CD274 and cancer: The incubation of cancer cells with DNA-damaging agents, including the topoisomerase inhibitors camptothecin [208], DOX [209,210,211], and irinotecan [212] or the alkylating agents carboplatin [213,214], cisplatin [215,216,217,218,219], and oxaliplatin [220], leads to up-regulation of PD-L1.