Repeat treatment for sustained response
Dr. Yadegar’s team offered another important takeaway: A single FMT treatment will not sustain a positive response, especially when treating chronic noncommunicable conditions in which intestinal dysbiosis may play a role. Repeat treatment will be needed, as with other chronic conditions. This has been shown even in C. difficile infection.
“Recent studies have documented a significant advantage of repeated FMT over single FMT on the cure rates of recurrent C. difficile,” especially for patients with inflammatory bowel disorder, Dr. Yadegar’s team told this news organization.
“What we don’t know is which patient is likely to respond to microbial-based therapy, or what the dose or frequency should be, or which bacteria are responsible for the effects,” Dr. Yadegar and team said.
Dr. Porcari and colleagues are examining whether FMT could be refined to improve its success against other diseases. This may involve selecting specific donors, monitoring the gut microbiome of both donors and recipients, or using a specific means of delivery, such as lyophilized capsules, Dr. Ianiro said.
A response to FMT for chronic, noncommunicable disorders typically is not sustained long term, note Dr. Porcari and colleagues. However, they add that “sequential transplants have been applied in this setting with promising results, suggesting that chronic modulation of the patient microbiome may be beneficial in noncommunicable chronic disorders.” Dr. Porcari and colleagues point to the success of repeated, long-term FMT in studies of patients with ulcerative colitis and irritable bowel syndrome.
The use of cutting-edge technologies for microbiome assessment and a change in the view of FMT as only an acute, single-use therapy could improve FMT protocols and outcomes for noncommunicable conditions, they write.
Expanding FMT beyond C. difficile
Dr. Yadegar and colleagues’ article “really breaks down what is known about the mechanisms of FMT in C. difficile infection, which is important as other live biotherapeutic products are developed,” Colleen Kelly, MD, an associate professor of medicine at Brown University in Providence, R.I., who was not involved with the reviews, said in an interview.
Dr. Yadegar and colleagues concur. They note in a press release that as the mechanisms behind FMT success are understood, that information should be used to design new standardized therapies.
“Although highly effective, there are substantial drawbacks with [FMT], including infectious risks and sparse long-term safety data,” they write. “Better treatment options for recurrent C. difficile infections that are targeted, safe, and donor-independent are thus desired.”
In December 2022, the U.S. Food and Drug Administration approved the first fecal microbiota product, Rebyota, to prevent recurrence of C. difficile. More recently, in April 2023, the FDA approved Vowst, a pill for treating recurrent C. difficile infections.
Dr. Kelly also noted that the article by Dr. Yadegar and colleagues “may help us understand why a small percentage of patients fail to achieve cure after FMT.”
Regarding Dr. Porcari and colleagues’ article, Dr. Kelly said, “There is a lot of hope that FMT or other gut microbiome therapies will be beneficial for conditions outside of C. difficile.
“They do a good job reviewing the state of the science of FMT and highlight the many unknowns around the use of FMT in conditions outside of C. difficile,” added Dr. Kelly, who has been using FMT to treat C. difficile for more than 15 years.
Data supporting FMT for conditions such as ulcerative colitis and autism are compelling, Dr. Kelly acknowledged. But in her view, FMT isn’t ready for “prime time” outside of C. difficile – at least not yet.
“Academic investigators and those in industry are actively conducting research in many non–C. difficile indications, and I predict we will see the emergence of gut microbiome–based therapies for other indications within the next 5-10 years,” Dr. Kelly said.
Dr. Yadegar reports no relevant financial relationships. One coauthor of the Yadegar study has served on the adjudication board for Finch Therapeutics and has received consulting fees and a speaking honorarium from Rebiotix/Ferring Pharmaceuticals. Dr. Ianiro reports no relevant financial relationships. Dr. Kelly has consulted for Sebela Pharmaceuticals and is one of the principal investigators for the FMT National Patient Registry funded by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health.
A version of this article originally appeared on Medscape.com.