These memory CD8+ T cells can provide long-term immunity against pathogens and cancers, as they can rapidly replenish effector CD8+ T cells upon restimulation.316 However, in the setting of cancer, chronic stimulation by antigens and/or inflammation causes their differentiation into a dysfunctional or exhausted phenotype, resulting in failure of cancer eradication by T cells in many patients. This evidence concerns the gene CD8A and cancer.