Letter: CYP3A4/5 genotype status and outcome of vonoprazan-containing Helicobacter pylori eradication therapy in Japan

Safety of potassium-competitive acid blockers in the treatment of gastroesophageal reflux disease

INTRODUCTION

Proton pump inhibitors (PPIs) are the first-line treatment for gastroesophageal reflux disease (GERD). However, due to their intrinsic limitations, there are still unmet clinical needs that have fostered the development of potassium-competitive acid blockers (P-CABs). Currently, four different drugs (vonoprazan, tegoprazan, fexuprazan, and keverprazan) are marketed in some Asian countries, whereas only vonoprazan and tegoprazan are available in Western countries (USA and Brazil or Mexico, respectively).

AREAS COVERED

This review summarizes the current knowledge on P-CABs acute and long-term safety in GERD treatment compared to that of PPIs. Full-text articles and abstracts were searched in PubMed.

EXPERT OPINION

P-CABs proved to address some of the unmet clinical needs in GERD, with a favorable risk-benefit ratio compared to conventional PPIs. Preclinical and clinical findings have highlighted P-CAB safety to be superimposable, to that of PPIs, in short-term treatments, although further studies are warranted to monitor their effects in long-term therapy. From an epidemiological point of view, the paucity of rigorous data for many variables (e.g. age, ethnicity, drug interactions, comorbidities, genetic polymorphisms, interindividual susceptibility, and gut dysbiosis) deserves a worldwide framework of continuous pre/post-marketing pharmacovigilance programs to reduce potential confounding factors and accurately link acute and chronic P-CAB therapy to adverse outcomes.

Efficacy and Safety of Vonoprazan in Dual/Triple/Quadruple Regimens Both in First-Line and Rescue Therapy for Helicobacter pylori Eradication: A Systematic Review With Meta-Analysis

BACKGROUND

The efficacy of Helicobacter pylori (H. pylori) eradication therapies encompassing one or more antibiotics and a proton pump inhibitor (PPI) has lately decreased. Vonoprazan (VPZ), a potassium-competitive acid blocker, provides higher gastric acid suppression than PPIs. We performed a meta-analysis evaluating the efficacy and safety of VPZ in H. pylori eradication therapies.

METHODS

Studies were searched in PubMed, Embase, and the Cochrane Library up to June 2023. Efficacy was evaluated by intention-to-treat analysis. Data were combined by meta-analyzing risk differences (RD). Heterogeneity was evaluated by subgrouping.

RESULTS

Seventy-seven studies (24 randomized clinical trials) evaluated 44,162 patients (22,297 receiving VPZ and 21,865 PPIs). Overall VPZ efficacy was 88% (95% CI = 87%-90%): 86%, 88%, and 94% for dual/triple/quadruple-VPZ-containing therapies. VPZ efficacy was 87% (86%-89%) in first-line and 90% (87%-93%) in rescue therapy. VPZ performed better than PPIs in treatment-naïve patients (87% vs. 70%; RD = 0.13, 95% CI = 0.11-0.15) and when using triple regimens. No significant differences were observed in rescue and quadruple therapies. In patients with clarithromycin-resistant infection, VPZ-based therapies demonstrated an 81% efficacy (76%-85%), surpassing PPIs (76% vs. 40%; RD = 0.33, 95% CI = 0.24-0.43). For clarithromycin-susceptible strains, VPZ efficacy was 92% (89%-95%), similar to PPIs. VPZ adverse events rate was 19% (16%-21%), comparable to PPI-based regimens (18% vs. 13%, respectively; RD = 0.00, 95% CI = -0.01 to 0.02, p = 0.57).

CONCLUSIONS

The efficacy of VPZ-based regimens was over 85% in all treatment combinations. In treatment-naïve and clarithromycin-resistant patients, VPZ performed better than PPIs. In rescue therapy, in clarithromycin-susceptible patients or when quadruple regimens were prescribed, this advantage was not confirmed. Tolerability was similar in both regimens.

