Integrated efficacy analysis from phase 3 studies of investigational microbiome therapeutic, SER-109, in recurrent Clostridioides difficile infection

Background: Antibiotics alone are often insufficient to treat recurrent C. difficile infection (rCDI) because they have no activity against C. difficile spores that germinate within a disrupted microbiome. SER-109, an investigational, oral, microbiome therapeutic comprised of purified Firmicutes spores, was designed to reduce rCDI through microbiome repair. We report an integrated efficacy analysis through week 24 for SER-109 from phase 3 studies, ECOSPOR III and ECOSPOR IV. Methods: ECOSPOR III was a randomized, placebo-controlled phase 3 trial conducted at 56 US or Canadian sites that included 182 participants with ≥2 CDI recurrences, confirmed via toxin EIA testing. Participants were stratified by age (