Combination treatment with oncolytic Vaccinia virus and cyclophosphamide results in synergistic antitumor effects in human lung adenocarcinoma bearing mice.

Abstract

BACKGROUND:

The capacity of the recombinant Vaccinia virus GLV-1h68 as a single agent to efficiently treat different human or canine cancers has been shown in several preclinical studies. Currently, its human safety and efficacy are investigated in phase I/II clinical trials. In this study we set out to evaluate the oncolytic activity of GLV-1h68 in the human lung adenocarcinoma cell line PC14PE6-RFP in cell cultures and analyzed the antitumor potency of a combined treatment strategy consisting of GLV-1h68 and cyclophosphamide (CPA) in a mouse model of PC14PE6-RFP lung adenocarcinoma.

METHODS:

PC14PE6-RFP cells were treated in cell culture with GLV-1h68. Viral replication and cell survival were determined by plaque assays and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, respectively. Subcutaneously implanted PC14PE6-RFP xenografts were treated by systemic injection of GLV-1h68, CPA or a combination of both. Tumor growth and viral biodistribution were monitored and immune-related antigen profiling of tumor lysates was performed.

RESULTS:

GLV-1h68 efficiently infected, replicated in and lysed human PC14PE6-RFP cells in cell cultures. PC14PE6-RFP tumors were efficiently colonized by GLV-1h68 leading to much delayed tumor growth in PC14PE6-RFP tumor-bearing nude mice. Combination treatment with GLV-1h68 and CPA significantly improved the antitumor efficacy of GLV-1h68 and led to an increased viral distribution within the tumors. Pro-inflammatory cytokines and chemokines were distinctly elevated in tumors of GLV-1h68-treated mice. Factors expressed by endothelial cells or present in the blood were decreased after combination treatment. A complete loss in the hemorrhagic phenotype of the PC14PE6-RFP tumors and a decrease in the number of blood vessels after combination treatment could be observed.

CONCLUSIONS:

CPA and GLV-1h68 have synergistic antitumor effects on PC14PE6-RFP xenografts. We strongly suppose that in the PC14PE6-RFP model the enhanced tumor growth inhibition achieved by combining GLV-1h68 with CPA is due to an effect on the vasculature rather than an immunosuppressive action of CPA. These results provide evidence to support further preclinical studies of combining GLV-1h68 and CPA in other highly angiogenic tumor models. Moreover, data presented here demonstrate that CPA can be combined successfully with GLV-1h68 based oncolytic virus therapy and therefore might be promising as combination therapy in human clinical trials.

• Authors: Elisabeth Hofmann, Stephanie Weibel, Aladar A Szalay
• Journal: Journal of translational medicine (J Transl Med) Vol. 12 Pg. 197 (Jul 17 2014) ISSN: 1479-5876 [Electronic] England
• PMID: 25030093 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antineoplastic Agents, Alkylating
• Cyclophosphamide

Topics

• Adenocarcinoma (drug therapy, therapy)
• Animals
• Antineoplastic Agents, Alkylating (therapeutic use)
• Cyclophosphamide (therapeutic use)
• Humans
• Lung Neoplasms (drug therapy, therapy)
• Mice
• Mice, Nude
• Oncolytic Virotherapy
• Vaccinia virus
• Xenograft Model Antitumor Assays