Xenon Pharmaceuticals Shares Plunge 30% Following Trial Enrollment Pause

The clinical setback involves the company's experimental treatment for major depressive disorder and bipolar depression. Following consultation with the Data Safety Monitoring Board, Xenon reported a spectrum of neuropsychiatric adverse events, including speech difficulties, coordination problems, confusion, and isolated psychotic episodes. These symptoms were notably absent during the earlier Phase 2 X-NOVA study.

Market reaction was swift. Deutsche Bank downgraded the stock to Hold, while Needham removed all projected sales for the psychiatric program from its financial models. Despite the halt, the company confirmed that patients already enrolled in the trials will continue their treatment. The firm expects to unblind the X-NOVA2 study at approximately 360 of 450 planned participants, with topline data anticipated in the first quarter of 2027. Law firm Levi & Korsinsky has since initiated an investigation into whether the company provided misleading information regarding the drug's safety profile.