Seres Therapeutics Reports Durable Microbiome Modulation with SER-155 in Allo-HCT Patients
Event summary
- SER-155 demonstrated durable GI microbiome shifts in Phase 1b allo-HCT patients, improving epithelial barrier integrity vs. placebo
- Symposium presentation highlighted microbiome's role in immunocompromised patient outcomes
- University of Leeds collaboration using MiGut model to study IBD patient-specific microbiome responses
- SER-155 has Breakthrough Therapy and Fast Track designations for allo-HCT indications
The big picture
Seres Therapeutics' data presentation at ESCMID Global 2026 underscores the growing clinical validation of microbiome-based interventions in immunocompromised populations. The company's strategic focus on live biotherapeutics positions it within an emerging sector where precision microbiome modulation is increasingly seen as critical for managing transplant-related complications and inflammatory diseases. With SER-155's Phase 2 readiness pending funding, the next phase will test whether the company can sustain momentum following its divestment of VOWST to Nestlé Health Science.
What we're watching
- Clinical Translation
- Whether SER-155's microbiome modulation can translate to reduced infection rates in larger allo-HCT studies
- Platform Expansion
- The pace at which Seres can leverage MiGut model for additional indications beyond IBD
- Regulatory Pathway
- How Breakthrough Therapy designation may accelerate SER-155's development timeline
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