CCR4 and neoplasm: Several members of the tumor necrosis receptor family superfamily [6] (TNFRSF) including TNFR2 [7], GITR [8], OX-40 [9], and 4-1BB [10, 11], chemokine receptors (CCR4 [12], CCR8 [13]) and co-inhibitory receptors (CTLA-4 [14–17], PD-1 [18, 19], LAG-3 [20], and Tim-3 [21]) appear to have enhanced expression on intra-tumoral Treg. While mAbs to some of these targets (CTLA-4, PD-1, CCR4 and CCR8) have anti-tumor effects by acting on Treg, the other targets are frequently expressed on activated Tconv populations and have not yet proven useful for the augmentation of tumor immunity.