Phathom Pharmaceuticals Announces FDA Acceptance for Filing of Vonoprazan NDA for the Treatment of Erosive Esophagitis

Phathom Pharmaceuticals, Inc. recently announced the US FDA has accepted for review the company’s New Drug Application (NDA) for vonoprazan as a treatment for adults for the healing of all grades of erosive esophagitis (EE) and relief of heartburn, and maintenance of healing of all grades of EE and relief of heartburn. The FDA has assigned the application standard review and a Prescription Drug User Fee Act (PDUFA) target action date of January 11, 2023.

Vonoprazan is a novel, orally administered investigational potassium-competitive acid blocker (PCAB) from a new class of acid suppressant agents and under development for the treatment of erosive esophagitis and non-erosive gastroesophageal reflux disease (NERD).

Erosive esophagitis is a major type of gastroesophageal reflux disease (GERD) and affects approximately 20 million people in the US In addition to experiencing troubling heartburn symptoms, patients with inadequately treated EE may progress to more severe diseases, including Barrett’s esophagus, a condition in which esophageal tissue changes can progress to cancer.

“The FDA’s commencement of a substantive review of our new drug application for vonoprazan in EE is an important milestone for Phathom and the patients we seek to serve, bringing us another step closer toward the approval of a new class of treatment and the first major innovation to the U.S. GERD market in over 30 years,” said Azmi Nabulsi, MD, Chief Operating Officer at Phathom. “With this NDA filing, we are excited about our potential to offer a treatment option to address the significant unmet needs that exist for the millions of patients suffering from painful erosions caused by all grades of EE.”

This NDA is supported by the positive data previously announced from Phathom’s pivotal Phase 3 PHALCON-EE trial, a randomized, double-blind, multicenter trial that enrolled 1,027 patients with EE in the US and Europe and compared vonoprazan to lansoprazole, a proton pump inhibitor (PPI), in the healing and maintenance of healing of EE, and heartburn symptom relief. PHALCON-EE successfully met its primary endpoints and key secondary superiority endpoints.

Under the terms of Phathom’s loan agreement with Hercules Capital, following Phathom’s recent approval of vonoprazan-based therapies for treatment of H. pylori infection in adults and the FDA’s acceptance for filing of the NDA for vonoprazan for the healing and maintenance of healing of EE, the remaining $50 million is now available to be drawn down.

Erosive Esophagitis (EE) is a major type of gastroesophageal reflux disease (GERD) characterized by erosions in the gastric mucosa caused by acidic reflux of stomach contents into the esophagus. There are estimated to be over 65 million individuals with GERD in the US, of which approximately 30% have EE. In addition to experiencing troubling heartburn symptoms, patients with inadequately treated EE may progress to more severe diseases including Barrett’s esophagus and esophageal cancer.

PHALCON-EE was a randomized, double-blind, two-phase, multicenter, Phase 3 trial that enrolled 1,024 patients with EE in the US and Europe. The first phase of the trial evaluated the efficacy and safety of vonoprazan 20 mg administered once-daily (QD) compared to lansoprazole 30 mg QD for the healing of EE for up to eight weeks. The second phase of the trial evaluated the efficacy and safety of vonoprazan 10 mg QD and 20 mg QD compared to lansoprazole 15 mg QD for the maintenance of healing of EE for 24 weeks. Both phases also evaluated heartburn symptoms.

Phathom Pharmaceuticals is a biopharmaceutical company focused on the development and commercialization of novel treatments for gastrointestinal diseases and disorders. Phathom has in-licensed the exclusive rights in the US, Europe, and Canada to vonoprazan, a first-in-class potassium-competitive acid blocker (PCAB). Vonoprazan-based regimens are approved in the US as part of a co-packaged product in combination with antibiotics for the treatment of H. pylori infection in adults, marketed as VOQUEZNA TRIPLE PAK (vonoprazan, amoxicillin, clarithromycin) and VOQUEZNA DUAL PAK (vonoprazan, amoxicillin). Phathom has submitted a New Drug Application to the FDA for vonoprazan in erosive esophagitis (EE) and is studying the use of vonoprazan for the treatment of non-erosive reflux disease (NERD). For more information, visit www.phathompharma.com.