A Phase 2 Study to Evaluate AL001 in C9orf72-Associated ALS

Inclusion Criteria: * Confirmation of C9orf72 mutation * Diagnosis of ALS by revised El Escorial criteria * Time since onset of muscle weakness due to ALS ≤36 months at the time of the Screening Visit * Slow Vital Capacity (VC) ≥50% of predicted capacity at the time of the Screening Visit * If taking riluzole, must be on a stable dose of riluzole for at least 30 days prior to the Screening Visit. Riluzole naive participants are allowed. * If taking edaravone, must have completed at least one cycle of edaravone prior to the Screening Visit and plan to continue edaravone during the study. Edaravone naive participants are allowed. * Females must not be pregnant, breastfeeding or planning to conceive within the study period. Males must agree to use acceptable contraception * Capable of providing informed consent at the Screening visit and complying with study procedures throughout the study Exclusion Criteria: * Clinically significant, unstable, medical condition (other than ALS) * Clinically significant heart disease, liver disease or kidney disease * Cognitive impairment or dementia * Current uncontrolled hypertension * History of unresolved cancer * Any experimental gene therapy * Any experimental vaccine (any vaccine against COVID-19 either approved or administered under an Emergency Use Authorization is allowed)