Zai Lab Limited announced that its partner argenx SE announced that the U.S. Food and Drug Administration (FDA) has approved VYVGART™ (efgartigimod alfa-fcab) for the treatment of generalized myasthenia gravis (gMG) in adult patients who are anti-acetylcholine receptor (AChR) antibody positive. These patients represent approximately 85% of the total gMG population1. With this regulatory milestone, VYVGART is the first and only FDA-approved neonatal Fc receptor (FcRn) blocker. Generalized myasthenia gravis is a rare and chronic neuromuscular disease characterized by debilitating and potentially life-threatening muscle weakness. VYVGART is a human IgG1 antibody fragment that binds to FcRn, resulting in the reduction of circulating immunoglobulin G (IgG) antibodies. The action of AChR autoantibodies at the neuromuscular junction is a key driver of gMG2. The approval of VYVGART is based on results from the global Phase 3 ADAPT trial, which were published in the July 2021 issue of The Lancet Neurology. The ADAPT trial met its primary endpoint, demonstrating that significantly more anti-AChR antibody positive gMG patients were responders on the MG-ADL scale following treatment with VYVGART compared with placebo (68% vs. 30%; p<0.0001). Responders were defined as having at least a two-point reduction on the MG-ADL scale sustained for four or more consecutive weeks during the first treatment cycle. There were additionally significantly more responders on the Quantitative Myasthenia Gravis (QMG) scale following treatment with VYVGART compared with placebo (63% vs. 14%; p<0.0001). Responders were defined as having at least a three-point reduction on the QMG scale sustained for four or more consecutive weeks during the first treatment cycle. VYVGART had a demonstrated safety profile in the ADAPT clinical trial. The most common adverse events in ADAPT were respiratory tract infection (33% vs 29% placebo), headache (32% vs 29% placebo), and urinary tract infection (10% vs. 5% placebo). Marketing Authorization Applications for efgartigimod for the treatment of gMG are currently under review with Japan’s Pharmaceuticals and Medical Devices Agency (PMDA) and the European Medicines Agency (EMA), with anticipated decisions from each agency in the first quarter and second half of 2022, respectively.