argenx SE, a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases, announced that Japan’s Ministry of Health, Labour and Welfare (MHLW) has approved Vyvgart (efgartigimod alfa) intravenous infusion for the treatment of adult patients with generalized myasthenia gravis (gMG) who do not have sufficient response to steroids or non-steroidal immunosuppressive therapies (ISTs). Vyvgart is the first-and-only neonatal Fc receptor (FcRn) blocker approved in Japan.

"People living with gMG around the world continue to experience severe disease burden despite treatment with commonly-used therapies. We are extremely proud to deliver the first-and-only approved FcRn blocker in Japan to a broad population of gMG patients, regardless of antibody status," said Tim Van Hauwermeiren, chief executive officer of argenx. “Our commercial teams are ready and motivated to be serving as many people as possible who are living with this debilitating disease and we look forward to collaborating with the Japanese government to enable patient access. With today’s approval of Vyvgart in Japan, the recent US FDA approval, and ongoing review of our application in Europe, we continue to advance rapidly toward achieving our goal of delivering this innovative, targeted treatment option globally.”

Generalized myasthenia gravis is a rare and chronic neuromuscular disease characterized by debilitating and potentially life-threatening muscle weakness. Vyvgart is a human IgG antibody fragment that binds to FcRn, resulting in the reduction of circulating immunoglobulin G (IgG) autoantibodies. The action of IgG autoantibodies at the neuromuscular junction is a key driver of gMG.

The approval of Vyvgart is 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-acetylcholine receptor (AChR) antibody positive gMG patients were responders on the myasthenia gravis activities of daily living (MG-ADL) scale following treatment with Vyvgart compared with placebo (68% vs. 30%; p<0.0001). 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.

There were also significantly more responders on the Quantitative Myasthenia Gravis (QMG) scale following treatment with Vyvgart compared with placebo (63% vs. 14%; p<0.0001). Responders were defined as having at least a three-point reduction on the QMG scale sustained for four or more consecutive weeks during the first treatment cycle.

Vyvgart had a demonstrated safety profile in the ADAPT clinical trial. The most common adverse events in ADAPT were respiratory tract infection (33% vs. 29% placebo), headache (32% vs. 29% placebo), and urinary tract infection (10% vs. 5% placebo).

Vyvgart was approved by the US Food and Drug Administration (FDA) on December 17, 2021 for the treatment of gMG in adult patients who are AChR antibody positive. A Marketing Authorization Application for efgartigimod for the treatment of gMG is currently under review by the European Medicines Agency (EMA), with a decision anticipated in the second half of 2022. argenx is evaluating efgartigimod in six high-need autoimmune conditions, set to expand to ten conditions by the end of 2022.

Vyvgart (efgartigimod alfa-fcab) is a human IgG1 antibody fragment that binds to the neonatal Fc receptor (FcRn), resulting in the reduction of circulating immunoglobulin G (IgG) autoantibodies. It is the first and only approved FcRn blocker. Vyvgart is approved in the United States for the treatment of adults with generalized myasthenia gravis (gMG) who are anti-acetylcholine receptor (AChR) antibody positive and in Japan for the treatment of adults with gMG who do not have sufficient response to steroids or non-steroidal immunosuppressive therapies (ISTs).

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% of people with MG progress to gMG within 24 months, where muscles throughout the body may be affected. Patients with confirmed AChR antibodies account for approximately 85% of the total gMG population.