Autoimmune Complications of Immune Checkpoint Inhibitors for Cancer

Immune checkpoint inhibitors, a type of immunotherapy used in the treatment of cancer, can cause adverse events due to excess immune activation. These immune-related adverse events (irAEs) may have similar clinical presentations to classic rheumatologic diseases, including inflammatory arthritis, sicca syndrome, myositis, and polymyalgia rheumatica. As use of immune checkpoint inhibitors increases, rheumatologists are increasingly faced with caring for these patients. Treating patients with irAEs is complicated due to the concomitant advanced stage cancer and theoretical concerns about effects of immunosuppression in this context. First, background on cancer immunotherapy in general, immune checkpoint inhibitors and their mechanism of action, and irAEs will be provided. Next, diagnosis and management of rheumatologic irAEs will be reviewed. Finally, the use of immune checkpoint inhibitors in patients with pre-existing autoimmune disease will be discussed.