Durability of SER-109 clinical response in patients with recurrent C. difficile infection

SER-109, also known as faecal microbiota spores, is a new oral microbiota-based therapy containing Firmicutes spores. This recently FDA-approved therapy has demonstrated both efficacy and durability in treating recurrent Clostridioides difficile infection, a condition frequently resistant to conventional antibiotic treatment.

The efficacy of SER-109 was previously emphasised in ECOSPOR III (NCT03183128), a phase 3, double-blind, placebo-controlled trial [1]. After 8 weeks, SER-109 recipients demonstrated a statistically significant lower incidence of C. difficile recurrence than the placebo group (12% and 40%, respectively; RR 0.32; 95% CI 0.18–0.58; P<0.001).

Subsequently, the ECOSPOR IV trial (NCT03183141), a phase 3, open-label, single-arm study, enrolled 263 adults and focused on the safety, efficacy, and durability of the response to SER-109 treatment. Participants received SER-109 following the remission of symptoms after antibiotics treatment, along with laxatives to wash out residual antibiotics from the gastrointestinal tract. The mean age was 64 years and 68% of participants were female. The overall C. difficile recurrence rate was 8.7% at week 8, and 95% of participants maintained this response through week 24, regardless of prior recurrences.

Adverse events were reported by 52% of the participants, most were mild to moderate and predominantly gastrointestinal in nature. There were 8 deaths within 8 weeks post-treatment, but none were deemed related to the study drug. “Recurrent C. difficile infection often has a debilitating impact on patients’ lives, and current treatments are often insufficient due to the persistence of microbiome disruption,” Dr Louis Korman (Chevy Chase Clinical Research, MD, USA) said. “Microbiome restoration, as provided by SER-109, could be a game-changer in treating this condition.”

In conclusion, SER-109 represents a promising advance in the treatment of recurrent C. difficile infection, due to its critical role in microbiome restoration.

1. Korman L, et al. Durability of the clinical response to SER-109, an investigational oral microbiome therapeutic, in a phase III open-label trial (ECOSPOR IV) in patients with recurrent Clostridioides difficile Lecture 694, DDW 2023, 6–9 May, Chicago, IL, USA.

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