Xenon Pharmaceuticals announced a voluntary pause in enrolling new patients in its phase 3 major depressive disorder and bipolar disorder trials of azetukalner after reports of neuropsychiatric adverse events. The company said patients already randomized will continue in the studies, including associated open-label extension cohorts. Separately, Xenon said the FDA has begun reviewing azetukalner for focal-onset seizures, with the epilepsy read-through historically supporting investor expectations for the Kv7 potassium channel opener. Xenon’s update, however, shifted attention to safety in psychiatric populations, where event signals emerged after earlier testing. Management indicated the adverse events were consistent with the drug’s known safety profile and noted work on potential dosing modifications. Trial enrollment has been suspended while the pause is assessed, with data expected on the remaining population into early 2027.