Xenon Announces Azetukalner NDA Submission to FDA for Focal Seizures and Provides Update on Psychiatry Clinical Program

VANCOUVER, BC and BOSTON, MA, Sept. 17, 2026 (GLOBE NEWSWIRE) — Xenon Pharmaceuticals Inc. (Nasdaq: XENE), a neuroscience-focused biopharmaceutical company dedicated to drug discovery, clinical development, and commercialization of life-changing therapeutics for patients in need, today announced it has submitted a New Drug Application (NDA) for azetukalner in focal seizures (FS) to the U.S. Food and Drug Administration (FDA).

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The NDA submission is based on positive clinical data from two global, randomized, double-blind, placebo-controlled trials for azetukalner in focal seizures, including the Phase 2b X-TOLE study and Phase 3 X-TOLE2 study. Across the two studies, treatment with all four doses of azetukalner demonstrated a statistically significant reduction from baseline in monthly seizure frequency compared with placebo, and azetukalner was generally well-tolerated with a consistent safety profile observed in both studies. These safety results are comparable with the long-term safety observed in the X-TOLE open label extension (OLE) study, with the entire epilepsy program generating more than 1,500 patient-years of safety and exposure data.

“We are very pleased to announce completion of the NDA submission for azetukalner in focal seizures in epilepsy. Azetukalner has the potential to deliver much needed innovation to treat people living with focal seizures, with strong efficacy, a differentiated mechanism of action that may enable rational polytherapy, once-daily dosing with no dose adjustments for other antiseizure medications, and a consistent and generally well-tolerated safety profile,” said Ian Mortimer, President and CEO of Xenon. “This is a significant milestone for Xenon as we continue to work toward the potential of our first approval and launch and becoming a fully integrated neuroscience company.”

The ongoing Phase 3 X-TOLE3 and X-ACKT studies of azetukalner in focal seizures and primary generalized tonic-clonic seizures (PGTCS), respectively, continue to enroll patients to support expansion of use across seizure types and global regions.

In addition, the Company announced today that it has implemented a voluntary pause on enrollment for new patients in its ongoing clinical studies in major depressive disorder (MDD) and bipolar depression (BPD), following an analysis of neuropsychiatric adverse events in these studies. Participants currently enrolled in the randomized controlled psychiatry studies and associated OLE studies will continue on study. The observed events, the rate of these events and their severity, are consistent with the known safety and tolerability profile of azetukalner and its mechanism; however, such adverse events had not previously been seen in the Phase 2 X‑NOVA clinical study in MDD. The enrollment pause is being implemented as a precautionary measure by Xenon in consultation with its Data Safety Monitoring Board (DSMB) and is expected to be temporary. Xenon is working to evaluate potential dosing modifications to help mitigate these adverse events. This voluntary action does not impact ongoing epilepsy studies.