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Ribaxamase reduces CDI incidence in patients receiving beta-lactam antibiotics
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Oral ribaxamase reduces the incidence of Clostridioides difficile infection, or CDI, compared with placebo in patients treated with IV ceftriaxone for lower respiratory tract infections, according to results from a phase 2b trial.
“Infections with [C.] difficile are a health threat, yet no products are currently licensed for prevention of primary C. difficile infections. Intravenous beta-lactam antibiotics are considered to confer a high risk of C. difficile infection because of their biliary excretion into the gastrointestinal tract and disruption of the gut microbiome,” John F. Kokai-Kun, PhD, vice president of project management and non-clinical affairs at Synthetic Biologics, and colleagues wrote.
“Ribaxamase (SYN-004) is an orally administered beta-lactamase that was designed to be given with intravenous beta-lactam antibiotics to degrade excess antibiotics in the upper gastrointestinal tract before they disrupt the gut microbiome and lead to C. difficile infection,” they explained.
In a parallel-group, double-blind, multicenter, phase 2b randomized placebo-controlled trial, Kokai-Kun and colleagues aimed to determine whether administering ribaxamase could prevent CDI in patients being treated with IV ceftriaxone.
According to the study, between Nov. 16, 2015, and Nov. 10, 2016, the researchers enrolled and randomly assigned 207 patients to receive ceftriaxone plus ribaxamase and 206 to receive ceftriaxone and a placebo. During the study and within 4 weeks after antibiotic treatment, two (1%) patients in the ribaxamase group and seven (3.4%) patients in the placebo group were diagnosed with CDI, a risk reduction of 2.4% (95%, CI = –0.6 to 5.9), Kokai-Kun and colleagues reported.
According to the study, adverse events were similar between groups, but more deaths were reported in the ribaxamase group than in the placebo group: 11 vs. five, respectively. Researchers attributed the disparity to a higher incidence of deaths was attributed to cardiac-associated causes in the ribaxamase group.
Still, Synthetic Biologics announced last year that it had voluntarily withdrawn a breakthrough therapy designation for ribaxamase after the FDA determined that the criteria for the status were not longer met due to the imbalance in fatal adverse events, which could not be fully evaluated. The company said it would address the safety concerns in a phase 3 trial.
“To date, the only products licensed for treatment of C. difficile infection are antibiotics such as oral vancomycin, metronidazole and fidaxomicin, or bezlotoxumab. Development is ongoing for other strategies for prevention and treatment of C. difficile infection but, to date, none of these treatments have been approved,” Kokai-Kun and colleagues concluded.
“Our study supports the continued clinical development of ribaxamase for prevention of C. difficile infection in at-risk patients treated with intravenous beta-lactam antibiotics, especially those being treated for extended durations for serious infections or who have other underlying risk factors for C. difficile infection.” – by Caitlyn Stulpin
Disclosures: All authors report being employees or paid consultants of Synthetic Biologics.
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