Immunosuppression promotes reovirus therapy of colorectal liver metastases

• Published in: Cancer gene therapy Vol. 13; no. 8; pp. 815 - 818
• Main Authors: Smakman, N, van der Bilt, J D W, van den Wollenberg, D J M, Hoeben, R C, Borel Rinkes, I H M, Kranenburg, O
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 01.08.2006
• Subjects: Animals; Bioluminescence; Care and treatment; Cell Line, Tumor; Colorectal cancer; Colorectal carcinoma; Colorectal Neoplasms - immunology; Colorectal Neoplasms - pathology; Colorectal Neoplasms - therapy; Combined Modality Therapy; Cyclosporin A; Cyclosporine - pharmacology; Diagnosis; Gene therapy; Genetic aspects; Health aspects; Hepatocytes; Immune system; Immunocompetence; Immunosuppression; Immunosuppressive Agents - pharmacology; Injection; Injections, Intralesional; Liver; Liver Neoplasms - immunology; Liver Neoplasms - secondary; Liver Neoplasms - therapy; Mammalian orthoreovirus 3; Metastases; Metastasis; Methods; Mice; Mice, Inbred BALB C; Mutation; Oncolysis; Oncolytic Virotherapy; Oncolytic Viruses; Physiological aspects; Reovirus; Risk factors; Transplantation, Isogeneic; Tumor cells; Xenograft Model Antitumor Assays; Netherlands
• ISSN: 0929-1903; 1476-5500
• DOI: 10.1038/sj.cgt.7700949

Mortality due to colorectal cancer (CRC) is high and is associated with the development of liver metastases. Approximately 40% of human CRCs harbor an activating mutation in the KRAS oncogene. Tumor cells with activated KRAS are particularly sensitive to Reovirus T3D, a non-pathogenic oncolytic virus. The efficacy of virus-based therapies may be positively or negatively modulated by the host immune system. This study was designed to assess the effect of immunosuppression on Reovirus T3D oncolysis of established colorectal micrometastases in the liver. Mouse C26 CRC cells harbor a mutant Kras gene and are susceptible to Kras-dependent oncolysis by Reovirus T3D in vitro. Isolated C26 liver tumors were established in syngenic immunocompetent BALB/c mice by intrahepatic injection. Reovirus T3D therapy was given as a single intratumoral injection in control mice and in cyclosporin A-treated immunosuppressed mice. Tumor growth was analyzed over time by non-invasive bioluminescence imaging. The outgrowth of established CRC liver metastases in immunocompetent mice was efficiently but temporarily inhibited with a single injection of Reovirus T3D. Immunosuppression with cyclosporin A markedly increased and prolonged the therapeutic effect and allowed complete Reovirus T3D-induced tumor eradication in a subpopulation of the mice. We conclude that Reovirus T3D is an effective therapeutic agent against established C26 colorectal liver metastases and that immunosuppression enhances treatment efficacy. Cancer Gene Therapy (2006) 13, 815-818. doi:10.1038/sj.cgt.7700949; published online 10 March 2006.