A Clinical Trial to Investigate the Long-term Safety and Tolerability, Efficacy, Pharmacodynamics, Pharmacokinetics, and Immunogenicity of ARGX-117 in Adults With Multifocal Motor Neuropathy

Inclusion Criteria: * Capable of providing signed informed consent and complying with protocol requirements. Participants must be able to read and write. * Must have completed the double-blinded treatment period of the ARGX-117-2002 trial and considered to be eligible for treatment with ARGX-117. Exclusion Criteria: * Clinically significant uncontrolled active or chronic bacterial, viral, or fungal infection. * Clinical evidence of other significant serious diseases, have had a recent major surgery, or who have any other condition, in the opinion of the investigator, that could confound the results of the trial or put the participant at undue risk. * Currently participating in another interventional clinical study. * Pregnant or lactating or intend to become pregnant during the trial or within 15 months after last dose of the study drug.