Seres Therapeutics Inc

Seres Therapeutics is a clinical-stage biotechnology company developing novel live biotherapeutics products (LBPs) designed to address unmet needs in oncology and inflammatory and immune diseases by modulating host function to protect and improve mucosal epithelial barrier integrity, induce immune homeostasis and tolerance, and prevent colonization and overgrowth of pathogens in the gastrointestinal tract. The company previously developed and gained FDA approval for VOWST, the first orally administered microbiome therapeutic, which was subsequently divested to Nestlé Health Science. Its lead candidate, SER-155, is an investigational cultivated multi-strain biotherapeutic with Breakthrough Therapy and Fast Track designations, being developed for prevention of bloodstream infections in allogeneic hematopoietic stem cell transplant (allo-HCT) patients and for treatment of immune checkpoint inhibitor-related enterocolitis (irEC). The company is also advancing IND-enabling studies for SER-603 for inflammatory bowel disease and developing SER-428, an oral liquid formulation based on SER-155 strains, for medical ICU patients at high risk of infection. Seres trades on the Nasdaq under the ticker MCRB. Updated Aug 5, 2026