Conference Coverage

Bezlotoxumab reduces CDI recurrence across antibiotic subgroups



– The monoclonal antibody bezlotoxumab significantly reduces the risk of Clostridium difficile infection (CDI) recurrence in adults receiving standard of care antibiotic treatment, regardless of whether that treatment is with metronidazole, vancomycin, or fidaxomicin, according to an analysis of data from the MODIFY I and II trials.

Dr. Erik R. Dubberke

Dr. Erik R. Dubberke

Of the 1,554 subjects included in the analysis, 781 (50.2%) received a single infusion of bezlotoxumab in addition to standard of care antibiotic therapy, and 773 (49.7%) received placebo. Overall, 48.5% received oral metronidazole and 48.5% received oral vancomycin either alone or with IV metronidazole as their standard of care antibiotic, and 3.6% received oral fidaxomicin alone or with IV metronidazole. Those being treated for recurrent CDI more often received vancomycin (71%), while those with primary CDI more often received metronidazole (60%), Dr. Dubberke said at the combined annual meetings of the Infectious Diseases Society of America, the Society of Healthcare Epidemiology of America, the HIV Medicine Association, and the Pediatric Infectious Diseases Society.

Consistent with the overall study results, clinical cure rates were similar with bezlotoxumab and placebo, regardless of the standard of care antibiotic received (80% vs. 80.3%, respectively, overall; 81% vs. 81.3% in the metronidazole group; 78.5% vs. 79.6% in the vancomycin group; and 86.7% vs. 76.9% in the fidaxomicin group), he said.

However, CDI recurrence rates were lower among those who received bezlotoxumab, compared with those who received placebo in all three standard of care subgroups, with 10%, 15%, and 12% fewer bezlotoxumab vs. placebo patients experiencing recurrence in the metronidazole, vancomycin, and fidaxomicin groups, respectively, and 12% fewer experiencing recurrence overall.

The primary endpoint of CDI recurrence was defined in the studies as a new episode of diarrhea (at least three unformed stools in 24 hours) and a positive stool test for toxigenic C. difficile after clinical cure of the baseline CDI episode. Clinical cure was defined as standard of care antibiotics given for 14 days or less and no diarrhea for 2 consecutive days after completing standard of care treatment.

Of note, the patients in the vancomycin group were older and sicker, and had more risk factors for CDI, he said, noting, for example, that 57% of vancomycin patients were aged at least 65 years and 33% were aged at least 75 years, vs. 46% and 26% for metronidazole, respectively, and 46% and 18% for fidaxomicin; 72% of vancomycin patients were inpatients, compared with 65% and 50% of metronidazole and fidaxomicin patients.

Further, 19% of vancomycin patients, vs. 13% and 14% of metronidazole and fidaxomicin patients met criteria for severe CDI.

The findings of the current analysis are important, because the incidence of CDI recurrence is about 25%, and the risk increases with each subsequent recurrence, Dr. Dubberke said, concluding that this novel, nonantibiotic approach to prevention of CDI recurrence using bezlotoxumab, which recently received Food and Drug Administration approval for this indication, is of benefit for reducing that risk, regardless of the antibiotic used as part of standard of care therapy for CDI.

Dr. Dubberke reported serving as an investigator, adviser and/or consultant for Merck, Rebiotix, Sanofi Pasteur, and Summit, and receiving consultant fees and/or grant/research support from these companies.

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