The two faces of CD8*T cells in cancer immunotherapy

In most cancers, CD8+T cells are associated with a good clinical prognosis and their infiltration correlates with the response to immunotherapy. Thus, a subpopulation of CD8+T cells called resident memory T cells (CD103+) are localized in contact with tumors via their interaction with E-Cadherin positive tumor cells. They play a role in the efficacy of cancer vaccines and their infiltration correlates with the efficacy of anti-PD-1 immunotherapy. They are preferentially induced by mucosal immunization and certain chemokine receptors such as CXCR6 expressed by these cells may explain their preferential migration in the microenvironment of lung and head and neck tumors. On the other hand, in some cancers, such as kidney and prostate cancer or glioblastoma, CD8+T cells are not associated with a good clinical outcome. In renal cell carcinoma, the interaction between CD27 expressed by CD8+T cells and CD70 present on tumor cells paradoxically leads to an apoptosis signal of these cells which may explain the lack of impact of these cells on the clinical outcome of patients. Blocking this interaction could constitute a new target for immunotherapy.