James Howard Jr, MD, Distinguished Professor of Neuromuscular Disease and Professor of Neurology and Medicine at UNC School of Medicine, discusses the phase 3 trial of efgartigimod in patients with myasthenia gravis, which recently led to the drug’s approval by the US Food and Drug Administration (FDA).

Myasthenia gravis is a chronic autoimmune neuromuscular disease characterized by weakness of the skeletal muscles. Common symptoms include weakness of the muscles that control the eyes, eyelids, facial expressions, chewing, talking, and swallowing. The condition is usually due to the presence of antibodies against acetylcholine receptors in the neuromuscular junction.

In December 2021, the U.S. Food and Drug Administration (FDA) approved efgartigimod for the treatment of generalized myasthenia gravis in adult patients who are anti-acetylcholine receptor (AChR) antibody positive. As Dr. Howard explains, this approval was 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 generalized myasthenia gravis patients were responders on the MG-ADL scale following treatment with efgartigimod alfa compared with placebo (68% vs. 30%). 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. In addition, there were significantly more responders on the Quantitative Myasthenia Gravis (QMG) scale following treatment with efgartigimod alfa compared with placebo (63% vs. 14%).

Efgartigimod alfa was also shown to be relatively safe in this study. The most common adverse events reported in the ADAPT trial were respiratory tract infection (33% vs 29% placebo), headache (32% vs 29% placebo), and urinary tract infection (10% vs. 5% placebo).

To learn more about myasthenia gravis, visit our Myasthenia Gravis Learning Center here.