Nature of the Business and Basis of Presentation	12 Months Ended
Dec. 31, 2022
Accounting Policies [Abstract]
Nature of the Business and Basis of Presentation	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 microbiome therapeutics company developing 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 lead product candidate, SER-109, is designed to reduce further recurrences of Clostridioides difficile infection (“CDI”), a debilitating infection of the colon, in patients who have received antibiotic therapy for recurrent CDI by restructuring the colonic microbiome and changing its function. If approved by the U.S. Food and Drug Administration (“FDA”), the Company believes SER-109 will be a first-in-field oral microbiome drug. Building upon SER-109, the Company is developing therapeutic candidates, such as SER-155, to specifically target infections and antimicrobial resistance. SER-155, a microbiome therapeutic candidate consisting of a consortium of cultivated bacteria, is designed to reduce incidences of gastrointestinal infections, bloodstream infections and graft versus host disease ("GvHD”) in patients receiving allogeneic hematopoietic stem cell transplantation (“allo-HSCT”). The Company is progressing additional preclinical stage programs to evaluate how microbiome therapeutics may reduce incidence of infection, which the Company refers to as Infection Protection, in indications such as cancer neutropenia, chronic liver disease, solid organ transplant, and antimicrobial resistant infections more broadly in settings of high-risk such as intensive care units. The Company is also continuing its research activities in ulcerative colitis ("UC"), including evaluating the potential to utilize biomarker-based patient selection and stratification for future studies. In addition, the Company continues to leverage microbiome pharmacokinetic and pharmacodynamic data from across its clinical and preclinical portfolios, using its reverse translational microbiome therapeutic development platform to conduct research on various indications, including inflammatory and immune diseases, cancer, and metabolic diseases. The Company has built and deploys a reverse translational platform for the discovery and development of microbiome therapeutics. 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. 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, 2022, the Company had an accumulated deficit of $864,511 and cash, cash equivalents and short- and long-term investments of $181,341. 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 Company’s product candidates are in development. 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. The Company's primary focus in recent months has been and will continue to be supporting the Biologics License Application ("BLA") submission for our lead product candidate, SER-109, and continuing to prepare for potential commercialization, including the manufacture of SER-109, until and continuing after the Prescription Drug User Fee Act ("PDUFA") target action date set by the FDA of April 26, 2023. The Company has commenced manufacture of SER-109 in consideration of potential commercialization, which requires capital and resources. Successful execution of the pre-commercialization activities required by our collaboration agreement with Société des Produits Nestlé S.A., successor in interest to Nestec Ltd., and NHSc Rx License GmbH, a significant stockholder of the Company and successor in interest to NHSc Pharma Partners (collectively, and together with their affiliates and subsidiaries, “Nestlé”), requires continued investment in readying for launch. Still, there can be no assurance that the BLA for SER-109, which is currently under priority review by the FDA, will be approved, that the FDA will complete its review of the BLA in the anticipated timeline, or that, in the event of approval, the demand for SER-109 will be sufficient to meet the Company's forecasted cash needs without raising significant additional capital. The Company also has a credit facility (the "New Credit Facility") pursuant to a Loan and Security Agreement (the “Loan Agreement”) with Hercules Capital, Inc. ("Hercules," see Note 8, Notes Payable), which is collateralized by substantially all of the Company’s assets excluding intellectual property. The Company is currently in compliance with the financial covenants in the New Credit Facility. The New Credit Facility includes a conditional liquidity covenant commencing on June 15, 2023, which ceases to apply if certain conditions are satisfied. Violation of any covenant under the New Credit Facility provides Hercules with the option to accelerate repayment of amounts borrowed and terminate its commitment to extend further credit, among other remedies as defined in the New Credit Facility. Primarily as a result of the increased and costly efforts to prepare for potential commercialization of SER-109, in conjunction with the Company's research and development efforts for other preclinical and product candidates, for the year ended December 31, 2022, the Company incurred a net loss of $250,157, and had net operating cash outflows of $228,816. The Company expects that its operating losses and negative cash flows will continue for the foreseeable future. The Company is eligible to receive contingent milestone payments under its license agreement with Nestlé executed in July 2021 (see Note 11, Collaboration Revenue) if certain development, regulatory approval or sales target milestones are achieved. Upon approval of the BLA, the Company is entitled to receive an additional $125,000 payment from Nestlé, and a $25,000 tranche under the New Credit Facility, which becomes available upon the satisfaction of certain conditions, including FDA approval of SER-109. Additionally, following FDA approval, the Company will be eligible to receive payments from Nestlé for the supply of SER-109. In the event of commercial sale of SER-109, the Company will be entitled to share equally in its commercial profits and losses. The payments under the 2021 License Agreement and the additional tranche under the New Credit Facility are uncertain and there is no assurance that the Company will receive any of them, because they are contingent upon approval of the Company's BLA, which is currently under priority review by the FDA. 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, in the absence of approval of SER-109 by the FDA, and therefore, without the receipt of the approval milestone and other payments to which it is entitled to receive as a result thereof, the Company believes it is reasonably likely that it will require additional funding in early 2024. These factors raise substantial doubt about the Company’s ability to continue as a going concern. Management's plans to mitigate the conditions that raise substantial doubt about the Company’s ability to continue as a going concern include continuing to seek regulatory approval of the BLA for SER-109 and therefore earning the $125,000 milestone payment from Nestlé and becoming eligible for the $25,000 tranche under the New Credit Facility, as well as the ability to commercialize SER-109 and receive payments from Nestlé for the supply of SER-109, and share equally in commercial profits and losses with Nestlé pursuant to the 2021 License Agreement. Management may also seek to raise additional capital through financing or other transactions, including the Company's at the market equity offering. Because certain elements of the Company’s operating plan are outside of the Company’s control, primarily the approval of its BLA for SER-109, which has not occurred as of the issuance of these consolidated financial statements, and 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.

