Besides, studies have shown that both PD-1 and PD-L1 were significantly upregulated in OS patients and correlated with the prognosis (8, 9), and a recent study found that blockade of PD-1/PD-L1 signaling dramatically promoted the activity of cytotoxic T lymphocytes, inhibiting the tumor growth and increasing the survival rate in the mouse model of metastatic OS (10). This evidence concerns the gene CD274 and neoplasm.