of the Oaktree Term Loan if prepaid after the third anniversary of the Oaktree Closing Date through and including the fourth anniversary of the Oaktree Closing Date, (iii) 1.0% of the principal amount of the Oaktree Term Loan if prepaid after the fourth anniversary of the Oaktree Closing Date through

 and including the fifth anniversary of the Oaktree Closing Date, with no prepayment premium due after the fifth anniversary of the Oaktree Closing Date through the Oaktree Maturity Date.

 Our obligations under the Oaktree Credit Agreement and the other Loan Documents (as defined in the Oaktree Credit Agreement) will be guaranteed by any of our domestic subsidiaries that become Guarantors (as defined in the Oaktree Credit Agreement), subject to certain exceptions. Our and our Guarantors', or collectively, the Loan Parties, respective obligations under the Oaktree Credit Agreement and the other Loan Documents are secured by first priority security interests in substantially all assets of the Loan Parties, including intellectual property, subject to certain customary thresholds and exceptions. As of December 31, 2023, there were no Guarantors.

 The Oaktree Credit Agreement contains customary representations, warranties and affirmative and negative covenants, including a financial covenant requiring us to maintain certain levels of cash and cash equivalents in accounts subject to a control agreement in favor of the Agent of at least $30.0 million at all times commencing from 30 days after the Oaktree Closing Date and decreasing to $25.0 million of cash and cash equivalents in such controlled accounts after we borrow any Tranche B Loan. As of December 31, 2023, we were in compliance with all financial covenants pursuant to the Oaktree Credit Agreement.

 In addition, the Oaktree Credit Agreement contains certain events of default that entitle the Agent to cause our indebtedness under the Oaktree Credit Agreement to become immediately due and payable, and to exercise remedies against the Loan Parties and the collateral securing the Oaktree Term Loan, including cash. Under the Oaktree Credit Agreement, an event of default will occur if, among other things, we fail to make payments under the Oaktree Credit Agreement (subject to specified periods), we or our subsidiaries breach any of the covenants under the Oaktree Credit Agreement (subject to specified cure periods with respect to certain breaches), a material adverse change occurs, we, our subsidiaries or our or their respective assets become subject to certain legal proceedings, such as bankruptcy proceedings, we and/or our subsidiaries are unable to pay our or their debts as they become due or default on contracts with third parties which would permit the holder of indebtedness in excess of a certain threshold to accelerate the maturity of such indebtedness or that could cause a material adverse change. Upon the occurrence and for the duration of an event of default, an additional default interest rate equal to 2.0% per annum may apply to all obligations owed under the Oaktree Credit Agreement.

 On the Oaktree Closing Date, we issued to the Oaktree Lenders of such Tranche A Loan warrants to purchase 647,589 shares (subject to certain adjustments) of our common stock, or the Warrant, at an exercise price per share of $6.69. The Tranche A Warrant is immediately exercisable and the exercise period expires on April 26, 2030. Upon the funding of each of the Tranche B Loan and the Tranche C Loan, we are required to issue to the Oaktree Lenders of the Oaktree Term Loan warrants to purchase 264,922 shares (subject to certain adjustments) of the Company's common stock on each such funding date at an exercise price equal to the trailing volume weighted average price of the Company's common stock for the 30 trading days prior to the funding date for each tranche, or the Tranche B Warrant, and the Tranche C Warrant, respectively, and together the Additional Warrants. The Additional Warrants will be immediately exercisable upon issuance, and the exercise period will expire seven years from the date of issuance.

 Cash Flows

 The following table summarizes our sources and uses of cash, cash equivalents and restricted cash for the years ended December 31, 2023 and 2022.

 2023

 2022

 (in thousands)

 Cash used in operating activities

 $

 (117,354

)

 $

 (228,816

)

 Cash provided by investing activities

 $

 10,582

 $

 82,428

 Cash provided by financing activities

 $

 71,705

 $

 129,602

 Net decrease in cash, cash equivalents and restricted cash

 $

 (35,067

)

 $

 (16,786

)

 Operating Activities

 During the year ended December 31, 2023, net cash used in operating activities was $117.4 million, primarily due to a net loss of $113.7 million and changes in our operating assets and liabilities of $59.0 million, partially offset by non-cash charges of $55.3 million. Non-cash charges consisted of $34.1 million of stock-based compensation expense, loss sharing under the 2021 License Agreement with Nestl of $5.2 million, $8.9 million related to the amortization of right-of-use assets, $6.2 million of depreciation, $0.9 million of net amortization of premiums related to our investments and amortization of debt issuance costs, and $1.6 million of loss from the extinguishment of the Hercules Credit Facility. These were partially offset by a $1.6 million decrease in the fair value of the Additional Warrants. Changes in our operating assets and liabilities during the year ended December 31, 2023 primarily consisted of a $29.1 million increase in prepaid expenses and other current and non-current assets, an increase in inventories of $29.6 million and an increase in collaboration receivable - related party of $8.7 million, as a result of the commencement of our commercial operations since the FDA approval of VOWST in April 2023, an $11.6 million decrease in accounts payable, a $1.3 million decrease in deferred revenue and a $2.2 million decrease in operating lease liabilities, partially offset by a $15.8 million increase in accrued

 expenses and other liabilities and an increase in deferred income - related party of $7.7 million. The increase in prepaid expenses and other current and non-current assets and accrued expenses and other liabilities was primarily due to the achievement of the substantial completion milestone pursuant to the Bacthera Agreement. The decrease in deferred revenue was due to recognition of revenue during the year for services performed under both the 2021 License Agreement and the 2016 License Agreement. The decrease in operating lease liabilities was due to the cash payment of lease obligations.

 During the year ended December 31, 2022, net cash used in operating activities was $228.8 million, primarily due to a net loss of $250.2 million and changes in our operating assets and liabilities of $18.4 million, partially offset by non-cash charges of $39.7 million. Non-cash charges consisted of $25.5 million of stock-based compensation expense, $5.2 million related to the amortization of right-of-use assets, $6.6 million of depreciation, $1.4 million of net amortization of premiums related to our investments and amortization of debt issuance costs, and collaboration loss sharing of $1.0 million related to the 2021 License Agreement with Nestl. Changes in our operating assets and liabilities during the year ended December 31, 2022 primarily consisted of a $12.6 million increase in prepaid expenses and other current and non-current assets, a $7.1 million decrease in deferred revenue and a $4.2 million decrease in operating lease liabilities, partially offset by a $3.3 million increase in accrued expenses and other liabilities and a $2.2 million increase in accounts payable. The increase in prepaid expenses and other current and non-current assets was primarily due to the remittance of the second milestone payment pursuant to the Bacthera Agreement. The decrease in deferred revenue was due to recognition of revenue during the year for services performed under both the 2021 License Agreement and the 2016 License Agreement. The decrease in operating lease liabilities was due to the cash payment of lease obligations.

 Investing Activities

 During the year ended December 31, 2023, net cash provided by investing activities was $10.6 million, primarily due to maturities of investments of $23.0 million, partially offset by purchases of investments of $4.4 million and purchases of property and equipment of $8.0 million.

 During the year ended December 31, 2022, net cash provided by investing activities was $82.4 million, primarily due to maturities of investments of $140.5 million, partially offset by purchases of investments of $48.2 million and purchases of property and equipment of $9.8 million.

 Financing Activities

 During the year ended December 31, 2023, net cash provided by financing activities was $71.7 million, consisting of $103.4 million in proceeds from the issuance of the Oaktree Term Loan, offset by $52.9 million for the repayment of the Hercules Credit Facility. Cash provided by financing activities also consisted of $18.2 million from the issuance of common stock under our at the market equity program, net of issuance costs. We also received $0.9 million from the issuance of common stock associated with the exercise of stock options, and $2.2 million in connection with the issuance of common stock under our 2015 Employee Stock Purchase Plan, or ESPP.

 During the year ended December 31, 2022, net cash provided by financing activities was $129.6 million, consisting of $96.7 million of net proceeds received from the Registered Direct Offering that we completed in July 2022, $27.6 million of proceeds received from the New Credit Facility, and $4.4 million from the issuance of common stock via our at the market equity program, net of issuance costs. We also received $1.0 million from the issuance of common stock associated with the exercise of stock options and $1.8 million in connection with the issuance of common stock under our ESPP. These cash inflows were partially offset by principal payments under the Original Credit Facility of $1.9 million.

 Funding Requirements

 Our expenses may increase substantially in connection with our ongoing clinical development activities and our research and development activities. In addition, we expect to continue to incur additional costs associated with operating as a public company. We anticipate that our expenses will increase substantially if and as we:

 • advance commercialization of VOWST;

 • continue the clinical development of SER-155 to reduce incidences of gastrointestinal infections, bloodstream infections and GvHD in patients receiving allo-HSCT;

 • continue evaluating preclinical stage programs to reduce incidence of infection, in indications such as cancer neutropenia, chronic liver disease, solid organ transplant, and antimicrobial resistant infections more broadly;

 • continue translational research activities, informed by the SER-287 Phase 2b and SER-301 Phase 1b study data, to evaluate the potential to utilize biomarker-based patient selection and stratification in future clinical development efforts;

 • make strategic investments in our research discovery and development platforms and capabilities to advance our priority programs;

 • make strategic investments in manufacturing capabilities;

 • maintain and augment our intellectual property portfolio and opportunistically acquire complementary intellectual property;

 • potentially establish a sales and distribution infrastructure and scale-up manufacturing capabilities to commercialize any products for which we may obtain regulatory approval;

 • perform our obligations under our agreements with our collaborators;

 • seek to obtain regulatory approvals for our product candidates; and

 • experience any delays or encounter any issues with any of the above, including but not limited to failed studies, complex results, safety issues or other regulatory challenges.

 Because of the numerous risks and uncertainties associated with the development of our product candidates, we are unable to estimate the amounts of increased capital outlays and operating expenses associated with completing the research and development of our product candidates. Our future capital requirements will depend on many factors, including:

 • the impact of the Restructuring Plan, including its anticipated benefits;

 • the impact of continued increase in inflation rates or interest rates;

 • the progress and results of our clinical studies and preclinical development;

 • the cost of manufacturing our product candidates;

 • the costs, timing and outcome of regulatory review of our product candidates and research activities;

 • the costs and timing of future commercialization activities, including manufacturing, marketing, sales and distribution, for any of our product candidates for which we receive marketing approval;

 • the revenue, if any, received from commercial sales of our product candidates for which we receive marketing approval;

 • the costs and timing of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property rights and defending any intellectual property-related claims;

 • the effect of competing technological and market developments; and

 • the extent to which we acquire or invest in businesses, products and technologies, including entering into licensing or collaboration arrangements for product candidates.

 Identifying potential product candidates and conducting preclinical testing and clinical trials is a time-consuming, expensive and uncertain process that takes years to complete, and we may never generate the necessary data or results required to obtain marketing approval and achieve product sales. In addition, our product candidates, if approved, may not achieve commercial success. Our commercial revenues, if any, will be derived from sales of products that we do not expect to be commercially available for many years, if ever. Accordingly, we will need to obtain substantial additional funds to achieve our business objectives.

 Adequate additional funds may not be available to us on acceptable terms, or at all. Additionally, market volatility resulting from macroeconomic conditions, the COVID-19 pandemic, or other factors could also adversely impact our ability to access capital as and when needed. To the extent that we raise additional capital through the sale of equity or convertible debt securities, our shareholders' ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect our shareholders' rights as common stockholders. Our Hercules Loan Agreement included and our Oaktree Term Loan includes, and any additional debt financing and preferred equity financing, if available, may involve agreements that include, covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. Additional debt or preferred equity financing may also require the issuance of warrants, which could potentially dilute our shareholders' ownership interest.

 If we raise additional funds through collaborations, strategic alliances or licensing arrangements with third parties, in addition to our existing collaboration agreements, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs, or product candidates or grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds through equity or debt financings when needed, we may be required to delay, limit, reduce or terminate our product development programs or any future commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

 As discussed in Note 1 of the consolidated financial statements included elsewhere in this Annual Report on Form 10-K, we have the responsibility to evaluate whether conditions or events raise substantial doubt about our ability to meet our future financial obligations as they become due within 12 months after the date the consolidated financial statements are issued. The receipt of

 potential funding from future equity issuances cannot be considered probable, as these events are outside of our control. Based on our currently available cash resources and our current level of operations and cash flow analysis for the 12-month period subsequent to the date of issuance of the consolidated financial statements, we believe it is reasonably likely that we will require additional funding prior to the end of 2024. Accordingly, management has concluded that these circumstances raise substantial doubt about our ability to continue as a going concern.

 Contractual Obligations and Commitments

 We have entered into arrangements that contractually obligate us to make payments that will affect our liquidity and cash flows in future periods. Such arrangements include those related to our lease commitments, long-term debt, and long-term manufacturing agreements.

 Lease Commitments

 Our lease commitments reflect payments due under our operating lease agreements for our corporate headquarters, office and laboratory space, and donor collection facilities, that expire between November 2028 and April 2033. As of December 31, 2023, our contractual commitments for our leases were $177.4 million, of which $19.9 million is expected to be paid within one year, and $157.5 million will be paid over the remaining term of such leases. Our lease commitments also include $0.8 million for leases that had not yet commenced as of December 31, 2023. For additional information on our leases and timing of future payments, please read Note 8, Leases, to the consolidated financial statements included in this Form 10-K.

 Loan Agreement

 Our commitments due for our term loan under our arrangement with Oaktree total $14.4 million in interest-only payments through December 31, 2024. Our remaining commitments are due through April 2029, and include principal and interest payments of $153.3 million, and an additional fee upon maturity of the loan of $1.7 million. The interest rate in effect at December 31, 2023 was 12.875%. See Note 9, Notes Payable, to the consolidated financial statements for further discussion of the Oaktree Term Loan.

 Bacthera Long Term Manufacturing Agreement

 Our commitments due under the Bacthera Agreement, inclusive of construction fees and annual operating fees, total $288.8 million. Under the Bacthera Agreement $30.0 million was due upon substantial completion of our dedicated production suite, which occurred in late 2023, and remains unpaid, accruing interest in accordance with the Bacthera Agreement. The remaining construction milestones are approximately $12.6 million and $29.2 million, which will be due and payable upon provisional acceptance and final acceptance, respectively, and are expected to be due within the next 12 months. We have entered into negotiations with Bacthera to realign the timing of milestone payments. The Bacthera Agreement also includes $14.6 million in operating fees expected to be paid in the next year, with the remaining $202.3 million in operating fees paid over the remaining 9 years of the contract, beginning in 2025.

 Other Obligations

 We enter into contracts in the normal course of business with CROs for clinical trials, preclinical research studies and testing, manufacturing and other services and products for operating purposes. These contracts generally provide for termination upon notice, and therefore we believe that our non-cancelable obligations under these agreements are not material.

 Recently Issued and Adopted Accounting Pronouncements

 For a discussion of recent accounting standards see Note 2, Summary of Significant Accounting Policies, to our consolidated financial statements included in this report.

 Item 7A. Quantitative and Qualitative Disclosures about Market Risk

 Interest Rate Fluctuation Risk

 We are exposed to market risk related to changes in interest rates.

 As of December 31, 2023, our cash and cash equivalents consisted of cash and money market accounts. Our interest income is sensitive to changes in the general level of U.S. interest rates. However, because of the short-term nature of the instruments in our portfolio, an immediate 10% change in market interest rates would not have a material impact on the fair market value of our investment portfolio or on our financial position or results of operations.

 As of December 31, 2023, we had outstanding borrowings under the Oaktree Term Loan. Borrowings under the Oaktree Term Loan bear interest at a rate per annum equal to three-month term Secured Overnight Financing Rate (subject to a 2.500% floor and a 5.000% cap), plus an applicable margin of 7.875%, payable quarterly in arrears. An immediate 10% change in the Secured Overnight Financing Rate would not have a material impact on our debt related obligations, financial position or results of operations.

 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, 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 our principal financial officer, has evaluated the effectiveness of our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended), 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 has concluded that as of December 31, 2023, our disclosure controls and procedures were effective at the reasonable assurance level.

 Management's Annual Report on Internal Control Over Financial Reporting

 Our management is responsible for establishing and maintaining adequate internal control over our financial reporting, as such term is defined in Rule 13a-15(f) and 15d-15(f) under the Securities Exchange Act of 1934, as amended.

 Our management conducted an assessment of the effectiveness of our internal control over financial reporting based on the criteria set forth in "Internal Control – Integrated Framework (2013)" issued by the Committee of Sponsoring Organizations of the Treadway Commission.

 Based on this assessment, our management concluded that, as of December 31, 2023, our internal control over financial reporting was effective.

 This Annual Report on Form 10-K does not include an attestation report of our independent registered public accounting firm regarding internal control over financial reporting. As we are a non-accelerated filer, management's report is not subject to attestation by our independent registered public accounting firm.

 Changes in Internal Control Over Financial Reporting

 There were no changes in our internal control over financial reporting during our most recent fiscal quarter 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 Arrangements and Policies.

 During the three months ended December 31, 2023, no director or officer 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

 Director Biographical Information

 Name

 Age

 Position

 Dennis A. Ausiello, M.D. (3)(4)

 Stephen Berenson (3)

 Chairman of the Board of Directors

 Paul R. Biondi (2)

 Willard H. Dere, M.D. (1)(4)

 Claire M. Fraser, Ph. D. (1)(4)

 Kurt C. Graves (2)

 Richard N. Kender (1)(2)

 Eric D. Shaff

 President, Chief Executive Officer and Director

 (1) Member of the audit committee.

 (2) Member of the compensation and talent committee.

 (3) Member of the nominating and corporate governance committee.

 (4) Member of the science and clinical development committee.

 Dennis A. Ausiello, M.D., has served as a member of our board of directors since April 2015. Dr. Ausiello has served as the Jackson Distinguished Professor of Clinical Medicine at Harvard Medical School and Director, Emeritus of Harvard Medical School's M.D./Ph. D. Program since 1996, Chair of Medicine, Emeritus, and Director of the Center for Assessment Technology and Continuous Health (CATCH) at Massachusetts General Hospital, which he co-founded, since 2012, and Physician-in-Chief Emeritus at Massachusetts General Hospital since 2013. From 1996 to April 2013, Dr. Ausiello served as the Chief of Medicine at Massachusetts General Hospital. Dr. Ausiello is a member of the Institute of Medicine of the National Academy of Sciences and a fellow of the American Academy of Arts and Sciences. Dr. Ausiello has served on the board of directors of Alnylam Pharmaceuticals since April 2012 and as Vice Chairman of the board of directors of Spexis AG, a clinical-stage biopharmaceutical company, since December 2021, and previously served on the board of directors of Pfizer Inc. from 2006 to 2020, where he currently serves on the advisory board since 2019. Dr. Ausiello also serves on the boards of directors of numerous privately held companies. Dr. Ausiello received a B.A. in Biochemistry from Harvard College and an M.D. from the University of Pennsylvania. We believe that Dr. Ausiello is qualified to serve on our board of directors because of his extensive experience as a physician and as a director of pharmaceutical companies.

 Stephen A. Berenson has served as Chairman of our board of directors since December 2019 and as a member of our board of directors since August 2019. Mr. Berenson has been a Managing Partner at Flagship Pioneering, a life sciences innovation firm which conceives, creates, resources and develops first-in-category bioplatform companies, since June 2017. Prior to Flagship, Mr. Berenson spent 33 years in various roles as an investment banker at J.P. Morgan, most recently serving in the role of Vice Chairman of Investment Banking from 2005 to April 2017, where he focused on providing high-touch strategic advice and complex transaction execution to leading companies across all industries globally. He was co-founder of J.P. Morgan's Global Strategic Advisory Council and co-founder of the firm's Board Initiative. Mr. Berenson has served as chairman of the board of directors of Cellarity, a privately held pharmaceutical company, since July 2021, and has served on the board of directors of Moderna, Inc., a pharmaceutical and biotechnology company, since October 2017. Mr. Berenson received an S.B. in Mathematics from the Massachusetts Institute of Technology. We believe that Mr. Berenson is qualified to serve on our board of directors because of his extensive experience working with rapidly-growing companies across various industries.

