PDCD1 and breast cancer: Composition of the inflammatory cell infiltrates in BC also correlates with clinical outcome, where an abundant infiltration of pro-tumorigenic cells is associated with poor outcome, while TME enriched in cells with anti-tumorigenic functions has a favourable effect on patient survival.13–15 Programmed cell death 1 (PD1) and its activating ligand, programmed death ligand 1 (PDL1) act in attenuating the anticancer immune response and promoting T-regulatory cell development and function.