Material Event (Form 8-K)

Item 8.01 Other Events.

On June 23, 2026, Phathom Pharmaceuticals, Inc. ("Phathom" or the "Company") announced it has completed enrollment in its Phase 2 pHalcon-EoE-201 clinical trial evaluating VOQUEZNA^® (vonoprazan) tablets as an investigational treatment for eosinophilic esophagitis ("EoE") in adults. The study has enrolled 95 patients at 41 U.S. sites. Topline results are anticipated in the fourth quarter 2026.

The pHalcon-EoE-201 study is a two-part, randomized, double-blind, placebo-controlled Phase 2 study. In Part 1, 95 adults with endoscopically confirmed EoE and dysphagia have been randomized evenly to receive VOQUEZNA 20 mg or placebo once daily for 12 weeks. Patients who complete Part 1 are eligible to enter Part 2, a 12-week extension phase in which all participants receive VOQUEZNA 20 mg once daily. If the Phase 2 pHalcon-EoE-201 study generates positive results, Phathom expects to discuss with FDA potential future development plans in EoE, including pediatric evaluation that could potentially support an extension of regulatory exclusivity.