Research progress of the application of immune checkpoints in tumor radiotherapy

Abstract

Radiation could induce DNA damage, cell death, and changes of tumor phenotype and tumor microenvironment leading to the regulation of immune response. Immune checkpoint signaling pathways are involved in the immune tolerance of anti-microorganism responses and thus limit tissue damage. In the anti-tumor immune response, these pathways are associated with anti-functional activation of specific cytotoxic T cells and also enhance the inhibition effect of immune response, which always result in immune escape. Blockade of the immune checkpoint signaling pathways benefits to the anti-tumor immune responses and could delay tumor progress. As a result, the combination treatment of radiotherapy and immune checkpoint blockade has attracted more attentions in clinical application. This paper reviews the recent research progresses in the radiation effect of immune system, the regulation of immune checkpoints and the combination treatment of radiotherapy and immune checkpoint blockade in tumor therapy, trying to arouse some new clues in cancer therapy. Key words: Radiotherapy; Checkpoint; CTLA-4; PD-1/PD-L1