免疫チェックポイント阻害薬による神経関連有害事象—新たな疾患概念の提唱

Distinctive Disease Entity of Neurological Adverse Events Associated with Immune Checkpoint Inhibitors

免疫チェックポイント阻害薬（ICIs）による神経筋関連有害事象は稀ではあるものの時に重篤化することがあり，適切な診断，管理が重要である。髄膜脳炎，多発神経根炎，重症筋無力症，筋炎が特に重要で，これらが免疫関連有害事象として発症した場合，臨床像，経過，検査所見，治療が通常と異なることがあり，正しい理解が求められる。ICIsを中止し，ステロイド治療を行うことが推奨されており，反応性は良好である。

Abstract

Neurological immune-related adverse events (irAEs) associated with cancer treatment with immune checkpoint inhibitors (ICIs) are infrequent but are sometimes serious and require prompt diagnosis and management. Among diverse clinical subsets, meningoencephalitis, polyradiculoneuropathy, myasthenia gravis, and myositis are particularly important. The clinical presentation may be different from that of patients with those conditions unrelated to ICIs. A broad range of clinical symptoms complicates the diagnosis of autoimmune encephalitis. The clinical features of aseptic meningitis induced by classical drugs and ICIs are different. Polyradiculoneuropathy, usually diagnosed as Guillain-Barré syndrome or chronic inflammatory demyelinating polyneuropathy, requires prompt diagnosis. However, the clinical manifestations and laboratory findings of patients with polyradiculoneuropathy may be unique and differ from those in the preexisting disease subset. Although myasthenia gravis and myositis are usually independent diseases, it is often difficult to diagnose myasthenia gravis or myositis independently when the disease is associated with irAEs. We believe that inflammatory myopathy associated with ICIs is a novel disease entity accompanied by possible biomarkers of anti-striational antibodies. Discontinuation of immune checkpoint inhibitors and steroid treatment is recommended with a good response. A correct understanding of neurological adverse events is required for the best management of cancer patients.