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406. Oncolytic Herpes Simplex Viruses Encoding an Antibody Retargeted C5a Complement Protein for Multiple Myeloma Therapy
CANCER - ONCOLYTIC VIRUSES I suggest that IL-15 gene therapy has potential for control metastatic breast cancer and the interaction of immunotherapy and mTOR inhibitor need further investigation for better outcome.
Cancer - Oncolytic Viruses I 405. Measles Virus for Immunovirotherapy of Cancer
Christian Grossardt,1 Christine E. Engeland,1 Sascha Bossow,1 Silke Hamzaoui-Nord,1 Niels Halama,2 Dirk Jäger,2 Christof von Kalle,1 Guy Ungerechts.1,2 1 Department of Translational Oncology, National Center for Tumor Diseases (NCT/DKFZ), Heidelberg, Germany; 2Department of Medical Oncology, National Center for Tumor Diseases (NCT/ DKFZ), Heidelberg, Germany. Oncolytic viruses are currently being evaluated in clinical trials as novel cancer therapeutics. Additionally, immunotherapy has gained importance as a potent treatment modality of cancer. By combining oncolytic virotherapy and immunotherapy, synergistic effects are anticipated. After lysis of infected tumor cells, tumor-associated antigens are exposed in an inflammatory milieu, supporting antitumor immunity and tumor vaccination effects. Here, therapeutic efficacy and adaptive immune response were evaluated in two recently established immunocompetent murine models for measles virus (MV) oncolysis. We generated immunomodulatory MV (MV-IT) encoding the cytokine GM-CSF or secretable antibodies against the T cell inhibitory factors CTLA4 and PD-L1, respectively. Therapeutic efficacy was evaluated in vivo using immunocompetent mouse models with subcutaneously implanted syngeneic colon carcinoma (MC38cea) and malignant melanoma (B16-CD20), respectively. Accordingly, these tumors allow for targeted infection with MV displaying corresponding single chain antibodies against CEA or CD20. To elucidate therapeutic mechanisms after intratumoral application, immunoassays were performed and tumor-infiltrating immune effectors were characterized. In the MC38cea model, mice treated with MV-GMCSF demonstrated a significantly enhanced tumor-specific cytotoxicity and activation of splenocytes compared to control virus or mock treated controls. Importantly, complete tumor regression was observed in 37% of the animals. Abortive tumor rechallenge indicated a robust immune clearance of tumor cells. Increased infiltration of CD3+ lymphocytes after treatment with MV-IT was detected. In the B16-CD20 model, MV-IT armed with antibodies against CTLA4 or PD-L1 are currently under investigation. Preliminary results suggest delayed tumor progression and prolonged overall survival in individuals treated with MV-IT. Immunovirotherapy can enhance adaptive anti-tumor immunity by recruiting immune effectors to the tumor site. Thus, combining targeted oncolytic MV with vector-mediated immunomodulation is a promising approach with direct implications for future clinical trials.
406. Oncolytic Herpes Simplex Viruses Encoding an Antibody Retargeted C5a Complement Protein for Multiple Myeloma Therapy Hongtao Li,1 Stephen J. Russell.1 Molecular Medicine, Mayo Clinic Rochester, Rochester, MN.
1
Incorporation of cytokine genes in oncolytic virus genomes can enhance their therapeutic potency. We recently reported that a single intravenous injection of 2 x 108 TCID50 of VSV-IFN-NIS, a recombinant VSV encoding mouse interferon- and the human thyroidal sodium iodide symporter, could eliminate syngeneic plasmacytomas in fully immunocompetent mice. The cross-primed anti-tumor immune response that follows intratumoral virus spread and the elimination of the virus infected cells is critical to prevent the relapse of the tumor in this model (Leukemia. 2012 Aug; 26(8):1870S156
8). Complement C5a is a potent immunomodulator and anaphylatoxin that can elicit a robust influx of innate immune effector cells to generate a strong inflammatory response. Absence of C5a signaling leads to autoinductive TGF-Beta1 signaling and the induction of Foxp3+ regulatory T cells (Nat Immunol. 2012 Dec 23). We therefore hypothesized that an oncolytic herpes simplex virus expressing C5a could break the host immune tolerance to tumors. However C5a is a small protein which is likely to dissipate rapidly from the tumor parenchyma into the bloodstream. In order to enhance the retention of the virally encoded C5a at the tumor site, we made C5a-single chain antibody fragment fusions using scFvs recognizing myeloma antigens CD38 and Wue1, or a control scFv targeting the human EGF receptor. The integrity of each of the expressed fusion proteins was confirmed by ELISA and Western blot analysis. At the time of writing, rescue of the corresponding oncolytic HSVs is underway and it is hoped that they will prove to be potent oncolytics for myeloma therapy.
407.
