In a significant pharmaceutical industry deal announced Tuesday, Biogen has secured exclusive rights to commercialize zorevunersen, a promising experimental treatment for Dravet syndrome, outside of North America. The agreement, valued at $165 million upfront, gives Biogen access to what could become the first therapy of its kind for this rare form of epilepsy.
Under the terms of the collaboration with Stoke Therapeutics, Biogen will handle sales of the drug in markets beyond the United States, Canada, and Mexico. The companies will share external development expenses at a 70-30 split, with additional milestone payments to Stoke potentially reaching $385 million. The deal also includes provisions for Biogen to potentially license similar follow-on products.
Zorevunersen, which is scheduled to begin Phase 3 clinical trials this year with results expected in 2027, represents a strategic fit for Biogen as the company faces revenue challenges. The biotech giant has experienced declining sales over recent years, with further decreases projected for 2025, primarily due to weakening performance of its established products like Spinraza and its multiple sclerosis portfolio.
The acquisition aligns with CEO Christopher Viehbacher’s aggressive business development strategy since taking the helm in late 2022. Under his leadership, Biogen has already completed several significant transactions, including the $7.3 billion purchase of Reata
Pharmaceuticals and a $1.2 billion deal for HI-Bio.
Stifel analyst Paul Matteis views the deal favorably, noting its logical alignment with Biogen’s existing rare disease franchise, which includes Spinraza and Skyclarys. The relatively modest upfront investment could yield substantial returns if zorevunersen achieves market success, though physicians indicate the drug will need to demonstrate significant efficacy in clinical trials.
A TD Cowen survey of 25 epilepsy specialists revealed that 60% considered zorevunersen more promising than current Dravet syndrome treatments. However, potential commercial hurdles exist, including the drug’s intravenous administration in a market dominated by oral medications and pricing challenges in international markets.
The drug’s mechanism of action involves antisense oligonucleotide technology, designed to enhance the expression of a specific sodium channel protein linked to Dravet syndrome. Recent clinical data has shown promise, with high-dose treatment significantly reducing convulsive seizure frequency compared to placebo. Regulatory authorities in the United States, Europe, and Japan have approved the Phase 3 trial design.
Biogen estimates the patient population for Dravet syndrome at approximately 38,000 across the U.S., U.K., Japan, and several European countries. Despite the deal’s strategic importance, Biogen’s stock remained relatively stable following the announcement.
For Stoke Therapeutics, the partnership provides crucial support for advancing zorevunersen’s development while maintaining commercial rights in key North American markets. The collaboration marks a significant milestone in the company’s efforts to bring this innovative treatment to patients globally.
The agreement reflects ongoing industry trends of larger
pharmaceutical companies seeking to bolster their pipelines through strategic partnerships with smaller biotechnology firms developing novel therapeutics. Such deals have become increasingly important as established companies look to offset revenue declines from aging product portfolios and maintain competitive positions in the evolving healthcare landscape.