Wednesday, the FDA approved Seres Therapeutics’ SER-109, now to be marketed as Vowst (fecal microbiota spores, live-brpk), to prevent recurrent Clostridioides difficile (C. diff) infection in adults.
Vowst is the first-ever orally administered live fecal microbiota-based product approved by the FDA. The microbiome pill is indicated for the treatment of patients who had received antibacterial intervention for recurrence C. diff. The drug is the second microbiota therapy cleared for use in the U.S. In late November, the FDA approved Ferring Pharmaceuticals’ Reybota, which is prepared from stool donations and given rectally.
Taken in four capsules once-daily for three days, Vowst is a live-bacteria therapeutic developed from human fecal matter from qualified donors, according to the FDA’s announcement of the approval. It works by shaping a disrupted gut microbiome to be resistant to C. diff colonization and growth.
Seres employs a stringent manufacturing purification process that eliminates unwanted microbes and minimizes the risk of transmitting pathogens. Nonetheless, Vowst’s label carries warnings for transmissible infectious agents and the potential presence of food allergens.
Recurrent C. diff is a life-threatening and often debilitating disease, Carl Crawford, M.D., assistant professor of clinical medicine, Weill Cornell Medical College, said in a statement. Current antibiotic regimens typically cannot completely address the dysbiosis of the gut microbiome, which is an underlying cause of recurrent C. diff.
The approval of Vowst provides patients and physicians with another effective and convenient treatment option for this disease, Crawford said.
To support the launch of Vowst, Seres has partnered with Nestlé Health Science, which has agreed to mobilize its global pharmaceutical business Aimmune Therapeutics to lead the commercialization of Vowst. The two inked the agreement in July 2021, which involved a $175 million upfront payment to Seres, along with the promise of up to 50% in commercial profits.
As per the terms of the deal, Seres is now also eligible for a $125 million payment triggered by Vowst’s approval.
The Data That Drove the Approval
Seres backed Vowst’s Biologics License Application (BLA) with data from its Phase III development program, which included the late-stage ECOSPOR III and ECOSPOR IV studies.
In May 2022, the company posted positive data from the randomized and placebo-controlled ECOSPOR III, showing that Vowst was able to prevent the recurrence C. diff infection in 88% of treated patients, while only 60% of placebo comparators remained recurrence-free over the same time period.
A post-hoc analysis of ECOSPOR III also showed that treatment with Vowst led to a rapid and sustained increase in levels of the medium-length fatty acids butyrate, valerate and hexanoate, which are known to prevent the growth of C. diff.
ECOSPOR IV, meanwhile, is the open-label extension study of ECOSPOR III. In June 2022, Seres posted strong safety data from the study, showing that Vowst induced a 91.3% sustained clinical response through eight weeks of follow-up. At 24 weeks, Seres’ oral microbiome drug still maintained an 86% response rate.
