CD274 and neoplasm: The results shown that SEP significantly induced the PD-L1 expression in melanoma cancer tissue, which may partially responsible for the synergistic anti-tumor effects of aPD-L1 and SEP as tumor PD-L1 expression disabling the antitumor function of preexisting tumor antigen-specific T cells has been thought to be prerequisite for αPD-1/αPD-L1 mAb therapy to work19.