(62) showed that a subset of histone deacetylase 6 (HDAC6)-deficient Th17 cells enhanced the production of IFN-γ by CD8+ T cells, which correlated with higher PD-1 and PD-L1 expression in hepatocellular carcinoma (HCC) tumor cells. This evidence concerns the gene PDCD1 and hepatocellular carcinoma.