 Paul R. Biondi has served as a member of our board of directors since March 2020. Mr. Biondi is an Executive Partner and President of Pioneering Medicines at Flagship Pioneering, a life sciences innovation firm which conceives, creates, resources and develops first-in-category bioplatform companies, roles he has held since November 2019. Mr. Biondi joined Flagship Pioneering following a seventeen-year tenure at Bristol-Myers Squibb, or BMS, a pharmaceutical company, where he was most recently the Senior Vice President of Strategy and Business Development from October 2015 to November 2019. Prior to serving in the role of Senior Vice President of Strategy, from 2002 to 2015, Mr. Biondi held a series of other leadership roles within BMS' Research and Development organization overseeing strategy, portfolio, and project management, as well as clinical and business operations. Mr. Biondi holds a bachelor's degree from Dartmouth College and an M.B.A. from the J.L. Kellogg School of Management at Northwestern University. We believe that Mr. Biondi is qualified to serve on our board of directors because of his extensive experience in biopharmaceutical strategy and corporate development.

 Willard H. Dere, M.D., has served as a member our board of directors since July 2017. Dr. Dere has been Professor Emeritus, Department of Internal Medicine, at the University of Utah School of Medicine since July 2022. Prior to retirement, and beginning in November 2014, Dr. Dere held multiple roles at the University of Utah Health Sciences Center, including Associate Vice President for

 Research, Co-Director of the Utah Clinical and Translational Science Institute, and Co-Director of the Center for Genomic Medicine. Prior to his professorship, from 2003 until 2014, Dr. Dere worked at Amgen, where he was Senior Vice President and head of Global Development, and led development programs in multiple therapeutic areas. From 1989 to 2014, he worked at Eli Lilly and led multiple development programs, and also worked in clinical pharmacology, regulatory affairs and safety. Dr. Dere has served on the boards of directors of BioMarin Pharmaceutical, Inc. since 2016, Mersana Therapeutics, Inc. since 2018, and Metagenomi, Inc. since August 2021, and previously served on the boards of directors of Ocera Therapeutics and Radius Health. Dr. Dere received his B.A. in History and Zoology and M.D. from the University of California, Davis, completed his internal medicine residency training at the University of Utah, and his postdoctoral training in endocrinology and metabolism at the University of California, San Francisco. We believe Dr. Dere is qualified to serve on our board of directors due to his extensive academic experience and his knowledge of the biotechnology industry.

 Claire M. Fraser, Ph. D., has served as a member of our board of directors since January 2023. Since 2007, Dr. Fraser has been the director of the Institute for Genome Sciences and a Professor of Medicine and Microbiology and Immunology at the University of Maryland School of Medicine in Baltimore, Maryland. From 1998 to 2007, she served as president and director of The Institute for Genomic Research, a not-for-profit research organization engaged in human and microbial genomics studies. Dr. Fraser has served on the board of directors of Becton, Dickinson, and Company, a medical technology company, since 2006, and previously served as the Chair of the Board and a director of the American Association for the Advancement of Science. Dr. Fraser received her bachelor's degree in Biology from Rensselaer Polytechnic Institute and her Ph. D. in Pharmacology from State University of New York-Buffalo. We believe Dr. Fraser is qualified to serve on our board of directors due to her extensive academic experience and her knowledge of the microbiome industry.

 Kurt C. Graves has served as a member of our board of directors since November 2015. Mr. Graves has served as the Chairman, President and Chief Executive Officer of i20 Therapeutics, Inc., a biotechnology company, since August 2023, and he previously served as the Executive Chairman of its board of directors from August 2021 to August 2023. Mr. Graves was previously the Chairman, President and Chief Executive Officer of Intarcia Therapeutics, Inc., a biotechnology company, from September 2010 to December 2020, and on its board of directors from August 2010 to December 2020. Previously, he served as Executive Vice President, Chief Commercial Officer and Head of Strategic Development at Vertex Pharmaceuticals Inc., or Vertex, from July 2007 to October 2009. Prior to joining Vertex, Mr. Graves held various senior leadership positions at Novartis Pharmaceuticals Corporation, or Novartis Corp., from 1999 to June 2007, including the Global General Medicines Business Unit Head and Global Chief Marketing Officer for the pharmaceuticals division of Novartis Corp. from September 2003 to June 2007. Prior to Novartis Corp., Mr. Graves held senior leadership positions at Merck and Astra-Merck where he led the U.S. Business Unit responsible for Prilosec, Nexium and Prilosec OTC over a 10-year period. He served as Chairman on the board of directors of Radius Health, Inc. from May 2011 to March 2020, and as a director on Achillion Pharmaceuticals, Inc., or Achillion, from June 2012 to January 2020, when Achillion was acquired. Mr. Graves received a B.S. in Biology from Hillsdale College. We believe Mr. Graves is qualified to serve as a member of our board of directors because of his extensive experience in the life sciences industry, membership on various boards of directors and his leadership and management experience.

 Richard N. Kender has served as a member of our board of directors since October 2014. From October 1978 to September 2013, Mr. Kender held positions in a variety of corporate areas at Merck & Co., Inc., or Merck, a pharmaceutical company, most recently serving as Senior Vice President of Business Development and Corporate Licensing. Mr. Kender has served on the boards of directors of Poxel S.A., a clinical stage biopharmaceutical company, since March 2015 and Bicycle Therapeutics PLC since July 2019. He previously served on the boards of directors of INC Research Holdings, Inc. (now known as Syneos Health) between December 2014 and August 2017, Abide Therapeutics, Inc., a privately held company, between December 2015 and May 2019, and ReViral Ltd., a privately held company, from November 2019 to June 2022. Mr. Kender received a B.S. in Accounting from Villanova University and an M.B.A. from Fairleigh Dickinson University. We believe Mr. Kender is qualified to serve on our board of directors because of his finance experience and knowledge of the biotechnology industry.

 Eric D. Shaff has served as our President and Chief Executive Officer and a member of our board of directors since January 2019. Previously, he served as our Chief Operating and Financial Officer and Executive Vice President from January 2018 until January 2019 and as our Chief Financial Officer from November 2014 until January 2019. From January 2012 to November 2014, Mr. Shaff was Vice President of Corporate Finance for Momenta Pharmaceuticals, or Momenta, a biotechnology company, where he helped manage Momenta's accounting, finance, planning, and procurement functions, as well as contributing to Momenta's investor relations efforts. Prior to Momenta, Mr. Shaff held a number of corporate development and finance positions with Genzyme Corporation, a biotechnology company, most recently as Vice President of Finance/Controller for the Personalized Genetic Health division. Mr. Shaff previously served on the board of directors of Sigilon Therapeutics, Inc. from 2017 to August 2023. Mr. Shaff received his B.A. from the University of Pennsylvania and his M.B.A. from Cornell University. We believe Mr. Shaff is qualified to serve on our board of directors because of his extensive business and finance experience and his knowledge of the biotechnology industry.

 Information about our Executive Officers

 Name

 Age

 Position

 Eric D. Shaff(1)(2)

 President, Chief Executive Officer and Director

 David Arkowitz(2)

 Executive Vice President, Chief Financial Officer and Head of Business Development

 Thomas J. DesRosier

 Executive Vice President and Chief Legal Officer

 David S. Ege, Ph. D.

 Executive Vice President and Chief Technology Officer

 Matthew Henn, Ph. D.

 Executive Vice President and Chief Scientific Officer

 Lisa von Moltke, M.D.

 Executive Vice President and Chief Medical Officer

 Teresa L. Young, Ph. D.

 Executive Vice President, Chief Commercial and Strategy Officer

 (1) Information concerning Eric D. Shaff, our President and Chief Executive Officer, may be found above in the section entitled "Director Biographical Information."

 (2) On February 26, 2024, the Company announced that David Arkowitz is retiring as Executive Vice President, Chief Financial Officer and Head of Business Development, principal financial officer and principal accounting officer of the Company, effective as of March 15, 2024. Effective as of Mr. Arkowitz's retirement, the Board has designated Eric Shaff to serve as the Company's interim principal financial officer and interim principal accounting officer until the expected commencement of employment of Marella Thorell as the Company's Executive Vice President and Chief Financial Officer, principal financial officer, and principal accounting officer on or about March 25, 2024.

 David Arkowitz has served as our Executive Vice President, Chief Financial Officer and Head of Business Development since June 2021. Previously, he served as the Chief Financial Officer of Flexion Therapeutics, Inc., a biotechnology company, from May 2018 to May 2021. From September 2013 to May 2018, Mr. Arkowitz served as Chief Operating Officer and Chief Financial Officer at Visterra, Inc., a biotechnology company that was acquired by Otsuka Pharmaceutical Co. He also previously served as Chief Financial Officer at each of Mascoma Corporation, AMAG Pharmaceuticals Inc., and Idenix Pharmaceuticals LLC and held additional leadership positions within each company. Preceding his tenure at Idenix, Mr. Arkowitz spent more than 13 years at Merck & Co., Inc. where he held roles of increasing responsibility, including Vice President and Controller of the U.S. operations, Controller of the global research and development division, and the Chief Financial Officer of Merck's Canadian subsidiary. Mr. Arkowitz currently serves on the board of directors of Kineta, Inc., and has previously served on the boards of directors of F-star Therapeutics, Inc., Yumanity Therapeutics, Inc., Spring Bank Pharmaceuticals, Inc. and Proteostasis Therapeutics, Inc. He obtained his B.A. in mathematics at Brandeis University and his M.B.A. in finance at Columbia University Business School.

 Thomas J. DesRosier has served as our Chief Legal Officer, Executive Vice President, and Secretary since May 2016. Previously, he served as Executive Vice President, Chief Legal and Administrative Officer and Secretary of ARIAD Pharmaceuticals, Inc., a biopharmaceutical company, from 2015 to 2016, Executive Vice President, Chief Legal and Administrative Officer and Secretary of Cubist Pharmaceuticals, Inc., or Cubist, a biopharmaceutical company, from 2014 to 2015 and Senior Vice President, Chief Legal Officer and Secretary of Cubist from 2013 to 2014. Before that, Mr. DesRosier served as Senior Vice President, General Counsel North America of Sanofi from 2011 to 2013. From 1999 to 2011, Mr. DesRosier held leadership roles of increasing seniority within the legal group of Genzyme Corporation, a biotechnology company, culminating in his role as Senior Vice President, Chief Legal Officer. Mr. DesRosier has served as a member of the board of directors of Avanir Pharmaceuticals, a privately held company and wholly-owned subsidiary of Otsuka Pharmaceutical Company, Ltd., since June 2017. Mr. DesRosier earned a B.A. in Chemistry from the University of Vermont and a J.D. from Wake Forest University School of Law.

 David S. Ege, Ph. D., has served as our Executive Vice President and Chief Technology Officer since October 2020. Previously, Dr. Ege served in a variety of technical and leadership roles in R&D and manufacturing at Merck from November 2003 to October 2020, most recently as global lead for digital strategy in Merck's Manufacturing Division from June 2019 to October 2020. From April 2015 to June 2019, Dr. Ege served as Executive Director of Vaccines & Biologics Manufacturing at Merck's plant in Elkton, Virginia, where he led bulk manufacturing operations for Gardasil, Gardasil9 and Cancidas. He has contributed to the successful first-in-class licensure and launch of cervical cancer vaccines, Gardasil (2006) and Gardasil9 (2014), and a breakthrough cancer immunotherapy, Keytruda (2014). He graduated summa cum laude from Princeton with a B.S.E. in chemical engineering and earned his Ph. D. in chemical engineering from the University of Pennsylvania.

 Matthew Henn, Ph. D., has served as our Executive Vice President and Chief Scientific Officer since February 2019. He has been involved in the discovery and development of multiple microbiome therapeutics across infectious, inflammatory, and oncology indications, and has authored over 75 peer-reviewed publications. His research has focused on microbial populations and the functional role of microbes in both environmental and human disease applications, and the development of genomic and functional technologies to study these populations. Prior to participating in the launch of our company in 2012, he was the Director of Viral Genomics and Assistant Director of the Genome Sequencing Center for Infectious Diseases at the Broad Institute of Massachusetts Institute of Technology and Harvard. He has served on various National Institutes of Health, or NIH, working groups on antimicrobial resistance and microbiome research, as a scientific advisor for NIH's Viral Pathogen Bioinformatics Resource Center, as an ad-hoc reviewer and editor of various peer-reviewed journals, and as a scientific advisor to non-profit and for-profit organizations. He currently serves on the Microbiome Therapeutics Innovation Group board of directors, the World Microbiome Partnership steering

 committee, Life Sciences Cares board of advisors, and the scientific advisory board of Growcentia, Inc., an agricultural microbiome company. Dr. Henn is formally trained in ecology and evolutionary biology and earned his Ph. D. in ecosystem sciences from the University of California at Berkeley, where he was a NASA Earth Systems Sciences Fellow, and trained as a NSF Postdoctoral Fellow in Microbiology at Duke University.

 Lisa von Moltke, M.D., has served as our Executive Vice President and Chief Medical Officer since March 2020. Previously, Dr. von Moltke worked for Alkermes, Inc., a pharmaceutical company, from June 2015 to December 2019, where she served in roles of increasing seniority, culminating as Senior Vice President and Head of Clinical Development. Beginning in June 2015, Dr. Moltke served as VP Clinical Pharmacology, DMPK and Bioanalytics, was promoted to Head of Clinical Development in November 2015, and became SVP in June 2018. Prior to joining Alkermes, Dr. von Moltke served as Vice President Clinical Pharmacology at Sanofi/Genzyme Corporation, a biotechnology company, from 2009 to 2015 and was US Head Clinical & Exploratory Pharmacology Sciences (CEP) and Early Development. Starting in 2014 she was Head CEP for Japan and China regions. From 2006 to 2009, Dr. von Moltke was Head, Translational Medicine for the Takeda Oncology Company, a biopharmaceutical company, in Cambridge, MA. Dr. von Moltke has served on the board of directors of Cara Therapeutics, Inc. since November 2022. She has served as President of the American College of Clinical Pharmacology, and as the Editor-in-Chief of The Journal of Clinical Pharmacology. Dr. von Moltke earned a B.A. degree at Wellesley College and her M.D. from Michigan State University, College of Human Medicine.

 Teresa L. Young, Ph. D., has served as our Executive Vice President, Chief Commercial and Strategy Officer since June 2020. Previously, Dr. Young served as Vice President, Global Commercial Strategy at Sage Therapeutics from March 2018 to June 2020, where she led development of Sage's global commercial capabilities, including global marketing, insights and analytics and new product planning. Prior to that, she held commercial leadership roles of increasing responsibility at Bristol-Myers Squibb from November 2010 to March 2018, culminating in her role as Vice President and General Manager, Cardiovascular, in which she led the global ELIQUIS business to become the company's largest product by revenue. Earlier in her career, Dr. Young held marketing and sales roles at GlaxoSmithKline from June 1993 to November 2010, where she catalyzed growth for the company's Urology, Diabetes and NeuroHealth organizations. Dr. Young is a member of the Women in Bio and Healthcare Businesswomen's Association and served on the Advisory Board of the Healthcare Businesswomen's Association. Dr. Young received her B.S. in pharmacy and her Ph. D. in healthcare marketing from the University of South Carolina.

 Code of Ethics

 Our board of directors has adopted a Code of Business Conduct and Ethics applicable to all officers, directors and employees, which is available on our website at www.serestherapeutics.com in the "Investors and News" section under "Corporate Governance." We intend to satisfy the disclosure requirement under Item 5.05 of Form 8-K regarding amendment to, or waiver from, a provision of our Code of Business Conduct and Ethics, as well as Nasdaq's requirement to disclose waivers with respect to directors and executive officers, by posting such information on our website at the address and location specified in the preceding sentence. The information contained on our website is not incorporated by reference into this Annual Report on Form 10-K.

 Other

 The remainder of the information required to be disclosed by this item will be contained in the Proxy Statement for our Annual Meeting of Stockholders to be held in 2024 and is incorporated herein by reference.

 Item 11. Executive Compensation

 The information required to be disclosed by this item will be contained in the Proxy Statement for our Annual Meeting of Stockholders to be held in 2024 and is incorporated herein by reference.

 Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

 The information required to be disclosed by this item will be contained in the Proxy Statement for our Annual Meeting of Stockholders to be held in 2024 and is incorporated herein by reference.

 Item 13. Certain Relationships and Related Transactions and Director Independence

 The information required to be disclosed by this item will be contained in the Proxy Statement for our Annual Meeting of Stockholders to be held in 2024 and is incorporated herein by reference.

 Item 14. Principal Accountant Fees and Services

 The information required to be disclosed by this item will be contained in the Proxy Statement for our Annual Meeting of Stockholders to be held in 2024 and is incorporated herein by reference.

 Item 15. Exhibits and Financial Statements Schedules

 (a)(1) Financial Statements.

 See the "Index to Consolidated Financial Statements" on page F-1 below for the list of financial statements filed as part of this report.

 (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 below beginning on page F-1.

 (a)(3) Exhibits.

 The following is a list of all exhibits filed as a part of this Annual Report on Form 10-K.

 Incorporated by Reference

 Filed/

 Exhibit
 Number

 Exhibit Description

 Form

 File No.

 Exhibit

 Filing
 Date

 Furnished
 Herewith

 3.1

 Restated Certificate of Incorporation

 3.1

 7/1/15

 3.2

 Certificate of Amendment to Restated Certificate of Incorporation of Registrant, dated June 27, 2023

 3.1

 6/28/23

 3.3

 Amended and Restated Bylaws

 3.1

 1/2/24

 4.1

 Specimen Stock Certificate evidencing the shares of common stock

 S-1/A

 333-204484

 4.2

 6/16/15

 4.2

 Description of Capital Stock

 *

 4.3

 Form of Warrant, dated April 27, 2023, issued by the Registrant to the Lenders, together with a schedule of warrant holders

 4.1

 4/27/23

 10.1#

 2015 Incentive Award Plan, as amended and forms of award agreements thereunder

 10.1

 3/7/23

 10.2#

 2015 Employee Stock Purchase Plan

 S-1/A

 333-204484

 10.3

 6/16/15

 10.3#

 2012 Stock Incentive Plan, as amended and form of option agreement thereunder

 S-1

 333-204484

 10.1

 5/27/15

 10.4#

 2022 Employment Inducement Award Plan and forms of award agreements thereunder

 10.4

 3/7/23

 10.5#

 Non-Employee Director Compensation Program

 10.5

 3/7/23

 10.6

 Lease, dated September 22, 2021, by and between the Registrant and HCP/KING 101 CPD LLC

 *

 10.7#

 Second Amended and Restated Employment Agreement, dated January 29, 2021, by and between the Registrant and Eric D. Shaff

 10.1

 2/1/21

 10.8#

 Amended and Restated Employment Agreement, dated January 29, 2021, by and between the Registrant and Thomas J. DesRosier

 10.2

 2/1/21

 10.9#

 Second Amended and Restated Employment Agreement, dated January 29, 2021, by and between the Registrant and Matthew R. Henn, Ph. D.

 10.3

 2/1/21

 10.10#

 Amended and Restated Employment Agreement, dated January 29, 2021, by and between the Registrant and David S. Ege, Ph. D.

 10.2

 8/3/21

 10.11#

 Letter Agreement, dated November 4, 2021, by and between the Registrant and David S. Ege, Ph. D.

 10.2

 11/10/21

 10.12#

 Amended and Restated Employment Agreement, dated January 29, 2021, by and between the Registrant and Teresa L. Young

 10.13

 3/2/21

 10.13#

 Amended and Restated Employment Agreement, dated January 29, 2021, by and between the Registrant and Lisa von Moltke, M.D.

 10.14

 3/2/21

 10.14#

 Employment Agreement, dated May 10, 2021 by and between the Registrant and David Arkowitz

 10.1

 5/20/21

 10.15^

 Collaboration and License Agreement, dated January 9, 2016, by and between the Registrant and Soci t des Produits Nestl S.A.

 10.1

 5/16/16

 10.16

 Amendment No. 1 to the Collaboration and License Agreement, dated August 10, 2016, by and between the Registrant and Nestec Ltd.

 10.22

 3/6/19

 10.17^

 Letter Agreement dated October 30, 2018, by and between the Registrant and Nestec Ltd.

 10.23

 3/6/19

 10.18

 Securities Purchase Agreement, dated August 12, 2020 by and between the Company and Soci t des Produits Nestl S.A.

