Potassium-competitive acid blockers and gastroesophageal reflux disease

Proton pump inhibitors(PPIs),the most commonly used antisecretory medications in the management of reflux illness,virtually eliminate elective surgery for ulcer disease,and relegate anti-reflux surgery to patients with gastroesophageal reflux disease(GERD)who are inadequately managed by medical therapy.However,PPI medications still leave some therapeutic demands of GERD unmet.Furthermore,up to 40%-55%of daily PPI users have chronic symptoms,due to PPI refractoriness.Potassium-competitive acid blockers(P-CABs)transcend many of the problems and limits of PPIs,delivering quick,powerful,and extended acid suppression and allowing for treatment of numerous unmet needs.Recently,it has become clear that compromised mucosal integrity plays a role in the etiology of GERD.As a result,esophageal mucosal protection has emerged as a novel and potential treatment approach.An increasing body of research demonstrates that when P-CABs are used as primary drugs or add-on drugs(to regular treatment),they provide a considerable extra benefit,particularly in alleviating symptoms that do not respond to PPI therapy.

Potassium-competitive acid blockers-are they the next generation of proton pump inhibitors?

The modern lifestyle caters to an increase in the incidence of peptic ulcer disease,gastroesophageal reflux disease and several other acid-related conditions of the gut. The drugs to prevent these conditions work either through H2 receptor blockade or inhibition of the H^+, K^+ ATPase enzyme. Although proton pump inhibitors have been proven to be efficacious, they have a slow onset of action with limited resolution of symptoms in most patients. Potassium-competitive acid blockers(P-CABs) are novel drugs that bind reversibly to K^+ ions and block the H^+, K^+ ATPase enzyme, thus preventing acid production. P-CABs have a fast onset of action and have dose-dependent effects on acid production. Animal studies exist that differentiate the better results of P-CABs from proton pump inhibitors; further human trials will give a comprehensive picture of the results and will help to elucidate the therapeutic benefits of this new group of drugs.

Maintenance for healed erosive esophagitis:PhaseⅢcomparison of vonoprazan with lansoprazole

AIM To compare vonoprazan 10 and 20 mg vs lansoprazole 15 mg as maintenance therapy in healed erosive esophagitis(EE).METHODS A total of 607 patients aged ≥ 20 years, with endoscopically-confirmed healed EE following 8 wk of treatment with vonoprazan 20 mg once daily, were randomized 1:1:1 to receive lansoprazole 15 mg(n = 201), vonoprazan 10 mg(n = 202), or vonoprazan 20 mg(n = 204), once daily. The primary endpoint of the study was the rate of endoscopically-confirmed EE recurrence during a 24-wk maintenance period. The secondary endpoint was the EE recurrence rate at Week 12 during maintenance treatment. Additional efficacy endpoints included the incidence of heartburn and acid reflux, and the EE healing rate 4 wk after the initiation of maintenance treatment. Safety endpoints comprised adverse events(AEs), vital signs, electrocardiogram findings, clinical laboratory results, serum gastrin and pepsinogen Ⅰ/Ⅱ levels, and gastric mucosa histopathology results.RESULTS Rates of EE recurrence during the 24-wk maintenance period were 16.8%, 5.1%, and 2.0% with lansoprazole 15 mg, vonoprazan 10 mg, and vonoprazan 20 mg, respectively. Vonoprazan was shown to be non-inferior to lansoprazole 15 mg(P < 0.0001 for both doses). In a post-hoc analysis, EE recurrence at Week 24 was significantly reduced with vonoprazan at both the 10 mg and the 20 mg dose vs lansoprazole 15 mg(5.1% vs 16.8%, P = 0.0002, and 2.0% vs 16.8%, P < 0.0001, respectively); by contrast, the EE recurrence rate did not differ significantly between the two doses of vonoprazan(P = 0.1090). The safety profiles of vonoprazan 10 and 20 mg were similar to that of lansoprazole 15 mg in patients with healed EE. Treatment-related AEs were reported in 11.4%, 10.4%, and 10.3% of patients in the lansoprazole 15 mg, vonoprazan 10 mg, and vonoprazan 20 mg arms, respectively.CONCLUSION Our findings confirm the non-inferiority of vonoprazan 10 and 20 mg to lansoprazole 15 mg as maintenance therapy for patients with healed EE.

