BEDFORD & CAMBRIDGE, Mass. — Stoke Therapeutics and Biogen presented new data on their investigational Dravet syndrome treatment, zorevunersen, during the 16th European Paediatric Neurology Society (EPNS) Congress. The analysis, based on a modeled dosing regimen set for evaluation in an ongoing Phase 3 trial, showed improvements in cognition and behavior at 68 weeks.
The findings, drawn from earlier Phase 1/2a and open-label extension (OLE) studies, suggest that patients receiving the zorevunersen dosing regimen planned for the Phase 3 EMPEROR study experienced cognitive and behavioral gains not typically seen in patients receiving standard anti-seizure treatments. The results contrast with those from a natural history study, known as BUTTERFLY, which tracked patients with Dravet syndrome treated only with current standard therapies.
Dravet syndrome is a rare and severe genetic epilepsy that begins in infancy and is associated with treatment-resistant seizures and significant developmental delays. Despite the availability of several anti-seizure medications, no therapies currently approved address the underlying causes of the disease or its cognitive and behavioral symptoms.
Dr. Andreas Brunklaus, a pediatric neurologist at the Royal Hospital for Children in Glasgow and a study investigator, noted the significance of the new data. “Natural history data show the limitations of treating this disease with anti-seizure medicines,” he said. “The zorevunersen data give us early evidence that this genetically targeted approach could result in both additional seizure control and improvements in cognition and behavior.”
Previous trial results showed sustained reductions in seizure frequency and gains in cognitive and behavioral measures over two years of treatment. Patients who received initial loading doses of 70mg followed by 45mg maintenance doses appeared to have stronger outcomes. The drug has generally been well-tolerated in studies so far.
The EMPEROR Phase 3 study is now evaluating effects on five specific areas of adaptive behavior—receptive and expressive communication, interpersonal relationships, coping skills, and personal skills—based on results from the earlier trials.
Biogen’s Katherine Dawson, head of the company’s therapeutics development unit, emphasized the need for new options. “Most patients with Dravet syndrome continue to experience seizures despite the best available treatments, and there are no approved therapies for the cognitive and behavioral aspects of the disease,” she said.
An estimated 38,000 people are living with Dravet syndrome in the U.S., U.K., major EU countries, and Japan. The zorevunersen program is among the most advanced efforts to develop a disease-modifying treatment for the condition.
