Biogen and Stoke Therapeutics have signed a deal to co-develop and sell Stoke’s experimental drug for Dravet syndrome, outside the U.S.

Stoke Therapeutics Inc. and Biogen Inc. said Tuesday they are entering a collaboration to develop and commercialize a treatment for Dravet syndrome, a severe form of epilepsy that starts in childhood.

Biogen has bolstered its pipeline by licensing ex-US rights to a drug for Dravet syndrome – a rare form of epilepsy – from Stoke Therapeutics in a deal that included an upfront payment of $165 million.

In exchange for $165 million, Biogen now has access to zorevunersen, a potential first-of-its-kind treatment for Dravet syndrome.

Biogen has entered a collaboration with Stoke Therapeutics to develop and and commercialise zorevunersen to treat Dravet syndrome in all territories outside Canada, Mexico and the US. Dravet syndrome is a genetic developmental and epileptic encephalopathy characterised by cognitive and behavioural impairments and recurrent seizures.

Under terms of the deal, Stoke will spearhead global development of zorevunersen, while Biogen will receive exclusive rights to commercialize the treatment outside of North America.

Biogen and Stoke Therapeutics have announced a partnership aimed at advancing a disease-modifying treatment for Dravet syndrome, with the deal worth $550m.

Biogen (NASDAQ:BIIB) and Stoke Therapeutics (NASDAQ:STOK) said on Tuesday they are collaborating to develop and commercialize zorevunersen, an investigational treatment for Dravet syndrome, in territories outside the United States,