Nature of the Business and Basis of Presentation

12 Months Ended

Dec. 31, 2022

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 microbiome therapeutics company developing 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 lead product candidate, SER-109, is designed to reduce further recurrences of Clostridioides difficile infection (“CDI”), a debilitating infection of the colon, in patients who have received antibiotic therapy for recurrent CDI by restructuring the colonic microbiome and changing its function. If approved by the U.S. Food and Drug Administration (“FDA”), the Company believes SER-109 will be a first-in-field oral microbiome drug. Building upon SER-109, the Company is developing therapeutic candidates, such as SER-155, to specifically target infections and antimicrobial resistance. SER-155, a microbiome therapeutic candidate consisting of a consortium of cultivated bacteria, is designed to reduce incidences of gastrointestinal infections, bloodstream infections and graft versus host disease ("GvHD”) in patients receiving allogeneic hematopoietic stem cell transplantation (“allo-HSCT”). The Company is progressing additional preclinical stage programs to evaluate how microbiome therapeutics may reduce incidence of infection, which the Company refers to as Infection Protection, in indications such as cancer neutropenia, chronic liver disease, solid organ transplant, and antimicrobial resistant infections more broadly in settings of high-risk such as intensive care units. The Company is also continuing its research activities in ulcerative colitis ("UC"), including evaluating the potential to utilize biomarker-based patient selection and stratification for future studies. In addition, the Company continues to leverage microbiome pharmacokinetic and pharmacodynamic data from across its clinical and preclinical portfolios, using its reverse translational microbiome therapeutic development platform to conduct research on various indications, including inflammatory and immune diseases, cancer, and metabolic diseases. The Company has built and deploys a reverse translational platform for the discovery and development of microbiome therapeutics. 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.

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, 2022, the Company had an accumulated deficit of $864,511 and cash, cash equivalents and short- and long-term investments of $181,341.

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 Company’s product candidates are in development. 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.

