CD274 and cancer: To this end, high surface expression of MHC-I molecules on cancer cells has been reported to elevate the amount of tumor-reactive CD8+ T-cell to elicit the antitumor immune response.42 Therefore, the combination of PD-L1 antibody and MMC may induce tumor regression by attenuating the immunosuppressive PD-1/PD-L1 signal to achieve maximal immune activation.