Efgartigimod Treatment Improves Function for People With Generalized Myasthenia Gravis 

Efgartigimod (Argenx, Boston, MA) vs placebo treatment of acetylcholine receptor-antibody positive (antiAChR+) generalized myasthenia gravis (gMG) resulted in clinical improvement for 67.7% vs 29.7% of those treated (P<.0001). 

Activities of daily living were measured with the Myasthenia Gravis-Activities of Daily Living (MG-ADL) scale and improvement was considered a decrease of at least 2 points for at least 4 weeks. These data come from the phase 3 double-blind placebo-controlled ADAPT trial (NCT03669588) and were published in the Lancet Neurology. 

Additionally, 40% of people treated with efgartigimod achieved minimal symptom expression defined as MG-ADL scores of 0 (symptom free) or 1, compared with 11.1% of participants who received placebo. Among antiAChR+ participants who had response to treatment, 84.1% had a clinically meaningful improvement within the first 2 weeks of treatment. 

Efgartigimod has been submitted for approval by the Food and Drug Administration (FDA) for the treatment of gMG with a target decision date of December 17, 2021. If approved, efgartigimod will be the first-and-only approved FcRn antagonist.

“In the ADAPT trial, we observed clinically meaningful improvements in the first 2 weeks of dosing in a majority of patients treated with efgartigimod,” said James F. Howard, Jr., MD, professor of Neurology, Medicine and Allied Health, Department of Neurology, The University of North Carolina at Chapel Hill School of Medicine. “These results are important for the MG community, and I am hopeful efgartigimod will provide a first-in-class, targeted therapy that can be dosed in an individual way for people living with this chronic autoimmune disease.”

Treatment-emergent adverse events occurred at similar rates in both treatment groups with headache and nasopharyngitis most common. Serious adverse events were more frequent with placebo (8%) than with efgartigimod treatment (5%) and the discontinuation rate was low at 4%. Efgartigimod is an FcRn antagonist, is an investigational antibody fragment designed to reduce disease-causing immunoglobulin G (IgG) antibodies and block the IgG recycling process.