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SER-155

Microbiome therapy · Immune activation · developed by Seres Therapeutics

Phase 1 Most advanced trial (none active)

MCRB Developer

1 Registered trials

What is SER-155?

SER-155 is an orally bioavailable cultivated microbiome therapeutic composed of fermented bacterial species designed to restore healthy gut microbiota. It aims to decrease antibiotic-resistant bacterial infection and translocation in the gastrointestinal tract while enhancing immunological activity. It is studied in allogeneic hematopoietic stem cell transplantation to reduce graft-versus-host disease and bacteremia risk.

Summary written with AI from the sources listed at the end of this page.

At a glance

Drug type: Microbiome therapy
Mechanism: Immune activation
Pathways: immune_activation, microbiome diversity and function
Therapy area: Immunology, Infectious disease
Developer: Seres Therapeutics, Inc. (MCRB)
FDA status: Investigational, not approved in the US. Most advanced trial: Phase 1

🧪 Clinical trials

Trial	Phase	Condition	Status	Sponsor
NCT04995653	Phase 1	Allogeneic Hematopoietic Stem Cell Transplantation	Completed	MCRB

Trials of the companies BioRadar tracks, from ClinicalTrials.gov, most advanced phase first.

Conditions studied

Allogeneic Hematopoietic Stem Cell Transplantation

More from Seres Therapeutics

SER-262 Phase 1 SER-287 Phase 2

Sources

Updated Oct 3, 2026. Something wrong or missing? Report it on the MCRB page.

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Data: FDA (Drugs@FDA, Purple Book, DailyMed), NIH (NCI Thesaurus, GSRS, RxNorm), ClinicalTrials.gov • Informational purposes only, not medical or investment advice. • All drugs A–Z