Combination with chemotherapy enhances efficacy of E1 double-mutant adnovirus for gene therapy of gallbladder cancer

Advanced gallbladder cancer (GBC) is one of the most difficult cancers to be cured by cmT~nt therapies and new treatments, such as gene therapy, are necessary, but little has been studied Recent studies have introduced E1B mntam adenoviruses fad) focusing on tmnor-specific replication, and clinical results have been promising. We have constructed AxdAdB-3, a E1 double-mutant Ad with a mutant EIA and E1B-55kD deletion and reported on its efficacy for GBC as well as enhanced safety m normal cells. ALMS: We aimed to study the combined effects of this Ad and chemotherapy with 5-fluoronracil (5-FU) on GBC in vivo, METHODS: We compared the replication and the cytopathic effects of AxdAdB-3 in several lines of GBC and prima~y normal cells with those of wild-t3~?e Ad The efficacy in vivo was examined in nude mice with subcataneously implanted or intraperitoneally disseminated GBC Mice were separated into the following groups; contrd, Ad monotherapy, 5-FU monotherapy, and combination therapy of Ad and 5-FU. Ad was intratumorally injected ~br subeutaneons xenografis and intraperitoneally injected for disseminated GBC with or wtdmut intraperitoneal injection of 5FU. RESULTS: Axcka-dB-3 replicated and caused oncolysis as efficient]y as wild-type Ad in several GBC cell lines, whereas it replicated much less effectively in normal cells and had only' a mild cytopathic eitect unlike wild-type Ad in vitro. Furthermore, cytotoxicity of Ax&a-dB-3 in normal cells was milder than AxE1AdB, a E1B55kD deleted Ad. AxdAdB-3 significantly suppressed the growth of subeutaneous GBC xenogmfis and also showed eft~:ctiveness in the treatment of peritoneaily disseminated GBC with significantly prolonged survival Combination therapy with 5-FU further regressed the subcutaneous GBC xenografts and significantly prolonged the survival of mice with disseminated GBC. CONCLUSIONS: E1 double-mntant Ad effectively and selectively replicated and caused oncolysis in GBC in vitro and in vivo with reduced negative eflects on normal cells, Combination therapy wifh 5-FU further enhanced its efficacy in vivo, suggesting a synergistic therapeutic effects of the virotherapy and chemotherapy for GBC.