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SER-109

Seres Therapeutics, Inc. · Phase 3 active Biologic

SER-109 is a spore-based microbiome therapeutic that restores healthy gut bacterial composition to prevent recurrent Clostridioides difficile infection.

SER-109 is a spore-based microbiome therapeutic that restores healthy gut bacterial composition to prevent recurrent Clostridioides difficile infection. Used for Recurrent Clostridioides difficile infection (rCDI) in adults.

At a glance

Generic nameSER-109
Also known asPurified Eubacterial Spores, Encapsulated, Firmicutes spores, Eubacterial Spores, Purified Suspension, Encapsulated
SponsorSeres Therapeutics, Inc.
Drug classMicrobiome therapeutic
ModalityBiologic
Therapeutic areaInfectious Disease / Gastroenterology
PhasePhase 3

Mechanism of action

SER-109 contains purified spores from a consortium of commensal Bacillus species that colonize the gut and restore microbial diversity. By re-establishing a healthy microbiome, it reduces the risk of C. difficile recurrence by outcompeting pathogenic strains and restoring colonization resistance. This approach addresses the underlying dysbiosis that predisposes patients to recurrent CDI.

Approved indications

Common side effects

Key clinical trials

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

SourceUsed for
ClinicalTrials.govTrial enrolment, design, endpoints, results

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