 10.1

 8/14/20

 10.19

 License Agreement, dated July 1, 2021, by and between the Registrant and NHSc Pharma Partners

 10.1

 11/10/21

 10.20

 Amendment No. 1 to License Agreement, dated March 24, 2022, by and between the Registrant and NHSc Pharma Partners

 10.3

 5/4/222

 10.21

 Long Term Manufacturing Agreement, dated November 8, 2021, by and between the Registrant and BacThera AG

 10.25

 3/1/22

 10.22

 Amendment to Long Term Manufacturing Agreement, dated December 14, 2022, by and between the Registrant and BacThera AG

 10.28

 3/7/23

 10.23

 Form of Non-Affiliate Purchase Agreement

 10.1

 6/30/22

 10.24

 Form of Affiliate Purchase Agreement

 10.2

 6/30/22

 10.25

 Placement Agency Agreement, dated June 29, 2022, by and between Registrant and J.P. Morgan Securities LLC

 10.3

 6/30/22

 10.26

 Supply Agreement, dated September 15, 2015, by and between Registrant and GenIbet BioPharmaceuticals, SA, as amended

 *

 10.27

 Supply Agreement, dated March 13, 2023, by and between the Registrant and Nestl Enterprises S.A.

 10.1

 5/9/23

 10.28

 Credit Agreement and Guaranty, dated April 27, 2023, among the Registrant, as the borrower, the subsidiary guarantors from time to time party thereto, the lenders from time to time party thereto, and Oaktree Fund Administration, LLC, as administrative agent for the lenders

 10.1

 4/27/23

 21.1

 Subsidiaries of Seres Therapeutics, Inc.

 21.1

 3/2/20

 23.1

 Consent of PricewaterhouseCoopers LLP, Independent Registered Public Accounting Firm

 *

 31.1

 Rule 13a-14(a)/15d-14(a) Certification of Chief Executive Officer

 *

 31.2

 Rule 13a-14(a)/15d-14(a) Certification of Chief Financial Officer

 *

 32.1

 Section 1350 Certification of Chief Executive Officer

 **

 32.2

 Section 1350 Certification of Chief Financial Officer

 **

 97.1#

 Policy for Recovery of Erroneously Awarded Compensation

 *

 101.INS

 *

 101.SCH

 *

 *

 * Filed herewith.

 ** Furnished herewith.

 # Indicates management contract or compensatory plan.

 ^ Confidential treatment has been granted with respect to redacted portions of this exhibit. Redacted portions of this exhibit have been filed separately with the SEC.

 Portions of this exhibit (indicated by asterisks) have been omitted pursuant to Regulation S-K, Item 601(b)(10)(iv). Such omitted information is both (i) not material and (ii) the type that the Registrant treats as private or confidential.

 Item 16. Form 10-K Summary

 None.

 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.

 Date: March 5, 2024

 By:

 /s/ Eric D. Shaff

 Eric D. Shaff

 President, Chief Executive Officer and Director

 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.

 Signature

 Title

 Date

 /s/ Eric D. Shaff

 President, Chief Executive Officer

 Eric D. Shaff

 and Director

 (Principal Executive Officer)

 /s/ David Arkowitz

 Executive Vice President, Chief Financial Officer, and Head of Business Development

 David Arkowitz

 (Principal Financial and Accounting Officer)

 /s/ Stephen Berenson

 Chairman of the Board

 Stephen Berenson

 /s/ Dennis A. Ausiello

 Dennis A. Ausiello, M.D.

 /s/ Paul R. Biondi

 Paul R. Biondi

 /s/ Willard H. Dere

 Willard H. Dere, M.D.

 /s/ Claire M. Fraser

 Claire M. Fraser, Ph. D.

 /s/ Kurt C. Graves

 Kurt C. Graves

 /s/ Richard N. Kender

 Richard N. Kender

 INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

 Page

 Report of Independent Registered Public Accounting Firm (PCAOB ID 238)

 Consolidated Balance Sheets as of December 31, 2023 and 2022

 Consolidated Statements of Operations and Comprehensive Loss for the years ended December 31, 2023, 2022 and 2021

 Consolidated Statements of Stockholders' (Deficit) Equity as of December 31, 2023, 2022 and 2021

 Consolidated Statements of Cash Flows for the years ended December 31, 2023, 2022 and 2021

 Notes to Consolidated Financial Statements

 Report of Independent Registered Public Accounting Firm

 To the Board of Directors and Stockholders of Seres Therapeutics, Inc.

 Opinion on the Financial Statements

 We have audited the accompanying consolidated balance sheets of Seres Therapeutics, Inc. and its subsidiaries (the "Company") as of December 31, 2023 and 2022, and the related consolidated statements of operations and comprehensive loss, of stockholders' (deficit) equity and of cash flows for each of the three years in the period ended December 31, 2023, including 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 as of December 31, 2023 and 2022, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2023 in conformity with accounting principles generally accepted in the United States of America.

 Substantial Doubt About 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 consolidated financial statements, the Company has incurred losses and negative cash flows from operations since its inception and needs to raise additional capital to fund future operations, which raises substantial doubt about its ability to continue as a going concern. Management's plans in regard to 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 consolidated financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's consolidated 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 of these consolidated financial statements in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidated 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 consolidated 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 consolidated 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 consolidated financial statements. We believe that our audits provide a reasonable basis for our opinion.

 Critical Audit Matters

 The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that (i) relates to accounts or disclosures that are material to the consolidated financial statements and (ii) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters 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.

 Recognition of Collaboration (Profit) Loss Sharing - License Agreement with NHSc Rx License GmbH (Nestl)

 As described in Note 15 to the consolidated financial statements, the Company recognizes collaboration (profit) loss sharing – related party arising from a license agreement with Nestl, which totaled $0.7 million for the year ended December 31, 2023. Under the 2021 License Agreement with Nestl, beginning with the first commercial sale of VOWST, which occurred in June 2023, net sales of VOWST are recorded by Nestl. The Company records its share of the profits or losses from the sales of VOWST, including commercial and medical affairs expenses incurred by the Company, on a net basis, as collaboration (profit) loss sharing - related party. The collaboration (profit) loss sharing - related party line item also includes the Company's profit on the transfer of VOWST inventory

 to Nestl, which represents the excess of the supply price paid by Nestl over the Company's cost to manufacture VOWST, subject to a supply price cap applicable to product manufactured prior to commercial launch.

 The principal consideration for our determination that performing procedures relating to the recognition of collaboration (profit) loss sharing arising from the license agreement with Nestl is a critical audit matter is a high degree of auditor effort in performing procedures related to the Company's recognition of collaboration (profit) loss sharing.

 Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included, among others (i) evaluating management's collaboration (profit) loss sharing accounting policy; (ii) testing the completeness and accuracy of certain data used to calculate the collaboration (profit) loss sharing by sending a confirmation and obtaining and inspecting source documents provided by Nestl; (iii) recalculating the Company's share of the profit or losses from the sales of VOWST; and (iv) recalculating the Company's profit on transfer of VOWST inventory to Nestl and obtaining and inspecting source documents, such as invoices and evidence of payment.

 /s/ PricewaterhouseCoopers LLP

 Boston, Massachusetts

 We have served as the Company's auditor since 2014.

 CONSOLIDATED BALANCE SHEETS

 (In thousands, except share and per share data)

 2023

 2022

 Assets

 Current assets:

 Cash and cash equivalents

 $

 127,965

 $

 163,030

 Short term investments

 —

 18,311

 Collaboration receivable - related party

 8,674

 —

 Inventories

 29,647

 —

 Prepaid expenses and other current assets

 9,124

 13,423

 Total current assets

 175,410

 194,764

 Property and equipment, net

 22,457

 22,985

 Operating lease assets

 109,793

 110,984

 Restricted cash

 8,185

 8,185

 Restricted investments

 1,401

 1,401

 Other non-current assets (1)

 41,354

 10,465

 Total assets

 $

 358,600

 $

 348,784

 Liabilities and Stockholder's Equity

 Current liabilities:

 Accounts payable

 $

 3,641

 $

 17,440

 Accrued expenses and other current liabilities (2)

 80,611

 59,840

 Operating lease liabilities

 6,677

 3,601

 Short term portion of note payable, net of discount

 —

 Deferred income - related party

 7,730

 —

 Deferred revenue - related party

 —

 4,259

 Total current liabilities

 98,659

 85,596

 Long term portion of note payable, net of discount

 101,544

 50,591

 Operating lease liabilities, net of current portion

 105,715

 107,942

 Deferred revenue, net of current portion - related party

 95,364

 92,430

 Warrant liability

 —

 Other long-term liabilities

 1,628

 1,442

 Total liabilities

 403,456

 338,001

 Commitments and contingencies (Note 16)

 Stockholders' (deficit) equity:

 Preferred stock, $ 0.001 par value; 10,000,000 shares authorized at December 31, 2023 and 2022; no shares issued and outstanding at December 31, 2023 and 2022

 —

 —

 Common stock, $ 0.001 par value; 240,000,000 and 200,000,000 shares authorized at December 31, 2023 and 2022, respectively; 135,041,467 and 125,222,273 shares issued and outstanding at December 31, 2023 and 2022, respectively

 Additional paid-in capital

 933,244

 875,181

 Accumulated other comprehensive loss

 —

 ( 12

)

 Accumulated deficit

 ( 978,235

)

 ( 864,511

)

 Total stockholders' (deficit) equity

 ( 44,856

)

 10,783

 Total liabilities and stockholders' equity

 $

 358,600

 $

 348,784

 [1] Includes $ 38,877 and $ 8,828 as of December 31, 2023 and December 31, 2022, respectively, of milestones related to the construction of the Company's dedicated manufacturing suite at BacThera AG, or Bacthera (see Note 16, Commitments and Contingencies). Such amounts will form part of the right-of-use asset upon lease commencement.

 [2] Includes related party amounts of $ 28,053 and $ 34,770 at December 31, 2023 and December 31, 2022, respectively (see Note 18)

 The accompanying notes are an integral part of these consolidated financial statements.

 CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS

 (In thousands, except share and per share data)

 2023

 2022

 2021

 Revenue:

 Collaboration revenue - related party

 $

 126,325

 $

 7,128

 $

 143,857

 Grant revenue

 —

 —

 1,070

 Total revenue

 126,325

 7,128

 144,927

 Operating expenses:

 Research and development expenses

 $

 145,860

 $

 172,920

 $

 141,891

 General and administrative expenses

 87,744

 79,694

 69,261

 Collaboration (profit) loss sharing - related party

 1,004

 ( 1,732

)

 Total operating expenses

 234,308

 253,618

 209,420

 Loss from operations

 ( 107,983

)

 ( 246,490

)

 ( 64,493

)

 Other (expense) income:

 Interest income

 7,301

 3,058

 2,870

 Interest expense

 ( 13,176

)

 ( 6,020

)

 ( 2,910

)

 Other income (expense)

 ( 705

)

 ( 1,045

)

 Total other (expense) income, net

 ( 5,741

)

 ( 3,667

)

 ( 1,085

)

 $

)

 $

)

 $

)

 Net loss per share attributable to common stockholders, basic and diluted

 $

 ( 0.89

)

 $

 ( 2.31

)

 $

 ( 0.72

)

 Weighted average common shares outstanding, basic and diluted

 128,003,294

 108,077,043

 91,702,866

 Other comprehensive income (loss):

 Unrealized gain (loss) on investments, net of tax of $ 0

 ( 12

)

 Currency translation adjustment

 ( 1

)

 ( 1

)

 Total other comprehensive income (loss)

 ( 13

)

 Comprehensive loss

 $

 ( 113,712

)

 $

 ( 250,109

)

 $

 ( 65,591

)

 The accompanying notes are an integral part of these consolidated financial statements.

 CONSOLIDATED STATEMENTS OF STOCKHOLDERS' (DEFICIT) EQUITY

 (In thousands, except share data)

 Accumulated

 Total

 Common Stock

 Additional

 Other

 Stockholders

 Par

 Paid-in

 Comprehensive

 Accumulated

 (Deficit)

 Shares

 Value

 Capital

 Loss (Income)

 Deficit

 Equity

 Balance at December 31, 2020

 91,459,239

 $

 $

 723,482

 $

 ( 47

)

 $

 ( 548,776

)

 $

 174,750

 Issuance of common stock upon exercise of stock options

 329,112

 1,298

 —

 —

 1,299

 Issuance of common stock under ESPP

 100,417

 —

 —

 —

 Issuance of common stock upon vesting of RSUs, net
 of tax withholdings

 —

 —

 —

 —

 —

 —

 —

 20,222

 —

 —

 20,222

 Other comprehensive loss

 —

 —

 —

 ( 13

)

 —

 ( 13

)

 —

 —

 —

 —

)

)

 Balance at December 31, 2021

 91,889,418

 745,829

 ( 60

)

 ( 614,354

)

 131,507

 Issuance of common stock upon exercise of stock options

 326,864

 —

 —

 —

 Issuance of common stock upon vesting of RSUs and PSUs,
 net of tax withholdings

 282,401

 —

 —

 —

 —

 —

 Issuance of common stock under ESPP

 322,560

 —

 1,769

 —

 —

 1,769

 Issuance of common stock net of issuance costs of $ 3,279

 31,746,030

 96,689

 —

 —

 96,721

 Issuance of common stock from at the market equity offering,
 net of issuance costs of $ 310

 655,000

 4,446

 —

 —

 4,447

 —

 —

 25,482

 —

 —

 25,482

 Other comprehensive income

 —

 —

 —

 —

 —

 —

 —

 —

)

)

 Balance at December 31, 2022

 125,222,273

 875,181

 ( 12

)

 ( 864,511

)

 10,783

 Issuance of common stock upon exercise of stock options

 260,640

 —

 —

 —

 Issuance of common stock upon vesting of RSUs and PSUs,
 net of tax withholdings

 1,244,663

 ( 1

)

 —

 —

 —

 Issuance of common stock under ESPP

 602,692

 2,149

 —

 —

 2,151

 Issuance of common stock from at the market equity offering, net of issuance costs of $ 772

 7,711,199

 18,152

 —

 —

 18,159

 Issuance of warrants

 —

 —

 2,785

 —

 —

 2,785

 —

 —

 34,101

 —

 —

 34,101

 Other comprehensive income

 —

 —

 —

 —

 —

 —

 —

 —

)

)

 Balance at December 31, 2023

 135,041,467

 $

 $

 933,244

 $

 —

 $

 ( 978,235

)

 $

 ( 44,856

)

 The accompanying notes are an integral part of these consolidated financial statements.

 CONSOLIDATED STATEMENTS OF CASH FLOWS

 (In thousands)

 2023

 2022

 2021

 Cash flows from operating activities:

 $

)

 $

)

 $

)

 Adjustments to reconcile net loss to net cash provided by (used in) operating activities:

 34,101

 25,482

 20,222

 Depreciation and amortization expense

 6,243

 6,629

 5,947

 Non-cash operating lease cost

 8,871

 5,224

 3,275

 Amortization of premiums on investments

 ( 236

)

 Amortization of debt issuance costs

 1,139

 2,526

 Loss on extinguishment of debt

 1,625

 —

 —

 Change in fair value of warrant liabilities

 ( 1,554

)

 —

 —

 Collaboration (profit) loss sharing - related party

 5,158

 1,004

 ( 1,732

)

 Changes in operating assets and liabilities:

 Prepaid expenses and other current and non-current assets

 ( 29,124

)

 ( 12,599

)

 ( 12,337

)

 Collaboration receivable - related party

 ( 8,674

)

 —

 —

 Inventories

 ( 29,647

)

 —

 —

 Accounts receivable

 —

 —

 9,387

 Deferred income - related party

 7,730

 —

 —

 Deferred revenue - related party

 ( 1,325

)

 ( 7,128

)

 ( 4,357

)

 Accounts payable

 ( 11,578

)

 2,203

 9,362

 Operating lease liabilities

 ( 2,197

)

 ( 4,203

)

 ( 3,550

)

 Accrued expenses and other current and long-term liabilities (3)

 15,838

 3,336

 43,025

 Net cash (used in) provided by operating activities

 ( 117,354

)

 ( 228,816

)

 6,688

 Cash flows from investing activities:

 Purchases of property and equipment

 ( 7,975

)

 ( 9,821

)

 ( 9,566

)

 Purchases of investments

 ( 4,426

)

 ( 48,221

)

 ( 95,971

)

 Sales and maturities of investments

 22,983

 140,470

 169,625

 Net cash provided by investing activities

 10,582

 82,428

 64,088

 Cash flows from financing activities:

 Proceeds from issuance of common stock, net of issuance costs

 —

 96,721

 —

 Proceeds from at the market equity offering, net of issuance costs

 18,159

 4,447

 —

 Proceeds from exercise of stock options

 1,299

 Issuance of common stock under ESPP

 2,151

 1,769

 Proceeds from issuance of debt, net of issuance costs

 103,378

 27,606

 —

 Repayment of notes payable

 ( 52,860

)

 ( 1,907

)

 ( 948

)

 Net cash provided by financing activities

 71,705

 129,602

 1,178

 Net (decrease) increase in cash, cash equivalents and restricted cash

 ( 35,067

)

 ( 16,786

)

 71,954

 Effect of exchange rate changes on cash, cash equivalents and restricted cash

 ( 1

)

 ( 1

)

 Cash, cash equivalents and restricted cash at beginning of year

 171,215

 188,002

 116,049

 Cash, cash equivalents and restricted cash at end of year

 $

 136,150

 $

 171,215

 $

 188,002

 Supplemental disclosure of cash flow information:

 Cash paid for interest

 $

 12,547

 $

 4,926

 $

 2,446

 Supplemental disclosure of non-cash investing and financing
 activities:

 Property and equipment purchases included in accounts payable and
 accrued expenses

 $

 $

 2,276

 $

 Lease liability arising from obtaining right-of-use assets

 $

 3,046

 $

 91,412

 $

 12,442

 Prepaid rent reclassified to right-of-use assets

 $

 4,634

 $

 6,822

 $

 —

 Recognition of warrant liabilities

 $

 2,100

 $

 —

 $

 —

 Warrants issued related to Term Loan and recorded as debt discount (Note 9)

 $

 2,785

 $

 —

 $

 —

 [3] Includes related party amounts of $( 6,717), $ 3,087, and $ 31,683 at December 31, 2023, 2022, and 2021, respectively (see Note 18)

 The accompanying notes are an integral part of these consolidated financial statements.

