Investigational microbiome therapy shows potential in recurrent CDI

Treatment with oral microbiome SER-109 in patients with recurrent Clostridioides difficile infection (CDI) appears is well tolerated and appears to reduce recurrence, as shown in a phase III ECOSPOR IV study.

The single-arm, open-label study included 263 participants (mean age 64.0 years, 68.4 percent women) who were grouped into two cohorts: (1) rollover patients from the ECOSPOR III trial who had CDI recurrence diagnosed by toxin enzyme immunoassay (EIA; n=29) and (2) patients with at least one episode of CDI recurrence (diagnosed by polymerase chain reaction [PCR] or toxin EIA), inclusive of their acute infection at study entry (n=234).

All participants received SER-109, taken orally as four capsules daily for 3 days following symptom resolution after antibiotic treatment for CDI. The key endpoints were safety and cumulative rates of recurrent CDI (toxin-positive diarrhoea requiring treatment) through week 24.

A total of 141 participants (53.6 percent) had treatment-emergent adverse events (TEAEs), which were mostly mild to moderate and gastrointestinal. There were eight deaths (3.0 percent) recorded. Thirty-three patients (12.5 percent) experienced serious TEAEs, although none of these were considered related to treatment.

CDI recurred in 23 patients (8.7 percent) at week 8, including four in cohort 1 and 19 in cohort 2, with recurrence rate remaining low through week 24 (13.7 percent). At week 8, recurrent CDI rates were similarly low in the group of participants with a first recurrence and in the group with at least two episodes of recurrence (18 of 186 [9.7 percent]).

Recurrent CDI rates were also low among younger participants (<65 years vs ≥65 years or older: 4.0 percent vs 13.1 percent) and those enrolled based on positive PCR results vs positive toxin EIA results (4.3 percent vs 10.4 percent).