重症筋無力症の治療の進歩

抄録

The revised version of the guidelines, including both myasthenia gravis (MG) and Lambert Eaton myasthenic syndrome (Japanese MG/LEMS guidelines 2022), were published. The new guidelines include the concept that treatment for MG is often lifelong and should aim to maintain a sufficient quality of life and mental health. The goal of MG treatment is minimal manifestations (MM) or a better status with an oral prednisolone dose of 5 mg/day or less (MM–5 mg). It was reported that approx. 10% to 20% of individuals with MG remain refractory to immunosuppressive therapy, and this high rate plus the side effects of treatment with corticosteroids and other immunosuppressive agents may require new MG treatments. Eculizumab, a humanized monoclonal antibody against the terminal C5 complement molecule, prevents the formation of the membrane attack complex and reduces damage caused by complement mediated acetylcholine receptor (AChR) antibodies. Both the international consensus guidance and the Japanese MG/LEMS guidelines state that eculizumab should be considered for the treatment of severe, refractory, AChR–positive generalized MG. Efgartigimod is an anti–neonatal fragment crystallizable (Fc) receptor immunoglobulin G (IgG)1 Fc fragment. The randomized, double–blind, placebo–controlled, phase III ADAPT trial showed that efgartigimod was well tolerated and efficacious in patients with generalized MG. Efgartigimod is expected to have benefits in not only AChR–positive but also muscle–specific tyrosine kinase–positive and seronegative refractory MG patients in Japan.