 1. Nature of the Business and Basis of Presentation

 Seres Therapeutics, Inc. (the "Company") was incorporated under the laws of the State of Delaware in October 2010 under the name Newco LS21, Inc. In October 2011, the Company changed its name to Seres Health, Inc., and in May 2015, the Company changed its name to Seres Therapeutics, Inc. The Company is a commercial-stage microbiome therapeutics company focused on the development and commercialization of a novel class of biological drugs, which are designed to treat disease by modulating the microbiome to restore health by repairing the function of a disrupted microbiome to a non-disease state.
 The Company's product, VOWST (fecal microbiota spores, live brkp), formerly called SER-109, was approved by the U.S. Food and Drug Administration ("FDA") on April 26, 2023 and is the first and only orally administered microbiome therapeutic. VOWST is indicated to prevent the recurrence of Clostridioides difficile infection ("CDI") in patients 18 or older following antibacterial treatment for recurrent CDI. The Company launched VOWST in the United States with its collaborator, Nestl Health Science ("Nestl "), in June 2023.
 Building upon VOWST, the Company is progressing the Phase 1b clinical trial of SER-155, a microbiome therapeutic candidate consisting of a 16-strain consortium of cultivated bacteria designed to prevent enteric-derived infections and resulting bloodstream infections, as well as induce immune tolerance responses to reduce the incidence of graft-versus-host disease ("GvHD") in patients undergoing allogeneic hematopoietic stem cell transplantation ("allo-HSCT"). Gastrointestinal microbiome data from the first 100 days of SER-155 Phase 1b open-label study cohort 1 showed the successful engraftment of SER-155 bacterial strains, and a substantial reduction in the cumulative incidence of pathogen domination as compared to a reference cohort of patients, a biomarker associated with the risk of serious enteric infections and resulting bloodstream infections, as well as GvHD. The tolerability profile observed was favorable, with no serious adverse events attributed to SER-155 administration. Enrollment in the placebo-controlled cohort 2 portion of the study is ongoing, and the cohort 2 data readout is anticipated in the third quarter of 2024.
 The Company has built and deploys a reverse translational platform and knowledge base for the discovery and development of microbiome therapeutics, and maintains extensive proprietary know-how that may be used to support future research and development efforts. This platform incorporates high-resolution analysis of human clinical data to identify microbiome biomarkers associated with disease and non-disease states; preclinical screening using human cell-based assays and in vitro/ex vivo and in vivo disease models customized for microbiome therapeutics; and microbiological capabilities and a strain library that spans broad biological and functional breadth to both identify specific microbes and microbial metabolites that are associated with disease and to design consortia of bacteria with specific pharmacological properties. In addition, the Company owns a valuable intellectual property estate related to the development and manufacture of microbiome therapeutics.
 On October 29, 2023, the Company's Board of Directors approved a restructuring plan to prioritize the commercialization of VOWST and the completion of the SER-155 Phase 1b study, while significantly reducing costs and supporting longer-term business sustainability (the "Restructuring Plan"). The Restructuring Plan included (i) a reduction of the Company's workforce by approximately 41 % across the organization, resulting in the elimination of approximately 160 positions; (ii) significantly scaling back all non-partnered research and development activities other than the completion of the SER-155 Phase 1b study; and (iii) reducing general and administrative expenses, including consolidating office space. For additional information on the Restructuring Plan, see Note 13, Restructuring.
 The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to commercialization. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees and consultants.
 The accompanying consolidated financial statements have been prepared on a basis that assumes that the Company will continue as a going concern and that contemplates the realization of assets and satisfaction of liabilities and commitments in the normal course of business. As of December 31, 2023, the Company had an accumulated deficit of $ 978,235 and cash and cash equivalents of $ 127,965.
 The Company's primary focus in recent months has been and will continue to be supporting commercialization, including the manufacture of VOWST, and the completion of the SER-155 Phase 1b study, which requires capital and resources. Other than VOWST, the Company's product candidates are in development, and will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to potential commercialization. There can be no assurance that the Company's research and development will be successfully completed, that adequate protection for the Company's intellectual property will be obtained, or maintained, that any product candidate developed will obtain necessary government regulatory approval, or that any approved product will be commercially viable. Even if the Company's product development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales.

 Primarily as a result of the increased and costly efforts to commercialize VOWST and to continue the research and development efforts for other product candidates and preclinical programs, for the year ended December 31, 2023, the Company incurred a net loss of $ 113,724, and had net operating cash outflows of $ 117,354. The Company expects that its operating losses and negative cash flows will continue for the foreseeable future. Based on the Company's currently available cash resources, current and forecasted level of operations, and forecasted cash flows for the 12-month period subsequent to the date of issuance of these consolidated financial statements, the Company will require additional funding to maintain commercial production of VOWST, continue to progress the SER-155 Phase 1b study, and meet its operational obligations as they come due. These factors raise substantial doubt about the Company's ability to continue as a going concern.
 The Company's ability to continue as a going concern is dependent upon its ability to obtain the necessary financing to meet its obligations and repay its liabilities arising from normal business operations when they come due, and to generate profitable operations in the future. Management plans to provide for the Company's capital requirements through financing or other transactions, including drawing the Tranche B Term Loan pursuant to the Oaktree Credit Agreement (see Note 9, Notes Payable), which is expected to become available to the Company based on VOWST net sales forecasts assuming continued quarter-over-quarter net sales growth, and selling shares under the Company's at the market equity offering. There can be no assurance that the Company will generate significant profit from the transfer of VOWST to Nestl or its share of collaboration profits resulting from net sales of VOWST, or that it will be able to raise additional capital to fund operations with terms acceptable to the Company, or at all. Because certain elements of management's plans to mitigate the conditions that raised substantial doubt about the Company's ability to continue as a going concern are outside of the Company's control, including the ability to raise capital through an equity or other financing, those elements cannot be considered probable according to Accounting Standards Codification ("ASC") 205-40, Going Concern ("ASC 205-40"), and therefore cannot be considered in the evaluation of mitigating factors. As a result, management has concluded that substantial doubt exists about the Company's ability to continue as a going concern for 12 months from the date these consolidated financial statements are issued.
 The accompanying financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP") and include the accounts of the Company and its wholly owned subsidiaries after elimination of all intercompany accounts and transactions.

 2. Summary of Significant Accounting Policies

 Use of Estimates
 The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting periods. In these consolidated financial statements, the Company uses estimates and assumptions related to revenue recognition and the accrual of research and development expenses. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company's estimates.

 Cash Equivalents
 The Company considers all short-term, highly liquid investments with original maturities of 90 days or less at acquisition date to be cash equivalents. Cash equivalents, which consist of money market accounts, commercial paper and corporate bonds purchased with original maturities of less than 90 days from the date of purchase, are stated at fair value.

 Investments
 The Company classifies all of its marketable debt securities as available-for-sale securities. Accordingly, these marketable debt securities are recorded at fair value and unrealized gains and losses are reported as a separate component of accumulated other comprehensive loss in stockholders' equity (deficit), unless the Company has determined that the security has experienced a credit loss, the Company expects to sell the security prior to the recovery of its unrealized losses, or it is more likely than not that the Company will be required to sell the security prior to the recovery of its amortized cost basis. When determining whether a credit loss exists, the Company considers several factors, including the estimated present value of expected cash flows from the security, whether the Company has the intent to sell the security or whether it is more likely than not that the Company will be required to sell the security prior to recovery of its amortized cost basis. If the Company has an intent to sell, or if it is more likely than not that the Company will be required to sell a debt security in an unrealized loss position before recovery of its amortized cost basis, the Company will write down the security to its fair value and record the corresponding charge to the consolidated statement of operations and comprehensive loss.

 The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense) within the consolidated statement of operations and comprehensive loss. No credit losses were recorded during the years ended December 31, 2023, 2022, and 2021.

 The Company classifies its available-for-sale marketable debt securities as current assets on the consolidated balance sheet if they mature within one year from the balance sheet date. Any available-for-sale marketable debt securities with maturities greater than one year from the balance sheet date are classified as long-term assets on the consolidated balance sheet.
 Restricted Investments

 The Company held investments of $ 1,401 as of December 31, 2023 and 2022, in a separate restricted bank account as a security deposit for the lease of the Company's headquarters in Cambridge, Massachusetts. The Company has classified these deposits as long-term restricted investments on its consolidated balance sheet.

 Restricted Cash

 The Company held restricted cash of $ 8,185 as of December 31, 2023 and 2022, respectively, which represents cash held for the benefit of the landlord for the Company's other leases. The Company has classified the restricted cash as long-term on its consolidated balance sheet as the underlying leases are greater than 1 year.
 Cash, cash equivalents and restricted cash were comprised of the following (in thousands):

 2023

 2022

 Cash and cash equivalents

 $

 127,965

 $

 163,030

 Restricted cash, non-current

 8,185

 8,185

 Total cash, cash equivalents and restricted cash

 $

 136,150

 $

 171,215

 Concentration of Credit Risk
 Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and investments. The Company has all cash, cash equivalents and investments balances at accredited financial institutions, in amounts that exceed federally insured limits. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships.

 Fair Value Measurements
 Certain assets and liabilities are carried at fair value in accordance with GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable:
 • Level 1—Quoted prices in active markets for identical assets or liabilities.

 • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data.

 • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.

 The Company's cash equivalents and investments are carried at fair value, determined according to the fair value hierarchy described above. The Company's investments in certificates of deposit are carried at amortized cost, which approximates fair value. The carrying values of the Company's prepaid expenses and other current and non-current assets, accounts payable and accrued expenses approximate their respective fair values due to the short-term nature of these assets and liabilities. The carrying value of the Company's long-term debt approximates its fair value (a level 2 measurement) at each balance sheet date due to its variable interest rate, which

 approximates a market interest rate. The warrant liabilities associated with the Company's credit facility with Oaktree for which there is no current market and the determination of fair value requires significant estimation are classified as Level 3 financial liabilities.
 Inventories
 Inventories are stated at the lower of cost or estimated net realizable value with cost based on the first-in first-out method. Inventory that can be used in either the production of clinical or commercial products is expensed as research and development costs when identified for use in clinical trials.
 Prior to the regulatory approval of its product candidates, the Company incurs expenses for the manufacture of drug product supplies to support clinical development that could potentially be available to support the commercial launch of those drugs. Until the date at which regulatory approval has been received or is otherwise considered probable, the Company records all such costs as research and development expenses.

 Property and Equipment
 Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method over the useful life of the asset, which are as follows:

 Estimated Useful Life (In Years)

 Laboratory equipment

 Computer equipment, furniture and office equipment

 Leasehold improvements

 Lesser of useful life
or lease term

 Expenditures for repairs and maintenance of assets are charged to expense as incurred. Upon retirement or sale, the cost and related accumulated depreciation of assets disposed of are removed from the accounts and any resulting gain or loss is included in loss from operations.

 Impairment of Long-Lived Assets
 Long-lived assets consist of property and equipment and right-of-use assets associated with our lease agreements. All of the Company's long-lived assets are to be held and used and have definitive lives and accordingly are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset or asset group to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset or asset group are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset over its fair value, determined based on discounted cash flows. To date, the Company has no t recorded any impairment losses on long-lived assets.

 Research and Development Costs
 Research and development costs are expensed as incurred. Research and development expenses include salaries, stock-based compensation and benefits of employees, third-party license fees and other operational costs related to the Company's research and development activities, including allocated facility-related expenses and external costs of outside vendors engaged to conduct both preclinical studies and clinical trials.

 Research Contract Costs and Accruals
 The Company has entered into various research and development contracts with research institutions and other companies. These agreements are generally cancelable, and related payments are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research costs based on reporting provided by third parties, typically contract research organizations. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies, including the

 phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued and prepaid balances at the end of any reporting period. Actual results could differ from the Company's estimates. The Company's historical accrual estimates have not been materially different from the actual costs.

 Patent Costs
 All patent-related costs incurred in connection with filing and prosecuting patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses.

 Accounting for Stock-Based Compensation
 The Company measures all stock options and other stock-based awards granted to employees, non-employees, and directors based on the fair value on the date of the grant and recognizes compensation expense of those awards over the requisite service period, which is generally the vesting period of the respective award. Generally, the Company issues stock options, restricted stock units and restricted stock awards with only service-based vesting conditions and records the expense for these awards using the straight-line method. For stock options or restricted stock units issued with performance-based vesting conditions, the stock compensation expense related to these awards is recognized based on the grant date fair value when achievement of the performance condition is deemed probable.
 The Company classifies stock-based compensation expense in its consolidated statement of operations and comprehensive loss in the same manner in which the award recipient's payroll costs are classified or in which the award recipients' service payments are classified.
 The Company accounts for forfeitures of stock-based awards as they occur rather than applying an estimated forfeiture rate to stock-based compensation expense.

 The fair value of each stock option grant is estimated on the date of grant using the Black- Scholes option-pricing model. The Company estimates its expected common stock volatility based on its historical common stock volatility for the same time period. The Company uses the simplified method prescribed by Securities and Exchange Commission Staff Accounting Bulletin No. 107, Share-Based Payment, to calculate the expected term of options granted to employees, non-employees and directors. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future.
 Revenue Recognition
 The Company recognizes revenue in accordance with the guidance under ASC 606, Revenue from Contracts with Customers ("ASC 606"). ASC 606 applies to all contracts with customers, except those contracts that are within the scope of other guidance, such as leases, insurance, and financial instruments. The Company enters into agreements that are within the scope of ASC 606, under which the Company licenses certain of the Company's product candidates and performs research and development services in connection with such arrangements. The terms of these arrangements typically include payment of one or more of the following: nonrefundable up-front fees, reimbursement of research and development costs, development, clinical, regulatory and commercial sales milestone payments, and royalties on net sales of licensed products. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. When determining the timing and extent of revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps:
 a. identify the contract(s) with a customer;

 b. identify the performance obligations in the contract;

 c. determine the transaction price;

 d. allocate the transaction price to the performance obligations in the contract; and

 e. 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 transferred to the customer.

 At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within the contract to determine whether each promised good or service is a performance obligation. The promised goods or services in the Company's arrangements typically consist of a license to the Company's intellectual property and/or research and development services. The Company may provide options to additional items in such arrangements, which are accounted for as separate contracts when the customer elects to exercise such options, unless the option provides a material right to the customer. Performance obligations are promises in a contract to transfer a distinct good or service to the customer that (i) the customer can benefit from on its own or together with other readily available resources, and (ii) is separately identifiable from other promises in the contract. Goods or services that are not individually distinct performance obligations are combined with other promised goods or services until such combined group of promises meet the requirements of a performance obligation.

 The Company determines the transaction price based on the amount of consideration the Company expects to receive for transferring the promised goods or services in the contract. Consideration may be fixed, variable, or a combination of both. At contract inception for arrangements that include variable consideration, the Company estimates the probability and extent of consideration it expects to receive under the contract utilizing either the most likely amount method or expected amount method, whichever best estimates the amount expected to be received. The Company then considers any constraints on the variable consideration and includes in the transaction price variable consideration to the extent it is deemed probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved.

 The Company then allocates the transaction price to each performance obligation based on the relative standalone selling price and recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) control is transferred to the customer and the performance obligation is satisfied. For performance obligations which consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition.
 The Company records amounts as accounts receivable when the right to consideration is deemed unconditional. When consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract, a contract liability is recorded for deferred revenue.
 The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less. Incremental costs of obtaining a contract are expensed as and when incurred if the expected period over which the Company would have amortized the asset is one year or less, or the amount is immaterial.

 Collaboration Revenue
 Arrangements with collaborators may include licenses to intellectual property, research and development services, manufacturing services for clinical and commercial supply, and participation on joint steering committees. The Company evaluates the promised goods or services to determine which promises, or group of promises, represent performance obligations. In contemplation of whether a promised good or service meets the criteria required of a performance obligation, the Company considers the stage of development of the underlying intellectual property, the capabilities and expertise of the customer relative to the underlying intellectual property, and whether the promised goods or services are integral to or dependent on other promises in the contract. When accounting for an arrangement that contains multiple performance obligations, the Company must develop judgmental assumptions, which may include market conditions, reimbursement rates for personnel costs, development timelines and probabilities of regulatory success to determine the stand-alone selling price for each performance obligation identified in the contract.
 When the Company concludes that a contract should be accounted for as a combined performance obligation and recognized over time, the Company must then determine the period over which revenue should be recognized and the method by which to measure revenue. The Company generally recognizes revenue using a cost-based input method.
 Licenses of intellectual property
 If a license to the Company's intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue allocated to the license when the license is transferred to the customer and the

 customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue associated with the bundled performance obligation. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of progress and related revenue recognition.
 Milestone Payments
 At the inception of each arrangement that includes developmental and regulatory milestone payments, the Company evaluates whether the achievement of each milestone specifically relates to the Company's efforts to satisfy a performance obligation or transfer a distinct good or service within a performance obligation. If the achievement of a milestone is considered a direct result of the Company's efforts to satisfy a performance obligation or transfer a distinct good or service and the receipt of the payment is based upon the achievement of the milestone, the associated milestone value is allocated to that distinct good or service, otherwise it will be allocated to all performance obligations of the arrangement based on the initial allocation.
 The Company evaluates each milestone to determine when and how much of the milestone to include in the transaction price. The Company first estimates the amount of the milestone payment that the Company could receive using either the expected value or the most likely amount approach. The Company primarily uses the most likely amount approach as that approach is generally most predictive for milestone payments with a binary outcome. Then, the Company considers whether any portion of that estimated amount is subject to the variable consideration constraint (that is, whether it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty). The Company updates the estimate of variable consideration included in the transaction price at each reporting date which includes updating the assessment of the likely amount of consideration and the application of the constraint to reflect current facts and circumstances.
 Royalties
 For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has no t recognized any revenue related to sales-based royalties or milestone payments based on the level of sales.
 Manufacturing supply services
 For arrangements that include a promise of supply of clinical or commercial product, the Company determines if the supply is a promise in the contract or a future obligation at the customer's option. If determined to be a promise at inception of the contract, the Company evaluates the promise to determine whether it is a separate performance obligation or a component of a bundled performance obligation. If determined to be an option, the Company determines if the option provides a material right to the customer and if so, accounts for the option as a separate performance obligation. If determined to be an option but not a material right, the Company accounts for the option as a separate contract when the customer elects to exercise the option.

 Grant Revenue

 The Company generates revenue from government contracts that reimburse the Company for certain allowable costs for funded projects. For contracts with government agencies, when the Company has concluded that it is the principal in conducting the research and development expenses, and where the funding arrangement is considered central to the Company's ongoing operations, the Company classifies the recognized funding received as revenue.

 The Company has concluded to recognize funding received as revenue, rather than as a reduction of research and development expenses, because the Company is the principal in conducting the research and development activities and these contracts are central to its ongoing operations. Revenue is recognized as the qualifying expenses related to the contracts are incurred. Revenue recognized upon incurring qualifying expenses in advance of receipt of funding is recorded in the Company's consolidated balance sheet as accounts receivable. The related costs incurred by the Company are included in research and development expense in the Company's consolidated statements of operations and comprehensive loss.

 Collaboration Profit and Loss
 The Company analyzes its collaboration arrangements to assess whether they are within the scope of ASC 808, Collaborative Arrangements ("ASC 808"), which includes determining whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. For collaboration arrangements within the scope of ASC 808 that contain multiple elements, the Company first determines which elements of the collaboration are deemed to be within the scope of ASC 808 and those that are more reflective of a vendor-customer relationship and therefore within the scope of ASC 606. For those elements of the arrangement that are accounted for pursuant to ASC 606, the Company applies the five-step model prescribed in ASC 606, as described above. For elements of collaboration arrangements that are accounted for pursuant to ASC 808, an appropriate recognition method is determined and applied consistently, generally by analogy to ASC 606. The Company records its share of the profits or losses from the sales of VOWST on a net basis, as collaboration (profit) loss sharing - related party because Nestl and the Company are both active participants in commercialization activities and are exposed to significant risks and rewards that are dependent on the commercial success of the activities in the arrangement. The collaboration (profit) loss sharing - related party line item also includes the Company's profit on the transfer of VOWST inventory to Nestl, which represents the excess of the supply price paid by Nestl over our cost to manufacture VOWST.

 Income Taxes
 The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the consolidated financial statements or in the Company's tax returns. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense.
 The Company applies ASC 740-10, Accounting for Uncertain Tax Positions. The Company accounts for uncertainty in income taxes recognized in the financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50 % likelihood of being realized upon ultimate settlement. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties.

 Segment Data
 The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company's singular focus is on developing microbiome therapeutics to treat the modulation of the colonic microbiome. Revenue to date has been generated solely through the Company's agreements with its collaborators, all of which has been earned in the United States. All tangible assets are held in the United States.

 Comprehensive Loss
 Comprehensive loss includes net loss as well as other changes in stockholders' equity (deficit) that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2023, 2022 and 2021, other comprehensive income (loss) consisted of changes in unrealized gains (losses) from available-for-sale investments and a currency translation adjustment.

 Net Loss per Share
 Basic net loss per share is computed using the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed using the sum of the weighted average number of common shares outstanding during the period and, if dilutive, the weighted average number of potential shares of common stock, including the assumed exercise of stock options and unvested restricted stock. The Company applies the two-class method to calculate its basic and diluted net loss per share attributable to

 common stockholders. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to common stockholders. However, the two-class method does not impact the net loss per share of common stock as the Company was in a net loss position for each of the periods presented.
 The Company's restricted stock awards entitle the holder of such awards to dividends declared or paid by the board of directors, regardless of whether such awards are unvested, as if such shares were outstanding common shares at the time of the dividend. However, the unvested restricted stock awards are not entitled to share in the residual net assets (deficit) of the Company. Accordingly, in periods in which the Company reports a net loss attributable to common stockholders, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive.

 Leases
 In accordance with ASC 842, Leases, the Company determines if an arrangement is or contains a lease at inception. A contract is or contains a lease if the contract conveys the right to control the use of an identified asset for a period of time in exchange for consideration. The Company classifies leases at the lease commencement date as operating or finance leases and records a right-of-use asset and a lease liability on the consolidated balance sheet for all leases with an initial lease term of greater than 12 months. Leases with an initial term of 12 months or less are not recorded on the balance sheet, but payments are recognized as expense on a straight-line basis over the lease term. The Company has elected not to record a right-of-use asset or lease liability for leases with terms of 12 months or less.

