Three years after a spinoff from Takeda, Phathom Pharmaceuticals has successfully crossed the FDA finish line with a drug it got from the Japanese pharma.
The FDA cleared Phathom’s vonoprazan in two combinations to treat Helicobacter pylori infection, which typically affects the stomach or the small intestine, the company said Tuesday. Takeda has been selling the therapy in several Asian markets.
For the twin approvals, Phathom combines vonoprazan, a novel potassium-competitive acid blocker, with the antibiotic amoxicillin in Voquezna Dual Pak and further adds clarithromycin in a triplet dubbed Voquezna Triple Pak. The company plans to launch the products in the third quarter.
Riding on the go-aheads, Phathom penned a financing deal of up to $260 million to support Voquezna's launch and its continued clinical development, including in non-erosive reflux disease, which could open up a much larger market.
The non-diluted capital infusion includes a $100 million upfront payment and an additional $160 million pegged to Voquezna's FDA approval in erosive esophagitis. In exchange, Phathom offers the investors 10% royalty on sales of vonoprazan-containing products. The total royalties are capped at two times that of the investment.
H. pylori is estimated to affect nearly 115 million people in the U.S. and has a declining eradication rate with growing antibiotic resistance.
Vonoprazan works by competitively blocking the potassium-binding site of the proton pump, which is a protein primarily responsible for stomach acid secretion. The drug proved its worth in H. pylori in the phase 3 PHALCON-HP trial.
In patients without a clarithromycin- or amoxicillin-resistant strain, the H. pylori eradication rate was 84.7% for Voquezna Triple Pak and 78.5% for Voquezna Dual Pak, compared with 78.8% for a triple therapy containing the traditional proton pump inhibitor lansoprazole.
In patients who had a clarithromycin-resistant strain of H. pylori, the eradication rates were 65.8%, 69.6% and 31.9% for Voquezna Triple Pak, Dual Pak and lansoprazole triple therapy, respectively.
Based on the data, clinicians view vonoprazan combos as a better option than standard of care, indicating they would use the Phathom drug in 51% of their patients, Jefferies analyst Caleb Ezell said in a Wednesday note. The data and the physician feedback have led Ezell to project $200 million in peak sales in H. pylori infection.
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Vonoprazan bears FDA designation as a qualified infectious disease product, which comes with an additional five years of market exclusivity. Combine that with a five-year new chemical entity exclusivity and potentially six months of pediatric exclusivity, the drug could be free from generic competition for at least 10 and a half years after approval, Ezell said.
That extended protection is critical for vonoprazan’s potential expansion into gastroesophageal reflux disease, which as Ezell noted, boasts over 6 billion proton pump inhibitor doses a year. In addition, Ezell believes the drug could nab an approval in erosive esophagitis in the first quarter of 2023 given the positive phase 3 data unveiled in October.