Since IFNγ was found to play an essential role in the adaptive immune resistance of tumors as an inducer of PD-L1 on tumor cells [12], i.e. on ovarian cancer cells in vitro [13], we further performed correlation analyses between IFNγ and PD-1 or PD-L1 to investigate the regulative role of the PD-1 pathway in OC. Here, PDCD1 is linked to ovarian cancer.