PDCD1 and neoplasm: Various mechanisms accounted for IL-35 pro-tumor role: promotion of myeloid cell accumulation in tumors and angiogenesis (7, 13), enhancement of neutrophil infiltration and inflammation (12), facilitation of tumor cell transendothelial extravasation and metastatic colonization (10, 14), and contribution to T cell exhaustion/dysfunction by induction of expression of PD1, TIM3, and LAG3 inhibitory receptors in tumor infiltrating lymphocytes (8).