CD274 and neoplasm: Therefore, the PD-1/PD-L1 pathway has been recognized as a negative modulator of immune response by restricting the function of TILs in the tumor immune microenvironment (TIME), and inhibition of the PD-1/PD-L1 pathway by administration of mAbs can reactivate the function of cytotoxic T lymphocytes (CTLs) and their ability to attack tumor cells (25).