Fecal Transplant Pill Approved for Recurrent C. Diff Infection

The first ever pill that mimics the effects of fecal transplants was approved on April 26, 2023, by the U.S. Food and Drug Administration (FDA). The treatment, called Vowst, is created with healthy bacteria from screened fecal donations, and is used to prevent the recurrence of C. difficile (C. diff) infection (CDI) in adults following antibacterial treatment for recurrent CDI.

“Today’s approval provides patients and healthcare providers a new way to help prevent recurrent C. difficile infection,” said Peter Marks, MD, PhD, the director of the FDA’s Center for Biologics Evaluation and Research, in the FDA statement.

“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,” said Dr. Marks.

C. Diff Infection Causes 15,000 to 30,000 Deaths per Year

CDI, caused by the bacterium C. difficile, is one of the most common healthcare-associated infections, and results in severe nausea, cramping, and diarrhea.

“When the community of microorganisms inhabiting the gut and supporting our health is disturbed with antibiotics — usually prescribed for the treatment of unrelated medical issues — C. difficile can expand in numbers and produce toxins that can damage the lining of the large gut,” says Niaz Banaei, MD, a professor of pathology and infectious diseases at Stanford Medicine in Palo Alto, California, who was not involved in the development of Vowst.

This can lead to symptoms such as diarrhea and gut inflammation, and even death if not treated appropriately, says Dr. Banaei. Approximately 15,000 to 30,000 people die from the infection each year.

Unfortunately, this disease process can recur because key members of the gut microbial community have vanished, he says. Besides taking antibiotics, other risk factors for recurrent CDI include:

Being older than 65
Being hospitalized
Living in an assisted care facility
Being immunocompromised
A previous history of CDI

Treatment Restores Gut Microbiome to a Healthy State

“Fecal microbiota transplant restores the gut microbial community back to a healthy state and reverses the pathologic state that occurred as a result of the disruption,” he says.

More than 10 years ago, doctors began successfully treating recurrent CDI with fecal transplants, a procedure that involves taking healthy bacteria from the feces of a screened donor and transferring them to the colon of the recipient, typically through a colonoscopy.

“Fecal microbiota transplant has been shown to be highly effective in restoring the gut microbiota and preventing recurrence of CDI,” says Banaei.

The Vowst treatment aims to offer those same benefits — restore the gut flora to prevent further episodes of CDI — but via oral capsules. Carefully screened donations plus rigorous manufacturing and quality control are all part of producing the capsules, says Carlo Tanzi, PhD, the head of investor relations and corporate communications for Seres Therapeutics, the manufacturer of Vowst.

After the stool samples are collected and tested, the samples are processed to remove the waste, isolate the healthy bacteria, and kill any other lingering organisms. Thousands of capsules can be made from each stool sample, making it a more efficient process than current fecal transplants, according to the company.

Nearly 9 in 10 People on Vowst Did Not Experience Reinfection Within 8 Weeks

FDA approval was based on a phase 3 study published January 20, 2022, in the New England Journal of Medicine. Of the 182 participants, 88 percent who took the capsules did not experience reinfection after eight weeks, compared with 60 percent of those who received placebo. At six months post-treatment, 79 percent of the Vowst group were recurrence-free, compared with 53 percent in the placebo group.

“The FDA approval of fecal capsules will simplify restoration of the gut microbiota and will make the intervention more accessible,” says Banaei.

This is an important advancement for those who suffer from the estimated nearly 156,000 episodes of recurrent CDI in the United States each year, says Dr. Tanzi. “These patients often suffer debilitating symptoms, like frequent diarrhea up to 15 times a day, which prevent them from participating in their normal daily activities. Patients often are unable to leave the house, go to work, and spend uninterrupted time with loved ones,” he says.

Is Vowst Safe?

In the clinical trials, recipients experienced some side effects acutely, including abdominal bloating, fatigue, constipation, chills, and diarrhea, but overall, the intervention did not raise any safety concerns, says Banaei.

Vowst “may carry a risk of transmitting infectious agents,” according to the FDA statement. “It is also possible for Vowst to contain food allergens,” the agency noted.

Vowst Dosing, Availability, and Price

The dosing regimen of Vowst is four capsules taken by mouth once a day, for three consecutive days. The therapy is expected to be available beginning June 2023, according to the product website.

The list price for Vowst is $17,500, according to a company presentation. The actual cost to consumers will depend on insurance coverage.

Researchers Investigating More Treatments That Work via the Microbiome

It will be interesting to see if other patient populations with disrupted gut microbiota but with non–C. diff diarrhea also benefit from Vowst, says Banaei.

The makers of Vowst believe there may be more opportunities to create new treatment modalities through the microbiome — not just in recurrent CDI, but in additional therapeutic areas where the microbiome has a direct connection to human health.

According to Tanzi, the company is continuing to investigate new products, including an investigational therapy designed to reduce the incidence of gastrointestinal antibiotic-resistant bacterial infections, bacteremia, and graft-versus-host disease (GvHD) in immunocompromised patients, including patients receiving allogeneic hematopoietic stem cell transplantation (HSCT).