PDCD1 and neoplasm: The levels of two pro-inflammatory cytokines, interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α), are significantly reduced in tumor microenvironments containing CD8+LAG-3+PD-1+ T-cells compared with those in the tumor milieu containing LAG-3+ or PD-1+CD8+ T-cells (Huang et al., 2015).