A Phase 3 Trial of SER-109 Was Well Tolerated and Displayed Benefits Through 24 Weeks
A phase 3 trial of SER-109 found the drug to be superior to placebo in reducing the rate of recurrent Clostridioides difficile infection (rCDI) by week 8 (12% vs. 40%; relative risk [RR], 0.32 [95% CI, 0.18-0.58]). SER-109 is an investigational oral microbiome therapeutic composed of purified Firmicutes spores. This double-blind, randomized, multicenter trial involved adults (mean age, 65.5 years) with rCDI who received either four capsules of SER-109 or a matching placebo daily for three days. All 182 participants were first given standard-of-care antibiotics to treat their infections before starting the trial. At the trial’s endpoint (24 weeks), 63 of 182 participants had rCDI (19 [21.3%] in the SER-109 group vs 44 [47.3%]). A significantly lower percentage of participants in the SER-109 group versus the placebo had rCDI at weeks 4, 8, 12, and 24. Among patients who experienced recurrence, 65.1% had a recurrence by week 4. However, only 6.3% of patients experienced recurrence between weeks 12 and 24. Benefits of SER-109 were apparent at week two and were seen through week 24, the trial’s endpoint. Adverse events (AEs) occurred in 5% of participants and more frequently in the SER-109 group than in the placebo group. AEs included abdominal distention, constipation, diarrhea, and urinary tract infection. In the end, the trial demonstrated that SER-109 durably reduces rCDI rates and is well-tolerated through 24 weeks in patients. Benefits from SER-109 were evident as early as week 2, which highlights the need for rapid microbiome repair after completing standard-of-care antibiotics.
