CD8A and cancer: The proliferation of CD8+ T cells is closely associated with the reduction in tumor volume observed in patients displaying a favorable response post-treatment.649,650 Furthermore, the efficacy of PD-1 and PD-L1 inhibitors in the management of various cancers like melanoma, lung cancer, and MSI-positive colorectal cancer is closely related to the presence of a substantial mutational load in the TME.651–653 By disrupting tolerance, ICB can unleash pre-existing immune responses against tumors.