PDCD1 and neoplasm: Data published in recent years have shown that immune‐checkpoint inhibitors (ICIs), including programmed cell death 1 (PD‐1)‐inhibitor monotherapy, combination therapy with PD‐1 and cytotoxic T‐lymphocyte associated protein 4 (CTLA4) inhibitors, and combination therapy with a PD‐1 inhibitor and an antibody against vascular endothelial growth factor, can maximize the anti‐tumor effects of T cells by relieving tumor cell‐dependent inhibition of T cell functions.4, 5, 6