Several studies have showed that targeting the expression of PD-1 on the T lymphocytes and PD-L1 on the cancer cells can inhibit the function or cause dysfunction of the T lymphocytes, induce apoptosis of T lymphocytes, and promote the production of the cytokine interleukin 10 (IL-10) in the tumor microenvironment (Sun et al., 2015). This evidence concerns the gene PDCD1 and neoplasm.