CD8A and neoplasm: Although the CD8+ T cell proportion was elevated in tumor sites, their ability to secrete the antitumor cytokines interferon γ (IFNγ), tumor necrosis factor β (TNFβ), T-bet and granzyme B was reduced compared to that of the CD8+ T cells in the PBMCs, while PD-1 was more frequently expressed on CD8+ T cells in PBMCs (Figure 3E).