FDA Approves First Fecal Transplant Therapy for Recurrent C. Diff Infection

Doctors may now prescribe a novel biologic—a drug called Rebyota—to prevent recurrent Clostridioides difficile (C. diff) infection, the Food and Drug Administration (FDA) announced last month. The therapy is the first fecal-based treatment to be approved by federal regulators.

“This is such a groundbreaking advancement in the field of medicine,” Sahil Khanna, MBBS, a gastroenterologist and hepatologist at the Mayo Clinic in Rochester, Minnesota, who co-led the phase 3 clinical trial on Rebyota, told Health. “Until now we have never had an FDA-approved microbiome therapeutic, this opens the door to studying microbiome therapeutics for other things.” 

C. diff is a germ that causes inflammation of the colon, leading to diarrhea, nausea, stomach pain, fever, and loss of appetite. About half a million C. diff infections (CDIs) occur in the U.S. each year—and about one in six patients who get a C. diff infection will get another within eight weeks, a condition known as recurrent CDI.

The risk of CDI recurrences increases with each additional infection. According to Khanna, if an infection has already recurred twice, there's about a 40% chance it will come back for a third time—after a third recurrence, there's a 65% chance it will come back again.

C. diff: A Hard-to-Treat Condition

C.diff bacteria can be found everywhere in our environment—the grocery store, the bathroom, the movie theater. But usually the microbiome in our digestive system can keep our exposure to it from causing an infection.

When a person takes antibiotics—or has recently ended a course of antibiotics—they become more susceptible to CDI, since the medication gets rid of both harmful and helpful bacteria in the body. People are seven to 10 times more likely to develop CDI while taking antibiotics, or in the month after treatment.

Being over 65 years old, having a weakened immune system, or recently having been hospitalized or in a nursing home can also increase the risk of CDI.

The only current treatment for CDI is antibiotics—despite antibiotics being a major cause of infection to begin with. In about 20% of patients, CDI will resolve on its own within days of discontinuing the antibiotic, but for most cases, an additional course of antibiotics (oral vancomycin or fidaxomicin) is needed.

Antibiotics decrease the amount of pathogen-fighting good bacteria in the large intestine, taking away the body’s natural defenses against C. diff. They often also do not attack bacteria in all phases of their life, leaving an opportunity for the pathogen to take hold again while the system is weak. 

Antibiotic use, then, causes a vicious cycle for CDIs: In treating the initial infection, they can also open the body up to repeat infections. “These antibiotics do a lot of collateral damage,” said Khanna. 

In addition to antibiotics as treatment, fecal microbiota transplants—or FMTs—have also been used to treat recurrent CDI.

These procedures involve delivering healthy human donor stool to another person, either through an enema or a capsule. But none have been FDA-approved—they’ve only been allowed as experimental therapies—meaning there isn’t any regulation concerning the procedures and how the donor samples are screened. 

“Fecal transplants have been done outside of FDA approval for years,” Brian Baggott, MD, a gastroenterologist at the Cleveland Clinic, told Health, adding that while a bank of research has shown the efficacy of FMT, there have also been very real safety concerns, like pathogenic organisms being transmitted between donors and patients.

A Safer, More Effective Treatment Option

Rebyota’s introduction offers a new alternative to antibiotics or FMTs in treating recurrent CDIs—and cuts down on the potential side effects seen with other treatments.

“We believe this is a major breakthrough in harnessing the power of the human microbiome to address significant unmet medical needs,” Per Falk, president of Ferring Pharmaceuticals, the manufacturers of Rebyota, said in a press release.

Rebyota is intended to prevent recurrent C. diff infection, and is meant to be prescribed after a patient undergoes a full course of antibiotics to clear the immediate infection.

According to Christine Lee, MD, a medical microbiologist at Island Health in Victoria, British Columbia, who specializes in fecal microbiota transplant and recurrent C. diff, Rebyota re-establishes these healthy microbiota, which keep C. diff from multiplying.

The medication, which comes in enema form, is administered by a physician in-office. Unlike FMTs, no colonoscopy, colonoscopy prep, or sedation is needed for Rebyota. After the enema is given, patients are instructed to continue lying down for up to 15 minutes.

The enema contains stool donated by qualified, vetted individuals. According to Ferring Pharmaceuticals, each donor’s stool and blood undergoes rigorous pathogen screening, including for infectious diseases like COVID-19, which would be transferred to the recipient.

This standardized process sets Rebyota apart from FMT, which has previously carried an increased risk of E. coli and other harmful pathogens.

“Since this FDA-approved product has gone through rigorous testing, it’s an exceedingly low risk,” said Dr. Baggott. “Not only are the donors screened and the stool heavily studied, they are re-studied for up to 6 months.”

Rebyota’s safety and efficacy was studied in five clinical trials including more than 1,000 participants—according to Ferring Pharmaceuticals, it was the largest clinical trial program in the field of microbiome-based therapeutics.

In one randomized, double-blind, placebo-controlled clinical trial, Rebyota was found to be superior, compared to placebo as a treatment to reduce recurrent CDI. Within eight weeks of treatment, 70.6% of patients on Rebyota did not see CDI diarrhea, compared to 57.5% patients on placebo. More than 90% of patients successfully treated with Rebyota remained free of CDI recurrence through six months.

Rebyota also yielded mild-to-moderate side effects—mainly mild gastrointestinal events—and there were no treatment-related serious adverse events.