A lease qualifies as a finance lease if any of the following criteria are met at the inception of the lease: (i) there is a transfer of ownership of the leased asset to the Company by the end of the lease term, (ii) the Company holds an option to purchase the leased asset that it is reasonably certain to exercise, (iii) the lease term is for a major part of the remaining economic life of the leased asset, (iv) the present value of the sum of lease payments equals or exceeds substantially all of the fair value of the leased asset, or (v) the nature of the leased asset is specialized to the point that it is expected to provide the lessor no alternative use at the end of the lease term.

The Company enters into contracts that contain both lease and non-lease components. Non-lease components may include maintenance, utilities, and other operating costs. The Company combines the lease and non-lease components of fixed costs in its lease arrangements as a single lease component. Variable costs, such as utilities or maintenance costs, are not included in the measurement of right-of-use assets and lease liabilities, but rather are expensed when the event determining the amount of variable consideration to be paid occurs.

Finance and operating lease assets and liabilities are recognized at the lease commencement date based on the present value of the lease payments over the lease term using the discount rate implicit in the lease. If the rate implicit is not readily determinable, the Company utilizes an estimate of its incremental borrowing rate based upon the available information at the lease commencement date. Operating lease assets are further adjusted for prepaid or accrued lease payments. Operating lease payments are expensed using the straight-line method as an operating expense over the lease term. The Company's lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Finance lease assets are amortized to depreciation expense using the straight-line method over the shorter of the useful life of the related asset or the lease term. Finance lease payments are bifurcated into (i) a portion that is recorded as imputed interest expense and (ii) a portion that reduces the finance liability associated with the lease.

 Right-of-use assets and lease liabilities are reassessed and remeasured when amendments to the terms of the lease agreement require reassessment and remeasurement of the lease payments and other inputs to the calculation of right-of-use assets and lease liabilities. The Company accounts for remeasurements and modifications to lease liabilities using the present value of remaining lease payments and estimated incremental borrowing rate at the date of remeasurement. The adjustment to the lease liability is recognized as a gain or loss in operating expenses, or as an adjustment to the right-of-use asset, as appropriate, based on the terms and conditions within the lease that are amended.
 Recently Adopted Accounting Pronouncements
 In June 2016, the FASB issued Accounting Standards Update ("ASU") No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (''ASU 2016-13''), which requires the measurement and recognition of

 expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss model. It also eliminates the concept of other-than-temporary impairment and requires credit losses related to available-for-sale debt securities to be recorded through an allowance for credit losses rather than as a reduction in the amortized cost basis of the securities. These changes may result in earlier recognition of credit losses. In November 2018, the FASB issued ASU No. 2018-19, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, which narrowed the scope and changed the effective date for non-public entities for ASU 2016-13. The FASB subsequently issued supplemental guidance within ASU No. 2019-05, Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief (''ASU 2019-05''). ASU 2019-05 provides an option to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost basis. The Company adopted the new standard using a modified retrospective approach as of January 1, 2022. The adoption of this standard did not have a material impact on the Company's consolidated financial statements.
 Recently Issued Accounting Pronouncements
 In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which requires public entities to disclose information about their reportable segments' significant expenses and other segment items on an interim and annual basis. Public entities with a single reportable segment are required to apply the disclosure requirements in ASU 2023-07, as well as all existing segment disclosures and reconciliation requirements in ASC 280, on an interim and annual basis. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact that the adoption of ASU 2023-07 may have on its consolidated financial statements.
 In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures which requires public entities to disclose specific categories in the effective tax rate reconciliation, as well as additional information for reconciling items that exceed a quantitative threshold. ASU 2023-09 also requires all entities to disclose income taxes paid disaggregated by federal, state and foreign taxes, and further disaggregated for specific jurisdictions that exceed 5% of total income taxes paid, among other expanded disclosures. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact that the adoption of ASU 2023-09 may have on its consolidated financial statements.

 3. Fair Value of Financial Assets and Liabilities

 The following tables present the Company's fair value hierarchy for its assets and liabilities that are measured at fair value on a recurring basis (in thousands):

 Fair Value Measurements as of December 31, 2023 Using:

 Level 1

 Level 2

 Level 3

 Total

 Cash equivalents:

 Money market funds

 $

 $

 —

 $

 —

 $

 Commercial paper

 —

 —

 —

 —

 Government securities

 —

 —

 —

 —

 Total assets

 $

 $

 —

 $

 —

 $

 Warrant liabilities

 $

 —

 $

 —

 $

 $

 Total liabilities

 $

 —

 $

 —

 $

 $

 Fair Value Measurements as of December 31, 2022 Using:

 Level 1

 Level 2

 Level 3

 Total

 Cash equivalents:

 Money market funds

 $

 47,863

 $

 —

 $

 —

 $

 47,863

 Commercial paper

 —

 11,691

 —

 11,691

 Government securities

 —

 4,966

 —

 4,966

 Investments:

 Commercial paper

 $

 —

 $

 2,465

 $

 —

 $

 2,465

 Corporate bonds

 —

 2,957

 —

 2,957

 Certificate of deposits

 —

 —

 —

 —

 Government securities

 —

 12,889

 —

 12,889

 $

 47,863

 $

 34,968

 $

 —

 $

 82,831

 Money market funds are valued by the Company based on quoted market prices, which represent a Level 1 measurement within the fair value hierarchy. Commercial paper, corporate bonds, and government securities are valued by the Company using quoted prices in active markets for similar securities, which represent a Level 2 measurement within the fair value hierarchy.
 As of December 31, 2023 and 2022 the Company held a restricted investment of $ 1,401, which represents a certificate of deposit that is classified as Level 2 in the fair value hierarchy.
 Level 3 financial liabilities consist of the warrant liabilities for which there is no current market such that the determination of fair value requires significant judgment or estimation. Changes in fair value measurements categorized within Level 3 of the fair value hierarchy are analyzed each period based on changes in estimates or assumptions and recorded through other income (expense). The Company uses a Monte-Carlo simulation model which includes the Black-Scholes option pricing model to value the Level 3 warrant liabilities at inception and on each subsequent reporting date. This model incorporates transaction details such as the Company's stock price, contractual terms of the underlying warrants, maturity, risk free rates, volatility, as well as the term to achievement of estimated sales targets. The unobservable inputs for all of the Level 3 warrant liabilities are volatility and the term to achievement of estimated sales targets. The Company utilizes its historical and implied volatility, using its closing common stock prices and market data, to reflect future volatility over the expected term of the warrants. The Company estimates the time to achievement of sales targets of VOWST using information and forecasts generated by the Company in consideration of the terms of the 2021 License Agreement.
 On the Closing Date (as defined in Note 9, Notes Payable) and as of December 31, 2023, the Level 3 inputs to the warrant liabilities are as follows:

 Closing Date

 December 31, 2023

 Volatility

 83.0

 %

 101.0

 %

 Term (in years)

 1.7

 1.3

 A reconciliation of the beginning and ending balances for the year ended December 31, 2023 for liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) is as follows (in thousands):

 Warrant Liabilities

 Balance as of December 31, 2022

 $

 —

 Issuance of warrants

 2,100

 Adjustment to fair value

 ( 1,554

)

 Balance as of December 31, 2023

 There were no assets or liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) during the year ended December 31, 2022. There were no transfers between Level 1, Level 2, or Level 3 during the years ended December 31, 2023 and 2022.

 4. Investments

 As of December 31, 2023, the Company held restricted investments of $ 1,401, the cost of which approximates current fair value. The Company did not hold any other investments as of December 31, 2023.
 Investments by security type consisted of the following at December 31, 2022 (in thousands):

 December 31, 2022

 Amortized
Cost

 Gross
Unrealized Gain

 Gross
Unrealized Loss

 Fair
Value

 Investments:

 Commercial paper

 $

 2,465

 $

 —

 $

 —

 $

 2,465

 Corporate bonds

 2,958

 —

 ( 1

)

 2,957

 Government securities

 12,898

 ( 12

)

 12,889

 $

 18,321

 $

 $

 ( 13

)

 $

 18,311

 Excluded from the table above at December 31, 2022 are restricted investments of $ 1,401, as the cost approximates current fair value. Investments with original maturities of less than 90 days are included in cash and cash equivalents on the consolidated balance sheets and are not included in the table above. Investments with maturities of less than twelve months are considered current assets and those investments with maturities greater than twelve months are considered non-current assets. As of December 31, 2022, all of the Company's investments were classified as available-for-sale and matured within 12 months of the balance sheet date.

 5. Inventories

 Capitalized inventories consist of the following at December 31, 2023 (in thousands):

 December 31, 2023

 December 31, 2022

 Raw materials

 $

 4,426

 $

 —

 Work in process

 25,221

 —

 Finished goods

 —

 —

 Total

 $

 29,647

 $

 —

 There were no inventories capitalized as of December 31, 2022, because the Company obtained approval for VOWST from the FDA on April 26, 2023. Prior to this approval, all costs for the manufacture of product supplies to support clinical development and commercial launch, including pre-launch inventory, were expensed as incurred or otherwise accounted for pursuant to the 2021 License Agreement. Pre-launch inventory manufactured prior to the FDA approval of VOWST, which was not capitalized into inventory but instead was expensed as research and development in previous periods, will be used in commercial production until it is depleted. Pre-launch inventory expensed as research and development totaled $ 26,794 for the year ended December 31, 2023.
 Inventory amounts written down as a result of excess, obsolescence, or unmarketability and determined not to be recoverable pursuant to the 2021 License Agreement are expensed in the period in which they are identified. There were no such write-downs during the year ended December 31, 2023.

 6. Property and Equipment, Net
 Property and equipment, net consisted of the following:

 2023

 2022

 Laboratory equipment

 $

 29,081

 $

 24,533

 Computer equipment

 4,142

 3,557

 Furniture and office equipment

 5,430

 3,491

 Leasehold improvements

 33,549

 32,474

 Construction in progress

 1,393

 3,970

 73,595

 68,025

 Less: Accumulated depreciation and amortization

 ( 51,138

)

 ( 45,040

)

 $

 22,457

 $

 22,985

 Depreciation and amortization expense was $ 6,243, $ 6,629 and $ 5,947 for the years ended December 31, 2023, 2022 and 2021, respectively. During the years ended December 31, 2023 and 2022, the Company disposed of certain fully-depreciated assets with a cost basis of $ 145 and $ 1,857, respectively.

 7. Accrued Expenses and Other Current Liabilities
 Accrued expenses and other current liabilities consisted of the following:

 2023

 2022

 Clinical and development costs

 $

 1,404

 $

 6,717

 Manufacturing and quality costs

 31,917

 —

 Payroll and payroll-related costs

 16,465

 14,709

 Collaboration payable - related party (Note 18)

 28,053

 34,770

 Facility and other

 2,772

 3,644

 $

 80,611

 $

 59,840

 As of December 31, 2023, the Company accrued a total of $ 30,049 payable to Bacthera for the substantial completion of the Company's dedicated production suite for long-term supply of VOWST, as the milestone was achieved during the year ended December 31, 2023. This amount is included in the Manufacturing and quality costs category above.
 Additionally, included within payroll and payroll-related costs is $ 5,080 of accrued severance related to the Restructuring Plan. See Note 13, Restructuring, for further details.

 8. Leases
 The Company leases real estate, primarily laboratory, office and manufacturing space. The Company's leases have remaining terms ranging from approximately one to nine years. Certain leases include one or more options to renew, exercisable at the Company's sole discretion, with renewal terms that can extend the lease from approximately one year to ten years. The Company evaluated the renewal options in its leases to determine if it was reasonably certain that the renewal option would be exercised, given the Company's current business structure, uncertainty of future growth, and the associated impact to real estate, the Company concluded that it is not reasonably certain that any renewal options would be exercised. Therefore, the operating lease assets and operating lease liabilities only contemplate the initial lease terms. All the Company's leases qualify as operating leases.
 In April 2022, the Company entered into a lease for additional laboratory and office space in Spring House, Pennsylvania, with a lease term of ten years and a renewal option, subject to certain conditions, for an additional five-year term. The undiscounted minimum lease payments were $ 3,029, net of a tenant improvement allowance of $ 1,184, over the original ten-year term. The lease commenced in April 2023. For the year ended December 31, 2023, the Company recorded a right-of-use asset of $ 3,571, which consists of the lease liability of $ 1,235, and $ 2,336 of leasehold improvements that revert back to the lessor at the termination of the lease.
 In December 2022, the Company amended its lease of its former corporate headquarters in Cambridge, Massachusetts (the "Lease Amendment"). The Lease Amendment reduced the office space subject to the lease while maintaining the laboratory and manufacturing space and extended the term to begin in November 2023, when the term of the original lease concludes, and continue through January 2030. The Company accounted for the Lease Amendment as a modification to the existing lease and not a new contract separate from the existing contract, and accordingly increased the associated lease liability and right-of-use asset by $ 32,837. Minimum lease payments total $ 60,022 throughout the term of the Lease Amendment, net of an estimated tenant improvement allowance of $ 1,000.
 The Company has committed to restore the leased space subject to the Lease Amendment to the condition specified in the original lease, and the Company updated its estimate of the costs required to fulfill this obligation in accordance with ASC 410, Asset Retirement Obligations, at the effective date of the modification. Based on current estimates, the Company recorded an additional asset retirement obligation of $ 452 in December 2022.
 In June 2023, the Company entered into a lease for a donor collection facility in Irvine, California, with a lease term of approximately six years and a renewal option, subject to certain conditions, for an additional five-year term. The undiscounted minimum lease payments are $ 1,079 over the original term. The lease commenced in December 2023. For the year ended December 31, 2023, the Company recorded a right-of-use asset of $ 1,830, which consists of the lease liability of $ 768, and $ 1,062 of leasehold improvements that revert back to the lessor at the termination of the lease.
 In January 2024, the Company entered into a sublease agreement with an unrelated third party to sublease a portion of its office and laboratory space in Cambridge, Massachusetts. The term of the sublease agreement commenced in March 2024 and ends on January 13, 2030. The Company will receive lease payments over the sublease term totaling $ 10,400. The sublessee is obligated to pay all real estate taxes and costs related to the subleased premises, including cost of operations, maintenance, repair, replacement and property management.

 The following table summarizes the presentation in the Company's consolidated balance sheets of its operating leases:

 2023

 2022

 Assets:

 Operating lease assets

 $

 109,793

 $

 110,984

 Liabilities:

 Operating lease liabilities

 $

 6,677

 $

 3,601

 Operating lease liabilities, net of current portion

 105,715

 107,942

 Total operating lease liabilities

 $

 112,392

 $

 111,543

 The following table summarizes the effect of lease costs in the Company's consolidated statement of operations and comprehensive loss:

 2023

 2022

 2021

 Operating lease costs

 $

 22,324

 $

 8,830

 $

 5,170

 Short-term lease costs

 1,477

 1,375

 1,452

 Variable lease costs

 7,229

 4,547

 3,300

 Sublease income

 —

 —

 ( 1,575

)

 Total lease costs

 $

 31,030

 $

 14,752

 $

 8,347

 During the years ended December 31, 2023, 2022, and 2021, the Company made cash payments for operating leases of $ 15,656, $ 7,809 and $ 6,821, respectively.
 As of December 31, 2023, future payments of operating lease liabilities are as follows (in thousands):

 As of December 31, 2023

 2024

 $

 19,869

 2025

 22,062

 2026

 22,674

 2027

 23,347

 2028

 23,580

 2029 and thereafter

 65,819

 Total future payments of operating lease liabilities

 $

 177,351

 Less: imputed interest

 ( 64,959

)

 Present value of operating lease liabilities

 $

 112,392

 As of December 31, 2023, the weighted average remaining lease term was 7.95 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 13 %. As of December 31, 2022, the weighted average remaining lease term was 8.92 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 13 %.

 9. Notes Payable
 On October 29, 2019 ("Hercules Closing Date"), the Company entered into a Loan and Security Agreement (the "Hercules Loan Agreement") with Hercules Capital, Inc. ("Hercules") pursuant to which a term loan in an aggregate principal amount of up to $ 50,000 (the "Original Credit Facility") was available to the Company in three tranches, subject to certain terms and conditions. Effective as of February 24, 2022 (the "Effective Date"), the Company entered into an Amendment to the Hercules Loan Agreement (the "Amendment"), with the lenders party thereto (the "Hercules Lenders"), and Hercules in its capacity as the administrative agent and the collateral agent for the Hercules Lenders, which amended the Original Credit Facility. Pursuant to the Amendment, a term loan facility in an amount of $ 100,000 (the "Hercules Credit Facility") became available to the Company in five tranches, including the first tranche of $ 25,000 previously drawn under the Original Credit Facility, subject to certain terms and conditions.

 The first tranche in an aggregate principal amount of $ 25,000 was outstanding as of the Effective Date, after taking into account reborrowing by the Company on the Effective Date of a previously-repaid principal amount of approximately $ 2,900. The second tranche in an aggregate principal amount of $ 12,500 and the third tranche in an aggregate principal amount of $ 12,500 were advanced to the Company and were outstanding as of the Effective Date. The fourth and fifth tranches, in an aggregate principal amounts of $ 25,000 each, were available upon satisfaction of certain conditions, but were not drawn before the repayment and extinguishment of the Hercules Credit Facility.
 All advances outstanding under the Hercules Credit Facility bore interest at a rate equal to the greater of either (i) the Prime Rate (as reported in The Wall Street Journal) plus 6.40 %, or (ii) 9.65 %. The Company had the option to prepay advances under the Hercules Credit Facility, in whole or in part, at any time subject to a prepayment charge, and the Hercules Loan Agreement included an end of term charge of 4.85 % of the aggregate amount of the advances made under the Original Credit Facility, as well as an additional end of term charge of 1.75 % of the aggregate amount of the advances under the Hercules Credit Facility (including the first tranche of $ 25,000), each due as specified in the Amendment.
 The Hercules Credit Facility was secured by substantially all of the Company's assets, other than the Company's intellectual property. The Company agreed to not pledge or secure its intellectual property to others.
 The Company accounted for the Amendment as a modification in accordance with the guidance in ASC 470-50, Debt ("ASC 470"). Amounts paid to the lenders were recorded as debt discount and a new effective interest rate was established. Upon issuance, the Hercules Credit Facility was recorded as a liability with an initial carrying value of $ 50,586, net of debt issuance costs. The initial carrying value was accreted to the repayment amount, which includes the outstanding principal plus the end of term charge, through interest expense using the effective interest rate method over the term of the debt. As of December 31, 2022, the carrying value of the debt was $ 51,047.
 On April 27, 2023 (the "Closing Date"), the Company entered into the Credit Agreement and Guaranty (the "Oaktree Credit Agreement") among the Company, the subsidiary guarantors from time to time party thereto, the lenders from time to time party thereto (the "Lenders"), and Oaktree Fund Administration, LLC, in its capacity as administrative agent for the Lenders (in such capacity, the "Agent"). The Oaktree Credit Agreement establishes a term loan facility of $ 250,000 (the "Term Loan") consisting of (i) $ 80,000 ("Tranche A-1") and (ii) $ 30,000 ("Tranche A-2" and collectively, "Tranche A Loan"), funded on the Closing Date. The Term Loan also consists of (i) $ 45,000 (the "Tranche B Loan") and (iii) $ 45,000 (the "Tranche C Loan"), each of which the Company may borrow subject to certain conditions, and (iv) $ 50,000 (the "Tranche D Loan") available in Oaktree's sole discretion. The Tranche B Loan may be drawn by the Company until September 30, 2024, if VOWST net sales for the trailing six consecutive months are at least $ 35,000 and at least 4.5 % greater in the calendar quarter prior to the Applicable Funding Date (as defined in the Oaktree Credit Agreement) over the calendar quarter immediately preceding it. The Tranche C Loan may be drawn until September 30, 2025, if VOWST net sales for the trailing 12 consecutive months are at least $ 120,000 and at least 4.5 % greater in each of the two calendar quarters prior to the Applicable Funding Date relative, in each case, to the calendar quarter immediately preceding it. The Term Loan has a maturity date of April 27, 2029 (the "Maturity Date").
 Of the $ 110,000 Tranche A Loan advanced by the Lenders at closing, approximately $ 53,380 repaid the Company's existing credit facility with Hercules. After deducting other transaction expenses and fees, the Company received net proceeds of approximately $ 50,446. The Company accounted for the repayment of the Hercules Credit Facility as an extinguishment in accordance with the guidance in ASC 470-50, and recognized a loss on extinguishment of $ 1,625 in other income (expense) in the accompanying consolidated statements of operations and comprehensive loss for the year ended December 31, 2023.
 Borrowings under the Term Loan bear interest at a rate per annum equal to the three-month term Secured Overnight Financing Rate ("SOFR") (subject to a 2.50 % floor and a 5.00 % cap), plus an applicable margin of 7.875 %, payable quarterly in arrears. If certain VOWST net sales targets are met, the applicable margin will be reduced from 7.875 % to 7.50 % through the Maturity Date. The Company is required to make quarterly interest-only payments on the Term Loan for the first three years after the Closing Date. Beginning on June 30, 2026, the Company will be required to make quarterly payments of interest, plus repay 7.50 % of the outstanding principal of the Term Loan in quarterly installments until the Maturity Date, unless the interest only period is extended based upon the achievement of certain VOWST net sales targets.
 The Company is obligated to pay the Lenders an exit fee equal to 1.50 % of the aggregate amount of the Term Loan funded, such exit fee to be due and payable upon the earliest to occur of (1) the Maturity Date, (2) the acceleration of the outstanding Term Loan, and (3) the prepayment of the outstanding Term Loan. The Company may voluntarily prepay the outstanding Term Loan, subject to a customary make-whole for the first two years following the Closing Date plus 4.0 % of the principal amount of the Term Loan prepaid, and thereafter a prepayment premium equal to (i) 4.0 % of the principal amount of the Term Loan prepaid, if prepaid after the second anniversary of the Closing Date through and including the third anniversary of the Closing Date, (ii) 2.0 % of the principal amount of the Term Loan if prepaid after the third anniversary of the Closing Date through and including the fourth anniversary of the Closing Date, (iii) 1.0 % of the principal amount of the Term Loan if prepaid after the fourth anniversary of the Closing Date through and

