Heavy! The world's first FcRn antagonist was approved by the FDA

The U.S. Food and Drug Administration (FDA) has approved efgartigimod (Vyvgart, argenx) for the treatment of adult patients with systemic myasthenia gravis (gMG) who test positive for anti-acetylcholine receptor (AChR) antibodies. Efgartigimod is a pioneering targeted therapy drug that has been approved to provide a new treatment option for patients with rare diseases.

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gMG is a rare chronic autoimmune neuromuscular disorder that causes debilitating and potentially life-threatening muscle weakness and seriously impairs a patient's independence and quality of life. Most patients with gMG have immunoglobulin G (IgG) antibodies, which most often target skeletal muscle nicotinic acetylcholine receptors. Efgartigimod is an antibody fragment designed to reduce pathogenic IgG antibodies in gMG patients and block the recirculation process of IgG. The novel drug binds to the neonatal Fc receptor (FcRn), which is widely expressed throughout the body and plays a central role in saving IgG antibodies from degradation. Blocking FcRn lowers IgG antibody levels.

In the Phase 3, randomized, placebo-controlled ADAPT trial, 187 adult patients with gMG were enrolled. Against the background of a stable dose of at least one MG drug, all patients with myasthenia gravis - activities of daily living score of at least 5 points. Within 26 weeks, 84 patients were randomly assigned to receive efgartigimod 10 mg/kg and 83 received a matched placebo. Both treatments are infusions 4 times per cycle, 1 infusion per week. Efgartigimod treatment reduces the burden of disease in gMG patients and improves the physical strength and quality of life of patients. In addition, these benefits are observed at an early stage and are reproducible and long-lasting.

Lead investigator Professor James Howard said that compared to other treatments that may take 4, 6 or even 10 months to take effect, efgartigimod is a drug that has a very rapid onset of treatment and its side effect characteristics are very similar to placebo. Patients with gMG have always needed new treatment regimens that target the underlying pathogenesis of the disease and are supported by clinical data, and the approval of efgartigimod represents an important new development for gMG patients and families affected by the disease. The therapy has the potential to reduce the burden of disease on gMG and change the way the disease is treated.

Compiled by: FDA Approves New Myasthenia Gravis Drug - Medscape - Dec 17, 2021.