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Humanized Mice with Subcutaneous Human Solid Tumors for Immune Response Analysis of Vaccinia Virus-Mediated Oncolysis.

ABSTRACT: Oncolytic vaccinia virus (VACV) therapy is an alternative cancer treatment modality that mediates targeted tumor destruction through a tumor-selective replication and an induction of anti-tumor immunity. We developed a humanized tumor mouse model with subcutaneous human tumors to analyze the interactions of VACV with the developing tumors and human immune system. A successful systemic reconstitution with human immune cells including functional T cells as well as development of tumors infiltrated with human T and natural killer (NK) cells was observed. We also demonstrated successful in vivo colonization of such tumors with systemically administered VACVs. Further, a new recombinant GLV-1h376 VACV encoding for a secreted human CTLA4-blocking single-chain antibody (CTLA4 scAb) was tested. Surprisingly, although proving CTLA4 scAb's in vitro binding ability and functionality in cell culture, beside the significant increase of CD56^bright NK cell subset, GLV-1h376 was not able to increase cytotoxic T or overall NK cell levels at the tumor site. Importantly, the virus-encoded ?-glucuronidase as a measure of viral titer and CTLA4 scAb amount was demonstrated. Therefore, studies in our "patient-like" humanized tumor mouse model allow the exploration of newly designed therapy strategies considering the complex relationships between the developing tumor, the oncolytic virus, and the human immune system.

SUBMITTER: Tsoneva D

PROVIDER: S-EPMC5415323 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Humanized Mice with Subcutaneous Human Solid Tumors for Immune Response Analysis of Vaccinia Virus-Mediated Oncolysis.

Tsoneva Desislava D Minev Boris B Frentzen Alexa A Zhang Qian Q Wege Anja K AK Szalay Aladar A AA

Molecular therapy oncolytics 20170321

Oncolytic vaccinia virus (VACV) therapy is an alternative cancer treatment modality that mediates targeted tumor destruction through a tumor-selective replication and an induction of anti-tumor immunity. We developed a humanized tumor mouse model with subcutaneous human tumors to analyze the interactions of VACV with the developing tumors and human immune system. A successful systemic reconstitution with human immune cells including functional T cells as well as development of tumors infiltrated ...[more]

PMID: 28480327

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Project description:Previously we reported that a recombinant vaccinia virus (VACV) carrying a light-emitting fusion gene enters, replicates in, and reveals the locations of tumors in mice. A new recombinant VACV, GLV-1h68, as a simultaneous diagnostic and therapeutic agent, was constructed by inserting three expression cassettes (encoding Renilla luciferase-green fluorescent protein (RUC-GFP) fusion, b-galactosidase, and b-glucuronidase) into the F14.5L, J2R (encoding thymidine kinase, TK), and A56R (encoding hemagglutinin, HA) loci of the viral genome, respectively. Intravenous (i.v.) injections of GLV-1h68 (1 × 107 pfu/mouse) into nude mice with established (500 mm3) subcutaneous (s.c.) GI-101A human breast tumors were used to evaluate its toxicity, tumor targeting specificity and oncolytic efficacy. GLV-1h68 demonstrated an enhanced tumor targeting specificity and much reduced toxicity compared to its parental LIVP strains. The tumors colonized by GLV-1h68 exhibited growth, inhibition, and regression phases followed by tumor eradication within 130 days in 95% of the mice tested. Tumor regression in live animals was monitored in real time based on decreasing light emission, hence demonstrating the concept of a combined oncolytic virus-mediated tumor diagnosis and therapy system. Transcriptional profiling of regressing tumors based on a mouse-specific platform revealed gene expression signatures consistent with immune defense activation, inclusive of interferon stimulated genes (STAT-1 and IRF-7), cytokines, chemokines and innate immune effector function. These findings suggest that immune activation may combine with viral oncolysis to induce tumor eradication in this model, providing a novel perspective for the design of oncolytic viral therapies for human cancers. Objective: To determine the gene expression changes induced by GLV-1h68 vaccinia virus injection in mouse carrying human breast cancer implant and leading to tumor eradication. Methods: Gene expression was analyzed using oligonucleotide microarrays. Responsiveness to vaccina virus injection was assessed by toxicity and survival study, gene expression anaysis and tumor volume change. Result: The tumors colonized by GLV-1h68 exhibited growth, inhibition, and regression phases followed by tumor eradication within 130 days in 95% of the mice tested. Tumor regression in live animals was monitored in real time based on decreasing light emission, hence demonstrating the concept of a combined oncolytic virus-mediated tumor diagnosis and therapy system. Transcriptional profiling of regressing tumors based on a mouse-specific platform revealed gene expression signatures consistent with immune defense activation, inclusive of interferon stimulated genes (STAT-1 and IRF-7), cytokines, chemokines and innate immune effector function. Conclusion: Our findings suggest that immune activation may combine with viral oncolysis to induce tumor eradication in this model, providing a novel perspective for the design of oncolytic viral therapies for human cancers. Keywords: Responsiveness to vaccina virus injection

