Tofersen for SOD1 ALS.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative condition affecting the motor system. The heterogenous nature of ALS complicates trial design. Genetic forms of ALS present an opportunity to intervene in a less heterogeneous population. ALS associated with gain of function mutations in SOD1 make 'knock-down' strategies an attractive therapeutic approach. Tofersen, an antisense oligonucleotide that reduces expression of SOD1 via RNAase mediated degradation of SOD1 mRNA, has shown robust effects on ALS biomarkers. While a Phase III trial of tofersen failed to meet its primary end point, open label extension data suggests that tofersen slows progression of SOD1 ALS.