FDA Approves Argenx’s Vyvgart Injection for Subcutaneous Use in Myasthenia Gravis

Rare Daily Staff

The U.S. Food and Drug Administration approved Argenx’s Vyvgart Hytrulo, an injection for subcutaneous use for the treatment of generalized myasthenia gravis in adult patients who are anti-acetylcholine receptor (AChR) antibody positive.

Vyvgart intravenous infusion won U.S. and European approval in 2021.

Generalized myasthenia gravis (gMG) is a rare and chronic autoimmune disease where IgG autoantibodies disrupt communication between nerves and muscles, causing debilitating and potentially life-threatening muscle weakness. Approximately 85 percent of people with MG progress to gMG within 24 months, where muscles throughout the body may be affected. Patients with confirmed anti-acetylcholine receptor (AChR) antibodies account for approximately 85 percent of the total gMG population.

Vyvgart Hytrulo is a subcutaneous product combination of efgartigimod alfa, a human IgG1 antibody fragment marketed for intravenous use as Vyvgart, and recombinant human hyaluronidase PH20 (rHuPH20), Halozyme’s Enhanze drug delivery technology to facilitate subcutaneous delivery of biologics. The product is to be administered subcutaneously by a healthcare professional as a single injection in cycles of once weekly injections for four weeks.

“With our broad gMG offering of both a first-in-class infusion and SC injection, we continue to offer an individualized treatment approach and possibility of staying symptom free, while providing patients options of how and where they want to seek treatment,” said Luc Truyen chief medical officer of Argenx.

This FDA approval is based on positive results from the phase 3 ADAPT-SC study, which established the efficacy of Vyvgart Hytrulo by demonstrating a reduction in anti-AChR antibody levels comparable to intravenous Vyvgart in adult gMG patients. ADAPT-SC was a bridging study to the phase 3 ADAPT study, which formed the basis for approval of intravenous Vyvgart in December 2021.

In the ADAPT-SC study, the primary endpoint of noninferiority was met and Vyvgart Hytrulo demonstrated mean total IgG reduction of 66.4 percent from baseline at day 29, compared to 62.2 percent with Vyvgart. Additional key secondary endpoints were met, which were consistent with efficacy measures from the ADAPT study identifying the correlation between total IgG reduction and clinical benefit in gMG.

Vyvgart Hytrulo has a demonstrated safety profile, consistent with the ADAPT clinical trial with the exception of injection site reactions, which were higher with Vyvgart Hytrulo. It was generally well-tolerated with injection site reactions being the most frequent adverse events. All injection site reactions, which are commonly observed with biologics administered subcutaneously, were mild to moderate, and resolved over time.

Vyvgart Hytrulo is expected to be available for patients in the United States in July 2023.