Recent evidence shows that increasing SIRT6 activity in tumor cells directly drives naive CD4+ T-cell differentiation toward regulatory T cells, elevates PD-1 expression in CD4+ T cells, and simultaneously upregulates PD-L1 and adenosine production in tumor cells, while reducing IFN-γ and other pro-inflammatory cytokines (151). This evidence concerns the gene SIRT6 and neoplasm.