Trial testing Dravet treatment enrolls children in US, Europe, China
Results from large, late-stage study expected in second half of 2027
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Enrollment has been wrapped up in a large, worldwide, late-stage clinical trial that’s testing the therapy candidate zorevunersen for reducing seizures in children and teens with Dravet syndrome.
According to developer Stoke Therapeutics, which is sponsoring the Phase 3 study, October marked the completion of recruitment of five participants from China. The enrollment of 34 patients in Germany, France, Spain, and Italy was completed in August.
The ongoing EMPEROR trial (NCT06872125) had enrolled 162 patients, ages 2 to 17, across the U.S., the U.K., and Japan in its primary analysis population. The addition of the 39 participants from these other European countries and Asia brings the trial’s total enrollment to more than 200.
“Global enrollment is now complete,” Stoke stated in a company press release announcing its financial results through the end of September and providing business updates, including on its development of zorevunersen. The company said it expects top-line data from the study to be available in the second half of 2027.
Ian F. Smith, Stoke’s CEO and director, said the EMPEROR trial “continues to progress well.”
In fact, data from the study are expected to support a new drug application (NDA) to the U.S. Food and Drug Administration (FDA) in the second half of next year, per the company.
Stoke’s updates included the progress of the global EMPEROR study, which launched in 2025. Participants in the primary group were randomly assigned to receive zorevunersen or a sham treatment for about a year, with the main goal of measuring how the experimental therapy affects seizure rates after approximately six months of follow-up.
According to Stoke, all participants have completed at least eight weeks, or about two months, of treatment, during which they received either two injections of zorevunersen or the sham therapy. Most of the children have been followed for at least six months, and nearly two dozen have finished the initial sham-controlled part of the study, the company noted.
No participants have dropped out of the trial to date, per the developer.
Zorevunersen being tested vs. sham treatment
Stoke also noted that all participants who completed the sham-controlled study have chosen to continue into an open-label extension, in which all will receive zorevunersen and be monitored for long-term outcomes.
“Approximately 110 of 162 enrolled patients have completed their Week 28 visit when the primary endpoint of change in major motor seizure frequency is measured and approximately 20 are through Week 52, the end of the treatment period,” Smith said. “All 20 of these patients are continuing into the open-label extension period of the study and to date, no patients have discontinued treatment.”
Assuming the results are positive, Stoke intends to use the EMPEROR results as a basis to apply for approval of zorevunersen in the U.S. Stoke said it hopes to submit an application before the end of 2027. The company recently met with the FDA to align on details of the planned application, including how cognitive data will be analyzed in the Phase 3 study.
We look forward to the Phase 3 data readout in the third quarter of 2027 and completing our [regulatory] submission [to the U.S. FDA] in the second half of 2027.
“Our NDA planning is on track following our recent discussion with the FDA,” Smith said. “Importantly, the key secondary endpoint of changes in patients’ cognition and behavior will be measured using a multicomponent assessment of four Vineland-3 subdomains. This multicomponent measure reflects the diversity of effects that people with Dravet syndrome experience and how to best evaluate them in a clinical trial.”
Smith added: “We look forward to the Phase 3 data readout in the third quarter of 2027 and completing our NDA submission in the second half of 2027.”
Dravet syndrome is a genetic disorder caused mainly by mutations in the gene that encodes NaV1.1, a protein that regulates nerve function. Zorevunersen is designed to increase production of functional NaV1.1 protein, thereby addressing the underlying cause of the disease. The experimental therapy is given by injection into the spinal canal, and early clinical trials have suggested it may facilitate long-term reductions in seizures for Dravet patients.
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