Efgartigimod Alfa

Myasthenia gravis (MG) is an autoimmune disorder characterized by significant muscle weakness - particularly in the eye, throat, and extremities - caused by autoantibodies attacking the neuromuscular junction. The production of IgG autoantibodies against acetylcholine receptors (AChRs) is one of the more common pathophysiological mechanisms behind MG, and results in the destruction of these receptors and a reduction in electrical nerve impulses. Efgartigimod alfa is a first-in-class antagonist of the neonatal Fc receptor (FcRn) used in the treatment of MG. IgG antibodies, including the autoantibodies responsible for MG symptoms, can be 'recycled', a process that significantly extends their half-life by evading lysosomal degradation via binding with FcRn. By antagonizing this interaction, efgartigimod alfa prevents this recycling phase and thus decreases the half-life of IgG, effectively lowering circulating levels of IgG autoantibodies against AChRs. Efgartigimod alfa for intravenous use was granted FDA approval on December 17, 2021 and European Commission approval on August 11, 2022. A formulation for subcutaneous use that combines efgartigimod alfa and hyaluronidase was approved by the FDA in June 2023.