Biogen and Stoke Therapeutics Enter into Collaboration to Develop and Commercialize Zorevunersen

• Biogen and Stoke Therapeutics announced a collaboration for the development and commercialization of zorevunersen outside the U.S., Canada, and Mexico.

• The agreement includes a $165 million upfront payment, with potential milestone payments up to $385 million. A Phase 3 study is set to begin in Q2 2025.

Biogen Inc. and Stoke Therapeutics, Inc. have entered into a collaboration to develop and commercialize zorevunersen, an investigational treatment for Dravet syndrome, in all territories outside the U.S., Canada, and Mexico. The agreement grants Biogen exclusive commercialization rights outside these regions, while Stoke retains control over development and commercialization within North America.

Zorevunersen is an antisense oligonucleotide (ASO) therapy designed to target the SCN1A gene, which is implicated in most cases of Dravet syndrome. The condition, a severe genetic epileptic disorder, currently lacks disease-modifying treatments. A Phase 3 registrational study (EMPEROR) is expected to begin in the second quarter of 2025, with pivotal results anticipated in the second half of 2027.

Under the terms of the agreement, Stoke will receive an upfront payment of $165 million, with potential development and commercial milestone payments reaching $385 million. Clinical development costs will be shared, with Biogen covering 30% and Stoke 70%. Additionally, Stoke will receive tiered royalties ranging from low double digits to high teens on potential net sales in Biogen’s licensed territories.

“With Biogen’s deep experience in neurology and track record of success in commercializing high-value disease-modifying medicines for rare genetic diseases globally, we aim to lead the treatment of Dravet syndrome into a new era by delivering zorevunersen to all patients who could benefit,” said Edward M. Kaye, M.D., CEO of Stoke Therapeutics.

Biogen also holds an option to license future ASO products from Stoke that target SCN1A, under separate financial terms. The Phase 1/2a and open-label extension studies for zorevunersen have shown promising results, with reductions in convulsive seizures and improvements in cognition and behavior. The drug has also been granted FDA Breakthrough Therapy Designation, highlighting its potential as a first-in-class disease-modifying therapy for Dravet syndrome.