Advances in PD-1/PD-L1 signaling pathway in tumor immune evasion and its clinical significance

With the deep understanding of tumor immune microenvironment， people find that immune evasion of tumor cells is the main factor of tumor progression. PD-1/PD-L1 signal pathway is a negative immune costimulatory molecule found in recent years which plays an important role in tumor immune evasion. This review briefly summarizes the mechanism of PD-1/PD-L1 signal pathway in tumor immune evasion and research progress of their antibodies in the treatment of tumor， which may provide new ideas and methods for tumor immunotherapy.