A Study to Assess the Safety of ARGX-124 in Healthy Volunteers

A Phase 1, Randomized, Double-Blinded, Placebo-Controlled Study to Investigate the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Immunogenicity of Single and Multiple Ascending Doses of ARGX-124 in Healthy Adult Participants

This study aims to assess the safety of ARGX-124 in healthy adults. Another aim is to measure the amount of ARGX-124 in the blood over time to learn how it acts and moves in the body and how the immune system responds to it. Participants will remain in the study for up to approximately 23 weeks.

Inclusion Criteria:

• Is at least the local legal age of consent and aged 18 to 65 years, inclusive, when signing the ICF.
• Is a female of Nonchildbearing Potential (postmenopausal or surgically sterilized) or a male.
• Has a body weight between 50 and 120 kg and a BMI between 18 and 30.5 kg/m2, inclusive.

Exclusion Criteria:

• Has any current or past clinically meaningful medical or psychiatric condition that, in the investigator's opinion, would confound the study results or put the participant at undue risk.
• Has IgG levels <6.0 g/L at screening.
• Has a history of an immunosuppressive disease or an immunosuppressive condition at screening.
• Previously participated in an ARGX-124, ARGX-213, or efgartigimod clinical study and received at least 1 dose of the study drug.