FDA Approves Efgartigimod for Generalized Myasthenia Gravis
The Food and Drug Administration (FDA) has approved efgartigimod (Vyvgart; Argenx, Boston, MA) for treatment of generalized myasthenia gravis (gMG) in adults with antiacetylcholine receptor antibodies (antiAChR).
“There are significant unmet medical needs for people living with myasthenia gravis, as with many other rare diseases,” said Billy Dunn, MD, director of the Office of Neuroscience, FDA Center for Drug Evaluation and Research. “Today’s approval is an important step in providing a novel therapy option for patients and underscores the agency’s commitment to help make new treatment options available for people living with rare diseases.”
In the phase 3 ADAPT trial (NCT03669588), 68% (44/65) of individuals with antiACHR+ gMG responded to a first cycle of efgartigimod compared with 30% (19/64; P<.0001) of those who received placebo. Response to treatment was defined as a 2 or more point reduction on the Myasthenia Gravis - Activities of Daily Living (MG-ADL) scale for 4 consecutive weeks. Additionally, on the Quantitative Myasthenia Gravis (QMG) scale, which measures muscle strength, 63% of those who received efgartigimod responded to treatment with a 3-point or more reduction for 4 or more consecutive weeks. Only 14% of those who received placebo had improved muscle strength (P<.0001).
“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 (Neuromuscular Disease), Medicine and Allied Health, Department of Neurology, The University of North Carolina at Chapel Hill School of Medicine 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 most common side effects associated with the use of efgartigimod include respiratory tract infections, headache, and urinary tract infections. Because efgartigimod reduces immunoglobin G (IgG) levels, the risk of infections may increase. Hypersensitivity reactions such as eyelid swelling, shortness of breath, and rash have occurred.
Efgartigimod is an antibody fragment that binds to the neonatal Fc receptor (FcRn), preventing FcRn from recycling IgG back into the blood. The medication causes a reduction in overall levels of IgG, including the antiAChR antibodies.