During the 9th Microbiome Movement Summit Europe, held recently in Barcelona (Spain) Microbiomepost sat down with Chris Ford, Senior Vice President, Translational Biology at Seres Therapeutics.

In this interview, Chris Ford discusses the development of SER-155, a cultivated bacterial consortium designed to address the unmet medical need of preventing bloodstream infections (BSIs) in allogeneic hematopoietic stem cell transplant (HSCT) patients. SER-155, which consists of 16 bacterial strains, was preclinically designed to restructure the microbiome, reduce pathogenic bacterial abundance, enhance epithelial barrier integrity, and modulate immune responses—all critical factors in preventing infection.

The discussion details the promising results of SER-155’s Phase 1b clinical trial, where it demonstrated a significant reduction in BSIs—down to 10% in patients receiving SER-155 compared to 43% in the placebo group. These results were also supported by improved clinical outcomes, such as fewer days in the hospital and less antibiotic use. The interview highlights the consistency between preclinical design attributes and early clinical data, with CER155 effectively restructuring the microbiome, improving barrier function, and enhancing immune responses.

Excitingly, based on these early-phase results, CERES received Breakthrough Therapy Designation from the FDA for SER-155 at the end of 2024, paving the way for future development. The company is now exploring next steps in advancing SER-155 toward broader clinical use in transplant and other medically compromised patient populations.