Characterization of plasma vonoprazan and CYP3A activity using its endogenous marker and genetic variants in patients with digestive system disorders

Factors that determine clinical responses to vonoprazan remain unknown. This study aimed to characterize plasma vonoprazan and CYP3A activity using its endogenous marker and genetic variants in patients with digestive system disorders. Fifty-three patients who were receiving vonoprazan for at least 3 days were enrolled. Blood samples for determination of plasma vonoprazan and its metabolite (ODA-VP) were obtained. Plasma 4β-hydroxycholesterol (4β-OHC), CYP3A5 and ABCB1 genotypes, and plasma gastrin were determined. CYP3A recognition for vonoprazan was evaluated using recombinant CYP3A proteins. Plasma vonoprazan levels exhibited a large interindividual variation. The absolute plasma concentration of vonoprazan was correlated with its dose-normalized value, and had a positive correlation with the inverse value of its metabolic ratio. A negative correlation was observed between plasma vonoprazan and 4β-OHC levels. The metabolic ratio of vonoprazan was positively correlated with the plasma 4β-OHC level. Genetic variants of CYP3A5 and ABCB1 were not associated with the plasma concentration of vonoprazan and its metabolic ratio. Possible saturated metabolism of vonoprazan to its major metabolite was observed at a therapeutic dose. Although the CYP3A5 genotype did not alter plasma vonoprazan, CYP3A activity based on plasma 4β-OHC partially explained the variation in plasma vonoprazan in patients with digestive system disorders.

Seven-Day Vonoprazan-Based Triple Therapy as First-Line Helicobacter pylori Treatment in Comparison With Extended Sequential Therapy: A Randomized Controlled Trial

BACKGROUND

Vonoprazan, a potassium-competitive acid blocker, has demonstrated greater potency and a longer duration of acid suppression when compared to the proton pump inhibitors. However, data regarding the comparison between vonoprazan-based triple therapy with standard treatment for first-line Helicobacter pylori treatment are limited. This study aimed to compare the efficacy between 7-day vonoprazan-based triple therapy with high-dose amoxicillin (VAC-7) and 14-day extended sequential therapy (S-14).

MATERIALS AND METHODS

This was a single-center prospective randomized controlled trial following a noninferiority design. Subjects over 20 years old with confirmed H. pylori infection were enrolled prospectively from Fu Jen Catholic University Hospital. They were randomly assigned to the VAC-7 or S-14 group. The primary endpoint was the eradication rate in first-line treatment, evaluated by urea breath test, with noninferiority determined using the Farrington-Manning method. The secondary outcome included adverse effect rates and compliance, assessed through self-administered questionnaires.

RESULTS

Between December 2021 and June 2023, a total of 628 patients were recruited. The eradication rates by per-protocol analysis and intention-to-treat analysis were 88.6%/81.8% for VAC-7 and 90.3%/81.4% for S-14, respectively. The VAC-7 was non-inferior to S-14 in terms of ITT analysis. Subjects experienced fewer incidences of nausea, anorexia, dizziness, fatigue, and any severe adverse events in the VAC-7 group. Compliance was higher in the VAC-7 group, with 94% taking all the pills correctly.

CONCLUSIONS

Our findings supported the use of 7-day vonoprazan triple therapy with high-dose amoxicillin as the standard first-line treatment for H. pylori infection.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT05371249.

Vonoprazan-amoxicillin dual therapy with different amoxicillin dosages for treatment-naive patients of Helicobacter pylori infection in China: a prospective, randomized controlled study

BACKGROUND

The vonoprazan (VPZ)-amoxicillin (AMO) dual therapy (VA) demonstrates a satisfactory eradication rate for Helicobacter pylori (H. pylori ). However, the optimal dosage of AMO in this regimen remains uncertain. The objective of this study is to investigate the efficacy of different doses of AMO in the VA regimen for first-line treatment of H. pylori infection.

METHODS

A total of 192 treatment-naive H. pylori -infected patients were randomly assigned to one of three groups: low-dose VA (LD-VA: VPZ 20 mg b.i.d + AMO 750 mg t.i.d), moderate-dose VA (MD-VA:VPZ 20 mg b.i.d + AMO 1000 mg t.i.d), and high-dose VA (HD-VA: VPZ 20 mg b.i.d + AMO 1250 mg t.i.d). All groups received 14 days of treatment. The study evaluated and compared the eradication rates, adverse events (AEs), and patient compliance among the three groups.

