筋疾患の治療の進歩

抄録

This article reviewed the representative papers of treatment of myasthenia gravis (MG) published in 2019. We focused on novel molecular target drugs for MG treatment. Rituximab has shown to be a remarkable effective drug for MG, especially seropositive for autoantibodies against muscle–specific kinase. Unfortunately, rituximab is not available for MG treatment in Japan. Eculizumab was effective and well tolerated in patients with anti–acetylcholine receptor (AChR) antibody–positive refractory generalized MG (REGAIN study). Eculizumab is now approved by the Japanese government for the treatment of AChR refractory MG. Eculizumab is expected to have treatment benefits for refractory and generalized MG patients, although Eculizumab is the most expensive treatment for MG in Japan. In addition, improvements with eculizumab in activities of daily living, muscle strength, functional ability, and quality of life in REGAIN were maintained through 3 years ; 56% of patients achieved minimal manifestations or pharmacological remission. Efgartigimod is designed as a first–in–class investigational antibody fragment to target the neonatal Fc receptor (FcRn). Phase II clinical trials revealed that efgartigimod was well–tolerated in MG patients, with no serious or severe adverse events reported. All patients treated with efgartigimod showed a rapid decrease in total IgG and anti–AChR autoantibody levels, and assessment using all 4 efficacy scales consistently demonstrated that 75% showed a rapid and long–lasting disease improvement.