Indeed, a reduced ex vivo expression of perforin and granzyme B among CD8+ TIL in HCC patients has been described.18 However, in contrast to HCV‐specific CD8+ T cells that also lack expression of perforin ex vivo, TAA‐specific CD8+ T cells were mostly incapable of up‐regulating perforin after antigen‐specific expansion.21 This evidence concerns the gene PRF1 and hepatocellular carcinoma.