Inclusion Criteria: 1. A diagnosis of sporadic or familial ALS, defined by the El Escorial criteria (possible, laboratory-supported probable, probable, or definite ALS). 2. ALS onset ≤ 36 months from Screening. 3. Documented meningococcal vaccination not more than 3 years prior to, or at the time of, initiating study treatment. 4. Upright slow vital capacity ≥ 65% predicted at Screening. 5. If on riluzole, participant must be on a stable dose for 30 days; if on edaravone, participant must be on a stable dose for 60 days (2 cycles). 6. Body weight ≥ 40 kilograms at Screening. 7. Contraceptive use by men or women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies. Exclusion Criteria: 1. History of Neisseria meningitidis infection. 2. Human immunodeficiency virus (HIV) infection (evidenced by HIV 1 or HIV 2 antibody titer). 3. Dependence on invasive or non-invasive mechanical ventilation. 4. Previously or currently treated with a complement inhibitor. 5. Exposure to an investigational drug or device within 30 days of Screening or 5 half lives of the study drug, whichever is greater.

• Alexion Pharmaceuticals

NCT04248465 (First Published: 1/27/2020)