Pharnext muscle wasting phase 3 hits primary endpoint

Paris Rooftops
Paris, where Pharnext is based (Richard Nahem)

A phase 3 trial of Pharnext’s PXT3003 in a rare, muscle wasting disease has met (PDF) its primary endpoint. The trial linked the fixed-dose combination to a statistically significant improvement on a measure of patient disability.

The condition Pharnext is trying to treat, Charcot-Marie-Tooth type 1A (CMT1A) disease, is a genetic disorder that leads to muscle wasting in the lower legs. Pharnext thinks a fixed-dose combination of the muscle relaxant baclofen, opioid antagonist naltrexone and sugar alcohol sorbitol can improve outcomes in this underserved population by protecting their nerves and inhibiting overexpression of PMP22.

Now, the French biotech has phase 3 data to support its belief in the drug. The 15-month study compared two doses of PXT3003 to placebo in 323 patients with CMT1A. Patients in the high-dose arm performed better on a measure of disability—the Overall Neuropathy Limitations Scale—causing the trial to hit its primary endpoint with a p value of 0.008.

The trial also linked the high dose to improved performance on the 10-meter walk test. Buoyed by the findings, Pharnext is talking up the potential for PXT3003 to rack up blockbuster sales by serving the estimated 100,000 people with mild-to-moderate CMT1A in Europe and the U.S. 

While Pharnext emerged from the trial with positive data, it hit some bumps along the way. The trial enrolled 323 patients, but the endpoint analysis was based on data from 235 subjects. The difference between the two populations stems from “unexpected formulation/stability issues” that resulted in the high-dose arm only including 55 patients. The other two arms had about 90 subjects each.  

Pharnext plans to hold a Type B meeting with the FDA early in 2019, file for approval on both sides of the Atlantic in the second half of the year and bring PXT3003 to market in 2020. 

Pharnext shares closed up 25% following publication of the data.  

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