CD274 and melanoma: More recently, two clinical trials of antibodies which target the negative immune checkpoint molecule PD-1 on T cells and its ligand B7-H1/PD-L1 on tumor cells were unexpectedly successful, with durable response rates of 20–25% in advanced melanoma, renal cell cancer, and nonsmall-cell lung cancer (NSCLC) [2, 4, 5], suggesting the critical role of enhancing immunity in cancer therapy.