Document Type : Review article
Authors
1
MSc. Department of Immunology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
2
Professor of Immunology, Immunology Research Center, Bu‐Ali Research Institute, Mashhad University of Medical Sciences, Mashhad, Iran. Professor of Immunology, Department of Immunology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
3
MSc. Department of Parasitology and Mycology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
4
Assistant professor of Immunology, Immunology Research Center, Bu‐Ali Research Institute, Mashhad University of Medical Sciences, Mashhad, Iran. Assistant professor of Immunology, Department of Immunology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Abstract
Immune checkpoints are immune receptors that negatively regulate immune responses and T-cells through multiple mechanisms. Immune checkpoints are upregulated in various tumor cells and allow cancer cells to escape and evade specific antitumor immune surveillance. One of the most prominent of these checkpoints is PD-1/PD-L1 pathway. The binding of PD-L1 expressed by tumor cells to PD-1 on the surface of tumor-specific cytotoxic T lymphocytes (CTL) leads to CTL suppression. Moreover, PD-L1 can dramatically increase tumorigenesis and metastasis, so the measurement of expression levels of PD-1/PD-L1 is lucrative for predicting the cancer prognosis. Accordingly, one of the most novel and important techniques that emerged as a revolutionary therapy to achieve potential anti-tumor immune responses is blocking these immune checkpoints by specific monoclonal antibodies called immune checkpoint inhibitors (ICIs). Since 2014, seven anti-PD-1/PD-L1 monoclonal antibodies have been approved by the Food and Drug Administration (FDA) for therapy in an extensive spectrum of cancers. Immune checkpoint therapy has been demonstrated to be a promising strategy for controlling advanced various types of cancers. Hence, studying these new approaches to cancer therapy is recommended. The present review will briefly summarize the interaction between PD-1/PD-L1 pathway and tumor cells as well as the effect of PD-1/PD-L1 inhibitors in cancer.
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