Seres Therapeutics announces three presentations at 2026 ESCMID congress

Seres Therapeutics (MCRB) announced three presentations at the 2026 European Society of Clinical Microbiology and Infectious Diseases, ESCMID, global congress, taking place April 17-21 in Munich, Germany. A poster presentation by Seres highlighted biomarker and clinical pharmacology data from the Company’s Phase 1b study of SER-155, evaluating changes in gastrointestinal microbiome composition following administration in patients undergoing allogeneic hematopoietic cell transplantation. Data showed that administration of SER-155 induced a significant and durable shift in GI microbiome composition relative to placebo, characterized by high SER-155 species relative abundance. This shift is associated with improved GI epithelial barrier integrity that could reduce the likelihood of bacterial translocation from the GI to the bloodstream. In contrast, placebo-treated participants showed low abundance of SER-155 species and related Firmicutes, high abundance of Bacteroidetes, and a compromised GI epithelial barrier. These findings are consistent with the intended mechanisms of action of SER-155, including protection of the GI epithelial barrier, and align with previously reported clinical observation of reduced incidence of bloodstream infections in SER-155-treated patients following allo-HCT.