For some malignancies, including NSCLC and melanoma, the upregulation of PD-L1 by tumor cells and PD-1 and CTLA-4 by effector T-cells leads to inhibitory interactions that attenuate tumor-directed T-cell cytotoxicity and antibodies directed at inhibiting these checkpoint interactions have had a profound impact on outcomes. This evidence concerns the gene CTLA4 and neoplasm.