ATHENS, Greece, September 1, 2026
Stoke Therapeutics and Biogen announced presentations of clinical data supporting the potential of zorevunersen, an investigational medicine being developed as a potential disease-modifying treatment for Dravet syndrome, at the 16th European Epilepsy Congress (EEC) taking place September 5-9, 2026, in Athens, Greece. The presentations will include the first medical meeting disclosure of four-year data from ongoing Phase 1/2a open-label extension studies, adding to more than five years of clinical experience with zorevunersen across the Phase 1/2a and extension programs. The companies said the long-term findings continue to support the potential of zorevunersen to address the underlying biology of Dravet syndrome rather than solely reducing seizure activity. The global pivotal Phase 3 EMPEROR study is currently underway, with topline results anticipated in the third quarter of 2027.
Four-Year Data Support Durable Clinical Effects
The EEC presentations will highlight sustained improvements observed with continued zorevunersen treatment, including reductions in seizure burden and improvements in cognition and behavior through 48 months. New exploratory analyses will also examine the treatment’s effects on severe seizure types and quality of life, providing additional insight into the potential broader clinical impact of the investigational therapy. According to the companies, these findings build on earlier Phase 1/2a results and demonstrate continued clinical effects during long-term treatment. Of the 81 patients who received treatment in the Phase 1/2a studies, 93% continued into one of two open-label extension studies, while 77% remained in the extension studies at the four-year data cutoff. Zorevunersen has generally been well tolerated during long-term treatment, with more than 930 doses administered as of July 31, 2026.
Phase 3 EMPEROR Study Underway
The long-term findings are being generated as zorevunersen advances through Phase 3 development in Dravet syndrome. The ongoing global EMPEROR Phase 3 study is designed to further evaluate the safety and efficacy of the investigational medicine and represents the next major clinical milestone for the program. Stoke and Biogen are pursuing zorevunersen as a potential first-in-class disease-modifying therapy, with the goal of addressing the underlying genetic mechanism associated with Dravet syndrome. The treatment is an investigational antisense oligonucleotide designed to increase production of functional NaV1.1 protein from the unaffected copy of the SCN1A gene. This approach is intended to potentially deliver benefits beyond conventional anti-seizure medicines, which primarily focus on controlling seizure activity. Results from the pivotal Phase 3 study are expected in Q3 2027, making the EMPEROR readout a key upcoming catalyst for the program.
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Zorevunersen Targets Underlying Dravet Biology
Dravet syndrome is a severe developmental and epileptic encephalopathy most commonly associated with mutations in one copy of the SCN1A gene, resulting in insufficient NaV1.1 protein in neurons. The condition can cause recurrent seizures alongside significant cognitive, behavioral and developmental impairments, creating substantial challenges for patients and caregivers. Currently, there are no approved disease-modifying therapies specifically addressing the underlying cause of Dravet syndrome. Zorevunersen is designed to increase functional NaV1.1 protein production and potentially influence both seizure control and neurodevelopmental outcomes. The EEC data will therefore be important in assessing whether the improvements observed during earlier development can remain durable with longer treatment. Zorevunersen has received FDA and EMA orphan drug designations, while the FDA has also granted Breakthrough Therapy Designation and Rare Pediatric Disease designation for the program. The companies’ continued presentation of long-term data alongside the ongoing Phase 3 program represents an important step in advancing a potential new treatment approach for patients living with Dravet syndrome.
Source:Stoke Therapeutics, press relese
