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Efgartigimod as a Treatment for Generalized Myasthenia Gravis: James F. Howard, MD

The Distinguished Professor of Neuromuscular Disease at UNC School of Medicine spoke to the results of the phase 3 ADAPT trial, and what else he’s like to see investigated with efgartigimod.

“What we also saw was that those who were AChR, MUSK, LRP4, triple-negative patients had similar responses. Now, their numbers are very small; they only represented 20% of the population—and that’s still undergoing analysis—but on the surface, they look to have similar responses as the larger population.”

Recently, data from the phase 3 ADAPT trial (NCT03669588) of efgartigimod were published, showing that the investigational Argenx therapy for generalized myasthenia gravis (gMG) is effective in treating the condition without any concerning safety effects. The full analysis, published by study author James F. Howard, MD, Distinguished Professor of Neuromuscular Disease, and professor of neurology and medicine, University of North Carolina School of Medicine, and colleagues, showed that the drug met the primary end point by improving gMG activities of daily living (MG-ADL) scores for patients with acetylcholine receptor-antibody positive (AChR-Ab+) gMG compared with those in the placebo group (67.7% vs. 29.7%; P <.0001).

The data on the first-in-class investigational antibody fragment to target the neonatal Fc receptor (FcRn) also showed that 40.0% of treated AChR-Ab+ patients achieved minimal or no symptoms compared to 11.1% treated with placebo. All told, 167 patients were randomized, 84 in the efgartigimod group and 83 in the placebo group. Of the full population, 77% (n = 129) were AChR-Ab+.

An open-label extension trial is ongoing, called ADAPT+ (NCT03770403), and there are plans to explore a potential subcutaneous administration of the agent in addition to its current intravenous infusion formulation. As well, the FDA is currently reviewing a biologics license application submitted by Argenx for efgartigimod for the treatment of gMG, with a PDUFA date of December 17, 2021. To find out more about the therapy and its potential to treat gMG and related disorders, NeurologyLive spoke with Howard in depth. He offered his insight into the data from ADAPT, and gave a recap of experience with and knowledge of efgaritigimod throughout its clinical development by Argenx.

REFERENCE
Howard JF, Bril V, Vu T, et al. Safety, efficacy, and tolerability of efgartigimod in patients with generalised myasthenia gravis (ADAPT): a multicentre, randomised, placebo-controlled, phase 3 trial. Lancet Neurol. 2021. 20:526-536.