Development of a novel oncolytic adenovirus controlled by CDX2 promoter for esophageal adenocarcinoma therapy.

Background: Prognosis of esophageal adenocarcinoma (EAC) is still poor. Therefore, the development of novel therapeutic modalities is necessary to improve therapeutic outcomes in EAC. Here, we report a novel promoter-controlled oncolytic adenovirus targeting CDX2 (Ad5/3-pCDX2) and its specific anticancer effect for EAC.

Methods: We used OE19, OE33, HT29, MKN28, RH30, and HEL299 cell lines. To establish CDX2 overexpressing OE19 cells, pCMV-GLI1 plasmid was transfected to OE19 (OE19 + GLI1). The virus replication and cytocidal effect of replication competent Ad5/3-pCDX2 were analyzed in vitro. Antitumor effect of Ad5/3-pCDX2 was assessed in xenograft mouse models by intratumoral injection of the viruses. Finally, efficacy of combination therapy with Ad5/3-pCDX2 and 5FU was evaluated.

Results: EAC cells and HT29 showed high mRNA levels of CDX2, but not MKN28, RH30, and HEL299. We confirmed that deoxycholic acid (DCA) exposure enhanced CDX2 expression in EAC cells and OE19 + GLI1 had persistent CDX2 overexpression without DCA. Ad5/3-pCDX2 showed stronger cytocidal effect in OE19 + GLI1 than OE19, whereas Ad5/3-pCDX2 did not kill CDX2-negative cells. Ad5/3-pCDX2 was significantly replicated in EAC cells and the virus replication was higher in OE19 + GLI1 and OE19 with DCA compared to OE19 without DCA exposure. In vivo, Ad5/3-pCDX2 significantly suppressed OE19 tumor growth and the antitumor effect was enhanced in OE19 + GLI1 tumor. In contrast, Ad5/3-pCDX2 did not show significant antitumor effect in MKN28 tumor. Moreover, Ad5/3-pCDX2 significantly increased the efficacy of 5FU in vitro and in vivo.

Conclusions: Ad5/3-pCDX2 showed specific anticancer effect for EAC, which was enhanced by bile acid exposure. Ad5/3-pCDX2 has promising potential for EAC therapy in the clinical setting.