Biogen rises as FDA clears higher-dose Spinraza for muscle disease

Shares of drugmaker Biogen BIIB.O rise 1.75% to $187.06 premarket

Co says the FDA approved a higher-dose version of Spinraza to treat spinal muscular atrophy, a rare genetic disease that causes severe muscle weakness and can be fatal

The new dosing can be used in both new patients and those already on Spinraza, co says

Says approval was based on a late-stage study showing infants had better movement and motor function than untreated patients, with overall safety similar to the older dose

Co says the high-dose version is already approved in the EU, Switzerland and Japan, and will launch in the U.S. in coming weeks

Shares rose ~15% in 2025