A recent meta-analysis of the frequency of irAEs over multiple trials revealed that irAEs occurred in 74% of cancer patients treated with anti–PD-1 or PD-L1 Abs, 89% of patients treated with anti–CTLA-4, 90% of patients in the ICI combination group, and 89% of patients in the ICIs with chemotherapy group (Wang et al., 2017b). This evidence concerns the gene PDCD1 and cancer.