The objective is to provide access to tofersen to participants with SOD1-ALS with the most rapidly progressive disease.
Administered as intrathecal bolus injection
Other Name: BIIB067
Key Inclusion Criteria: - Medically able to undergo the program procedures, as determined by the treating healthcare professional (HCP). - Weakness attributable to ALS and associated with a mutation in the SOD1 gene (SOD1-ALS). - Amyotrophic Lateral Sclerosis Functional Rating Scale - Revised (ALSFRS-R) decline faster than 2.0 points per month (points/month) at most recent assessment, with slope calculated as: [(48) - (ALSFRS-R score at entry)] / [months since symptom onset].
Key Exclusion Criteria: - Previous or current participation in a clinical trial of tofersen. - Use of an investigational medicinal product (IMP) for amyotrophic lateral sclerosis (ALS) within 5 half-lives of the IMP before the first dose of tofersen. - Participant's primary place of residence is outside of the country of treatment.
NOTE: Other protocol defined Inclusion/Exclusion criteria may apply