Project description:BackgroundIn principle, the elimination of malignancies by oncolytic virotherapy could proceed by different mechanisms--e.g. tumor cell specific oncolysis, destruction of the tumor vasculature or an anti-tumoral immunological response. In this study, we analyzed the contribution of these factors to elucidate the responsible mechanism for regression of human breast tumor xenografts upon colonization with an attenuated vaccinia virus (VACV).MethodsBreast tumor xenografts were analyzed 6 weeks post VACV infection (p.i.; regression phase) by immunohistochemistry and mouse-specific expression arrays. Viral-mediated oncolysis was determined by tumor growth analysis combined with microscopic studies of intratumoral virus distribution. The tumor vasculature was morphologically characterized by diameter and density measurements and vessel functionality was analyzed by lectin perfusion and extravasation studies. Immunological aspects of viral-mediated tumor regression were studied in either immune-deficient mouse strains (T-, B-, NK-cell-deficient) or upon cyclophosphamide-induced immunosuppression (MHCII+-cell depletion) in nude mice.ResultsLate stage VACV-infected breast tumors showed extensive necrosis, which was highly specific to cancer cells. The tumor vasculature in infected tumor areas remained functional and the endothelial cells were not infected. However, viral colonization triggers hyperpermeability and dilatation of the tumor vessels, which resembled the activated endothelium in wounded tissue. Moreover, we demonstrated an increased expression of genes involved in leukocyte-endothelial cell interaction in VACV-infected tumors, which orchestrate perivascular inflammatory cell infiltration. The immunohistochemical analysis of infected tumors displayed intense infiltration of MHCII-positive cells and colocalization of tumor vessels with MHCII+/CD31+ vascular leukocytes. However, GI-101A tumor growth analysis upon VACV-infection in either immunosuppressed nude mice (MHCII+-cell depleted) or in immune-deficient mouse strains (T-, B-, NK-cell-deficient) revealed that neither MHCII-positive immune cells nor T-, B-, or NK cells contributed significantly to VACV-mediated tumor regression. In contrast, tumors of immunosuppressed mice showed enhanced viral spreading and tumor necrosis.ConclusionsTaken together, these results indicate that VACV-mediated oncolysis is the primary mechanism of tumor shrinkage in the late regression phase. Neither the destruction of the tumor vasculature nor the massive VACV-mediated intratumoral inflammation was a prerequisite for tumor regression. We propose that approaches to enhance viral replication and spread within the tumor microenvironment should improve therapeutical outcome.

Dataset Information

Humanized Mice with Subcutaneous Human Solid Tumors for Immune Response Analysis of Vaccinia Virus-Mediated Oncolysis.

Publications

Humanized Mice with Subcutaneous Human Solid Tumors for Immune Response Analysis of Vaccinia Virus-Mediated Oncolysis.

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