The Effect of Efgartigimod’s Approval on the Myasthenia Gravis Landscape: James F. Howard, MD

WATCH TIME: 3 minutes

"The approval of efgartigimod by the FDA is going to again transform our management of myasthenia gravis, without question. The ability of this drug to reduce levels of circulating antibody IgG will provide patients with a new option for therapy, a much safer option for therapy, and one that has been demonstrated in clinical trials to be of substantial durability in its duration of effect."

In mid-December, the FDA approved Argenx’s first-in-class investigational antibody fragment to target the neonatal Fc receptor (FcRn) for the treatment of generalized myasthenia gravis (gMG) in adults who test positive for the anti-acetylcholine receptor (AChR) antibody. The agent, efgartigimod, is being marketed as Vyvgart.

The biologics license application for the Argenx agent was supported by data from the phase 3 ADAPT trial (NCT03669588), in which 167 patients were randomized, 84 to the efgartigimod group and 83 to the placebo group. Of the full population, 77% (n = 129) were acetylcholine receptor-antibody positive (AChR-Ab+). The findings of that study suggest that efgartigimod was well-tolerated and efficacious in treating patients with gMG, with the drug meeting the primary end point by improving gMG activities of daily living (MG-ADL) scores for patients with AChR-Ab+ gMG compared with those in the placebo group (67.7% vs. 29.7%; P <.0001). Additionally, 40.0% of efgartigimod-treated AChR-Ab+ patients achieved minimal or no symptoms compared with 11.1% treated with placebo.

Clinical trial investigator James F. Howard, MD, Distinguished Professor of Neuromuscular Disease, University of North Carolina School of Medicine, told NeurologyLive® in this interview that he anticipates that the approval will have an impact on the use of both plasma exchange and intravenous—and perhaps subcutaneous—immunoglobulin in clinical practice because of efgartigimod’s efficacy.

REFERENCE
FDA Approves New Treatment for Myasthenia Gravis. News release. FDA. December 17, 2021. Accessed December 23, 2021. https://www.fda.gov/news-events/press-announcements/fda-approves-new-treatment-myasthenia-gravis