Tofersen (BIIB067) is an antisense oligonucleotide that mediates RNase H-dependent degradation of superoxide dismutase 1 (SOD1) mRNA to reduce the synthesis of SOD1 protein. Tofersen can be used for the research of amyotrophic lateral sclerosis (ALS).In Vitro: Tofersen targets the SOD1 mRNA using antisense oligonucleotides (ASOs) that bind to the SOD1 mRNA by Watson-Crick base pairing. Tofersen activates RNase H1 that destroys the targeted RNA[2].