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. The gene discussed is CTLA4; the disease is non-small cell lung carcinoma.