Zorevunersen's Phase 3 EMPEROR readout in Dravet syndrome will determine whether 4-year OLE efficacy translates into a registrational win

Bull

A positive outcome would be statistically significant reduction in convulsive seizure frequency versus sham control across the 52-week treatment period, consistent with the durable seizure reductions and cognition/behavior improvements seen through four years in OLE. This would validate zorevunersen's SCN1A upregulation mechanism in a controlled setting, support NDA completion, and underpin a potential U.S. commercial launch in early 2028 — transforming Stoke from a clinical-stage company into a near-commercial one with a first-in-class approved therapy for Dravet syndrome.

Bear

The most likely failure mode is a loss of effect magnitude in a controlled trial relative to the uncontrolled OLE: placebo/sham response in a pediatric seizure study can be substantial, potentially narrowing or eliminating the treatment effect seen in open-label data. Secondary risks include heterogeneity in SCN1A variant response across the broader Phase 3 population, tolerability signals that complicate the benefit-risk profile, or a trial not adequately powered to capture the cognitive/behavioral endpoints that have been a key differentiator — any of which would jeopardize NDA submission and the commercial timeline.