[Clinical Features of Myasthenia Gravis as an Immune-related Adverse Event].

Neurological and muscular immune-related adverse events (irAEs) associated with cancer treatment using immune checkpoint inhibitors (ICIs) may show a diverse clinical presentation. Myasthenia gravis (MG) represents a serious irAE associated with the aforementioned therapy. Recent studies have discussed the clinical features of MG that occurs as an irAE (irAE-MG). The incidence of irAE-MG is estimated to be 1%. This complication occurs during the early phase of ICI treatment and rapidly worsens, resulting in severe bulbar muscle involvement and myasthenic crisis and significantly elevated serum creatine kinase levels. MG and myositis, which may occur concomitantly as irAEs are often indistinguishable. Myocarditis is occasionally observed in patients with irAE-MG and can cause severe heart failure and lethal arrhythmias, with a fatal outcome. Kv1.4 antibodies serve as biomarkers of severe irAE-MG and myocarditis. Immunotherapy with corticosteroids is effective for management of irAE-MG and should be initiated promptly. Collaboration between consulting neurologists is necessary for safe management of cancer immunotherapy.