In the process of tumor development, the combination of PD-1 and PD-L1 will cause tumor immune escape, mainly by inhibiting the activity of tumor-infiltrating lymphocytes, inhibiting the production of cytotoxic T lymphocyte perforin and granular enzymes, reducing the secretion of anti-inflammatory factors, arresting T cell cycle, as well as promoting tumor cell epithelization and tumor infiltration 23. This evidence concerns the gene PRF1 and neoplasm.