08:24 AM EDT, 08/11/2025 (MT Newswires) -- Biogen (BIIB) and Stoke Therapeutics ( STOK ) said Monday they have dosed a first participant in a phase 3 trial evaluating zorevunersen, an investigational antisense oligonucleotide, for the treatment of Dravet syndrome.

The phase 3 trial will evaluate the safety and efficacy of zorevunersen compared to sham over a 52-week period, Biogen and Stoke said.

Biogen and Stoke said they intend to enroll participants between the ages of two and up to 18 with a confirmed variant in the SCN1A gene.

The companies said they will give two 70-milligram loading doses, at day 1 and week 8, followed by two 45-milligram maintenance doses, at week 24 and week 40, to participants in the active treatment arm, to evaluate the primary endpoint of change in major motor seizure frequency at week 28.

Biogen and Stoke will also monitor secondary endpoints of change in major motor seizure frequency at week 52 and change in cognition and behavior as measured by the Vineland-3 subdomains, according to the companies.