Long-term follow-up of patients developing gastric mucosal lesions after initiating the potassium-competitive acid blocker vonoprazan

Vonoprazan has recently been developed and approved for clinical use in Japan 1 as a drug of the potassium-competitive acid blocker (P-CAB) class reported to reversibly inhibit gastric acid output through K + -competitive ionic binding to H + /K + -ATPase. 2 Vonoprazan has been shown to selectively accumulate in gastric parietal cells in the mucosal layer of the rat stomach, 3 and gastric cracked mucosa (GCM), redness, white spots (WS), and gastric polyps (GP) have been reported as P-CAB-associated gastric mucosal lesions. 4-10However, only a few cases have demonstrated a causal relationship between vonoprazan and gastric mucosal lesions through long-term follow-up from before drug initiation to after its discontinuation. 5,6We herein report two cases in which GCM, WS, and GP newly appeared after the initiation of vonoprazan treatment and were followed up after switching to proton pump inhibitors (PPIs).