Randomized, Double-blind, Active-controlled Phase 3 Study to Evaluate Efficacy and Safety of Zastaprazan compared to Esomeprazole in Erosive Esophagitis

INTRODUCTION: Zastaprazan is a potent potassium-competitive acid blocker (P-CAB) developed to treat gastroesophageal reflux disease. This study aims to evaluate the efficacy and safety of zastaprazan compared to esomeprazole in patient with erosive esophagitis (EE). METHODS: A phase III, multicenter, randomized, double-blind, non-inferiority clinical study was conducted with 300 subjects with confirmed EE. Subjects were randomized to receive zastaprazan 20 mg or esomeprazole 40 mg once daily up to 8 weeks. The primary endpoint was the cumulative proportion of subject with healed EE confirmed by endoscopy at week 8. The secondary endpoints included the healing rate at week 4, symptom response and quality of life assessment. Safety profiles and serum gastrin levels were also assessed. RESULTS: In the full analysis set, the cumulative healing rate at week 8 were 97.92% (141/144) for zastaprazan and 94.93% (131/138) ( P = 0.178) for esomeprazole. The healing rate at week 4 in the zastaprazan group was higher than esomeprazole group (95.14% (137/144) vs. 87.68% (121/138); P = 0.026). There was no significant difference between groups in healing rates (the per-protocol set) at week 8 and week 4, symptom responses, quality of life assessments and safety profiles. In addition, serum gastrin levels increased during treatment in both groups, with a significant difference between the two groups ( P = 0.047), but both decreased after treatment. DISCUSSION: An 8-week therapy of zastaprazan 20 mg is non-inferior to esomeprazole 40 mg in subjects with predominantly low-grade EE. The healing rate at week 4 appears to be higher for zastaprazan than esomeprazole.