Bedford, Mass. — Stoke Therapeutics has completed enrollment of 162 patients in the Phase 3 EMPEROR study evaluating zorevunersen as a potential disease-modifying treatment for Dravet syndrome, the biotechnology company said.
Stoke plans to begin a rolling New Drug Application submission to the U.S. Food and Drug Administration in the first quarter of 2027. A Phase 3 data readout is expected in the third quarter of 2027, with completion of the rolling submission planned for the second half of the year.
Zorevunersen is an investigational RNA medicine designed to restore protein expression and address the underlying genetic cause of Dravet syndrome.
About 50 of the 162 patients enrolled in the United States, United Kingdom and Japan have completed 28 weeks of treatment, when the study’s primary endpoint of change in major motor seizure frequency is measured.
An additional cohort of about 30 patients is being enrolled in Europe, with the final patient expected to enter the study in August. Stoke said no patients have discontinued treatment.
“The rapid enrollment of the Phase 3 EMPEROR study reflects the severity of Dravet syndrome and the potential of zorevunersen to address the underlying genetic cause of the disease, resulting in reduced seizure burden and the opportunity for more neurotypical development,” said Ian F. Smith, Chief Executive Officer and Director of Stoke Therapeutics. “With five years of clinical data for zorevunersen and strong awareness among patients, families and investigators, we completed enrollment in just 10 months and are on track for a Phase 3 data readout in the third quarter of 2027. We expect to complete our rolling NDA submission shortly thereafter based on these data, and we continue to build our organization and capabilities to deliver zorevunersen to all patients in the U.S. who may benefit following a potential FDA approval and U.S. launch by early 2028.”
“The Dravet Syndrome Foundation was founded to advance understanding of this devastating disease and fight for better treatments. We are deeply gratified to have played a role in designing and delivering clinical studies to create potential new medicines, from early natural history studies of Dravet syndrome through to the successful enrollment of this first-of-its-kind Phase 3 study,” said Mary Anne Meskis, Chief Executive Officer of the Dravet Syndrome Foundation. “This progress reflects our shared commitment to improving outcomes for patients, and we look forward to continuing to advance zorevunersen with the goal of building a very different future for people living with Dravet syndrome and their families.”
EMPEROR is a global, double-blind, sham-controlled study. Its primary endpoint is the change in major motor seizure frequency at Week 28. The study will remain blinded through the end of the 52-week treatment period, when secondary endpoints assessing cognition and behavior will also be evaluated.
The primary analysis population includes 162 patients in the United States, United Kingdom and Japan who receive either zorevunersen or a sham procedure administered through lumbar puncture.
Stoke expects data from those patients to provide the final information needed to complete its planned U.S. regulatory submission.
The additional European cohort is enrolling patients in Germany, France, Spain and Italy and uses a needle-prick sham control. Sites are also being activated in China, where zorevunersen recently received Breakthrough Therapy Status.
Data from the European and Chinese cohorts are not expected to be included in the U.S. application.
