A brain biotech slumps even with ‘best case’ seizure data

Positive results from a mid-stage study apparently weren’t enough to raise investor confidence in Praxis Precision Medicines and its experimental drug for epilepsy.

A brain-focused biotechnology company saw a double-digit stock drop Monday morning even as it unveiled clinical trial results that some on Wall Street considered top notch.

The mid-stage study recruited adults with either of two epileptic disorders, and gave them all a drug from Praxis Precision Medicines once a day for about two months. According to Praxis, by the end of the treatment period, median seizure frequency had declined 56%.

The company also said its drug, now called vormatrigine, appeared fast-acting, with a little over half of the participants experiencing a 50% reduction in frequency in the first week of treatment. Around 22% achieved “seizure freedom,” meaning they stopped having seizures, at the eight-week mark.

Participants were taking an average of two other anti-seizure medications, which, Praxis noted, made it very challenging to show its drug was having a positive effect. More than 80% were on a long-established type of treatment known as “sodium channel blockers,” with 30% taking a product sold by the South Korea-based developer SK Biopharmaceutical. Sales of that medicine, Xcopri, rose 47% between the first quarter of 2024 and the same period this year, where they reached 133.3 billion won or roughly $96 million.

While there are many sodium channel blockers already available for the two types of seizures — “focal onset” and “tonic-clonic” — at the center of Praxis’ study, they often come with drawbacks. Some elicit side effects like dizziness or drowsiness, or need to be administered through time-consuming titrations. Xcorpi, for instance, has “set the efficacy bar” in focal onset seizures, yet its “slow titration scheme” and adverse events have “driven clinicians to reserve its use” for the most severe, hard-to-treat cases of focal onset seizures, according to TD Cowen analyst Ritu Baral.

In a client note last month, Baral, who covers Praxis, wrote that key doctors in the neurology field have “repeatedly underscored” the need for new sodium channel drugs that avoid these problems. That’s what Praxis is hoping to do with its medicine, which is taken orally.

Praxis said vormatrigine was generally well tolerated. Across 61 patients, researchers saw treatment-emergent adverse events in 36. Most were mild or moderate, with the most common being dizziness, drowsiness and headache. There were three cases each of “severe” and “serious” adverse events, though they all resolved. Almost one in four participants discontinued the study.

Baral, in her note, wrote the “best case” scenario for Praxis is that its study would show a 55% or greater reduction in median monthly seizure frequency among patients with focal onset seizures. Such a result, Baral predicted, could lead to a 30-40% bump in the company’s stock price.

Instead, Praxis shares were down 13% by late Monday morning, to trade just under $47 apiece.

To Brian Abrahams, an analyst at RBC Capital Markets, the seizure reductions seen in the trial could make vormatrigine “reasonably competitive.” Abrahams, though, covers Xenon Pharmaceuticals, which is developing its own seizure medication that could rival Praxis’. The analyst argued in a client note Monday that not only is Xenon years ahead in development, but Praxis’ data do not yet show a “clear efficacy advantage.” And even if vormatrigine does eventually win approval, it would likely be used in combination with generics or other branded products like Xenon’s azetukalner.

Praxis plans to present more detailed data from the trial later this month, at an epilepsy medical conference in Portugal.

Praxis released the trial results alongside its latest earnings report. For the three-month period from April through June, the company reported a net loss of $71.1 million, up from the $32.7 million loss recorded during the second quarter last year.

Source: https://www.biopharmadive.com/news/praxis-epilepsy-data-trial-ion-channel/756709/