CD8A and cancer: Metformin and phenformin are indeed known to inhibit the activity of pro-tumor MDSC and macrophages, and to enhance the generation of anti-tumor memory CD8+T-cell, consequently improving the efficacy of anti-cancer vaccine and PD-1 blockade (Eikawa et al., 2015; Kim et al., 2017; Scharping et al., 2017).