SERES THERAPEUTICS   Cambridge, MA, USA
serestherapeutics.com

SER-155 LF
Novel live biotherapeutic

Seres Therapeutics is developing SER-155 LF, a novel live biotherapeutic formulated for oral liquid delivery to prevent gut-seeded antimicrobial-resistant (AMR) infections in patients in the medical intensive care unit (ICU). It is designed to target specific microbial functions to improve gastrointestinal epithelial barrier integrity and reduce pathogen colonization to prevent bacterial translocation of gastrointestinal pathogens such as Escherichia coli into the bloodstream without increasing AMR organism carriage.

In 2017, CARB-X welcomed SER-155 into the portfolio and supported the development of this FDA Breakthrough Therapy Designated biotherapeutic to prevent life-threatening bacterial infections and graft versus host disease in patients following solid organ and allogeneic stem cell transplantation. This new award will advance the development of an oral, liquid formulation broadening the potential use of this drug in medically compromised patients at high-risk of AMR infections. In addition, the new funding and support will position the program for clinical evaluation in ICU patients through a Phase 1b clinical trial designed to evaluate safety, engraftment, and exploratory endpoints related to E. coli colonization and antimicrobial resistance.

Current Development Stage: Pre-clinical

CARB-X Investment: US$3.6 million

Initial CARB-X Investment Date: December 2, 2025