CD8A and neoplasm: qRT-PCR was performed on RNA isolated from the MBMs for a 5-gene signature indicative of activated CD8+ cytotoxic T cells, and 5 genes from the aforementioned 6-gene IFNγ mRNA signature (HLA-DRA is only found in humans and was therefore excluded).29,30 Metformin treatment significantly increased the expression of all 11 genes (P < .05 – P < .0001), consistent with improved immune functionality in the tumor microenvironment (Figure 5A and B).