BEDFORD, Mass.– Stoke Therapeutics and Biogen said new clinical data on zorevunersen, an investigational treatment for Dravet syndrome, will be presented at the 16th European Epilepsy Congress in Athens, Greece, from Sept. 5-9.
The companies said four-year data from ongoing Phase 1/2a open-label extension studies showed sustained improvements in cognition and behavior, durable reductions in seizures and a generally well-tolerated safety profile.
Zorevunersen is being developed as a potential disease-modifying treatment for Dravet syndrome, a severe genetic form of epilepsy. A global pivotal Phase 3 study, EMPEROR, is underway to evaluate the treatment’s safety and efficacy, with results expected in the third quarter of 2027.
New exploratory analyses from the Phase 1/2a extension studies also examined the treatment’s effects on severe seizure types and quality of life. Severe seizures are a major risk factor for sudden unexpected death in epilepsy.
“Together with the Phase 1/2a results, the ongoing OLE studies provide more than 5 years of clinical data that continue to deepen our understanding of zorevunersen’s long-term safety and benefits,” said Barry Ticho, M.D., Ph.D., Chief Medical Officer of Stoke Therapeutics.
“These data have consistently shown substantial and durable seizure reductions with continued treatment. For the first time at EEC, we will share an additional analysis showing zorevunersen’s effects on the most severe seizure types. Alongside continuing improvements in cognition and behavior over time, these new findings support the potential of zorevunersen to change the course of Dravet syndrome by targeting the underlying genetic cause of the disease,” Ticho added.
“Dravet syndrome is a devastating neurodevelopmental disease that impacts nearly every aspect of daily life for patients and those who care for them,” said Stephanie Fradette, Pharm.D., Head of the Rare Neurology Development Unit at Biogen.
“The data shared at EEC provide continued support for the potential of zorevunersen to give people living with Dravet syndrome the possibility of more neurotypical development. We look forward to discussing these data with the epilepsy community at EEC,” Fradette added.
Following treatment in the Phase 1/2a studies, 75 of 81 patients, or 93%, continued into one of two open-label extension studies. At the four-year data cutoff, 58 of those 75 patients remained in the studies.
As of July 31, more than 930 doses of zorevunersen had been administered, with some patients receiving treatment for more than five years.
The companies said elevated cerebrospinal fluid protein levels occurred in about 94% of patients, with 59% classified as treatment-emergent adverse events. No serious or severe clinical effects associated with the elevated protein levels were reported, and there were no reports of hydrocephalus.
