NEW YORK, March 9, 2026, 09:36 EDT
- Xenon said its Phase 3 X-TOLE2 study of azetukalner in focal onset seizures met its main goal
- The company said it plans a U.S. FDA filing in the third quarter of 2026
- Shares jumped sharply in premarket trading after the data update
Xenon Pharmaceuticals Inc said on Monday its experimental epilepsy pill azetukalner cut monthly focal onset seizures in a late-stage trial, sending the company’s shares up more than 40% in premarket trading. William Blair analyst Myles Minter called the readout “unprecedented” in a note to clients. 1
The data land at a sensitive moment for Xenon, which has pinned much of its near-term value on whether azetukalner can support an approval filing this year. The company said it now expects to submit a New Drug Application, or NDA — the package drugmakers file to seek U.S. approval — in the third quarter of 2026. 2
Azetukalner is a Kv7 potassium channel opener, a class aimed at calming overactive nerve firing by keeping those channels open longer. Xenon is developing the drug in epilepsy as well as depression, but the seizure program is the nearer catalyst.
In X-TOLE2, the 25 mg dose showed a 53.2% median percent change from baseline in monthly seizure frequency over 12 weeks, compared with a 10.4% reduction for placebo, Xenon said. The 15 mg dose showed a 34.5% reduction, it added.
Chief executive Ian Mortimer said the company would focus next on its FDA filing and “commercial-readiness activities” ahead of what would be Xenon’s first launch. 3
Jacqueline A. French, a neurologist at NYU Langone Health and chair of the trial’s steering committee, said the results support a “differentiated clinical profile” for azetukalner, pointing to once-daily dosing and no need for titration. 4
Xenon said azetukalner was generally well tolerated, with dizziness the most common treatment-emergent adverse event. Discontinuations due to adverse events were higher in the 25 mg group than in the placebo arm, the company said.
Some analysts framed the readout as a reset point for expectations. Stifel analysts wrote the data represent a “best-case scenario,” and said investors may revisit assumptions around uptake and peak sales. 5
The space is crowded. Praxis Precision Medicines and Rapport Therapeutics are among biotechs running studies in focal epilepsy, a market dominated by older antiseizure medicines with mixed seizure control for many patients. 6
But the next steps are not automatic. The FDA can push back on dose selection, safety labeling, or the size of benefit needed versus existing drugs, and real-world tolerability can look different once a medicine reaches broader use.
Xenon said it will present the X-TOLE2 results as a late-breaking oral session at the American Academy of Neurology meeting in April, and it hosted an investor call on Monday morning.
