Xenon Pharmaceuticals voluntarily paused new patient enrollment in its phase 3 depression program after reports of adverse events involving psychosis. The company said events were mostly mild or moderate, but the pause reflects how quickly safety signals can disrupt late-stage timelines. The decision halts further recruitment in response to the accumulating reports, leaving existing study participants to continue under protocol-defined monitoring. Phase 3 pauses can also raise questions about trial conduct, statistical power, and the timing of future readouts. The move highlights ongoing sensitivity around neuropsychiatric safety in depression studies, particularly when efficacy and tolerability are both needed for regulatory success. For Xenon, the enrollment stop creates uncertainty in the path to topline data while the company and investigators assess the nature and frequency of events.