Argenx Reports Positive Data from Pivotal gMG Study

Rare Daily Staff

Argenx reported Vyvgart met its primary endpoint in a pivotal study in patients with AChR-Ab seronegative generalized myasthenia gravis, showing statistically significant and clinically meaningful improvement in a scale measuring daily living activities compared with placebo.

Argenx said the ADAPT SERON trial is the first global phase 3 study to demonstrate clinically meaningful improvement in disease activity across all three generalized myasthenia gravis (gMG) subtypes — MuSK+, LRP4+, and triple seronegative — underscoring Vyvgart’s potential to be a targeted, effective, safe, and necessary gMG treatment, regardless of autoantibody status.

Vyvgart was well tolerated and safe across AChR-Ab seronegative subtypes and consistent with the established safety profile in patients with AChR-Ab seropositive gMG and other indications. No new safety concerns were identified.

The company said that based on these results, it plans to apply to the U.S. Food and Drug Administration by the end of 2025 to seek an expansion of the Vyvgart label.

gMG is a rare, chronic, neuromuscular autoimmune disease caused by pathogenic IgGs that target the neuromuscular junction, resulting in impaired neuromuscular transmission and debilitating, potentially life-threatening muscle weakness and chronic fatigue.

Vyvgart is a human IgG1 antibody fragment that binds to the neonatal Fc receptor (FcRn), reducing circulating IgG autoantibodies. It is the first approved FcRn blocker in the United States, European Union, China, and Canada for the treatment of adults with gMG who are anti-acetylcholine receptor (AChR) antibody positive, and in Japan for the treatment of adults with gMG who do not have sufficient response to steroids or nonsteroidal immunosuppressive therapies.

“The results of the ADAPT SERON study, the largest study to date of AChR-Ab seronegative gMG, confirm that Vyvgart now has the potential to be a targeted, effective, safe, and necessary treatment for patients living with gMG, regardless of autoantibody status,” said James Howard Jr., professor of neurology, medicine, and allied health at the University of North Carolina at Chapel Hill School of Medicine and principal investigator for the ADAPT SERON trial. “Paired with our existing knowledge, these data demonstrate that pathogenic IgGs are underlying drivers of gMG across patient subtypes. This is a critical advancement in the management of this debilitating and unpredictable disease for patients with limited treatment options.”