PD-1/PD-L1 pathway: current researches in cancer

Cancer Immunotherapy has been accompanied by promising results over the past few years. Programmed Cell Death Protein 1 (PD-1) plays a vital role in inhibiting immune responses and promoting self-tolerance through modulating the activity of T-cells, activating Apoptosis of antigen-specific T cells and inhibiting Apoptosis of regulatory T cells. Programmed Cell Death Ligand 1 (PD-L1) is a trans-membrane protein that is considered to be a co-inhibitory factor of the immune response, it can combine with PD-1 to reduce the proliferation of PD-1 positive cells, inhibit their cytokine secretion and induce Apoptosis. PD-L1 also plays an important role in various malignancies where it can attenuate the host immune response to tumor cells. Based on these perspectives, PD-1/PD-L1 axis is responsible for Cancer immune escape and makes a huge effect on Cancer therapy. This review is aimed to summarize the role of PD-1 and PD-L1 in Cancer, looking forward to improve the therapy of Cancer.