E1B-55K-deleted adenovirus expressing E1A-13S by AFP-enhancer/promoter is capable of highly specific replication in AFP-producing hepatocellular carcinoma and eradication of established tumor

Here, we constructed a recombinant replication-competent adenovirus (rRCAd; AdAFPep/Rep) that expresses both E1A-13S driven by the alpha-fetoprotein (AFP) enhancer/promoter (AFPep) lacking any silencers in the 5'-flanking region of the AFP gene, and 55K-deleted E1B driven by the cytomegalovirus (CMV) promoter. We then examined the feasibility of gene therapy utilizing this virus for AFP-producing hepatocellular carcinoma (HCC). AdAFPep/Rep lysed all the AFP-producing HCC cell lines (HuH7, HepG2, PLC/PRF/5 (P5)) examined at a multiplicity of infection (MOI) as low as 0.1 and did not lyse primary human hepatocytes (Hc) at a MOI as high as 100, indicating that the rRCAd virus can lyse AFP-producing HCC cells with a higher specificity and potency than previously reported. Furthermore, this virus was capable of complete eradication of a preestablished HuH7-cell tumor by a single intratumoral injection of 10(8) plaque-forming units (pfu) of AdAFPep/Rep. Thus, AdAFPep/Rep may be applicable for clinical use.