Cancer immunotherapy by targeting immune checkpoints: mechanism of T cell dysfunction in cancer immunity and new therapeutic targets

J Biomed Sci. 2017 May 25;24(1):35. doi: 10.1186/s12929-017-0341-0.


Immune checkpoints or coinhibitory receptors, such as cytotoxic T lymphocyte antigen (CTLA)-4 and programmed death (PD)-1, play important roles in regulating T cell responses, and they were proven to be effective targets in treating cancer. In chronic viral infections and cancer, T cells are chronically exposed to persistent antigen stimulation. This is often associated with deterioration of T cell function with constitutive activation of immune checkpoints, a state called 'exhaustion', which is commonly associated with inefficient control of tumors and persistent viral infections. Immune checkpoint blockade can reinvigorate dysfunctional/exhausted T cells by restoring immunity to eliminate cancer or virus-infected cells. These immune checkpoint blocking antibodies have moved immunotherapy into a new era, and they represent paradigm-shifting therapeutic strategies for cancer treatment. A clearer understanding of the regulatory roles of these receptors and elucidation of the mechanisms of T cell dysfunction will provide more insights for rational design and development of cancer therapies that target immune checkpoints. This article reviews recent advance(s) in molecular understanding of T cell dysfunction in tumor microenvironments. In addition, we also discuss new immune checkpoint targets in cancer therapy.

Keywords: Cancer immunotherapy; Immune checkpoint; New therapeutic targets; T cell exhaustion.

Publication types

  • Review

MeSH terms

  • Animals
  • Cell Cycle Checkpoints
  • Humans
  • Immunotherapy*
  • Mice
  • Neoplasms / therapy*
  • T-Lymphocytes / immunology*
  • Tumor Microenvironment / immunology*