Seres Therapeutics Receives Feedback From FDA on SER-155 Allogeneic Hematopoietic Stem Cell Transplant (allo-HSCT) Development Approach

Core Insights - The FDA has provided constructive feedback on Seres Therapeutics' SER-155 development plans, supporting a Phase 2 study with a primary efficacy endpoint focused on reducing bloodstream infections (BSIs) post-allo-HSCT [1][2][4] - Seres Therapeutics plans to submit a proposed protocol for the next SER-155 study to the FDA in Q2 2025, incorporating the agency's feedback [1][2] - SER-155 has shown a 77% relative risk reduction in BSIs in a Phase 1b study, along with reduced systemic antibiotic exposure and lower incidence of febrile neutropenia [2][4] Company Overview - Seres Therapeutics, Inc. is a clinical-stage company focused on live biotherapeutics aimed at improving outcomes for medically vulnerable populations [5] - The company has received Breakthrough Therapy designation for SER-155, targeting the reduction of BSIs in allo-HSCT patients, and Fast Track designation for reducing infection risk and graft-versus-host disease [5][4] - SER-155 is designed to decolonize gastrointestinal pathogens and improve immune tolerance in patients undergoing allo-HSCT for hematological malignancies [3][5] Future Development Plans - The next study design for SER-155 may retain elements from the previous Phase 1b trial, which demonstrated significant clinical benefits [2][4] - The company is actively seeking partnerships to support the further development of SER-155 in allo-HSCT [2]