Editing T cell (section)

====During cancer====
{{See also|Immunosenescence#T cell functional dysregulation as a biomarker for immunosenescence|label 1 = Immunosenescence}}

During cancer T cell exhaustion plays a role in tumor protection. According to research some cancer-associated cells as well as tumor cells themselves can actively induce T cell exhaustion at the site of tumor.<ref>{{cite journal|vauthors = Zelle-Rieser C, Thangavadivel S, Biedermann R, Brunner A, Stoitzner P, Willenbacher E, Greil R, Jöhrer K|display-authors = 6|title = T cells in multiple myeloma display features of exhaustion and senescence at the tumor site|language = En|journal = Journal of Hematology & Oncology|volume = 9|issue = 1|pages = 116|date = November 2016|pmid = 27809856|pmc = 5093947|doi = 10.1186/s13045-016-0345-3|doi-access = free}}</ref><ref>{{cite journal|vauthors = Lakins MA, Ghorani E, Munir H, Martins CP, Shields JD|title = Cancer-associated fibroblasts induce antigen-specific deletion of CD8 <sup>+</sup> T Cells to protect tumour cells|journal = Nature Communications|volume = 9|issue = 1|pages = 948|date = March 2018|pmid = 29507342|pmc = 5838096|doi = 10.1038/s41467-018-03347-0|bibcode=2018NatCo...9..948L }}</ref><ref>{{cite journal|vauthors = Conforti L|title = The ion channel network in T lymphocytes, a target for immunotherapy|journal = Clinical Immunology|volume = 142|issue = 2|pages = 105–106|date = February 2012|pmid = 22189042|doi = 10.1016/j.clim.2011.11.009}}</ref> T cell exhaustion can also play a role in cancer relapses as was shown on leukemia.<ref>{{cite journal|vauthors = Liu L, Chang YJ, Xu LP, Zhang XH, Wang Y, Liu KY, Huang XJ|title = T cell exhaustion characterized by compromised MHC class I and II restricted cytotoxic activity associates with acute B lymphoblastic leukemia relapse after allogeneic hematopoietic stem cell transplantation|journal = Clinical Immunology|volume = 190|pages = 32–40|date = May 2018|pmid = 29477343|doi = 10.1016/j.clim.2018.02.009}}</ref> Some studies have suggested that it is possible to predict relapse of leukemia based on expression of inhibitory receptors PD-1 and TIM-3 by T cells.<ref>{{cite journal|vauthors = Kong Y, Zhang J, Claxton DF, Ehmann WC, Rybka WB, Zhu L, Zeng H, Schell TD, Zheng H|display-authors = 6|title = PD-1(hi)TIM-3(+) T cells associate with and predict leukemia relapse in AML patients post allogeneic stem cell transplantation|language = En|journal = Blood Cancer Journal|volume = 5|issue = 7|pages = e330|date = July 2015|pmid = 26230954|pmc = 4526784|doi = 10.1038/bcj.2015.58}}</ref> Many experiments and clinical trials have focused on immune checkpoint blockers in cancer therapy, with some of these approved as valid therapies that are now in clinical use.<ref>{{Cite news|url=https://medi-paper.com/us-fda-approved-immune-checkpoint-inhibitors-approved-immunotherapies/|title=U.S. FDA Approved Immune-Checkpoint Inhibitors and Immunotherapies|date=2018-08-21|work=Medical Writer Agency {{!}} 香港醫學作家 {{!}} MediPR {{!}} MediPaper Hong Kong|access-date=2018-09-22|language=en-GB}}</ref> Inhibitory receptors targeted by those medical procedures are vital in T cell exhaustion and blocking them can reverse these changes.<ref>{{cite journal|vauthors = Bhadra R, Gigley JP, Weiss LM, Khan IA|title = Control of Toxoplasma reactivation by rescue of dysfunctional CD8+ T-cell response via PD-1-PDL-1 blockade|journal = Proceedings of the National Academy of Sciences of the United States of America|volume = 108|issue = 22|pages = 9196–9201|date = May 2011|pmid = 21576466|pmc = 3107287|doi = 10.1073/pnas.1015298108|doi-access = free|bibcode = 2011PNAS..108.9196B}}</ref>