RESULTS

Eradication rates for LD-VA, MD-VA, and HD-VA were 76.6% (49/64), 79.7% (51/64), and 84.4% (54/64), respectively, as determined by intention-to-treat analysis; 90.6% (48/53), 94.3% (50/53), and 98.1% (53/54) according to per-protocol analysis; 89.1% (49/55), 94.4% (51/54), and 96.4% (54/56) with modified intention-to-treat analysis (all P  > 0.05). Although not statistically significant, numerically higher eradication rates were observed with the higher dose AMO VA regimen. There were no statistically significant differences in the incidence of AEs and compliance among the three VA regimens.

CONCLUSION

Fourteen-day VA regimens with AMO doses exceeding 2 g/day demonstrated satisfactory eradication rates. HD-VA therapy is potentially the most effective regimen. Large-sample clinical trials are required to further validate these findings.

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.

Host Genetic Determinants Associated With Helicobacter pylori Eradication Treatment Failure: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Helicobacter pylori infects approximately 50% of individuals worldwide. Successful H pylori eradication is associated with reduced risk of gastric cancer and peptic ulcer disease, among other conditions. We hypothesized that host genetic determinants, especially those affecting gastric pH, might contribute to eradication therapy failure, particularly when treatment adherence and antibiotic susceptibility are confirmed. We aimed to conduct a meta-analysis of host genetic variants associated with H pylori eradication failure.

METHODS

We searched the literature for studies comparing posttreatment H pylori eradication failure vs success (outcome) according to host genetic polymorphisms (exposure). Reference groups were defined according to genotypes (or corresponding phenotypes) hypothesized to be associated with successful eradication. We pooled estimates using a random-effects model and performed comprehensive sensitivity analyses.

RESULTS

We analyzed 57 studies from 11 countries; the vast majority analyzed CYP2C19 polymorphisms. Among individuals prescribed eradication regimens with proton pump inhibitors predominantly CYP2C19 metabolized, enhanced vs poor metabolizer phenotypes were associated with a 2.52-fold significantly higher likelihood of eradication failure and 4.44-fold significantly higher likelihood when treatment adherence and H pylori clarithromycin susceptibility (if relevant) were confirmed. There was no association between CYP2C19 variants and eradication failure if proton pump inhibitors less metabolized by or that bypass CYP2C19 metabolism were used. IL1B polymorphisms that are vs are not associated with less gastric acid suppression were associated with 1.72-fold significantly higher likelihood of eradication failure. There was no association between MDR1 polymorphisms and H pylori eradication failure. The certainty of evidence was moderate.

CONCLUSION

Based on meta-analysis, we identified host genetic polymorphisms significantly associated with H pylori eradication failure; host genetics might underlie eradication failure among treatment-adherent individuals with confirmed H pylori antibiotic susceptibility.

Is a Potassium-Competitive Acid Blocker Truly Superior to Proton Pump Inhibitors in Terms of Helicobacter pylori Eradication?

Vonoprazan (VPZ), a new potassium-competitive acid blocker, has been approved and used for Helicobacterpylori eradication in Japan. To date, many studies, as well as several systematic reviews and meta-analyses (MAs), have compared VPZ-based 7-day triple therapy with proton pump inhibitor (PPI)-based therapy. An MA of randomized controlled trials (RCTs) comparing first-line VPZ- with PPI-based triple therapy, the latter featuring amoxicillin (AMPC) and clarithromycin (CAM), found that approximately 30% of patients hosted CAM-resistant H. pylori; however, the reliability was poor because of high heterogeneity and a risk of selection bias. VPZ-based triple therapy is superior to PPI-based triple therapy for patients with CAM-resistant H. pylori, but not for those with CAM-susceptible H. pylori. An MA of non-RCTs found that second-line VPZ-based triple therapies were slightly (~2.6%) better than PPI-based triple therapies (with AMPC and metronidazole). However, the reliability of that MA was also low because of selection bias, confounding variables and a risk of publication bias; in addition, it is difficult to generalize the results because of a lack of data on antibiotic resistance. VPZ-based triple therapy (involving AMPC and sitafloxacin) was more effective than PPI-based triple therapy in a third-line setting, but a confirmatory RCT is needed. Non-RCT studies indicated that VPZ-based triple therapy involving CAM and metronidazole may be promising. Any further RCTs must explore the antibiotic-resistance status when evaluating the possible superiority of a potassium-competitive acid blocker.

