Phathom announces top line results from Phase 3 PHALCON-NERD-301 trial

Phathom Pharmaceuticals announced top line results from PHALCON-NERD-301, a Phase 3 study evaluating the efficacy and safety of vonoprazan for the daily treatment of adults in symptomatic non-erosive gastroesophageal reflux disease. Vonoprazan is an investigational first-in-class potassium-competitive acid blocker from a novel class of medicines that block acid secretion in the stomach. Full results from the study are expected later this year. The top line results from the four-week, double-blind, placebo-controlled period showed both doses of vonoprazan 10 mg and 20 mg met the primary endpoint and demonstrated significantly greater percentage of 24-hour heartburn-free days versus placebo. The median percentage of 24-hour heartburn-free days was 48.3%, 46.7% and 17.0% for vonoprazan 10 mg, vonoprazan 20 mg, and placebo, respectively. The primary endpoint of the double-blind Phase 3 PHALCON-NERD-301 study evaluated the efficacy of vonoprazan 10 mg and 20 mg as a daily dosing treatment, as compared to placebo, in the relief of heartburn over four weeks in participants with symptomatic NERD. The trial also includes a blinded 20-week long-term extension period, which is currently ongoing, to further evaluate the safety and efficacy of both doses of vonoprazan after six months of continuous use. A total of 776 patients with symptomatic NERD were enrolled and randomized in the multisite U.S. trial. Full results from the trial are expected to be presented later in 2023. Vonoprazan was generally well tolerated in the initial four-week double-blind, placebo-controlled phase of the trial. The overall adverse events for all vonoprazan arms were comparable to placebo and consistent with what was reported in previous studies. Full safety data from the study will be available following the completion of the 20-week long-term extension period. Phathom is currently in discussions with the FDA on a separate Phase 3 trial design to evaluate the novel dosing regimen for vonoprazan as an on-demand or "as needed" treatment for episodic heartburn relief in patients with symptomatic NERD, a dosing treatment regimen not approved in the U.S. for proton pump inhibitors.