Vowst Maintains Consistent Safety Profile in rCDI Patients with Comorbidities
At MAD-ID, Dianne Nguyen, MD, shares Phase 3 data showing consistent tolerability of the microbiome therapy across high-risk patient populations
At the 2025 MAD-ID meeting, Dianne Nguyen, MD, head of medical affairs for the pharmaceutical division at Nestlé Health Science, presented new data demonstrating the consistent safety profile of VOWST™ (fecal microbiota spores, live–brpk) in adults with recurrent Clostridioides difficile infection (rCDI), including those with significant comorbid conditions.
The findings come from an integrated analysis of two Phase 3 trials: the randomized, double-blind, placebo-controlled ECOSPOR III study (n=182) and the open-label, single-arm ECOSPOR IV study (n=263). In both trials, VOWST was administered orally as four capsules daily for three consecutive days following the completion of antibacterial treatment.
“This integrated analysis helps us better understand the product's safety and how it looks in this particularly more vulnerable patient population,” Nguyen said.
Among the 349 participants who received VOWST, 51% (n=178) had comorbid conditions such as renal impairment/failure, diabetes, cardiac disease, or were immunocompromised/immunosuppressed (IC/IS). Despite these underlying conditions, safety findings remained favorable.
For example:
- In patients with renal impairment/failure, TEAEs occurred in 80%, serious TEAEs in 35%, and adverse events of special interest (TEAESIs) in 26%.
- Those with diabetes experienced TEAEs at 70%, serious TEAEs at 20%, and TEAESIs at 9%.
- Among those with cardiac disease, respective rates were 75%, 27%, and 12%.
- The IC/IS subgroup showed rates of 77%, 20%, and 14%.
By comparison, placebo-treated participants in ECOSPOR III experienced even higher rates in several categories, for example, 100% of renal impairment patients reported TEAEs and 57% had serious TEAEs.
“First of all, patients with comorbidities—especially those with multiple—are more likely to experience treatment-emergent adverse events regardless of whether they received active treatment or placebo,” Nguyen explained. “That’s not surprising. But what we observed is that among those who did receive VOWST, the safety profile was consistent regardless of comorbidity status. That’s very encouraging.”
Importantly, no serious adverse events were attributed to VOWST, and no patients discontinued the study due to treatment-related side effects. TEAEs leading to death were infrequent across all subgroups and in the overall integrated population.
Looking ahead, Nguyen noted that while no formal controlled trials are planned in these high-risk groups, real-world studies are already underway. “We’re doing some work right now looking at clinical experience in these patient populations,” she said. “That’s going to give us more information about groups who may have been underrepresented in our clinical trials.”
She added that broader awareness of VOWST’s tolerability could support its use in routine care, “I’m looking forward to getting more information out there to really better describe how this particular product looks in terms of its effectiveness in a routine clinical setting.”