 including the fifth anniversary of the Closing Date, with no prepayment premium due after the fifth anniversary of the Closing Date through the Maturity Date.
 The Company's obligations under the Oaktree Credit Agreement and the other Loan Documents (as defined in the Oaktree Credit Agreement) will be guaranteed by any domestic subsidiaries of the Company that become Guarantors (as defined in the Oaktree Credit Agreement), subject to certain exceptions. The Company's and the Guarantors' (collectively, the "Loan Parties") respective obligations under the Oaktree Credit Agreement and the other Loan Documents are secured by first priority security interests in substantially all assets of the Loan Parties, including intellectual property, subject to certain customary thresholds and exceptions. As of December 31, 2023, there were no Guarantors.
 The Oaktree Credit Agreement contains customary representations, warranties and affirmative and negative covenants, including a financial covenant requiring the Company to maintain certain levels of cash and cash equivalents in accounts subject to a control agreement in favor of the Agent of at least $ 30,000 at all times commencing from 30 days after the Closing Date and decreasing to $ 25,000 of cash and cash equivalents in such controlled accounts after the Company borrows any Tranche B Loan. As of December 31, 2023, the Company was in compliance with all financial covenants pursuant to the Oaktree Credit Agreement.
 In addition, the Oaktree Credit Agreement contains certain events of default that entitle the Agent to cause the Company's indebtedness under the Oaktree Credit Agreement to become immediately due and payable, and to exercise remedies against the Loan Parties and the collateral securing the Term Loan, including cash. In an event of default and for its duration, as defined in the Oaktree Credit Agreement, an additional default interest rate equal to 2.0 % per annum may apply to all obligations owed under the Oaktree Credit Agreement.
 On the Closing Date, the Company issued to the Lenders warrants to purchase 647,589 shares (subject to certain adjustments) of the Company's common stock (the "Tranche A Warrant"), at an exercise price per share of $ 6.69. The Tranche A Warrant is immediately exercisable and the exercise period expires on April 26, 2030. Upon the funding of each of the Tranche B Loan and the Tranche C Loan, the Company is required to issue to the Lenders warrants to purchase 264,922 shares (subject to certain adjustments) of the Company's common stock on each such funding date at an exercise price equal to the trailing volume weighted average price of the Company's common stock for the 30 trading days prior to the funding date for each tranche (the "Tranche B Warrant" and the "Tranche C Warrant," respectively, and together the "Additional Warrants"). The Additional Warrants will be immediately exercisable upon issuance, and the exercise period will expire seven years from the date of issuance.
 The Company determined that the Tranche A Loan, the Tranche A Warrant, the commitment by the Lenders to fund the Tranche B Loan and the Tranche C Loan, and the Tranche B Warrant and Tranche C Warrant, are all freestanding financial instruments. On the Closing Date, the Company evaluated the Tranche A Warrant and determined that it meets the requirements for equity classification under ASC 815, Derivatives and Hedging ("ASC 815"). The net proceeds from the Tranche A Loan were allocated to the Tranche A Warrant and the Tranche A Loan using the relative fair value method, and the relative fair value of the Tranche A Warrant, $ 2,785, is recorded as an increase to additional paid-in-capital on the consolidated statements of stockholder's equity (deficit), and as a discount to the Tranche A Loan that will be amortized over the life of the Tranche A Loan using the effective interest method. The Company used the Black-Scholes option pricing model to determine the fair value of the Tranche A Warrant. Assumptions used in the Black-Scholes model included the fair market value per share of common stock on the valuation date of $ 5.32, the exercise price per warrant equal to $ 6.69, the expected volatility of 111.6 %, the risk-free interest rate of 3.57 %, the expected term of 7 years and the absence of a dividend.
 The Additional Warrants are considered outstanding instruments at the Closing Date of the Oaktree Credit Agreement and in accordance with ASC 815, are initially recognized at their respective fair values as derivative liabilities given the variable settlement amount of their respective aggregate exercise prices. The Company adjusts the carrying values of the Additional Warrants to their respective fair values at each reporting period, until such time that the Additional Warrants are issued and their respective exercise prices become fixed, and the value of the Additional Warrants is reclassified to additional paid-in capital. The Company uses a simulation model to determine the fair value of the Additional Warrants, as described in Note 3, Fair Value Measurements. The fair value of the Tranche B Warrant and Tranche C Warrant derivative liabilities was $ 1,077, $ 1,023, $ 276, and $ 270 on the Closing Date and at December 31, 2023, respectively.
 Changes in the fair values of the Additional Warrants are recorded as other income (expense) in the consolidated statements of operations and comprehensive loss. In addition to the relative fair value of the Tranche A Warrant, the original issue discount and certain debt issuance costs were recorded as a discount to the Tranche A Loan, the total of which will be accreted to the Tranche A Loan as interest expense over the life of the Tranche A Loan using the effective interest method. The fair values of the derivative liabilities associated with the Tranche B Warrant and Tranche C Warrant are recorded as loan commitment prepaid assets on the Closing Date,

 which are included in the consolidated balance sheets in other non-current assets, and will be reclassified as discounts to the associated Term Loan balances at such time that they are drawn.
 The effective interest rate in effect as of December 31, 2023 was 15.9 %. As of December 31, 2023, the carrying value of the Term Loan was $ 101,544, which is classified as a long-term liability on the consolidated balance sheets. The future principal payments due under the Oaktree Credit Agreement, excluding interest and the end of term charge, are as follows:

 Year Ending December 31,

 Principal

 2024

 $

 —

 2025

 —

 2026

 24,750

 2027

 33,000

 2028

 33,000

 Thereafter

 19,250

 Total

 $

 110,000

 During the year ended December 31, 2023, the Company recognized $ 2,468 and $ 10,708 of interest expense under the Hercules Credit Facility and Oaktree Credit Agreement, respectively, which is reflected in interest expense on the consolidated statement of operations and comprehensive loss. During the year ended December 31, 2022, the Company recognized $ 6,020 of interest expense related to the Hercules Credit Facility.

 10. Preferred Stock
 On July 1, 2015, in connection with the closing of the initial public offering of the Company's common stock ("IPO"), the Company effected its Restated Certificate of Incorporation, which authorizes the Company to issue 10,000,000 shares of preferred stock, $ 0.001 par value per share.

 11. Common Stock and Stock-Based Awards
 On July 1, 2015, in connection with the closing of the IPO, the Company effected its Restated Certificate of Incorporation, which authorizes the Company to issue 200,000,000 shares of common stock, $ 0.001 par value per share. On March 29, 2023, the Company's board of directors adopted a resolution to amend the Restated Certificate of Incorporation, subject to stockholder approval, by increasing the number of authorized shares of the Company's Common Stock from 200,000,000 shares to 240,000,000 shares (the "Share Increase Amendment"). At the Company's annual meeting of stockholders held on June 22, 2023, the Company's stockholders approved the Share Increase Amendment. On June 27, 2023, the Company amended its Restated Certificate of Incorporation to reflect the Share Increase Amendment.
 In November 2019, the Company entered into a common stock sales agreement, or the 2019 Sales Agreement, with Cowen to sell shares of the Company's common stock with aggregate gross sales proceeds of up to $ 25,000, from time to time, through an "at the market" equity offering program, or ATM, under which Cowen acts as sales agent. In March 2020, the Company entered into a new common stock sales agreement, or the 2020 Sales Agreement, with Cowen on substantially the same terms as the 2019 Sales Agreement and terminated the 2019 Sales Agreement. In May 2021, the Company entered into a new common stock sales agreement, or the 2021 Sales Agreement, with Cowen to sell shares of its common stock with aggregate gross sales proceeds of up to $ 150,000, from time to time, through an ATM under which Cowen acts as sales agent, and terminated the 2020 Sales Agreement. During the year ended December 31, 2023, the Company sold 7,711,199 shares of common stock under the 2021 Sales Agreement, at an average price of approximately $ 2.46 per share, raising aggregate net proceeds of approximately $ 18,159 after deducting an aggregate commission of approximately 3 % and other issuance costs. During the year ended December 31, 2022, the Company sold 655,000 shares of common stock under the 2021 Sales Agreement, at an average price of approximately $ 7.26 per share, raising aggregate net proceeds of approximately $ 4,447 after deducting an aggregate commission of approximately 3 % and other issuance costs. During the year ended December 31, 2021, the Company did no t sell any shares of common stock under the 2020 Sales Agreement or the 2021 Sales Agreement.
 Between December 31, 2023 and February 29, 2024, the Company sold 15,366,630 shares of common stock under the 2021 Sales Agreement, at an average price of approximately $ 1.23 per share, raising aggregate net proceeds of approximately $ 18,484 after deducting an aggregate commission of approximately 3 % and other issuance costs.
 On June 29, 2022, the Company entered into securities purchase agreements with new and existing investors and certain directors and officers in a registered direct offering, or the Registered Direct Offering, of an aggregate of 31,746,030 shares of its common stock

 at a purchase price of $ 3.15 per share for total net proceeds of approximately $ 96,721, after deducting placement agent's fees and other estimated offering expenses. Net proceeds included an aggregate of $ 27,525 received from Flagship Pioneering Fund VII, L.P. and Nutritional Health LTP Fund, L.P., affiliates of Flagship Pioneering, or Flagship, one of its significant stockholders, in exchange for 8,738,243 shares. The closing date of the Registered Direct Offering was July 5, 2022.
 2012 Stock Incentive Plan
 The Company's 2012 Stock Incentive Plan, as amended, (the "2012 Plan") provided for the Company to sell or issue common stock or restricted common stock, or to grant incentive stock options or nonqualified stock options for the purchase of common stock, to employees, members of the board of directors and consultants of the Company. The 2012 Plan is administered by the board of directors, or at the discretion of the board of directors, by a committee of the board of directors. The exercise prices, vesting and other restrictions are determined at the discretion of the board of directors, or their committee if so delegated, except that the exercise price per share of stock options may not be less than 100 % of the fair market value of the share of common stock on the date of grant and the term of stock option may not be greater than ten years. The Company generally granted stock-based awards with service conditions only ("service-based" awards).
 Stock options granted under the 2012 Plan generally vest over four years and expire after ten years, although options have been granted with vesting terms less than four years. As of December 31, 2023, there were no shares available for future grant under the 2012 Plan.
 2015 Incentive Award Plan
 On June 16, 2015, the Company's stockholders approved the 2015 Incentive Award Plan (the "2015 Plan"), which became effective on June 25, 2015. The 2015 Plan was subsequently amended on December 14, 2022, and provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. The number of shares initially reserved for issuance under the 2015 Plan was the sum of (i) 2,200,000 shares of common stock and (ii) the number of shares subject to awards outstanding under the 2012 Plan that expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by the Company on or after the effective date of the 2015 Plan. In addition, the number of shares of common stock that may be issued under the 2015 Plan is subject to increase on the first day of each calendar year, beginning in 2016 and ending in 2025, equal to the lesser of (i) 4 % of the number of shares of the Company's common stock outstanding on the last day of the preceding applicable calendar year and (ii) an amount determined by the Company's board of directors.
 Stock awards granted under the 2015 Plan generally vest over four years and expire after ten years, although options have been granted with vesting terms less than four years. As of December 31, 2023, there were 2,545,586 shares available for future grant under the 2015 Plan.
 2015 Employee Stock Purchase Plan
 On June 16, 2015, the Company's stockholders approved the 2015 Employee Stock Purchase Plan (the "ESPP"), which became effective on June 25, 2015. A total of 365,000 shares of common stock were reserved for issuance under the ESPP. In addition, the number of shares of common stock that may be issued under the ESPP automatically increase on the first day of each calendar year, beginning in 2016 and ending in 2025, by an amount equal to the lesser of (i) 400,000 shares, (ii) 1 % of the number of shares of the Company's common stock outstanding on the last day of the applicable preceding calendar year and (iii) an amount determined by the Company's board of directors. Offering periods under the ESPP will commence when determined by the plan administrator. During the year ended and as of December 31, 2023, there were 602,692 shares issued and 2,266,512 shares were reserved and available for issuance under the ESPP, respectively.
 The ESPP provides that eligible employees may contribute up to 15 % of their eligible earnings toward the semi-annual purchase of the Company's common stock. Purchase rights issued under the ESPP are intended to be qualified under Section 423 of the Internal Revenue Code ("IRC"). The employee's purchase price is derived from a formula based on the closing price of the common stock on the first day of the offering period versus the closing price on the date of purchase (or, if not a trading day, on the immediately preceding trading day). The offering period under the ESPP has a duration of six months, and the purchase price with respect to each offering period beginning on or after such date is, until otherwise amended, equal to 85 % of the lesser of (i) the fair market value of the Company's common stock at the commencement of the applicable six-month offering period or (ii) the fair market value of the Company's common stock on the purchase date.

 2022 Employment Inducement Award Plan
 On December 14, 2022, the Company's board of directors approved the 2022 Employment Inducement Award Plan (the "2022 Plan"), which became effective on such date without stockholder approval pursuant to Rule 5635(c)(4) of The Nasdaq Stock Market LLC listing rules ("Rule 5635(c)(4)"). The 2022 Plan provides for the grant of nonqualified stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock- or cash-based awards. In accordance with Rule 5635(c)(4), awards under the 2022 Plan may only be made to a newly hired employee who has not previously been a member of our board of directors, or an employee who is being rehired following a bona fide period of non-employment by us as a material inducement to the employee's entering into employment with us. A total of 2,500,000 shares of common stock were reserved for issuance under the 2022 Plan. Any shares subject to awards previously granted under the 2022 Plan that expire, terminate or are otherwise surrendered, canceled, or forfeited in any case, in a manner that results in the Company acquiring the shares covered by the award at a price not greater than the price (as adjusted to reflect any equity restructuring) paid by the Participant for such shares or not issuing any shares covered by the award, the unused shares covered by the award will again be available for award grants under the 2022 Plan.
 As of December 31, 2023, there were 2,382,884 shares available for future grant under the 2022 Plan.
 Stock Options
 The following table summarizes the Company's stock option activity for the year ended December 31, 2023:

 Number of
Shares

 Weighted
Average
Exercise
Price

 Weighted
Average
Remaining
Contractual
Term

 Aggregate
Intrinsic
Value

 (in years)

 Outstanding as of December 31, 2022

 14,940,034

 $

 10.03

 7.25

 $

 11,608

 Granted

 2,508,553

 5.44

 Exercised

 ( 260,640

)

 3.36

 Forfeited

 ( 2,343,835

)

 8.30

 Outstanding as of December 31, 2023

 14,844,112

 $

 9.64

 5.71

 $

 —

 Vested or expected to vest as of December 31, 2023

 14,844,112

 $

 9.64

 5.66

 $

 —

 Options exercisable as of December 31, 2023

 10,488,694

 $

 10.09

 4.61

 $

 —

 The weighted average grant-date fair value of stock options granted during the years ended December 31, 2023, 2022, and 2021 was $ 4.51, $ 5.53, and $ 15.33 per share, respectively. The total intrinsic value of stock options exercised during the years ended December 31, 2023, 2022, and 2021 was $ 438, $ 981, and $ 4,727, respectively.
 The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company's common stock for those stock options that had exercise prices lower than the fair value of the Company's common stock.
 During the year ended December 31, 2021, the Company granted performance-based stock options to employees for the purchase of an aggregate of 562,000 shares of common stock with a grant date fair value of $ 5.53 per share. These stock options are exercisable only upon achievement of specified performance targets. In April 2023, the performance target associated with 50 % of the performance-based stock options was achieved. Accordingly, the Company recorded $ 2,051 of compensation expense during the year ended December 31, 2023, with respect to these performance-based stock options, which represents a cumulative catch-up from the grant date through the achievement of the performance targets, and vesting of the remaining 50 % of the options beginning in April 2023, partially offset by the reversal of stock-based compensation expense associated with the forfeiture of unvested awards. The remaining compensation expense associated with these performance-based stock options will be recognized ratably through April 2024, for all such options for which ongoing performance targets are achieved and service requirements are met.
 Restricted Stock Units
 The Company has granted restricted stock units with service-based vesting conditions ("RSUs") and restricted stock units with performance-based vesting conditions ("PSUs"). RSUs and PSUs represent the right to receive shares of common stock upon meeting

 specified vesting requirements. Restricted stock units may not be sold or transferred by the holder and vest according to the vesting conditions of each award. The table below summarizes the Company's RSU and PSU activity for the year ended December 31, 2023:

 Number
of Shares

 Weighted
Average Grant
Date Fair Value

 Unvested restricted stock units as of December 31, 2022

 1,549,540

 $

 9.37

 Granted

 4,424,479

 $

 4.14

 Forfeited

 ( 1,071,571

)

 $

 6.94

 Vested

 ( 1,524,644

)

 $

 7.22

 Unvested restricted stock units as of December 31, 2023

 3,377,804

 $

 4.26

 During the years ended December 31, 2023, 2022, and 2021, the Company granted 3,101,764, 1,302,844 and 643,998 RSUs, respectively. During the year ended December 31, 2023, 2022, and 2021, the Company granted 1,322,715, 0, and 125,000 PSUs, respectively. RSUs generally vest over four years, with 25 % vesting after one year, and the remaining 75 % vesting quarterly over the next 3 years, subject to continued service to the Company through the applicable vesting date. PSUs vest according to the performance requirements of the awards, generally when the Company has determined that the specified performance targets have been achieved.
 The aggregate intrinsic value of RSUs, including PSUs for which the performance conditions have been met, that vested during the years ended December 31, 2023, 2022 and 2021 was $ 4,729, $ 1,809, and $ 16, respectively.
 In November 2023, as part of the corporate restructuring described in Note 13, Restructuring, the Company issued retention awards to employees of the Company in the form of RSUs which vest in two tranches on August 15, 2024, and May 15, 2025, subject to remaining actively employed with the Company through such date. The $ 1,255 in compensation expense associated with these awards will be recognized ratably over the vesting period. For the year ended December 31, 2023, the Company recognized $ 92 in compensation expense with respect to the retention awards.
 In connection with the Restructuring Plan, the Company elected to accelerate the vesting of certain RSUs and PSUs previously granted to employees who were terminated as part of the Restructuring Plan. The Company accounted for the acceleration as a modification under applicable accounting standards, in which awards that were previously deemed not probable of vesting due to the employees' terminations became probable. Accordingly, the Company reversed $ 1,191 of compensation cost that had previously been recognized during the year ended December 31, 2023 on these awards and recorded the incremental fair value of the awards on the modification date of $ 261.
 During the year ended December 31, 2021, the Company granted PSUs to two employees covering an aggregate of 85,000 shares of common stock with a grant date fair value of $ 9.59 per share and 40,000 shares with a grant date fair value of $ 20.35 per share. These PSUs vest only upon achievement of specified performance targets. As of December 31, 2021, these awards were no t vested because the specified performance targets had not been achieved. In addition, the performance targets were not deemed probable of achievement. Accordingly, the Company did no t record any expense for these awards from the dates of issuance through December 31, 2021. In October 2022, 42,500 of the awards with a grant date fair value of $ 9.59, and 20,000 of the awards with a grant date fair value of $ 20.35, vested fully, as the associated performance targets were achieved. Accordingly, the Company recorded $ 815 in compensation expense during the year ended December 31, 2022, with respect to these awards. In April 2023, the remaining PSUs underlying these awards vested because the associated targets were achieved. Accordingly, the Company recorded the remaining $ 815 in compensation expense during the year ended December 31, 2023, with respect to these PSUs.
 During the year ended December 31, 2023, the Company granted PSUs to employees covering an aggregate of 1,322,715 shares of common stock with a grant date fair value of $ 5.50. These PSUs begin to vest ratably only upon achievement of specified performance targets, which were achieved in April 2023. Accordingly, the Company recorded $ 4,293 in compensation expense during the year ended December 31, 2023, with respect to these PSUs. The remaining $ 1,092 in compensation expense associated with these PSUs will be recognized ratably through October 2024.

