Abstract
Programmed death-1 (PD-1) is a cell surface receptor that functions as a T cell checkpoint and plays a central role in regulating T cell collapse. The binding of PD-1 to its ligand programmed death-ligand 1 (PD-L1) activates downstream signaling pathways and inhibits T cell activation in the perspective of immune system mechanism and regulation in tumor progression. It is well reported that tumors adopt certain immune-checkpoint pathways as a mechanism of resistance against immune cells such as T cells that are specific for tumor antigens. Indeed, the PD-1/PD-L1 pathway controls the induction and maintenance of immune tolerance within the tumor microenvironment. Thus, the PD-1/PD-L1 checkpoint regulation appears to be of extreme importance as well as the immunotherapy targeting that via and the using of PD-1/PD-L1 inhibitors that have changed the scenario of brain cancer treatment and survival. Here, we review the mechanism of action of PD-1 and PD-L1, the PD/PDL-1 signaling pathway involved in the progression of brain tumors, and its application as cancer immunotherapy counteracting tumor escape in central nervous system.