Phathom passes acid tests, capturing 2 FDA approvals for Voquezna after impurity setback

In a span of three days, Phathom Pharmaceuticals has scored two green lights from the FDA for its first-in-class heartburn drug Voquezna (vonoprazan).

The first came Monday when the regulator signed off on Phathom’s reformulation of Voquezna to treat Helicobacter pylori infection. The second came Wednesday when the FDA blessed Voquezna for gastroesophageal reflux disease erosive esophagitis (erosive GERD) and associated heartburn.

Two approvals for the same compound in a week is unusual. The FDA originally endorsed Voquezna for H. pylori in May of last year, but then it put Phathom’s launch plans on hold when trace levels of a cancer-causing agent were discovered in commercial batches of the treatment. That initial approval was later revoked.

During the impurity-related holdup, the FDA also iced Phathom’s application for approval for erosive GERD. In April, after receiving complete response letters for both applications, Phathom said that it had shown the FDA stability data that demonstrated Voquezna tablets could stay below an acceptable threshold of daily intake of the nitrosamine N-nitro-vonoprazan.

With that, Phathom’s two applications were back in the FDA hopper.

With the approvals, Voquezna becomes the first acid suppressant available in the U.S. to demonstrate superiority to the standard of care, proton pump inhibitors (PPIs), in a variety of indications, the company said. It is the first new innovation in the treatment of acid suppression in three decades, as well.

There are 20 million people in the U.S. who are treated for acid-related stomach problems, Phathom said. The company plans to make Voquezna available immediately for erosive GERD patients and in December for those with H. pylori. The company has a sales force of 320 people.

Phathom said it will charge $650 for a 30-dose bottle of the treatment, for both its 20-mg (healing) and 10-mg (maintenance) doses.

“We believe there is tremendous growth opportunity building off the rapid, potent and durable acid-suppression profile,” Terrie Curran, Phathom’s CEO, said on a conference call.

There is one more indication Phathom is going after with Voquezna—non-erosive GERD. The company expects an FDA decision on that indication in the second half of next year. Curran said the company has estimated peak sales potential at more than $3 billion.

Despite the availability of over-the-counter options, 85% of PPI sales volume is driven by prescriptions, Phathom said.

The erosive GERD approval was based on a study of 1,024 patients, which compared vonoprazan to the PPI lansoprazole. It showed a 93% healing rate for a daily, 20-mg dose of vonoprazan versus an 85% healing rate for those on a 30-mg regimen of lansoprazole. In the maintenance phase, a 10-mg dose of vonoprazan also showed superiority to a 15-mg dose of lansoprazole in healing at six months.

Vonoprazan works by competitively blocking the potassium-binding site of the proton pump, which is a protein primarily responsible for stomach acid secretion.

Phathom is a spinout of Takeda, specifically establshed to develop and market vonoprazan outside of Asia, where it is already on the market.