PDCD1 and neoplasm: In line with these observations, Ozao-Choy and colleagues have shown that sunitinib, a VEGFR2 inhibitor, is able to modulate the tumor microenvironment not only by decreasing Treg and MDSC levels inside the tumor but also by down-regulating cytokines, such as IL-10 and TGF-β, and the immune suppressive costimulatory receptors, such as PD-1 and CTLA4 [98].