A Safety and Efficacy Study of ARGX-119 in Adult Patients With Amyotrophic Lateral Sclerosis (ALS)

Inclusion Criteria: * The participant is at least 18 and ≤80 years of age * The participant is diagnosed with familial or sporadic ALS according to Gold Coast criteria * The participant has a Treatment Research Initiative to Cure ALS (TRICALS) risk profile of ≥ -6.0 to \< -2.0 * Slow vital capacity (SVC) of ≥ 60% of the predicted value according to Global Lung Function Initiative 2012 Exclusion Criteria: * Use of noninvasive ventilation more than 10 hours a day or use of a tracheostomy for ventilatory support * Any history of or current exposure to any gene or cell therapies (off-label use or investigational) for ALS * Pregnant or lactating state or intention to become pregnant during the study