Xenon pauses enrollment in phase 3 depression trials after reports of psychosis and other neuropsychiatric events

Xenon Pharmaceuticals announced it has voluntarily stopped enrolling new patients in its two phase 3 studies of azetukalner for major depressive disorder and bipolar depression.

The decision follows reports of adverse events, including psychosis, confusion, aphasia and ataxia, observed in a small number of participants. Existing participants will continue to receive treatment and be monitored.

Xenon’s chief medical officer noted that similar neuropsychiatric events have been seen in the company’s epilepsy program, where over 1,500 patient‑years of exposure produced only isolated psychosis cases that were short‑lived and reversible.

The company has also filed for FDA approval of azetukalner in focal seizures, indicating the drug’s broader development program continues despite the pause in psychiatric trials.