Core Insights - Seres Therapeutics is advancing its SER-155 Phase 2 study protocol for preventing bloodstream infections in adults undergoing allogeneic hematopoietic stem cell transplant, following positive feedback from the FDA [1][2][4] - The company is actively seeking capital to support the Phase 2 study and has implemented cost-reduction measures, including a 25% workforce reduction, to extend its cash runway into Q2 2026 [2][3][5] Company Developments - The SER-155 Phase 2 study is designed to be a placebo-controlled trial with approximately 248 participants, focusing on the prevention of bloodstream infections through 30 days post-transplant as the primary endpoint [4][7] - Interim clinical results are expected within 12 months of study initiation, which will facilitate timely engagement with the FDA regarding a potential Phase 3 study [4][7] - The company has received Breakthrough Therapy designation for SER-155, which has shown a 77% relative risk reduction in bloodstream infections in a prior Phase 1b study [7][8] Financial and Operational Strategy - The workforce reduction is expected to incur cash payments of approximately $1.0 to $1.4 million, primarily for severance costs, to be paid in Q4 2025 [5] - Cost-saving initiatives are anticipated to provide the company with additional opportunities to advance its strategic priorities and support its broader portfolio of product candidates [3][4]

Seres Therapeutics Overview - Seres' VOWST, the first-ever oral live microbiome therapeutic, received FDA approval in April 2023 for preventing C difficile infection recurrence, demonstrating approximately 88% sustained clinical response rate[6,9] - The sale of the VOWST asset, completed in September 2024, provided Seres with capital to support pipeline advancement and streamline the organization[9,10] - As of June 30, 2025, Seres had approximately $45.4 million in cash and cash equivalents, projecting a cash runway into Q1 2026[92] SER-155 Clinical Development - SER-155 Phase 1b data in allo-HSCT showed a 77% relative risk reduction in bacterial bloodstream infections (BSIs) compared to placebo[6,45,92] - SER-155 Phase 1b data also showed significantly lower mean cumulative exposure to systemic antibacterials/antimycotics compared to placebo (9.2 days vs 21.1 days)[45,50] - SER-155 Phase 1b data also showed a lower incidence rate of febrile neutropenia in SER-155-treated subjects vs placebo[46] - A Phase 2 study protocol for SER-155 in allo-HSCT was submitted to the FDA in May 2025, with study commencement dependent on funding and aiming to enroll 248 patients[6,31,78] Pipeline and Future Opportunities - Seres is developing SER-147 to prevent infections in chronic liver disease patients, with preclinical data showing a 1-3 log reduction of E coli in in vitro models[6,80] - Seres is also developing SER-603 to target inflammatory drivers of Inflammatory Bowel Disease (IBD)[83] - Seres is engaging with multiple parties regarding various deal structures to secure capital for the clinical advancement of SER-155 and other live biotherapeutic product candidates[6,78,92]

SER-155 Clinical Data and Development - SER-155 Phase 1b study showed a 77% relative risk reduction in bacterial bloodstream infections (BSIs) compared to placebo[6,44,83] - SER-155 treatment was associated with significantly lower mean cumulative exposure to systemic antibacterials/antimycotics compared to placebo[44,49] - The company plans to submit a Phase 2 protocol to the FDA in Q2 2025, incorporating FDA feedback[6,31,73,83] - The FDA granted SER-155 Breakthrough Therapy designation in December 2024[6,73,82] Financial Position and Strategy - The VOWST asset sale to Nestlé closed in September 2024, providing capital to support SER-155 advancement[6,9,10,12,83] - The VOWST asset sale included a $100 million upfront payment, less ~$20 million in net obligations, a $15 million equity investment, and a $60 million prepaid sales-based milestone at closing[10] - As of March 31, 2025, the company had approximately $588 million in cash/cash equivalents, projecting a cash runway into Q1 2026[83] - The company is pursuing a strategic partnership for SER-155 to accelerate the next study in allo-HSCT and expand to multiple target populations[6,73,83] Pipeline and Platform - VOWST was FDA approved in April 2023 to prevent the recurrence of C difficile infection in adults, demonstrating an approximately 88% sustained clinical response rate[6,9] - SER-155 is being developed initially in allo-HSCT, with potential to expand to autologous-HSCT, blood cancers, and CAR-T recipients[6,30] - SER-147 is designed to prevent infections in chronic liver disease, with IND-enabling activities underway[6,30,74,82]

