Conference Coverage

A pill for C. difficile works by increasing microbiome diversity


AT ACG 2021

LAS VEGAS – An oral treatment with freeze-dried human stool can successfully treat Clostridioides difficile infections by increasing the diversity of microorganisms in the colon, researchers say.

CP101, under development by Finch Therapeutics, proved more effective than a placebo in preventing recurrent infections for up to 24 weeks.

The CP101 capsules contain a powder of freeze-dried human stools from screened donors. They restore natural diversity that has been disrupted by antibiotics, said Jessica Allegretti, MD, MPH a gastroenterologist at Brigham and Women’s Hospital in Boston.

The treatment offers an alternative to fecal microbiota transplant, which can effectively treat antibiotic-resistant C. difficile infections but is difficult to standardize and administer – and doesn’t have full approval from the U.S. Food and Drug Administration, she added.

“I think this marks a moment in this space where we’re going to have better, safer, and more available options for patients,” she said in an interview. “It’s exciting.”

Dr. Allegretti is an author on three presentations of results from PRISM3, a phase 2 trial of CP101. They will be presented this week at the annual meeting of the American College of Gastroenterology. These results extend out to 24 weeks, whereas the 8-week results of this trial were presented a year ago at the same meeting.

Study details

The study enrolled 198 people who received antibiotics for recurrent C. difficile infections. Some patients had two or more recurrences, while others had only one recurrence but were 65 years of age or older.

“That was a unique aspect of this study, to see the effect of bringing a therapy like CP101 earlier in the treatment paradigm,” said Dr. Allegretti. “You can imagine for an older, frail, or more fragile patient that you would want to get rid of this [infection] earlier.”

After waiting 2-6 days for the antibiotics to wash out, the researchers randomly assigned 102 of these patients to take the CP101 pills orally and 96 to take placebo pills, both without bowel preparation.

The two groups were not significantly different in age, gender, comorbidities, the number of C. difficile recurrences, or the type of test used to diagnose the infection (PCR-based vs. toxin EIA-based).

After 8 weeks, 74.5% of those given the CP101 pills had not had a recurrence, compared with 61.5% of those given the placebo. The difference was just barely statistically significant (P = .0488).

Sixteen weeks later, the effect endured, with 73.5% of the CP101 group and 59.4% of the placebo group still free of recurrence. The statistical significance of the difference improved slightly (P = .0347).

Drug-related emergent adverse events were similar between the two groups: 16.3% for the CP101 group vs. 19.2% for the placebo group. These were mostly gastrointestinal symptoms, and none were serious.

Some of the patients received vancomycin as a first-line treatment for C. difficile infections, and the researchers wondered if the washout period was not sufficient to purge that antibiotic, leaving enough to interfere with the effectiveness of CP101.

Therefore, they separately analyzed 40 patients treated with fidaxomicin, which they expected to wash out more quickly. Among these patients, 81% who received CP101 were free of recurrences, at 8 weeks and 24 weeks. This compared with 42.1% of those who received the placebo, at both time points. This difference was more statistically significant (P = .0211).


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