PDCD1 and neoplasm: Based on these observations, an anti-PD-1 antibody with pure blocking activity would be more desirable, since an anti-PD-1 antibody with FcγR-binding activity can mediate cross-linking between PD-1+ T-cells and FcγR+ macrophages, induce the depletion of PD-1+ T effector cells, and thus compromise the T-cell activity of tumor growth inhibition (9, 37, 74) (Figure 1B).