Efgartigimod: Clinical Development of a Novel FcRn Antagonist in the Treatment of Autoimmune Diseases

The neonatal Fc receptor, FcRn, recycles immunoglobulin G (IgG), extending its half-life and serum concentration 1• Efgartigimod is a human IgG1 Fc fragment, a natural ligand of FcRn, engineered for increased affinity for FcRn 2• Efgartigimod was designed to outcompete endogenous IgG, preventing recycling and promoting lysosomal degradation of IgG, without impacting its production 2-5 o Targeted reduction of all IgG subtypes o No impact on IgM or IgA o No reduction in albumin levels o No increase in cholesterol 1.