Immune-related adverse events of immune checkpoint inhibitors.

  Development and application of anti-CTLA-4 antibody and anti-PD-1 antibody to cancer immunotherapy brought great survival benefits to advanced cancer patients. They have been applied to various cancers such as melanoma, non-small cell lung cancer, renal cell cancer, Hodgkin's disease, and head and neck cancers, and there is no doubt that immunotherapy is becoming a standard therapy as well as surgery, chemotherapy, and radiotherapy. On the other hand, immune-related adverse events (irAEs) have been increasingly reported. Nevertheless, mechanisms of the immune-mediated toxicities are still unclear. There has been a growing interest in the elucidation of the mechanisms. This review describes the general characteristics of irAEs induced by immune checkpoint inhibitors, especially 1. Heterogeneity, 2. Multiplicity, 3. Durability, and 4. Correlativity.