FDA approves Vowst as first oral microbiota biotherapeutic for recurrent C. difficile
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The FDA has approved Vowst, the first orally administered fecal microbiota product indicated for the prevention of recurrent Clostridioides difficile infection in adults following antibacterial treatment.
With this approval, Vowst (SER-109, Seres Therapeutics) becomes the second microbiota-based live biotherapeutic approved for recurrent C. difficile infection following the approval of Rebyota (fecal microbiota, live-jslm; Ferring Pharmaceuticals) in 2022.
“Today’s approval provides patients and health care providers a new way to help prevent recurrent C. difficile infection,” Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, said in an FDA press release. “The availability of a fecal microbiota product that can be taken orally is a significant step forward in advancing patient care and accessibility for individuals who have experienced this disease that can be potentially life-threatening.”
Vowst is manufactured from human fecal matter collected from qualified donors and contains live bacteria. The approved dosing regimen for Vowst includes four capsules taken orally once a day for 3 consecutive days, according to the release.
The FDA based its approval on safety results from a randomized, double-blind, placebo-controlled clinical study, as well as an open-label clinical study conducted in the U.S. and Canada. Included patients exhibited recurrent C. difficile infection and been administered antibacterial treatment 48 to 96 hours before, with controlled symptoms. For both studies, 346 patients with recurrent C. difficile infection received all scheduled doses of Vowst.
In an additional analysis of 90 patients who received Vowst compared with 92 patients who received placebo, the most common adverse events included abdominal bloating, fatigue, constipation, chills and diarrhea.
Drug efficacy was assessed in a randomized, placebo-controlled clinical study, in which patients who received Vowst (n = 89) demonstrated lower C. difficile infection recurrence compared with patients who received placebo (n = 93) (12.4% vs. 39.8%).
The FDA stated that Vowst may contain food allergens, and it remains unknown whether there is potential for adverse reactions associated with food allergens. Additionally, there is a risk that Vowst may carry transmissible infectious agents, although the donors and donated stool are tested for a panel of transmissible pathogens, the agency noted.
Perspective
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Brian B. Baggott, MD, FACG
Of the more than 460,000 cases of C. difficile infection in the United States each year, 25% will have a course of recurrent infection. This life-changing event is the result of latent C. difficile spore generation that is heavily influenced by the background colonic microbiota. When antibiotics are used to treat the active infection, the suppressive background flora is altered as well, allowing for C. difficile spore germination and onset of a cycle of recurrent active disease.
The advent of microbiome restorative therapeutics is an exciting new pathway that can break the cycle. Our group has been an active participant in the trials leading up to FDA approval of Rebyota (fecal microbiota, live-jslm/RBX2660; Ferring Pharmaceuticals), an enema prep of highly screened human stool, and Vowst (fecal microbiota spores, live-brpk capsules; Seres Therapeutics), purified Firmicutes spores. Vowst is felt to modulate the production and consumption of colonic metabolites, leading to a higher concentration of secondary bile acids that inhibit C. difficile spore germination.
Both agents have been shown to be highly effective in breaking the cycle of recurrent C. difficile infection with minimal side effects. They are not intended for primary treatment of C. difficile infection but are approved for adult patients with recurrent disease with the goal of preventing recurrence.
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