 Stock-based Compensation Valuation
 The assumptions that the Company used to determine the fair value of the stock options granted to employees and directors were as follows, presented on a weighted average basis:

 2023

 2022

 2021

 Risk-free interest rate

 3.64

 %

 1.67

 %

 0.73

 %

 Expected term (in years)

 6.0

 6.0

 5.4

 Expected volatility

 107.2

 %

 104.0

 %

 106.5

 %

 Expected dividend yield

 %

 %

 %

 The Company estimates the fair value of rights to acquire common stock under the ESPP using a Black-Scholes valuation model on the date of grant and the straight-line attribution approach to recognize the expense. The assumptions that the Company used to determine the fair value of rights to acquire common stock under the ESPP were as follows, presented on a weighted average basis:

 2023

 2022

 2021

 Risk-free interest rate

 5.01

 %

 2.11

 %

 0.97

 %

 Expected term (in years)

 0.5

 0.5

 0.5

 Expected volatility

 79.1

 %

 99.0

 %

 123.8

 %

 Expected dividend yield

 %

 %

 %

 Stock-based Compensation
 The Company recorded stock-based compensation expense related to stock options and restricted stock units in the following expense categories of its consolidated statements of operations and comprehensive loss:

 2023

 2022

 2021

 Research and development expenses

 $

 19,341

 $

 13,429

 $

 10,146

 General and administrative expenses

 14,760

 12,053

 10,076

 $

 34,101

 $

 25,482

 $

 20,222

 As of December 31, 2023, the Company had an aggregate of $ 35,036 of unrecognized stock-based compensation cost, which is expected to be recognized over a weighted average period of 2.1 years.

 12. Net Loss per Share
 Basic and diluted net loss per share attributable to common stockholders was calculated as follows:

 2023

 2022

 2021

 Numerator:

 Net loss attributable to common stockholders

 $

)

 $

)

 $

)

 Denominator:

 Weighted average common shares outstanding, basic and diluted

 128,003,294

 108,077,043

 91,702,866

 Net loss per share attributable to common stockholders, basic and diluted

 $

 ( 0.89

)

 $

 ( 2.31

)

 $

 ( 0.72

)

 Anti-dilutive potential common stock equivalents excluded from the calculation of net loss per share:

 Stock options to purchase common stock

 14,844,112

 14,940,034

 11,517,189

 Unvested restricted stock units

 3,377,804

 1,549,540

 734,755

 Shares issuable under employee stock purchase plan

 297,784

 89,593

 165,047

 Warrants to purchase common stock

 1,177,433

 —

 —

 The Company's potential dilutive securities, which include stock options, unvested restricted common stock and shares issuable under the ESPP, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share and therefore been anti-dilutive. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. Additionally, for the year ended December 31, 2023, the warrants to purchase common stock were excluded because the exercise price of the Tranche A Warrants is greater than the average fair value of the Company's common shares, and the necessary conditions for exercise of the Tranche B and Tranche C Warrants had not been met.

 13. Restructuring
 On November 2, 2023, the Company announced the Restructuring Plan to prioritize the commercialization of VOWST and the completion of the SER-155 Phase 1b study, while significantly reducing costs and supporting longer-term business sustainability. The Restructuring Plan included (i) a reduction of the Company's workforce by approximately 41 % across the organization, resulting in the elimination of approximately 160 positions; (ii) significantly scaling back all non-partnered research and development activities other than the completion of the SER-155 Phase 1b study; and (iii) reducing general and administrative expenses, including consolidating office space.
 During the year ended December 31, 2023, the Company recognized a restructuring charge of $ 5,606, which was incurred entirely in the fourth quarter of 2023, and which represents all restructuring charges expected to be incurred. Restructuring charges included approximately $ 5,345 of employee related termination costs in the form of salary continuation and cash severance payments, and $ 261 related to the acceleration of vesting of certain previously granted RSUs and PSUs. The following tables summarize the restructuring related charges and classification by line item within the Company's consolidated statements of operations during the year ended December 31, 2023:

 Year Ended December 31, 2023

 Research and development

 General and administrative

 Total

 Severance and other employee costs

 3,318

 2,027

 5,345

 Acceleration of unvested equity awards

 Total restructuring charges

 3,481

 2,125

 5,606

 The restructuring charge is included in accrued expenses and other current liabilities in the Company's consolidated balance sheets. The following table presents changes in the restructuring liability for the year ended December 31, 2023 (in thousands):

 As of December 31, 2023

 Restructuring expenses

 $

 5,606

 Less: stock-based compensation

 $

 ( 261

)

 Cash payments made

 ( 265

)

 Remaining liability included in accrued expenses and other current liabilities

 $

 5,080

 The Company expects that substantially all of the accrued restructuring charges as of December 31, 2023 will be paid in cash by March 31, 2024.

 Retention Awards
 In November 2023, upon recommendation of the Company's Compensation Committee, the Board of Directors approved retention awards for employees of the Company in the form of RSUs which vest in two tranches on August 15, 2024, and May 15, 2025, subject to remaining actively employed with the Company through such date. The $ 1,255 in compensation expense associated with these awards will be recognized ratably over the vesting period.

 14. Revenue from Contracts with Customers
 License Agreement with NHSc Rx License GmbH (Nestl)
 Summary of Agreement
 In July 2021, the Company entered into the 2021 License Agreement with NHSc Pharma Partners, succeeded by NHSc Rx License GmbH (together with Soci t des Produits Nestl S.A., their affiliates, and their subsidiaries, "Nestl ") (the "2021 License Agreement"). Under the terms of the 2021 License Agreement, the Company granted Nestl a co-exclusive, sublicensable (under certain circumstances) license to develop, commercialize and conduct medical affairs activities for (i) therapeutic products based on the Company's microbiome technology (including VOWST, previously the Company's SER-109 product candidate) that are developed by the Company or on the Company's behalf for the treatment of CDI and recurrent CDI, as well as any other indications pursued for the products upon mutual agreement of the parties (the "2021 Field") in the United States and Canada (the "2021 Licensed Territory"), and (ii) VOWST and any improvements and modifications thereto developed pursuant to the terms of the 2021 License Agreement (the "2021 Collaboration Products") for any indications in the 2021 Licensed Territory. The Company is responsible for completing development of the first 2021 Collaboration Product, which is VOWST, in the 2021 Field in the United States until first regulatory approval, which was obtained on April 26, 2023.
 Nestl has the sole right to commercialize the 2021 Collaboration Products in the 2021 Licensed Territory in accordance with a commercialization plan. Both parties will perform medical affairs activities in the 2021 Licensed Territory in accordance with a medical affairs plan. The Company is responsible for the manufacturing and supply for commercialization under a supply agreement that has been executed between the parties. Both parties performed pre-launch activities of VOWST prior to the first commercial sale in the United States, which occurred in June 2023. The Company was responsible for funding the pre-launch activities until first commercial sale of VOWST in the 2021 Licensed Territory and in accordance with a pre-launch plan, up to a specified cap. The Company is entitled to share equally in the commercial profits and losses of VOWST.
 In connection with the 2021 License Agreement, the Company received an upfront payment of $ 175,000, and the Company received an additional $ 125,000 milestone payment in May 2023 after FDA approval of VOWST. The Company is eligible to receive additional payments of up to $ 235,000 if certain regulatory and sales milestones are achieved. The potential future milestone payments include up to $ 10,000 for the achievement of specified regulatory milestones and up to $ 225,000 for the achievement of specified net sales milestones.
 The 2021 License Agreement continues in effect until all development and commercialization activities for all 2021 Collaboration Products in the 2021 Licensed Territory have permanently ceased. The 2021 License Agreement may be terminated by either party upon sixty days ' written notice for the other party's material breach that remains uncured during such sixty-day period, or immediately upon written notice for the other party's insolvency. Nestl may also terminate the 2021 License Agreement at-will with twelve months' prior written notice, effective only on or after the third anniversary of first commercial sale of VOWST in the 2021 Licensed Territory. The Company may also terminate the 2021 License Agreement immediately upon written notice if Nestl challenges any licensed patent in the 2021 Licensed Territory. Upon termination of the 2021 License Agreement, all licenses granted to Nestl by the Company will terminate. If the Company commits a material breach of the 2021 License Agreement, Nestl may elect not to terminate the 2021 License Agreement but instead apply specified adjustments to the payment terms and other terms and conditions of the 2021 License Agreement.

 Accounting Analysis
 The 2021 License Agreement represents a separate contract between Nestl and the Company. The 2021 License Agreement is within the scope of Accounting Standard Update 2018-18, Collaborative Arrangements (Topic 808) (see Note 15, Collaboration Profit and Loss), and has elements that are within the scope of ASC 606 - Revenue From Contracts with Customers (Topic 606) and Topic 808.
 The Company identified the following promises in the 2021 License Agreement that were evaluated under the scope of Topic 606: (i) delivery of a co-exclusive license for VOWST to develop, commercialize and conduct medical affairs in the United States and Canada; (ii) services to be performed in accordance with the development and regulatory activity plan to obtain regulatory approval of VOWST in the United States. The Company also evaluated whether certain options outlined within the 2021 License Agreement represented material rights that would give rise to a performance obligation and concluded that none of the options convey a material right to Nestl and therefore are not considered separate performance obligations within the 2021 License Agreement.
 The Company assessed the above promises and determined that the co-exclusive license for VOWST and the services to obtain regulatory approval of VOWST in the United States are reflective of a vendor-customer relationship and therefore represent performance obligations within the scope of Topic 606. The co-exclusive license for VOWST in the United States and Canada is considered functional intellectual property and distinct from other promises under the contract as Nestl can benefit from the license on its own or together with other readily available resources. The services performed by the Company to obtain regulatory approval of VOWST were not complex or specialized, could be performed by another qualified third party, were not expected to significantly modify or customize the license given that VOWST was late-stage intellectual property that completed clinical development and the services were performed over a short period of time. Therefore, the license and the services each represents a separate performance obligation within a contract with a customer under the scope of Topic 606 at contract inception.
 The up-front payment of $ 175,000 compensated the Company for: (i) the co-exclusive license for VOWST to develop, commercialize and conduct medical affairs in the United States and Canada, (ii) services performed in accordance with the development and regulatory activity plan to obtain regulatory approval of VOWST in the United States and (iii) pre-launch activities performed by Nestl and the Company until the first commercial sale of VOWST in the United States. The commercialization activities, which include the commercial manufacturing, participation on joint steering committees and medical affairs work, that occur after regulatory approval of VOWST in the United States, are part of the 50 / 50 sharing of commercial profits. Therefore, the up-front payment of $ 175,000 does not compensate the Company for these activities.
 The Company allocated the $ 175,000 between the Topic 606 unit of account and the Topic 808 unit of account by determining the standalone selling price (SSP) of each good or service. The selling price of each good or service was determined based on the Company's SSP with the objective of determining the price at which it would sell such an item if it were to be sold regularly on a standalone basis. The Company determined the transaction price under Topic 606 to be $ 139,500 and the Topic 808 amount to be $ 35,500 at the inception of the 2021 License Agreement (see Note 15, Collaboration Profit and Loss).
 The Topic 606 transaction price of $ 139,500 was allocated to the co-exclusive license for VOWST and the services performed in accordance with the development and regulatory activity plan to obtain regulatory approval of VOWST in the United States based on the Company's SSP. The Company recognized revenue for the license performance obligation at a point in time, that is upon transfer of the license to Nestl. As control of the license was transferred in July 2021, the Company recognized $ 131,343 of collaboration revenue - related party during the year ended December 31, 2021 pertaining to the license performance obligation. The remaining amount of the Topic 606 transaction price of $ 8,157 was allocated to the services performance obligation and was recognized over time as the Company performed the services, which it completed in April 2023. During the years ended December 31, 2023, 2022, and 2021, the Company recognized $ 1,975, $ 4,114, and $ 2,068 of collaboration revenue - related party, respectively, related to the services performance obligation under the 2021 License Agreement.
 The Company determined that any variable consideration related to the remaining regulatory milestones is deemed to be fully constrained and therefore excluded from the transaction price due to the high degree of uncertainty and risk associated with these potential payments, as the Company determined that it could not assert that it was probable that a significant reversal in the amount of cumulative revenue recognized will not occur. The Company also determined that sales milestones relate solely to the license of intellectual property and are therefore excluded from the transaction price under the sales- or usage-based royalty exception of Topic 606. Revenue related to these sales milestones will only be recognized when the associated sales occur, and relevant thresholds are met.

 The Company recognized the $ 125,000 regulatory milestone payment received in May 2023, which was fully allocated to the license performance obligation, as revenue in the consolidated statements of operations and comprehensive loss during the year ended December 31, 2023.
 Collaboration and License Agreement with Soci t des Produits Nestl S.A. (Nestl)
 Summary of Agreement
 In January 2016, the Company entered into a collaboration and license agreement with Nestec Ltd., succeeded by Soci t des Produits Nestl S.A. (together with NHSc Rx License GmbH, their affiliates and their subsidiaries, "Nestl ") (the "2016 License Agreement") for the development and commercialization of certain product candidates for the treatment and management of CDI and inflammatory bowel disease ("IBD"), including UC and Crohn's disease. The 2016 License Agreement supports the development of the Company's portfolio of products for CDI and IBD in markets outside of the United States and Canada (the "2016 Licensed Territory").
 Under the 2016 License Agreement, the Company granted to Nestl an exclusive, royalty-bearing license to develop and commercialize, in the 2016 Licensed Territory, certain products based on its microbiome technology that are being developed or commercialized, as applicable, for the treatment of CDI and IBD, including VOWST, SER-262, SER-287 and SER-301 (collectively, the "2016 Collaboration Products"). The 2016 License Agreement sets forth the Company's and Nestl 's respective obligations for development, commercialization, regulatory and manufacturing and supply activities for the 2016 Collaboration Products with respect to the licensed fields and the 2016 Licensed Territory.
 Under the 2016 License Agreement, Nestl agreed to pay the Company an upfront cash payment of $ 120,000, which the Company received in February 2016. The Company is eligible to receive up to $ 285,000 in development milestone payments, $ 375,000 in regulatory payments and up to an aggregate of $ 1,125,000 for the achievement of certain commercial milestones related to the sales of the 2016 Collaboration Products. Nestl also agreed to pay the Company tiered royalties, at percentages ranging from the high single digits to high teens, of net sales of 2016 Collaboration Products in the 2016 Licensed Territory.
 Under the 2016 License Agreement, the Company is entitled to receive a $ 20,000 milestone payment from Nestl following initiation of a SER-287 Phase 2 study and a $ 20,000 milestone payment from Nestl following the initiation of a SER-287 Phase 3 study. In November 2018, the Company entered into a letter agreement with Nestl which modified the 2016 License Agreement to address the current clinical plans for SER-287. Pursuant to the letter agreement, the Company and Nestl agreed that following initiation of the SER-287 Phase 2b study, the Company would be entitled to receive $ 40,000 in milestone payments from Nestl, which represent the milestone payments due to the Company for the initiation of a SER-287 Phase 2 study and a Phase 3 study. The SER-287 Phase 2b study was initiated and the $ 40,000 of milestone payments were received in December 2018.
 The 2016 License Agreement continues in effect until terminated by either party on the following bases: (i) Nestl may terminate the 2016 License Agreement in the event of serious safety issues related to any of the 2016 Collaboration Products; (ii) the Company may terminate the 2016 License Agreement if Nestl challenges the validity or enforceability of any of the Company's licensed patents; and (iii) either party may terminate the 2016 License Agreement in the event of the other party's uncured material breach or insolvency. Upon termination of the 2016 License Agreement, all licenses granted to Nestl by the Company will terminate, and all rights in and to the 2016 Collaboration Products in the 2016 Licensed Territory will revert to the Company. If the Company commits a material breach

 of the 2016 License Agreement, Nestl may elect not to terminate the 2016 License Agreement but instead apply specified adjustments to its payment obligations and other terms and conditions of the 2016 License Agreement.
 Accounting Analysis

 The Company assessed the 2016 License Agreement in accordance with Topic 606 and concluded that Nestl is a customer. The Company identified the following promises under the contract: (i) a license to develop and commercialize the 2016 Collaboration Products in the 2016 Licensed Territory, (ii) obligation to perform research and development services, (iii) participation on a joint steering committee, and (iv) manufacturing services to provide clinical supply to complete future clinical trials. In addition, the Company identified a contingent obligation to perform manufacturing services to provide commercial supply if commercialization occurs, which is contingent upon regulatory approval. This contingent obligation is not a performance obligation at inception and has been excluded from the initial allocation as it represents a separate buying decision at market rates, rather than a material right in the contract. The Company assessed the promised goods and services to determine if they are distinct. Based on this assessment, the Company determined that Nestl cannot benefit from the promised goods and services separately from the others as they are highly interrelated and therefore not distinct. Accordingly, the promised goods and services represent one combined performance obligation and the entire transaction price will be allocated to that single combined performance obligation.
 At contract inception, the Company determined that the $ 120,000 non-refundable upfront amount constituted the entirety of the consideration to be included in the transaction price as the development, regulatory, and commercial milestones were fully constrained. During the year ended December 31, 2016, the Company received $ 10,000 from Nestl in connection with the initiation of the Phase 1b study for SER-262 in CDI. During the year ended December 31, 2017, the Company received $ 20,000 from Nestl in connection with the initiation of the Phase 3 study for VOWST, then SER-109. During the year ended December 31, 2018, the Company received $ 40,000 from Nestl in connection with the initiation of the Phase 2b study for SER-287. During the year ended December 31, 2020, the Company received $ 10,000 from Nestl in connection with the initiation of the Phase 1b SER-301 study. As of December 31, 2023, the aggregate amount of the transaction price allocated to the performance obligation of the 2016 License Agreement was approximately $ 200,000.
 During the years ended December 31, 2023, 2022, and 2021 using the cost-to-cost method, which best depicts the transfer of control to the customer, the Company recognized ($ 650), $ 3,014, and $ 10,446 of collaboration revenue – related party, respectively, relating to the 2016 License Agreement.
 As of December 31, 2023 and 2022, there was $ 95,364, and $ 96,689 of deferred revenue related to the unsatisfied portion of the performance obligation under the Nestl agreements. As of December 31, 2023, deferred revenue is classified as current or non-current in the consolidated balance sheets based on the Company's estimate of revenue that will be recognized within the next twelve months, which is determined by the cost-to-cost method which measures the extent of progress towards completion based on the ratio of actual costs incurred to the total estimated costs expected upon satisfying the performance obligation. All costs associated with the 2016 License Agreement are recorded in research and development expense in the consolidated statements of operations and comprehensive loss.
 Contract Balances from Contracts with Customers
 The following tables present changes in the Company's contract liabilities during the year ended December 31, 2023 and 2022:

 Balance as of December 31, 2022

 Additions

 Deductions

 Balance as of December 31, 2023

 Year ended December 31, 2023

 Contract liabilities:

 Deferred revenue - related party

 $

 96,689

 1,644

 ( 2,969

)

 $

 95,364

 Balance as of December 31, 2021

 Additions

 Deductions

 Balance as of December 31, 2022

 Year ended December 31, 2022

 Contract liabilities:

 Deferred revenue - related party

 $

 103,817

 —

 ( 7,128

)

 $

 96,689

 During the year ended December 31, 2023, the Company recognized the following revenues as a result of changes in the contract liability balances in the respective periods (in thousands):

 2023

 2022

 Revenue recognized in the period from:

 Amounts included in the contract liability at the beginning of the period

 $

 1,325

 $

 7,128

 When consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract, a contract liability is recorded. Revenue is recognized from the contract liability over time using the cost-to-cost method.