Financial Data and Key Metrics Changes - The company reported a net income from continuing operations of $32.7 million in Q1 2025, compared to a net loss of $32.9 million in Q1 2024, primarily driven by a $50 million installment payment received from Nestle [15][16] - Research and development expenses decreased to $11.8 million from $19.5 million in the same quarter last year, reflecting lower personnel expenses and reduced costs related to the SER-155 Phase Ib study [16] - General and administrative expenses were $11.9 million, down from $14.9 million in Q1 2024, primarily due to lower personnel and contractor expenses [16] - As of March 31, 2025, the company had cash and cash equivalents of $58.8 million, with an expected second installment payment of approximately $23.5 million from Nestle in July 2025 [16][17] Business Line Data and Key Metrics Changes - SER-155 remains the top corporate priority, with significant progress towards initiating the next clinical study, following a Phase 1b study that showed a 77% relative risk reduction in bloodstream infections compared to placebo [5][6] - The Phase 1b study also demonstrated a favorable safety profile consistent with historical data across the live biotherapeutic product platform [6] Market Data and Key Metrics Changes - The company received positive feedback from the transplant community at the European Society for Blood and Marrow Transplantation Conference, emphasizing the need for new approaches to prevent bloodstream infections [7][8] - The SER-155 poster received the best clinical poster award, validating the patient need and the scientific rigor of the study [9] Company Strategy and Development Direction - The company aims to develop SER-155 and other live biotherapeutics to prevent infections in various patient groups, including allo HSCT, autologous HSCT, cancer patients with neutropenia, and solid organ transplant recipients [12] - The strategic focus includes addressing gut-related inflammatory and immune diseases such as IBD, with an emphasis on the compromised gut epithelial barrier as a core component of underlying pathology [12] Management's Comments on Operating Environment and Future Outlook - Management expressed confidence in the constructive interactions with the FDA, which have been regular and supportive, particularly due to the breakthrough therapy designation for SER-155 [36] - The company is actively exploring partnerships to secure financial support and maximize the clinical and commercial value of SER-155, given the challenging biotech financing environment [12][17] Other Important Information - A one-for-20 reverse stock split was executed, and the company regained compliance with NASDAQ's bid price requirement [17] - The company is prioritizing activities that advance clinical and strategic goals while preserving cash [17] Q&A Session Summary Question: Are partnership discussions gated by progress around SER-155? - Management indicated that securing a partnership is a key long lead time item for moving forward with the study, while they are advancing other necessary preparations [24][25] Question: Can you outline the proposed powering assumptions for the Phase II study? - Management stated that the powering included in the design will allow data from this study to be used for both efficacy and safety components for FDA submission [27][28] Question: Have there been any large staffing changes at the FDA? - Management noted that their interactions with the FDA have been constructive and regular, and they are pleased with the feedback received [36] Question: Will the Phase II study be designed to evaluate overall survival? - The primary endpoint for the Phase II study is bloodstream infection reductions, with discussions ongoing regarding potential efficacy measures for Phase III [50][52]

Core Insights - Seres Therapeutics, Inc. will present three related posters at the 2025 Digestive Disease Week (DDW) Conference, highlighting advancements in live biotherapeutics for inflammatory and immune diseases [1][2] Company Developments - The company previously reported exploratory translational biomarker data from its SER-155 Phase 1b study, indicating its potential to enhance intestinal epithelial barrier integrity and modulate systemic inflammatory responses [2] - Seres is actively seeking partnership opportunities to further develop its biotherapeutics targeting inflammatory and immune diseases [3] Presentation Details - The first presentation will focus on the characterization of IBD microbiomes to evaluate candidate biomarkers for patient selection, scheduled for May 3, 2025 [4] - The second presentation will discuss candidate biomarkers of microbiome disruption for patient selection in clinical trials of microbiome therapeutics in ulcerative colitis, also on May 3, 2025 [4] - An encore presentation will cover pharmacokinetic and pharmacodynamic results from a Phase 1b study of SER-155 in adults undergoing allo-HCT, set for May 4, 2025 [5] Industry Context - The Digestive Disease Week (DDW) is a significant international event in gastroenterology, showcasing nearly 6,000 abstracts and over 1,000 invited talks on the latest advances in GI research, medicine, and technology [5]