Long-term vonoprazan therapy is effective for controlling symptomatic proton pump inhibitor-resistant gastroesophageal reflux disease

Vonoprazan, a novel potassium-competitive acid blocker, results in greater inhibition of gastric acid secretion than proton pump inhibitors (PPI). The aim of this study was to assess the long-term outcomes of patients with PPI-resistant gastroesophageal reflux disease (GERD) treated with vonoprazan. The medical records of patients with symptomatic GERD treated with vonoprazan for 1 year were retrospectively reviewed. Changes in abdominal symptoms were assessed using the Izumo scale, a self-reported questionnaire which is useful in evaluating the symptoms of GERD, epigastric pain, postprandial distress, constipation and diarrhea, and is commonly used in routine clinical practice. A total of 30 patients were included and stratified into a non-erosive (n=22) and erosive group (n=8). At baseline, postprandial distress symptoms were significantly greater in the non-erosive group compared with the erosive group (P=0.013). Even with vonoprazan therapy, symptoms of GERD in the non-erosive group were refractory compared with the erosive group, and required additional treatment in a larger proportion of patients (45 vs. 13%). GERD symptoms in the non-erosive group significantly improved from baseline and remained better after 1 year of vonoprazan therapy, similar to the erosive group. In addition, vonoprazan improved epigastric pain and postprandial distress symptoms in the non-erosive group, and 1 year of vonoprazan therapy did not aggravate constipation or diarrhea. In conclusion, 1 year of vonoprazan therapy improves GERD symptoms in patients with PPI-resistant GERD.

Effect of Antibiotic Susceptibility and CYP3A4/5 and CYP2C19 Genotype on the Outcome of Vonoprazan-Containing Helicobacter pylori Eradication Therapy

BACKGROUND

Helicobacter pylori eradication containing the potassium-competitive acid blocker, vonoprazan, achieves a higher eradication rate than therapy with proton pump inhibitors (PPIs). Because vonoprazan is mainly metabolized by CYP3A4/5, CYP genotype may affect the eradication rate. We investigated the influence of antibiotic susceptibility and CYP3A4/5 and CYP2C19 genotypes on the eradication rates.

METHODS

A total of 307 Japanese who were genotyped for CYP3A4 *1/*22, CYP3A5 *1/*3 and CYP2C19 *1/*2/*3/*17, and investigated for susceptibility to antimicrobial agents, received vonoprazan-containing regimens: (1) With amoxicillin and clarithromycin as the first-line treatment; (2) with amoxicillin and metronidazole as the second-line treatment; or (3) with amoxicillin and sitafloxacin as the third-line treatment.

RESULTS

The eradication rate was 84.5% (95% confidence interval [CI]: 78.9-89.1%) using first-line, 92.6% (95% CI: 82.1-97.9%) using second-line and 87.5% (95% CI: 73.1-95.8%) using third-line treatment. Infection with clarithromycin-resistant strains was a predictive factor for failed eradication (odds ratio: 5.788, 95% CI: 1.916-17.485, p = 0.002) in multivariate analysis. No significant differences were observed in the eradication rate of regimens among CYP3A4, CYP3A5 and CYP2C19 genotypes.

CONCLUSIONS

Genotyping for CYP3A4 *1/*22, CYP3A5 *1/*3 and CYP2C19 *1/*2/*3/*17 before vonoprazan-containing eradication treatment may not be useful for predicting clinical outcomes.

