The selective killing effect of Ad-mediated CD combined with the TK suicide gene system on HCC cells in vitro and in vivo was studied by constructing the double suicide gene system AD-VEGFp-CDglyTK containing vascular endothelial growth factor promoter (VEGFp), thereby confirming that the combined suicide gene system of TK/GCV and CD/5-FC driven by VEGFp can effectively inhibit the growth of HCC cells, which may provide a potential therapeutic strategy for the treatment of HCC [82]. This evidence concerns the gene CTLA4 and hepatocellular carcinoma.