09:05 AM EST, 02/18/2025 (MT Newswires) -- Biogen (BIIB) and Stoke Therapeutics ( STOK ) said Tuesday they have partnered to develop and commercialize zorevunersen, Stoke's investigational treatment for Dravet syndrome, a rare genetic epilepsy.

Stoke will receive $165 million upfront and may earn up to $385 million in milestone payments, along with royalties on sales in Biogen's territories, according to the joint statement.

The companies said they will share development costs, with Stoke covering 70% and Biogen 30%.

A phase 3 trial for zorevunersen, which has been granted the US Food and Drug Administration's Breakthrough Therapy designation, is expected to begin in Q2 with data anticipated in H2 2027.

Stoke will retain rights in the US, Canada, and Mexico, while Biogen will gain exclusive rights elsewhere, they added.

Stoke shares were down more than 2% in recent Tuesday premarket activity while Biogen was up 0.4%.