Efficacy of Vonoprazan for Helicobacter pylori Eradication

Helicobacter pylori can infect the gastric mucosa and cause chronic inflammation, resulting in various diseases, including gastric cancer. Eradication of H. pylori in all infected subjects is recommended; however, the number of H. pylori strains with antibiotic resistance has increased, and the eradication rate has decreased. Vonoprazan, a potassium-competitive acid blocker, produces a stronger acid-inhibitory effect than proton pump inhibitors (PPIs). The H. pylori eradication rate with vonoprazan was found to be higher than that with PPIs. The H. pylori eradication rate with vonoprazan-based triple therapy (vonoprazan, amoxicillin, and clarithromycin) was approximately 90% and had an incidence of adverse events similar to that of PPIs. We review the current situation of H. pylori eradication in Japan, the first country in which vonoprazan was made available.

Role of Vonoprazan in Helicobacter pylori Eradication Therapy in Japan

Complete eradication of Helicobacter pylori is important for preventing the development of gastric cancer. The outcome of H. pylori eradication therapy is mainly dependent on bacterial susceptibility to antimicrobial agents and potent neutralization of intragastric pH across 24 h, especially when using acid-sensitive antimicrobial agents such as clarithromycin (CLR), amoxicillin and sitafloxacin. However, conventional regimens comprising twice-daily doses (bid) of proton pump inhibitors (PPIs) are generally insufficient for maintaining the required gastric acid secretion for 24 h for successful eradication in all H. pylori-positive patients. Further, the increasing prevalence of CLR-resistant strains with each year has led to a decrease in eradication rates of first-line PPI- and CLR-containing therapies in developed countries, including Japan. In 2015, the potassium-competitive acid blocker vonoprazan (VPZ) became clinically available in Japan. VPZ competitively inhibits H+/K+-ATPase activity more potently than PPIs (e.g., omeprazole, lansoprazole, rabeprazole, pantoprazole, and esomeprazole). Therefore, a VPZ-containing H. pylori eradication regimen is expected to increase the eradication rate compared with conventional regimens containing a standard dose of PPI. In fact, a recent meta-analysis that investigated the efficacy of first-line eradication therapy showed that a VPZ-containing regimen achieved a higher eradication rate than a PPI-containing regimen. While the Maastricht V/Florence Consensus Report recommends selecting a bismuth or non-bismuth quadruple therapy and concomitant therapy for patients living in areas with high prevalence of CLR resistance, a VPZ-containing regimen demonstrates effectiveness for patients infected with CLR-resistant strains and patients living in areas where the prevalence of CLR-resistant strains is >15%. As a next step, studies are needed to determine the factors affecting the clinical outcome of VPZ-containing therapy and optimal VPZ-containing alternative regimens for tailored treatments. In this review, we summarize the advantages and disadvantages of VPZ in H. pylori eradication therapy.

Evaluation of gastric acid suppression with vonoprazan using calcium carbonate breath test

Vonoprazan, a potassium-competitive acid blocker, is a new class of acid-suppressing agent. The acid-inhibitory effect of vonoprazan has been well-documented. However, there is no report on the extent to which the amount of gastric acid secretion is suppressed, not pH measurement, by the use of vonoprazan. The aim of this study was to evaluate this suppression effect. This was a single-arm, interventional pilot study involving 7 healthy Japanese men. The subjects were administered 20 mg vonoprazan for 6 days. The amount of gastric acid secretion was determined using the calcium carbonate breath test. The acid outputs were defined as the maximum Δ¹³C‰ (Δ¹³C max) and area under the curve (AUC) during the 30 min sampling period. The Δ¹³C max and AUC values significantly decreased on the administration of 20 mg vonoprazan. The AUC dropped by approximately 78% on day 1 and by 84% on day 6 and subsequently returned to the control level after cessation of vonoprazan therapy (reduction by 68% on day 7 and by 42% on day 8). In conclusion, the amount of gastric acid secretion rapidly decreased by the administration of vonoprazan; this inhibitory effect was found to be potent and long-lasting. (UMIN ID: UMIN000025469).

