Immune checkpoint inhibitors (ICIs), which target programmed cell death 1 (PD-1) and its ligand (PD-L1), are capable of inducing sustained antitumor effects, ushering in the therapeutic era for multiple malignant neoplasms (Okazaki et al., 2013; Ribas and Wolchok, 2018). This evidence concerns the gene PDCD1 and cancer.