The Company's primary focus in recent months has been and will continue to be supporting the Biologics License Application ("BLA") submission for our lead product candidate, SER-109, and continuing to prepare for potential commercialization, including the manufacture of SER-109, until and continuing after the Prescription Drug User Fee Act ("PDUFA") target action date set by the FDA of April 26, 2023. The Company has commenced manufacture of SER-109 in consideration of potential commercialization, which requires capital and resources. Successful execution of the pre-commercialization activities required by our collaboration agreement with Société des Produits Nestlé S.A., successor in interest to Nestec Ltd., and NHSc Rx License GmbH, a significant stockholder of the Company and successor in interest to NHSc Pharma Partners (collectively, and together with their affiliates and subsidiaries, “Nestlé”), requires continued investment in readying for launch. Still, there can be no assurance that the BLA for SER-109, which is currently under priority review by the FDA, will be approved, that the FDA will complete its review of the BLA in the anticipated timeline, or that, in the event of approval, the demand for SER-109 will be sufficient to meet the Company's forecasted cash needs without raising significant additional capital.

The Company also has a credit facility (the "New Credit Facility") pursuant to a Loan and Security Agreement (the “Loan Agreement”) with Hercules Capital, Inc. ("Hercules," see Note 8, Notes Payable), which is collateralized by substantially all of the

Company’s assets excluding intellectual property. The Company is currently in compliance with the financial covenants in the New Credit Facility. The New Credit Facility includes a conditional liquidity covenant commencing on June 15, 2023, which ceases to apply if certain conditions are satisfied. Violation of any covenant under the New Credit Facility provides Hercules with the option to accelerate repayment of amounts borrowed and terminate its commitment to extend further credit, among other remedies as defined in the New Credit Facility.

Primarily as a result of the increased and costly efforts to prepare for potential commercialization of SER-109, in conjunction with the Company's research and development efforts for other preclinical and product candidates, for the year ended December 31, 2022, the Company incurred a net loss of $250,157, and had net operating cash outflows of $228,816. The Company expects that its operating losses and negative cash flows will continue for the foreseeable future. The Company is eligible to receive contingent milestone payments under its license agreement with Nestlé executed in July 2021 (see Note 11, Collaboration Revenue) if certain development, regulatory approval or sales target milestones are achieved. Upon approval of the BLA, the Company is entitled to receive an additional $125,000 payment from Nestlé, and a $25,000 tranche under the New Credit Facility, which becomes available upon the satisfaction of certain conditions, including FDA approval of SER-109. Additionally, following FDA approval, the Company will be eligible to receive payments from Nestlé for the supply of SER-109. In the event of commercial sale of SER-109, the Company will be entitled to share equally in its commercial profits and losses. The payments under the 2021 License Agreement and the additional tranche under the New Credit Facility are uncertain and there is no assurance that the Company will receive any of them, because they are contingent upon approval of the Company's BLA, which is currently under priority review by the FDA. 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, in the absence of approval of SER-109 by the FDA, and therefore, without the receipt of the approval milestone and other payments to which it is entitled to receive as a result thereof, the Company believes it is reasonably likely that it will require additional funding in early 2024. These factors raise substantial doubt about the Company’s ability to continue as a going concern.

Management's plans to mitigate the conditions that raise substantial doubt about the Company’s ability to continue as a going concern include continuing to seek regulatory approval of the BLA for SER-109 and therefore earning the $125,000 milestone payment from Nestlé and becoming eligible for the $25,000 tranche under the New Credit Facility, as well as the ability to commercialize SER-109 and receive payments from Nestlé for the supply of SER-109, and share equally in commercial profits and losses with Nestlé pursuant to the 2021 License Agreement. Management may also seek to raise additional capital through financing or other transactions, including the Company's at the market equity offering. Because certain elements of the Company’s operating plan are outside of the Company’s control, primarily the approval of its BLA for SER-109, which has not occurred as of the issuance of these consolidated financial statements, and 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.