CD8A and neoplasm: In another 4T1 murine tumor model, metformin combined with a tumor membrane vesicles (TMVs) vaccine enhances CD8+ TILs infiltration, accompanied by a significant increase in central memory CD8+ T cells, CD8+ IFNγ+ TNF-α+, and CD8+ IFNγ+ IL-2+ compared to control group indicating the activity of CD8+ T cells.