Thus, the d19 backbone was chosen to generate an HCC-specific oncolytic Ad by regulating the expression of E1A with either an enhancer region-modified AFP promoter (a2bm) or hypoxia-responsive variant (Ha2bm) promoter, producing a2bm-d19 and Ha2bm-d19, respectively (Fig. 3A). This evidence concerns the gene DHTKD1 and hepatocellular carcinoma.