Preexisting Autoimmune Disease: Implications for Immune Checkpoint Inhibitor Therapy in Solid Tumors

: The use of immune checkpoint inhibitors (ICIs) is rapidly expanding to the treatment of many cancer types, both in the metastatic setting and as an adjuvant to other therapies. Clinical trials using ICIs have largely excluded patients with preexisting autoimmune diseases due to concerns for increased toxicity. However, emerging evidence shows that ICIs may be considered in some patients with autoimmunity. This review discusses the commonalities between clinical autoimmune diseases and ICI-induced immunotherapy-related adverse events, and summarizes the existing case series that describes patients with solid tumors who have a preexisting autoimmune disease. This review also discusses which patients with autoimmunity could be considered reasonable candidates for ICI therapy.