MDSCs were found in multiple tumor models of mice and in patients with cancer to have been able to increase programmed cell death ligand 1 (PD-L1) expression, promote T-cell anergy by interacting with the programmed cell death protein 1 (PD-1) on T cells infiltrating tumor lesions, and in turn to drastically downregulate T cell-mediated antitumor reactivity (Weber et al., 2018). Here, PDCD1 is linked to cancer.