Previous studies also showed that metformin polarised M2-like macrophages to the M1-like phenotype within the tumour microenvironment, which led to the recruitment of CD8+ T-cells into the tumour and reduction in immunosuppressive infiltration of myeloid-derived suppressor cells and regulatory T-cells, which may be mediated by the secretion of proinflammatory cytokines [110,111,112,113]. The gene discussed is CD8A; the disease is neoplasm.