CD8A and neoplasm: Results from the phase III CheckMate 067 study in advanced melanoma suggest that the combination of PD-1 and CTLA-4 receptor blockade may improve antitumor activity [23] through increased INF-γ production, enhanced CD4/CD8 tumor-infiltrating T-effector cells, and decreased intra-tumor T regulatory cells, as compared to either agent alone [24].