Rifasutenizol

Due to the rapid development of antimicrobial resistance, the efficacy of most Helicobacter pylori eradication therapies have progressively decreased to an unacceptable level. Rifasutenizol (TNP-2198) is a new molecular entity with a synergistic dual mechanism of action currently under clinical development for the treatment of microaerophilic and anaerobic bacterial infections. We aimed to evaluate the safety, pharmacokinetics, and efficacy of rifasutenizol in healthy Chinese participants and patients with H pylori.

We conducted four clinical trials of rifasutenizol capsules in healthy participants (aged 18-55 years) and patients with asymptomatic H pylori infection (aged 18-65 years) in a clinical trial centre in Jilin province, China. Trial 1 was a phase 1, double-blind, randomised, placebo-controlled, single ascending dose study, in which participants were enrolled into one of seven rifasutenizol dose groups (50 mg, 100 mg, 200 mg, 400 mg, 600 mg, 800 mg, or 1000 mg) and were randomly assigned in a 4:1 ratio to study drug or placebo. Trial 2 was a phase 1, double-blind, randomised, placebo-controlled, multiple ascending dose study, in which patients were enrolled into one of three rifasutenizol dose groups (200 mg, 400 mg, or 600 mg) and were randomly assigned in a 3:1 ratio to study drug or placebo. Trial 3 was a phase 2a, open-label, randomised, multiple-dose, dose-finding study in which patients enrolled into one of four cohorts were randomly assigned in a 1:1:1:1 ratio to a rifasutenizol dual or triple regimen. Trial 4 was a phase 2b, open-label, randomised, multiple-dose, regimen exploration study, in which patients enrolled into one of five cohorts were randomly assigned in a 2:2:1:1:2 ratio to a rifasutenizol dual therapy, triple therapy, or a control cohort. Block randomisation (block size 4 or 8) was used in all four trials. The key primary endpoints for trials 1, 2, and 3 were the tolerability, safety, and pharmacokinetics of rifasutenizol. For trial 4, the primary endpoint was the eradication rate of H pylori. These four trials were registered at ClinicalTrials.gov (NCT06081699, NCT06081712, NCT06076681, and NCT06076694) and chinadrugtrials.org.cn (CTR20190734, CTR20192553, CTR20212050, and CTR20220625) and are completed.

Between May 9, 2019, and Sept 14, 2022, 78 healthy participants (trial 1: n=10 per cohort in a 4:1 rifasutenizol:placebo ratio; and an additional eight for the food-effect cohort) and 168 patients with asymptomatic H pylori infection (trial 2: n=16 per cohort in a 3:1 rifasutenizol:placebo ratio; trial 3: n=10 per cohort; trial 4: n=10 or n=20 per cohort) were enrolled in the four clinical trials. Single doses of rifasutenizol (50-1000 mg) and multiple doses of rifasutenizol (200 mg to 600 mg, twice a day), either as monotherapy or co-administered with rabeprazole and amoxicillin, showed favourable safety and tolerability profiles. Most adverse events were mild, and no serious adverse events were reported. Rifasutenizol demonstrated a linear pharmacokinetic profile over the dose range of 50-800 mg, and there were no apparent pharmacokinetic interactions between rifasutenizol and the co-administrated drugs. Food intake slightly elevated the area under the plasma concentration-time curve (AUC) of rifasutenizol, and the geometric mean of AUC from time 0 to the last timepoint with a quantifiable concentration (AUC_0-t) and AUC from time 0 to infinity (AUC_0-∞) in the fed state were 1·334 and 1·396 times of those in the fasted state, respectively. There was mild accumulation after continuous administration of rifasutenizol, and the R_ac(AUC) of rifasutenizol 400 mg in the dual and triple regiments in trial 3 were 1·37 and 1·49, respectively. In trial 3, the eradication rates of H pylori with 200 mg, 400 mg, or 600 mg of rifasutenizol in combination with rabeprazole, twice a day for 14 days, were 0% (95% CI 0-31), 30% (7-65), and 40% (12-74), respectively, identifying rifasutenizol 400 mg as the effective dose. In trial 4, H pylori eradication rates with the triple regimen in cohort A (400 mg rifasutenizol, 20 mg rabeprazole sodium, and 1 g amoxicillin) twice a day for 14 days was 95% (95% CI 74-100), and triple therapy (600 mg rifasutenizol, 20 mg rabeprazole sodium, and 1 g amoxicillin) three times a day for 7 days was 100% (69-100).

Rifasutenizol monotherapy and combination therapy was generally safe and well tolerated in healthy participants and patients with H pylori infection. A triple regimen of 400 mg rifasutenizol capsules, 20 mg rabeprazole sodium enteric-coated tablets, and 1 g amoxicillin capsules twice a day for 14 days showed promising efficacy as a new treatment regimen for H pylori infection.

TenNor Therapeutics and National Natural Science Foundation of China.

For the Chinese translation of the abstract see Supplementary Materials section.