Helicobacter pylori therapy and clinical perspective

Helicobacter pylori induces chronic gastritis and duodenal ulcer in a small fraction of the colonised population. Three decades after the discovery of H. pylori and disclosure of an urgent need for eliminating the bacterium in patients, it seems that we are still in the first steps of dealing with this mysterious organism. Treatment of H. pylori is a complex dilemma for clinicians, a repeating sentence by many scientists who spend years on this research topic. Apart from many modifications in initial first-line treatment of H. pylori, gastroenterologists are unable to overcome the problem of therapeutic failure. Choosing the best regimen in any region depends on many factors, which have been the focus of many randomised clinical trials. A potential increase in efficacy of future therapies may be influenced by adding the novel potassium-competitive acid blocker vonoprazan. Undeniably, in-depth analysis is necessary to propose more effective therapeutic regimens. Meanwhile, we recommend the performance of antimicrobial susceptibility testing before any antimicrobial prescription.

Severity of gastric mucosal atrophy affects the healing speed of post-endoscopic submucosal dissection ulcers

AIM

To investigate factors associated with the healing of endoscopic submucosal dissection (ESD)-induced ulcers.

METHODS

We enrolled 132 patients with gastric tumors scheduled for ESD. Following ESD, patients were treated with daily lansoprazole 30 mg or vonoprazan 20 mg. Ulcer size was endoscopically measured on the day after ESD and at 4 and 8 wk. The gastric mucosa was endoscopically graded according to the Kyoto gastritis scoring system. We assessed the number of patients with and without a 90% reduction in ulcer area at 4 wk post-ESD and scar formation at 8 wk, and looked for risk factors for slower healing.

RESULTS

The mean size of gastric tumors and post-ESD ulcers was 17.4 ± 12.1 mm and 32.9 ± 13.0 mm. The mean reduction rates in ulcer area were 90.4% ± 0.8% at 4 wk and 99.8% ± 0.1% at 8 wk. The reduction rate was associated with the Kyoto grade of gastric atrophy at 4 wk (A0: 97.9% ± 0.6%, A1: 93.4% ± 4.1%, and A2: 89.7% ± 1.0%, respectively). In multivariate analysis, the factor predicting 90% reduction at 4 wk was gastric atrophy (Odds ratio: 5.678, 95%CI: 1.190-27.085, P = 0.029).

CONCLUSION

The healing speed of post-ESD ulcers was associated with the degree of gastric mucosal atrophy, and Helicobacter pylori eradication therapy is required to perform at younger age.

Pre-treatment with proton pump inhibitors decreases the success of primary Helicobacter pylori eradication using a vonoprazan-based regimen

Vonoprazan-based regimens have improved the rate of successful Helicobacter pylori (H. pylori) eradication, but it has not reached 100%. The aim of this study is to clarify significant predictors of successful H. pylori eradication using a vonoprazan-based regimen. In this retrospective cohort study, 174 patients who underwent primary H. pylori eradication therapy were included. All patients underwent esophagogastroduodenoscopy before treatment. The vonoprazan-based regimen includes amoxicillin 750 mg, clarithromycin 200 mg and vonoprazan 20 mg twice daily for one week. Pre-treatment with a proton pump inhibitor (PPI) was defined as continued PPI use for more than four weeks prior to eradication therapy. The rates of successful eradication were 83% (145/174) in intention-to-treat analysis and 85% (145/171) in per-protocol analysis. Predictors of successful eradication among 171 patients were evaluated in per-protocol analysis. In univariate analysis, male gender was a significant positive predictor of successful eradication (odds ratio [OR] 3.813, 95% confidence interval [CI] 1.363-10.663, p = 0.010) and pre-treatment with PPIs was a negative predictor (OR 0.193, 95%CI 0.076-0.485, p < 0.001). In multivariate analysis, male gender remained a positive predictor (OR 3.826, 95%CI 1.317-11.116, p = 0.013), and pre-treatment with PPIs (OR 0.232, 95%CI 0.087-0.615, p = 0.003) remained a negative predictor. In conclusion, pre-treatment with PPIs before eradication therapy decreases the rate of successful eradication. Therefore, it may be desirable to discontinue pre-treatment with PPIs prior to eradication therapy, because of the potential to improve the rate of successful eradication.