In a systematic review (Abdel-Wahab et al., 2018) of 123 cancer patients with preexisting autoimmune diseases, after treatment with PD-1/PD-L1 inhibitors, 92 (75%) patients had exacerbations of preexisting autoimmune diseases (41%), de novo irAEs (25%), or both (9%). Here, PDCD1 is linked to cancer.