The FDA decision on argenx SE’s (ARGX) Efgartigimod, proposed for the treatment of generalized myasthenia gravis, is expected on December 17.Myasthenia gravis (MG) is an autoimmune disease characterized by elevated level of antibodies that target neuromuscular junction proteins, often causing debilitating and potentially life-threatening muscle weakness. There are approximately 65,000 people in the United States living with the disease.Efgartigimod in intravenous formulation is designed as a first-in-class investigational antibody fragment to target neonatal Fc receptor (FcRn), thereby reducing IgG antibodies.If approved, Efgartigimod will have to compete with Alexion Pharmaceuticals Inc’s (ALXN) Soliris. Analysts expect Efgartigimod to achieve peak sales of $1 billion.Argenx has licensed the development and commercial rights of Efgartigimod in Greater China, covering the mainland, Hong Kong, Taiwan and Macau to Zai Lab Limited (ZLAB) under an agreement signed in January 2021.ARGX closed Friday’s trading at $276.10, down 0.29%.