Biogen's ALS drug receives FDA approval for rare form of the disease.

The FDA has granted accelerated approval for Biogen's drug tofersen, which targets a rare and aggressive form of ALS caused by mutations in the SOD1 gene. While the drug failed to meet its main goal of slowing disease progression, it significantly reduced SOD1 protein levels and showed promise in reducing neurofilament light levels, which are more strongly associated with disease severity and progression. Biogen and its co-developer Ionis will conduct further studies to verify the drug's clinical benefits. The approval could pave the way for new research on targeting the genetic cause of ALS, which afflicts an estimated 5,000 new people in the U.S. every year.