|Efgartigimod alfa (ARGX-113) is a first-in-class antibody fragment designed for the treatment of patients with severe autoimmune diseases associated with high levels of pathogenic immunoglobulin G (IgG) autoantibodies . It binds to the IgG receptor, major histocompatibility complex class I-like Fc receptor (FcRn, the protein product of the FCGRT gene). Efgartigimod alfa inactivates FcRn's IgG binding ability (the FcRn-IgG interaction normally protects IgG from degradation) thus facilitating accelerated catabolism of native pathogenic autoantibodies [3,5]. The mechanism of this drug action is discussed more comprehensively in Roopenian and Akilesh (2007)  and Vaccaro et al. (2005) .