Xenon Pharmaceuticals paused enrollment in its major depressive disorder and bipolar disorder trials of azetukalner after neuropsychiatric adverse events appeared that were not seen in earlier studies. The pause is voluntary, with currently enrolled participants continuing and the company targeting data generation into early 2027. Xenon said the events were consistent with the drug’s known safety profile and mechanism, while regulators are also reviewing azetukalner in focal onset seizures through an NDA submission. The dual-track status—trial pause in psychiatry alongside regulatory review in epilepsy—has shifted investor attention to differentiating safety expectations across indications. The company also discussed the possibility of dosing modifications as a mitigation step, positioning the pause as temporary while it reassesses how to run broader enrollment safely.