Role of potassium in acid secretion

Potassium (K+) ions are critical for the activation and catalytic cycle of the gastric H+,K+-ATPase, resulting in the secretion of hydrochloric acid into the parietal cell canaliculus. As both symptom, severity and esophageal mucosal damage in gastro-esophageal reflux disease (GERD) are related to the degree of acid exposure, K+ is a logical target for approaches to inhibit acid production.The probable K+ binding site on the gastric H+,K+-ATPase has recently been described and studies are elucidating how K+ activates the enzyme. K+ channels in the apical membrane of the parietal cell are implicated in the recycling of K+ and, to date, three potential K+ channels (KCNQ1, Kir2.1 and Kir4.1) have been identified. The channels represent theoretical sites for agents to control acid secretion but it will be difficult to develop selective blockers. An alternative strategy is to prevent K+ from activating gastric H+,K+-ATPase; the potassiumcompetitive acid blocker (P-CAB) class inhibits acidsecretion by binding at or near the K+ binding site.Ongoing research is further defining the role of K+ in the functioning of the gastric H+,K+-ATPase, as well as determining the clinical utility of agents directed toward this important cation.

Vonoprazan 20 mg vs lansoprazole 30 mg for endoscopic submucosal dissection-induced gastric ulcers

AIM To compare the healing effects of vonoprazan and lansoprazole on gastric ulcers induced by endoscopic submucosal dissection(ESD).METHODS Data were obtained from a total of 26 patients.Fourteen patients were randomized to the vonoprazan group and 12 were randomized to the lansoprazole group.Patients were administered either 20 mg vonoprazan or 30 mg lansoprazole per day after ESD.Endoscopic images just after ESD,on day 8,and on day 28 were used for the evaluation of the shrinking rate of ESD ulcers.The shrinking rates and the incidence of delayed bleeding were compared between the 2 groups.RESULTS The shrinking rates of ESD ulcers on day 8 [vonoprazangroup: 61.8%(range: 24.0%-91.1%),lansoprazole group: 71.3%(range: 25.2%-88.6%)] and on day 28 [vonoprazan group: 95.3%(range: 76.2%-100%),lansoprazole group: 97.2%(range: 81.1%-99.8%)] were not statistically different between the 2 groups.On day 28,most of the ulcers in both groups healed to more than 90%,whereas 3 of 14(21.4%) in the vonoprazan group and 1 of 12(8.3%) in the lansoprazole group had delayed ulcer healing,which was not statistically different(P = 0.356).The frequency of delayed bleeding was 0 in the both groups.Taken together,there were no significant differences between the two drug groups.CONCLUSION Our study indicates that vonoprazan is potent for the management of ESD ulcers although lansoprazole is also sufficient and cost-effective.

Vonoprazan 10 mg or 20 mg vs.lansoprazole 15 mg as maintenance therapy in Asian patients with healed erosive esophagitis:A randomized controlled trial

Background:Erosive esophagitis(EE)is a gastroesophageal reflux disease characterized by mucosal breaks in the esophagus.Proton pump inhibitors are widely used as maintenance therapy for EE,but many patients still relapse.In this trial,we evaluated the noninferiority of vonoprazan vs.lansoprazole as maintenance therapy in patients with healed EE.Methods:We performed a double-blind,double-dummy,multicenter,phase 3 clinical trial among non-Japanese Asian adults with endoscopically confirmed healed EE from April 2015 to February 2019.Patients from China,South Korea,and Malaysia were randomized to vonoprazan 10 mg or 20 mg once daily or lansoprazole 15 mg once daily for 24 weeks.The primary endpoint was endoscopically confirmed EE recurrence rate over 24 weeks with a noninferiority margin of 10%using a two-sided 95%confidence interval(CI).Treatment-emergent adverse events(TEAEs)were recorded.Results:Among 703 patients,EE recurrence was observed in 24/181(13.3%)and 21/171(12.3%)patients receiving vonoprazan 10 mg or 20 mg,respectively,and 47/184(25.5%)patients receiving lansoprazole(differences:-12.3%[95%CI,-20.3%to-4.3%]and-13.3%[95%CI,-21.3%to-5.3%],respectively),meeting the primary endpoint of noninferiority to lansoprazole in preventing EE recurrence at 24 weeks.Evidence of superiority(upper bound of 95%CI<0%)was also observed.At 12 weeks,endoscopically confirmed EE recurrence was observed in 5/18,2/20,and 7/20 of patients receiving vonoprazan 10 mg,vonoprazan 20 mg,and lansoprazole,respectively.TEAEs were experienced by 66.8%(157/235),69.0%(156/226),and 65.3%(158/242)of patients receiving vonoprazan 10 mg,vonoprazan 20 mg,and lansoprazole,respectively.The most common TEAE was upper respiratory tract infection in 12.8%(30/235)and 12.8%(29/226)patients in vonoprazan 10 mg and 20 mg groups,respectively and 8.7%(21/242)patients in lansoprazole group.Conclusion:Vonoprazan maintenance therapy was well-tolerated and noninferior to lansoprazole for preventing EE recurrence in Asian patients with healed EE.Trial Registration:https://clinicaltrials.gov;NCT02388737.