Pilot studies of vonoprazan-containing Helicobacter pylori eradication therapy suggest Thailand may be more similar to the US than Japan

Background: Vonoprazan-containing Helicobacter pylori eradication is reliably effective in Japan. Its effectiveness in other countries remains unclear. Here, we examined vonoprazan-H. pylori therapies in Thailand. Materials and Methods: This was pilot study of four different vonoprazan containing therapies. Subjects were randomized to: 14-day dual therapy (500 mg amoxicillin q.i.d. plus 20 mg vonoprazan b.i.d.), 14-day triple therapy (amoxicillin 1 g b.i.d., slow release clarithromycin-MR, 1 g daily plus vonoprazan 20 mg b.i.d.), 7-day high-dose vonoprazan triple therapy (amoxicillin 1 g b.i.d., clarithromycin-MR 1 g daily and 60 mg vonoprazan once daily), and 14-day vonoprazan triple therapy plus bismuth (amoxicillin 1 g b.i.d., clarithromycin-MR 1 g daily, vonoprazan 20 mg b.i.d., and bismuth subsalicylate 1048 mg b.i.d.). Eradication was confirmed 4 weeks after therapy. Antimicrobial susceptibility and CYP3A4/5 genotyping were performed. Results: One hundred H. pylori-infected patients (mean age 54.3 ± 13 years, 51% men) were randomized. All were CYP3A4 extensive metabolizers. Cure rates with both 14-day vonoprazan dual therapy and 14-day triple therapy were low: 66.7%; 95% CI = 43–85% (14/21), and 59.3%; 95% CI = 39–78%) (16/27), respectively. In contrast, 7-day high-dose vonoprazan triple therapy and 14-day vonoprazan triple plus bismuth proved effective 92.3%; 95% CI = 75%–99% (24/26) and 96.2%; 95% CI = 80%–100% (25/26), respectively. Conclusion: Both 14-day vonoprazan dual and triple therapy were ineffective for H. pylori eradication in Thailand. Higher dosage of vonoprazan, and/or the addition of bismuth may be required to achieve high H. pylori eradication rates. High-dose vonoprazan triple therapy and vonoprazan triple therapy adding bismuth might be used as first-line treatments in some regions with high efficacy irrespective of CYP3A4/5 genotype and clarithromycin resistance.