Effects of amoxicillin dosage on cure rate, gut microbiota, and antibiotic resistome in vonoprazan and amoxicillin dual therapy for Helicobacter pylori: a multicentre, open-label, non-inferiority randomised controlled trial

Abstract

Background

Vonoprazan and amoxicillin (VA) dual therapy as a mainstream Helicobacter pylori regimen has gained momentum worldwide, but the optimum dosages remain unclear. We aimed to compare the efficacy and safety of VA dual therapy with 2 g amoxicillin or 3 g amoxicillin, and to assess the short-term effects of therapy on the gut microbiota and antibiotic resistome.

Methods

We conducted an open-label, non-inferiority randomised controlled trial at 12 centres in China. Individuals infected with H pylori, aged 18–70 years, and without previous eradication therapy were recruited. Participants were randomly assigned at a 1:1 ratio (block size of six) to receive vonoprazan (20 mg twice a day) with either low-dose amoxicillin (1 g twice a day; LVA therapy) or high-dose amoxicillin (1 g three times a day; HVA therapy) for 14 days. Gastric biopsies were collected before treatment for detection of antibiotic resistance. Stool samples were collected at baseline, week 2, and week 8–10 for shotgun metagenomic sequencing. The primary outcome was the eradication rate of H pylori, assessed by ¹³C urea breath test, in both intention-to-treat and per-protocol analyses. Secondary outcomes were adverse events, adherence, antibiotic resistance, and alterations to the gut microbiota and antibiotic resistome. The margin used to establish non-inferiority was –0·10. The trial was registered with ClinicalTrials.gov, NCT05649709.

Findings

Between Feb 13, 2023, and Jan 25, 2024, 504 patients (204 [40%] male and 300 [60%] female; mean age 43 years [SD 13]) were randomly assigned to LVA therapy or HVA therapy (n=252 in each group). No infections were resistant to amoxicillin. The H pylori eradication rate was 85·3% (215 of 252; 95% CI 80·4 to 89·2) in the LVA group and 86·5% (218 of 252; 81·7 to 90·2) in the HVA group in the intention-to-treat analysis (p=0·70) and 88·8% (213 of 240; 84·1 to 92·2) and 92·4% (218 of 236; 88·3 to 95·1), respectively, in the per-protocol analysis (p=0·18). The efficacy of LVA was non-inferior to HVA in the intention-to-treat analysis (risk difference –1·2%, 95% CI –7·3 to 4·9, p=0·0022) and the per-protocol analysis (–3·6%, –9·0 to 1·7, p=0·0085). 31 (12%) patients in the LVA group and 43 (17%) patients in the HVA group reported adverse events. Adherence to therapy was 97% in the LVA group and 96% in the HVA group. The diversity of gut microbiota decreased after treatment but was restored to baseline at week 8–10 in both groups. The abundance of beta-lactam-related resistance genes was increased at week 2 after treatment, and was restored to pretreatment level at week 8–10 for the LVA group but not the HVA group.

Interpretation

LVA dual therapy was effective and non-inferior to HVA dual therapy as first-line treatment of H pylori infection and showed a non-lasting effect on the abundance of beta-lactam-related resistance genes. High amoxicillin dosage (eg, 3 g per day) is not required to achieve high cure rates with vonoprazan dual therapy.

Funding

National Natural Science Foundation of China, Project for Academic and Technical Leaders of Major Disciplines in Jiangxi Province, and Key Research and Development Program of Jiangxi Province.