Phathom Pharmaceuticals Completes Enrollment in Phase 2 Vonoprazan EoE Trial Ahead of Schedule

Phathom Pharmaceuticals has closed enrollment in its pHalcon-EoE-201 Phase 2 study of vonoprazan (VOQUEZNA) in eosinophilic esophagitis, positioning the program as the first large, placebo-controlled trial of an acid suppression therapy in this indication, a gap that has left clinicians relying on PPIs without an FDA-approved label for EoE use.

The study enrolled 95 adults with endoscopically confirmed EoE and dysphagia across 41 U.S. sites, randomized evenly to VOQUEZNA 20 mg once daily or placebo over a 12-week double-blind treatment period. Patients completing Part 1 are eligible for a 12-week open-label extension in which all participants receive the active agent. Topline data from the blinded portion are expected in Q4 2026.

For regulatory affairs leads, the study design carries forward-looking weight beyond the immediate readout. Phathom has indicated that positive Phase 2 results would trigger discussions with FDA on a broader development pathway in EoE, including a pediatric evaluation program. A pediatric extension could support regulatory exclusivity beyond the current VOQUEZNA approvals, which cover erosive GERD in adults under a potassium-competitive acid blocker (PCAB) mechanism distinct from conventional PPI pharmacology.

The clinical context is relevant to QA and medical affairs teams tracking the EoE treatment landscape. No acid suppression therapy currently carries an FDA-approved indication for EoE, yet PPI use in this population is widespread as off-label first-line management. Vonoprazan's PCAB mechanism offers more consistent acid suppression than PPIs, a pharmacological distinction the trial is designed to interrogate under controlled conditions for the first time at this scale.

Enrollment completion ahead of the original timeline compresses the interval to the Q4 2026 topline readout, which will determine whether Phathom advances to a Phase 3 program and formal regulatory engagement on an EoE-specific NDA or sNDA pathway.

Source: Phathom Pharmaceuticals via GlobeNewswire, June 23, 2026.