 15. Collaboration Profit and Loss
 License Agreement with NHSc Rx License GmbH (Nestl)
 Accounting Analysis
 The 2021 License Agreement represents a separate contract between Nestl and the Company. The 2021 License Agreement is within the scope of Topic 808, and has elements that are within the scope of Topic 606 (see Note 14, Revenue from Contracts with Customers) and Topic 808.
 The Company considers the collaborative pre-launch activities and commercialization activities to be separate units of account within the scope of Topic 808 and are not performance obligations under Topic 606. The Company and Nestl were both active participants in the pre-launch activities and commercialization activities and were exposed to significant risks and rewards that were dependent on the commercial success of the activities in the arrangement. The amount allocated to the Topic 808 unit of accounting relates to the pre-launch activities performed prior to the first commercial sale of VOWST and was determined to be $ 35,500 based on standalone selling price.
 The Company recorded the $ 35,500 in total liabilities on its consolidated balance sheets at the inception of the arrangement. On a quarterly basis, the Company and Nestl provided financial information about the pre-launch activities performed by both parties. The Company reduced the $ 35,500 liability as the pre-launch activities were performed and it made payments to Nestl for the pre-launch costs Nestl incurred. As of December 31, 2023 and 2022, there was $ 10,064 and $ 34,770, respectively, included in accrued expenses and other current liabilities which represents costs incurred by Nestl for pre-launch activities that have not yet been reimbursed by Seres.
 The cost associated with pre-launch activities performed by the Company is recorded within total operating expenses in the Company's consolidated statements of operations and comprehensive loss. In the years ended December 31, 2023, 2022, and 2021, the Company recognized $ 1,446, $ 6,102, and $ 2,168 in research and development expenses and $ 4,242, $ 8,953, and $ 3,383 in general and administrative expenses, respectively, associated with pre-launch activities performed. The pre-launch activities were completed prior to the first commercial sale of VOWST, which occurred in June 2023.
 Under the 2021 License Agreement with Nestl, beginning with the first commercial sale of VOWST, which occurred in June 2023, net sales of VOWST are recorded by Nestl and include gross sales net of discounts, rebates, allowances, and other applicable deductions. These amounts include the use of estimates and judgments, which could be adjusted based on actual results in the future. The Company records its share of the profits or losses from the sales of VOWST, including commercial and medical affairs expenses incurred by the Company, on a net basis, as collaboration (profit) loss sharing - related party. This treatment is in accordance with the Company's revenue recognition and collaboration policy, given that Nestl and the Company are both active participants in commercialization activities and are exposed to significant risks and rewards that are dependent on the commercial success of the activities in the 2021 License Agreement. Nestl provides the Company with reporting related to net sales of VOWST in accordance with U.S. generally accepted accounting principles in order to calculate and record collaboration profit or loss.
 The collaboration (profit) loss sharing - related party line item also includes the Company's profit on the transfer of VOWST inventory to Nestl, which represents the excess of the supply price paid by Nestl over the Company's cost to manufacture VOWST, subject to a supply price cap applicable to product manufactured prior to commercial launch.
 The collaboration (profit) loss sharing - related party line item also includes the collaboration loss related to pre-launch activities, which were completed prior to the first commercial sale of VOWST.

 The components of the collaboration profit (loss) sharing for the years ended December 31, 2023, 2022, and 2021 are as follows:

 For the Year Ended December 31,

 2023

 2022

 2021

 Share of VOWST net loss

 $

 18,873

 $

 —

 $

 —

 Profit on transfer of VOWST inventory to Nestl

 ( 23,327

)

 —

 —

 Collaboration (profit)/loss related to pre-launch activities

 5,158

 1,004

 ( 1,732

)

 Total collaboration (profit) loss sharing - related party

 $

 $

 1,004

 $

 ( 1,732

)

 16. Commitments and Contingencies
 Leases
 Refer to Note 8 "Leases" for discussion of the commitments associated with the Company's lease portfolio.
 Indemnification Agreements
 In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third-parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and its officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company does not believe that the outcome of any claims under indemnification arrangements will have a material effect on its financial position, results of operations or cash flows, and it has no t accrued any liabilities related to such obligations in its consolidated financial statements as of December 31, 2023 or 2022.
 Legal Contingencies
 The Company accrues a liability for legal contingencies when it believes that it is both probable that a liability has been incurred and that the Company can reasonably estimate the amount of the loss. The Company reviews these accruals and adjusts them to reflect ongoing negotiations, settlements, rulings, advice of legal counsel and other relevant information. To the extent new information is obtained and the views on the probable outcomes of claims, suits, assessments, investigations or legal proceedings change, changes in the Company's accrued liabilities would be recorded in the period in which such determination is made.
 In addition, in accordance with the relevant authoritative guidance, for any matters in which the likelihood of material loss is at least reasonably possible, the Company will provide disclosure of the possible loss or range of loss. If a reasonable estimate cannot be made, however, the Company will provide disclosure to that effect. The Company expenses legal costs as they are incurred.
 The Company did no t accrue any liabilities related to legal contingencies in its consolidated financial statements as of December 31, 2023 and 2022.
 Bacthera Long Term Manufacturing Agreement
 On November 8, 2021, the Company entered into a Long Term Manufacturing Agreement with BacThera AG ("Bacthera"), a joint venture between Chr. Hansen and a Lonza Group affiliate, which was amended on December 14, 2022 (the "Bacthera Agreement"). The Bacthera Agreement governs the general terms under which Bacthera, or one of its affiliates, will (i) construct a dedicated full-scale production suite for the Company at Bacthera's Microbiome Center of Excellence in Visp, Switzerland, which is substantially complete; and (ii) provide manufacturing services to the Company for its then SER-109 product candidate (now VOWST) and other products, as agreed to by the parties.
 Under the terms of the Bacthera Agreement, the Company agreed to pay Bacthera a total of at least 256,000 CHF (or approximately $ 301,000) for the initial term of the agreement, inclusive of the construction fees and annual operating fees. Bacthera is funding the majority of the construction costs and will own and control the manufacturing suite during construction. The construction

 fees that the Company is responsible for represent a small percentage of the overall construction costs and are payable upon the achievement of certain milestones related to the construction of the dedicated manufacturing suite. The annual operating fee includes the cost of a baseline annual batch production volume. The Company has also agreed to pay certain other ancillary fees and a per-batch fee in excess of the baseline batches. These fees are subject to adjustment during construction for certain items outside of Bacthera's control and annually against an agreed index. The Company will supply the active pharmaceutical ingredients to Bacthera to enable it to perform the services and pay for certain other raw materials and manufacturing components, which will be acquired by Bacthera.
 The Bacthera Agreement has an initial term that continues until the tenth anniversary of the earlier of (a) successful completion of construction and demonstration of Bacthera's readiness for commercial production or (b) the commencement of manufacturing.
 The initial term is subject to renewals, which could extend the term to 16 years, and additional three-year terms thereafter. Each party has the ability to terminate the Bacthera Agreement upon the occurrence of certain customary conditions. The Company may also terminate the Bacthera Agreement for convenience after a defined period. In the event of a termination, the Company has certain financial obligations that would apply, and Bacthera has agreed to grant a license to Bacthera-developed manufacturing know how, if any, and provide technical assistance to the Company, so that the Company could transfer the manufacturing operations to itself or a third party. The Bacthera Agreement also contains representations, warranties and indemnity obligations as well as limitations of liability that are customary for agreements of this type.

 The Bacthera Agreement represents a lease as the Company will have the right to use the dedicated manufacturing suite for a period of time following completion of the construction of the manufacturing suite and approval by regulatory authorities. As of December 31, 2023, the lease commencement date has not occurred and therefore the Company has not recorded an operating lease asset or an operating lease liability on its consolidated balance sheets. As of December 31, 2023, the Company has paid Bacthera $ 12,276 related to the construction of the dedicated manufacturing suite. As of December 31, 2023, the Company recorded $ 38,877 in other non-current assets in the accompanying consolidated balance sheet, including $ 30,049 related to the achievement of the substantial completion milestone that occurred in late 2023. These amounts will be recorded as part of the right-of-use asset upon lease commencement.

 17. Income Taxes
 During the years ended December 31, 2023, 2022 and 2021, the Company recorded no income tax benefits for the net operating losses incurred in each year or interim period, due to its uncertainty of realizing a benefit from those items.
 A reconciliation of the U.S. federal statutory income tax rate to the Company's effective income tax rate is as follows:

 2023

 2022

 2021

 Federal statutory income tax rate

 ( 21.0

)%

 ( 21.0

)%

 ( 21.0

)%

 Research and development tax credits

 ( 4.3

)

 ( 3.1

)

 ( 16.6

)

 State taxes, net of federal benefit

 ( 7.8

)

 ( 4.3

)

 ( 2.8

)

 Stock-based compensation

 1.4

 0.6

 ( 0.4

)

 Uncertain tax position reserves

 0.8

 4.6

 —

 Other

 ( 0.3

)

 0.3

 0.4

 Change in deferred tax asset valuation allowance

 31.2

 22.9

 40.4

 Effective income tax rate

 —

 %

 —

 %

 —

 %

 Net deferred tax assets as of December 31, 2023 and 2022 consisted of the following:

 2023

 2022

 Deferred tax assets:

 Net operating loss carryforwards

 $

 142,506

 $

 132,560

 Research and development tax credit carryforwards

 52,843

 48,854

 Section 174 capitalized research and development expenses

 55,572

 38,894

 25,898

 20,048

 Lease liability

 29,855

 29,717

 Deferred revenue

 27,452

 29,922

 Accrued expenses

 3,540

 4,044

 Section 163(j) limitation

 3,741

 2,303

 Depreciation and amortization

 Other

 Total deferred tax assets

 $

 341,974

 $

 306,938

 Deferred tax liabilities:

 Depreciation and amortization

 —

 —

 Right of use assets

 ( 29,165

)

 ( 29,568

)

 Total deferred tax liabilities

 ( 29,165

)

 ( 29,568

)

 Valuation allowance

 $

 ( 312,809

)

 $

 ( 277,370

)

 Net deferred tax assets

 $

 —

 $

 —

 The Tax Cuts and Jobs Act ("TCJA") requires taxpayers to capitalize and amortize research and experimental expenditures under IRC Section 174 for tax years beginning after December 31, 2021. This rule became effective for the Company during the year ended December 31, 2022 and resulted in the capitalization of research and development costs of $ 102,558 and $ 160,586 for the years ended December 31, 2023 and 2022, respectively. The Company will amortize these costs for tax purposes over five years if the research and development was performed in the U.S. and over 15 years if the research and development was performed outside the U.S.
 As of December 31, 2023, the Company had net operating loss carryforwards ("NOLs") for federal and state income tax purposes of $ 527,065 and $ 504,215, respectively. Federal NOLs of $ 119,800, generated before 2018, will begin expiring in varying amounts in 2035 unless utilized. The remaining federal NOLs of $ 407,265, generated after 2017, will be carried forward indefinitely and could be used to offset up to 80 % of taxable income in future tax years. The Company's state NOLs will expire at various times starting in 2035. As of December 31, 2023, the Company also had available gross research and development tax credit carryforwards for federal and state income tax purposes of $ 53,928 and $ 11,455, respectively, which begin to expire in 2031 and 2028, respectively. The federal research and development tax credits include an orphan drug credit carryforward of $ 25,873.
 Utilization of the NOLs and research and development tax credit carryforwards may be subject to a substantial annual limitation under Sections 382 and 383 of the IRC due to ownership changes that have occurred previously or that could occur in the future. These ownership changes may limit the amount of carryforwards that can be utilized annually to offset future taxable income. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50% over a three-year period. Since its formation, the Company has raised capital through the issuance of capital stock on several occasions. These financings, combined with the purchasing shareholders' subsequent disposition of those shares, may have resulted in a change of control or could result in a change of control in the future upon subsequent disposition. The Company conducted an analysis to determine if historical changes in ownership through December 31, 2020 would limit or otherwise restrict its ability to utilize these NOLs and research and development credit carryforwards. As a result of this analysis, the Company does not believe there are any significant limitations on its ability to utilize these carryforwards. However, future changes in ownership after December 31, 2020 could affect the limitation in future years. Any limitation may result in expiration of a portion of the NOLs or research and development credit carryforwards before utilization.
 The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets. Management has considered the Company's history of cumulative net losses incurred since inception and its lack of commercialization of any products or generation of any revenue from product sales since inception and has concluded that it is more likely than not that the Company will not realize the benefits of the deferred tax assets. Accordingly, a full valuation allowance has been established against

 the deferred tax assets as of December 31, 2023 and 2022. Management reevaluates the positive and negative evidence at each reporting period.
 Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2023, 2022 and 2021 related primarily to the increases in NOLs, research and development tax credit carryforwards and capitalized research and development expenses pursuant to IRC Section 174, and stock-based compensation were as follows:

 2023

 2022

 2021

 Valuation allowance at beginning of year

 $

 ( 277,370

)

 $

 ( 220,114

)

 $

 ( 193,736

)

 Decreases recorded as benefit to income tax provision

 —

 —

 —

 Increases recorded to income tax provision

 ( 35,439

)

 ( 57,256

)

 ( 26,378

)

 Valuation allowance as of end of year

 $

 ( 312,809

)

 $

 ( 277,370

)

 $

 ( 220,114

)

 During the year ended December 31, 2023, the Internal Revenue Service ("IRS") concluded their examination of the Company for the period ended December 31, 2018 related to the Company's 2018 research and development tax credits ("R&D Credit(s)"). The Company has adjusted its 2018 R&D Credits and its overall federal and state R&D Credit carryforward balance from the Company's inception to December 31, 2023 to account for the conclusions drawn by the IRS. Also, the Company has reviewed each of its overall filing positions since inception and has not identified any additional positions that do not meet the more likely than not threshold. The Company does not anticipate a material change to its uncertain tax position reserves in the next 12 months. The changes in the Company's unrecognized tax benefits for the years ended December 31, 2023, 2022, and 2021 were as follows:

 2023

 2022

 2021

 Balance at beginning of year

 $

 12,528

 $

 —

 $

 —

 Increase in unrecognized tax benefits as a result of tax positions taken
 during the year

 1,001

 12,528

 —

 Reduction to unrecognized tax benefits

 —

 —

 —

 Balance at end of year

 $

 13,529

 $

 12,528

 $

 —

 The Company has not yet conducted a study of its research and development credit carry forwards. This study may result in further adjustment to the Company's R&D Credits; however, a full valuation allowance has been provided against the Company's R&D Credits, and if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the consolidated balance sheet or statement of operations if an adjustment were required. The Company had no other unrecognized tax benefits accrued for the years ended December 31, 2023 and 2022, or related interest and penalties as of such dates. The Company will recognize any interest and penalties related to uncertain tax positions in income tax expense.
 The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. The Company's tax years are still open under statute from 2011 to present. All years may be examined to the extent the tax credit or net operating loss carryforwards are used in future periods.

 18. Related Party Transactions
 As described in Notes 14 and 15, in July 2021, the Company entered into the 2021 License Agreement with NHSc Pharma Partners, succeeded by NHSc Rx License GmbH (together with Soci t des Produits Nestl S.A., their affiliates, and their subsidiaries, "Nestl "). NHSc Rx License GmbH is an affiliate of one of the Company's significant stockholders, Soci t des Produits Nestl S.A. During the years ended December 31, 2023, 2022, and 2021, the Company recognized $ 126,975, $ 4,114, and $ 133,411 of related party revenue, respectively, associated with the 2021 License Agreement. As of the years ended December 31, 2023 and 2022, there was $ 0 and $ 1,976 of deferred revenue related to the 2021 License Agreement, respectively, which is classified as current in the consolidated balance sheets. As of December 31, 2023 and 2022 there was $ 28,053 and $ 34,770 included in accrued expenses and other liabilities, which represents amounts due to Nestl pursuant to the 2021 License Agreement. As of December 31, 2023 and 2022, there was $ 7,730 and $ 0 of deferred income - related party included on the accompanying consolidated balance sheets, which represents the inventory transferred to Nestl that Nestl has not yet sold through to customers or transferred as free goods. The Company recognizes deferred income - related party as collaboration profit upon Nestl 's sale or transfer of such inventory to third parties. During the years ended

 December 31, 2023 and 2022, the Company paid Nestl $ 37,387 and $ 0 for Nestl 's share of the collaboration expenses pursuant to the 2021 License Agreement. During the years ended December 31, 2023 and 2022, the Company received $ 31,243 and $ 0 in payments from Nestl for the transfer of VOWST to Nestl. As of December 31, 2023 and 2022, there is $ 8,674 and $ 0 due from Nestl pursuant to the 2021 License Agreement.
 As described in Note 14, Revenue from Contracts with Customers, in January 2016, the Company entered into the 2016 License Agreement with Nestec, Ltd, succeeded by Soci t des Produits Nestl S.A. for the development and commercialization of certain product candidates in development for the treatment and management of CDI and IBD, including UC and Crohn's disease. Soci t des Produits Nestl S.A. is one of the Company's significant stockholders. During the years ended December 31, 2023, 2022, and 2021, the Company recognized ($ 650), $ 3,014 and $ 10,446, respectively, of related party revenue associated with the 2016 License Agreement. As of December 31, 2023 and 2022, there was $ 95,364 and $ 94,713, respectively, of deferred revenue related to the 2016 License Agreement, which is classified as current or non-current in the consolidated balance sheets. The Company did not make any payment to or receive any payment from Nestl during the years ended December 31, 2023 and 2022 pursuant to the 2016 License Agreement. There was no amount due from Nestl pursuant to the 2016 License Agreement as of December 31, 2023 and 2022.
 As described in Note 11, the Company entered into a securities purchase agreement with Flagship Pioneering Fund VII, L.P. and Nutritional Health LTP Fund, L.P., affiliates of Flagship, one of the Company's significant stockholders, for the sale of 8,738,243 shares of its common stock at a purchase price of $ 3.15 per share as part of the Registered Direct Offering, which closed on July 5, 2022. The Company received proceeds from Flagship of $ 27,525.
 In July 2022, the Company entered into a Pledge and Utilization Agreement with Flagship Pioneering Labs TPC, Inc., an affiliate of Flagship, for an option to lease certain manufacturing space. The Company paid $ 833 for this option which is classified in other non-current assets on the Company's consolidated balance sheet as of December 31, 2022. In June 2023, the Company elected not to renew the option and accordingly at such time, expensed the $ 833 option payment.

 In July 2019, the Company entered into a sublease agreement with Flagship to sublease a portion of its office and laboratory space in Cambridge, Massachusetts. The term of the sublease agreement commenced in July 2019 and ended in November 2021. Under this agreement, the Company recorded other income of $ 0, $ 0, and $ 1,575 during the years ended December 31, 2023, 2022, and 2021.

 19. 401(k) Savings Plan
 The Company has a defined contribution savings plan under Section 401(k) of the IRC. This plan covers substantially all employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. Effective January 1, 2016, the Company elected to match 50 % of the first 6 % of an employee's deferral. Company contributions are expensed in the year for which they are declared. During the years ended December 31, 2023, 2022, and 2021 the Company recorded expense of $ 2,003, $ 1,921, and $ 1,087, respectively, for 401(k) match contributions.