The FDA decision on the expanded use of argenx SE's (ARGX) VYVGART for the treatment of adults with acetylcholine receptor antibody (AChR-Ab) seronegative generalized myasthenia gravis is due on May 10, 2026.Generalized myasthenia gravis (gMG) is a rare, chronic neuromuscular autoimmune disease caused by pathogenic IgG antibodies targeting the neuromuscular junction (NMJ), resulting in impaired neuromuscular transmission, as well as debilitating and potentially life-threatening muscle weakness and chronic fatigue.Approximately 80% of patients with gMG have detectable antibodies against the acetylcholine receptor (AChR) in their serum and are classified as AChR antibody (AChR-Ab) seropositive gMG. In contrast, approximately 20% of patients with gMG do not have detectable serum antibodies against AChR and are referred to as AChR-Ab seronegative gMG.VYVGART is already approved for the treatment of generalized myasthenia gravis (gMG) in adult patients who are anti-acetylcholine receptor (AChR) antibody positive. The drug generated net sales of $4.2 billion in full-year 2025, compared to $2.2 billion in 2024.Zai Lab has an exclusive license agreement with argenx to develop and commercialize VYVGART in mainland China, Hong Kong, Macau, and Taiwan (collectively, Greater China).ARGX closed Monday's trading at $783.74, up 0.45%.