PDCD1 and neoplasm: In concert with CXCL10 and –11, CXCL9 stimulates immune cells through Th1 polarization and activation leading to IFN-γ, TNF-α induction [both cytokines whose expression was also found to be up-regulated by anti-TIGIT:mIgG2a + anti-PD-1 combination treatment in our studies (Figures 5, 6)], and IL-2-mediated anti-tumor activity of cytotoxic T cells, NK cells and macrophages (27).