Phathom Pharmaceuticals Announces Vonoprazan NDA Submission for Non-Erosive GERD

Phathom Pharmaceuticals, Inc. recently announced the submission of an NDA to the FDA for vonoprazan as a daily treatment for Non-Erosive gastroesophageal reflux disease (GERD) in adults. The regulatory submission is supported by the positive data from the PHALCON-NERD-301 study, a Phase 3 study evaluating the efficacy and safety of vonoprazan for the daily treatment of adults with Non-Erosive GERD (NERD). Vonoprazan is an investigational first-in-class potassium-competitive acid blocker (PCAB) from a novel class of medicines that block acid secretion in the stomach.

“The submission of the NERD daily dosing NDA represents a major potential advancement for the estimated 38 million adults in the US suffering from the symptoms of Non-Erosive GERD, many of whom are dissatisfied with currently available therapies,” said Terrie Curran, President and Chief Executive Officer at Phathom. “Our NDA is supported by the results of our successfully completed PHALCON-NERD-301 study, which demonstrated vonoprazan’s durable 24-hour heartburn control over six months and reaffirmed its known safety profile.”

The effectiveness and safety of vonoprazan 10 mg and 20 mg given once daily in NERD was evaluated in a randomized, placebo-controlled, double-blind, 4-week trial with a 20-week blinded extension conducted in the United States in 772 adult patients. As previously reported, both vonoprazan doses met the primary endpoint for the mean percentage of heartburn free days over the 4-week placebo-controlled period at 45%, 44%, and 28% for vonoprazan 10 mg, vonoprazan 20 mg, and placebo, respectively (p<0.0001 for both doses).

Patients randomized to vonoprazan 10 mg and 20 mg during the initial 4-week period remained on their blinded treatment assignment for the 20-week extension period. The mean percentage of heartburn free days reported over the 20-week extension period for these patients was 63% for vonoprazan 10 mg and 61% for vonoprazan 20 mg.

Additionally, patients who were randomized to placebo during the initial 4-week period were re-randomized to either vonoprazan 10 mg or 20 mg for the 20-week extension period. For these patients, the mean percentage of heartburn free days reported over the 20-week extension period was 62% for vonoprazan 10 mg and 63% for vonoprazan 20 mg.

As previously reported, the overall adverse events were comparable between vonoprazan and placebo during the 4-week placebo-controlled period of which the most common events were nausea, abdominal pain, constipation, and diarrhea, reported at or below 3% for either vonoprazan 10 mg or 20 mg doses. The most common adverse events reported for the two vonoprazan doses during the 20-week extension period were upper respiratory tract infection, sinusitis, influenza, urinary tract infection, nasopharyngitis, nausea, and gastroenteritis, reported at or below 5%.

Phathom expects a 10-month regulatory review and if approved, anticipates a third quarter 2024 US launch for vonoprazan as a daily treatment for Non-Erosive GERD. Phathom also plans to initiate an additional Phase 3 study to evaluate vonoprazan as an As Needed treatment for episodic heartburn relief in adults with Non-Erosive GERD, a novel dosing treatment regimen.

“While our Non-Erosive daily dosing NDA is under review, we plan to initiate a separate Phase 3 trial studying the As Needed dosing of vonoprazan for active heartburn episodes, a dosing regimen for which proton pump inhibitors (PPIs) are not approved in the US, thereby representing a significant unmet need,” said Azmi Nabulsi, MD, Chief Operating Officer at Phathom. “We look forward to confirming the positive results from our previous Phase 2 As Needed study of vonoprazan in Non-Erosive GERD and, if our Phase 3 study is successful, vonoprazan has the potential to offer a new treatment option for Non-Erosive GERD patients with flexibility to be taken either daily, or for heartburn symptoms that require rapid and sustained relief, on an as-needed basis.”

Vonoprazan is under active review by the FDA as a treatment of Erosive GERD and relief of heartburn associated with Erosive GERD in adults, with a Prescription Drug User Fee Act (PDUFA) goal date of November 17, 2023. If approved, a commercial launch is planned for the fourth quarter of 2023.

Non-Erosive GERD is the largest subcategory of gastroesophageal reflux disease (GERD) and is characterized by reflux-related symptoms in the absence of esophageal mucosal erosions. There are an estimated 38 million US adults living with Non-Erosive GERD, of these approximately 15 million are treated with a prescription medicine annually. Symptoms of NERD impact overall quality of life and can include episodic heartburn, especially at night, regurgitation, problems swallowing, and chest pain.

Phathom Pharmaceuticals is a biopharmaceutical company focused on the development and commercialization of novel treatments for gastrointestinal diseases. Phathom has in-licensed the exclusive rights in the US, Europe, and Canada to vonoprazan, a first-in-class potassium-competitive acid blocker (PCAB). For more information, visit  www.phathompharma.com.