Seres Therapeutics Secures $3.6M CARB-X Award, Plans Phase 1b SER-428 Trial

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Seres Therapeutics will present its live biotherapeutics platform and collaboration with CARB-X at the CARB-X Investor Day on April 16, preceding ESCMID in Munich. The company received a $3.6 million non-dilutive CARB-X award in 2025 to advance SER-428 oral liquid formulation and is designing a Phase 1b ICU trial.

1. CARB-X Investor Day Presentation

On April 16 Seres Therapeutics will showcase its live biotherapeutics platform and longstanding collaboration with CARB-X at the CARB-X Investor Day in Munich, highlighting its strategy to combat antimicrobial resistance with novel therapeutics.

2. CARB-X Non-Dilutive Award

In 2025 Seres received a second CARB-X grant totaling $3.6 million to support development of an oral liquid formulation based on SER-155 strains, now dubbed SER-428, for patients unable to swallow capsules such as those in medical ICUs.

3. SER-428 Phase 1b Trial Design

The company is designing a Phase 1b open-label trial in partnership with Dr. Dan Freedberg at Columbia University to evaluate SER-428 dosing in ICU patients at high risk of drug-resistant infections.

4. Additional Pipeline Initiatives

Seres is also advancing its broader pipeline, including Phase 2-ready SER-155 for bloodstream infections in allo-HSCT patients, SER-603 for inflammatory bowel disease, and an investigator-sponsored SER-155 trial in immune checkpoint inhibitor–related enterocolitis.

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