|
Back to 2014 Annual Meeting Posters
Interferon Expressing Oncolytic Adenovirus for Esophageal Cancer
Christopher J. Larocca*, Amanda Oliveira, Julia Davydova, Masato Yamamoto
Surgery, University of Minnesota, Minneapolis, MN
Introduction: Esophageal cancer remains a highly lethal malignancy with a low overall survival rate. In recent years, Western countries have seen a rapid increase in the incidence of esophageal adenocarcinoma. We have already demonstrated the effectiveness of cyclooxygenase-2 controlled conditionally replicative adenoviruses (CRAd) in esophageal adenocarcinoma cell lines in both in vitro and in vivo models. We now hypothesize that CRAds designed to express interferon alpha (IFN) could provide for increased cell killing capabilities. Additionally, when used as part of combination therapy with chemotherapy and radiation we hope to exploit IFN's properties as a chemoradiotherapy sensitizer to overcome barriers of conventional regimens for esophageal adenocarcinoma.
Methods: An infectivity enhanced IFN-expressing CRAd was designed and generated (5/3 Cox2 CRAd ΔE3 ADP IFN). Crystal violet assays were used to determine the in vitro cytocidal effects of the virus across multiple esophageal cancer cell lines (OE19, OE33, and TE7) when compared to three control vectors. Furthermore, the IFN-expressing CRAd was used in conjunction with varying doses of cisplatin and radiation as part of a combination regimen.
Results: Genetic modification of the virus capsid (Ad5/Ad3) was used to overcome esophageal adenocarcinoma's low expression of the primary adenovirus receptor and improve infectivity. The virus was also armed with the adenoviral death protein (ADP) to maximize adenoviral spread.
At low viral titers, the IFN-expressing CRAd had a much improved cytocidal effect compared to its otherwise identical counterpart that expressed luciferase instead of IFN. Furthermore, the IFN-expressing CRAd had an equivalent cytocidal effect as a non-selective IFN-expressing virus at later time points. The IFN-expressing CRAd also greatly outperformed the standard control adenovirus (Ad5 Wt).
The combination of the IFN-expressing CRAd with chemoradiation outperformed all monotherapy treatments (virus alone, chemotherapy alone, radiation alone) across all cell lines tested. Of note, when chemotherapy and radiation were tested in the OE19 cell line, increasing concentrations of cisplatin (up to 9 μM) and doses of radiation (up to 16 Gy) were unable to yield a complete cytocidal effect. Importantly, it was not until the addition of the IFN-expressing CRAd to the chemoradiotherapy regimen that total cancer cell death was achieved.
Conclusion: We have demonstrated that an IFN-expressing CRAd has a potent cytocidal effect across multiple esophageal cancer cell lines. When used as part of a combination regimen with chemotherapy and radiation, the IFN-expressing CRAd affords greatly increased cancer cell death. Given these promising results, we are currently testing the IFN-expressing CRAd in an in vivo setting.
Back to 2014 Annual Meeting Posters
|
