Overview
Efgartigimod is an antibody fragment and a first-in-class neonatal Fc receptor (FcRn) antagonist that is being evaluated for the treatment of patients with severe autoimmune diseases mediated by pathogenic immunoglobulin G (IgG) autoantibodies, including generalized myasthenia gravis (gMG), primary immune thrombocytopenia (ITP), chronic inflammatory demyelinating polyneuropathy (CIDP), and Bullous Pemphigoid (BP). In 2021, Zai Lab was granted exclusive rights to develop and commercialize efgartigimod in greater China by argenx.
Mechanism of Action
FcRn has been shown to bind IgGs and rescue them from lysosomal degradation, extending IgG half-life by about 21 days, compared to IgM or IgA (~5 days), which is not recycled by FcRn. Efgartigimod, an IgG1 Fc fragment, is designed for increased affinity for FcRn. It competes with IgG to occupy FcRn and reduce overall IgG recycling. In preclinical and clinical studies, efgartigimod has been shown to rapidly and consistently reduce IgG levels without impacting IgM, IgA, or albumin.