Tofersen, sold under the brand name Qalsody, is a medication used for the treatment of amyotrophic lateral sclerosis (ALS).

[2] Tofersen is an antisense oligonucleotide that targets the production of superoxide dismutase 1, an enzyme whose mutant form is commonly associated with amyotrophic lateral sclerosis.

[6] Tofersen is indicated to treat people with amyotrophic lateral sclerosis (ALS) associated with a mutation in the superoxide dismutase 1 (SOD1) gene (SOD1-ALS).

[7][8] The effectiveness of tofersen was evaluated in a 28-week, randomized, double-blind, placebo-controlled clinical study in 147 participants with weakness attributable to amyotrophic lateral sclerosis and a superoxide dismutase 1 (SOD-1) mutation confirmed by a central laboratory.

[2][6] Only around 1-2% of ALS cases diagnosed in the United States each year carry the specific SOD1 mutation targeted by the drug.