Biogen's targeted ALS treatment is reversing decline in some patients. Can more be helped?

Biogen's targeted ALS treatment, Qalsody (tofersen), is the first drug to treat a genetic form of ALS caused by SOD1 gene mutations, which accounts for about 2% of all ALS cases.

In clinical trials and real‑world studies, Qalsody has not only slowed decline in many patients but also led to stabilization or improvement of function in roughly 25–27% of treated participants over about three years of therapy.

Some patients have regained previously lost strength and respiratory function, and long‑term data show extended survival and reduced neurodegeneration markers such as neurofilament.

The drug is administered by monthly intrathecal (spinal canal) injections and is not a cure; patients must continue treatment to maintain benefits.

Because SOD1‑ALS is rare, current eligibility is limited to a small subset of ALS patients, but these results have sparked renewed optimism that earlier diagnosis, broader genetic screening, and combination therapies may help more people in the future.