Study of ANX005 in Adults With Amyotrophic Lateral Sclerosis (ALS)

Key Inclusion Criteria: * Diagnosis of ALS according to the World Federation of Neurology revised EI Escorial criteria. * Onset of weakness within 3 years prior to Day 1 visit. * Slow Vital Capacity ≥ 50% of predicted normal adjusted for sex, age, and height (from the sitting position). * ALS Functional Rating Scale-Revised (ALSFRS-R) ≥ 30 at the Screening visit (Week -2). * If female, must be postmenopausal, surgically sterilized, or childbearing potential must agree to use highly effective methods of contraception from Screening until 3 months after the last infusion with study medication. * Males with a woman partner of childbearing potential must agree to use highly effective methods of contraception from Screening until Week until 3 months after the last infusion with study medication. * Documented history of vaccinations within 5 years prior to Screening visit against encapsulated bacterial pathogens or willing to undergo vaccinations. Key Exclusion Criteria: * Clinically significant intercurrent illness, medical condition, or medical history that would jeopardize the safety of the participant, limit participation, or compromise the interpretation of the data derived from the participant. * Participants with body weight \> 150 kilograms. * Antinuclear antibodies (ANA) titer ≥ 1:160 (for either of the 2 ANA results a minimum of 2 weeks apart) during the Screening Period.