CD8A and neoplasm: Aside from ICIs, metformin, in combination with various anticancer therapies, showed promising effects on the infiltrated CD8+ TILs, e.g., metformin combined with an oncolytic HSV-1 virus, C-REV, enhanced the infiltration of CD8+ TILs accompanied by a significant increase in IFNγ production in bilateral Pan02 tumor-bearing mice [40].