FDA approves new drug to treat generalized myasthenia gravis (gMG)

James F. Howard Jr., MD, professor in the UNC Department of Neurology, was principal investigator of the phase 3 trial for the experimental drug efgartigimod, developed by Belgian pharmaceutical company Argenx.

Argenx, a Belgian drug maker, recently announced that the U.S. Food and Drug Administration (FDA) has approved VYVGART™ (efgartigimod alfa-facab) 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 population. With this regulatory milestone, VYVGART is the first-and-only FDA-approved neonatal Fc receptor blocker.

Generalized myasthenia gravis is a rare and chronic autoimmune disease where communication between nerves and muscles is disrupted, causing debilitating muscle weakness. Efgartigimod is an antibody fragment that binds to the neonatal Fc receptor resulting in a reduction of disease-causing immunoglobulin G antibodies.

"People living with gMG have been in need of new treatment options that are targeted to the underlying pathogenesis of the disease and supported by clinical data," said James F. Howard Jr., MD, Professor of Neurology and Principal Investigator for the ADAPT trial. "Today's approval represents an important new advance for gMG patients and families affected by this debilitating disease. This therapy has the potential to reduce the disease burden of gMG and transform the way we treat this disease."

"The gMG community has long-awaited the FDA approval of VYVGART, especially for those patients who struggle with basic personal tasks such as speaking, chewing and swallowing food, brushing teeth and hair, and in some severe cases, breathing," commented Samantha Masterson, President and Chief Executive Officer of the Myasthenia Gravis Foundation of America. "We thank Argenx for its continued commitment to the gMG patient community, which led them to deliver this much-needed new treatment option with the potential to change the lives of many gMG patients."

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.