Review/Advances in Neurological Therapeutics (2023). Advances in treatment of myasthenia gravis

Abstract

The management of generalized myasthenia gravis (gMG) has been improved due to immunotherapy advances, but 20% of individuals with MG are refractory to the conventional therapy. To provide better management of refractory MG patients, new biological drugs are necessary. The Japanese clinical guidelines for MG published in May 2022 include the concept that treatment is often lifelong and should aim to maintain a sufficient quality of life (QOL) and mental health. Minimal manifestations (MM) or better status with an oral prednisolone dose of 5 mg/day or less (MM–5 mg) is recommended as the first goal to achieve favorable QOL. Japan MG study group conducted the fourth largest multi–center survey in 2021, obtained detailed clinical information from 1,710 consecutive MG patients all over Japan. This review summarizes the clinical efficacy, safety, and tolerability of the biological drugs including anti–complement and anti–neonatal Fc receptor inhibitors for generalized MG based on the real–world date of Japan MG study group. Eculizumab was administered in only 3.3% of anti–acetylcholine receptor–positive gMG patients, although 5 years had passed since the approval of eculizumab for gMG in Japan. Eculizumab was preferentially used in severe and refractory gMG patients. The duration of eculizumab treatment was 35 months in average. MG–ADL improved from 9.4±4.9 to 5.9±5.1, and 25 (70%) of the 36 gMG patients were responders. Postintervention status was markedly improved after the eculizumab treatment. In contrast, 36 (2.7%) started efgartigimod among 1,343 gMG patients. Twenty–six patients (72%) had refractory MG. Twenty–one (62%) patients were responders. Efgartigimod can be considered for the treatment of patients with generalized MG who do not achieve minimal manifestations, with a broad flexibility of patient selection and treatment schedules.