A novel rifabutin-based therapy (RHB-105) has shown promise as a first-line defense against Helicobacter pylori (H. pylori) infection, according to results from a phase 3, double-blind clinical trial published in the Annals of Internal Medicine.

Researchers recruited a total of 455 treatment-naïve patients with confirmed H pylori infection receiving care at 55 clinical research institutions in the United States. Patients were randomly assigned to receive either RHB-105 (n=228; 3 g amoxicillin, 120 mg omeprazole, and 150 mg rifabutin) or active comparator (n=227; 3 g amoxicillin and 120 mg omeprazole) treatments, which were administered as 4 capsules every 8 hours for 14 days. A 13C urea breath test was administered 4 weeks after treatment.

The H. pylori eradication rate was 83.8% in the RHB-105 cohort (95% CI, 78.4-88.0%; P <.001) and 57.7% in the active comparator group (95% CI, 51.2-64.0%; P <.001). Patients with infections resistant to metronidazole-only treatment also showed significantly different eradication rates in RHB-105 (80.8%; 95% CI, 48.7%-97.4%) and active comparator cohorts (53.6%; 95% CI, 40.7%-66.0%), respectively (P =.003). Observed eradication rates were not significantly affected by clarithromycin, amoxicillin, double, or triple resistant infection. No rifabutin resistance was detected among the study participants.

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Adverse effects in patients were low overall, with 155 reporting instances of any adverse event. These included diarrhea (10.1% vs 7.9%), headache (7.5% vs 7.0%), and nausea (4.8% vs 5.3%) in the RHB-105 and active comparator groups, respectively.

One limitation of this study was that researchers excluded patients of Asian descent due to the higher rate of poor cytochrome P450 2C19 metabolizers in this population. Overall, the cytochrome P450 2C19 statuses of patients in the study cohort were 48.6% normal, 22.0% intermediate, 22.0% rapid, 2.9% ultrarapid, and 2.0% poor metabolizers. Data collected from the poor and intermediate metabolizers did not suggest safety and efficacy would differ in patients who are poor metabolizers.

The investigators concluded that these data indicated that rifabutin-based therapy could be effective in eradicating H. pylori infection in affected patients without increasing antibiotic resistance.

Disclosures: Some authors declared receiving consulting or funding from the pharmaceutical industry. A complete list of disclosures can be found in the original study.

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Reference

Graham D Y, Canaan Y, Maher J, et al. Rifabutin-based triple therapy (RHB-105) for Helicobacter pylori eradication [available online May 5, 2020]. Ann Intern Med. doi:10.7326/M19-3734