Mengovirus Therapy for Multiple Myeloma
Autumn Ruiz,1 Elizabeth M. Hadac,1 Stephen J. Russell.1 1 Molecular Medicine, Mayo Clinic, Rochester, MN.
Despite significant advancements in treatment, multiple myeloma, a malignancy of antibody-producing plasma cells, remains largely incurable emphasizing the need for novel therapeutic approaches. Multiple myeloma represents an ideal candidate for oncolytic virotherapy because it is disseminated from the outset, highly vascular, expresses minimal extracellular matrix, is metabolically active and provides an excellent substrate for virus propagation. Oncolytic picornaviruses undergo rapid lytic propagation and extravasate efficiently through tumor vessels allowing widespread dissemination through continuous release of virus progeny into the bloodstream from the primary intratumoral (IT) injection site. We previously demonstrated the utility of picornaviruses as oncolytic agents using Coxsackievirus A21 (CVA21). MicroRNA targeting was used to eliminate the undesirable muscle toxicity of this virus and the targeted virus resulted in rapid destruction of subcutaneous myeloma xenografts following intravenous (IV) administration. However, similar to the majority of currently studied oncolytic viruses, the CVA21 system lacks a relevant immunocompetent animal model hindering the preclinical evaluation of this virus. The importance of performing preclinical evaluation in the presence of an immune system is becoming increasingly apparent with the emerging trend of oncolytic viruses demonstrating potent activity in the absence of an immune system while proving inadequate in clinical trials. Mengo encephalomyocarditis virus (Mengo-EMCV) is a well-studied zoonotic picornaviral pathogen of low human seroprevalence with a broad species tropism. Mengovirus causes encephalitis and/or myocarditis but can be attenuated by shortening the poly(C) tract in the 5’ noncoding region (NCR). The attenuated Mengovirus is potently oncolytic for a wide range of mouse and human tumor cell lines and when administered by IT or IV routes exhibits moderate oncolytic activity against syngeneic mouse plasmacytomas in immunocompetent mice providing a better model for preclinical evaluation. The goal of this study was to improve the utility of Mengovirus as an oncolytic agent by eliminating the CNS and cardiac toxicities of the virus through microRNA targeting for future optimization as an anti-cancer therapy. Insertion of microRNA target sequences into both the 5’ and 3’ NCRs resulted in diminished replication of the virus in the presence of the corresponding miRNAs.
Molecular Therapy Volume 21, Supplement 1, May 2013 Copyright © The American Society of Gene & Cell Therapy
Cancer - Oncolytic Viruses I 405. Measles Virus for Immunovirotherapy of Cancer
Christian Grossardt,1 Christine E. Engeland,1 Sascha Bossow,1 Silke Hamzaoui-Nord,1 Niels Halama,2 Dirk Jäger,2 Christof von Kalle,1 Guy Ungerechts.1,2 1 Department of Translational Oncology, National Center for Tumor Diseases (NCT/DKFZ), Heidelberg, Germany; 2Department of Medical Oncology, National Center for Tumor Diseases (NCT/ DKFZ), Heidelberg, Germany. Oncolytic viruses are currently being evaluated in clinical trials as novel cancer therapeutics. Additionally, immunotherapy has gained importance as a potent treatment modality of cancer. By combining oncolytic virotherapy and immunotherapy, synergistic effects are anticipated. After lysis of infected tumor cells, tumor-associated antigens are exposed in an inflammatory milieu, supporting antitumor immunity and tumor vaccination effects. Here, therapeutic efficacy and adaptive immune response were evaluated in two recently established immunocompetent murine models for measles virus (MV) oncolysis. We generated immunomodulatory MV (MV-IT) encoding the cytokine GM-CSF or secretable antibodies against the T cell inhibitory factors CTLA4 and PD-L1, respectively. Therapeutic efficacy was evaluated in vivo using immunocompetent mouse models with subcutaneously implanted syngeneic colon carcinoma (MC38cea) and malignant melanoma (B16-CD20), respectively. Accordingly, these tumors allow for targeted infection with MV displaying corresponding single chain antibodies against CEA or CD20. To elucidate therapeutic mechanisms after intratumoral application, immunoassays were performed and tumor-infiltrating immune effectors were characterized. In the MC38cea model, mice treated with MV-GMCSF demonstrated a significantly enhanced tumor-specific cytotoxicity and activation of splenocytes compared to control virus or mock treated controls. Importantly, complete tumor regression was observed in 37% of the animals. Abortive tumor rechallenge indicated a robust immune clearance of tumor cells. Increased infiltration of CD3+ lymphocytes after treatment with MV-IT was detected. In the B16-CD20 model, MV-IT armed with antibodies against CTLA4 or PD-L1 are currently under investigation. Preliminary results suggest delayed tumor progression and prolonged overall survival in individuals treated with MV-IT. Immunovirotherapy can enhance adaptive anti-tumor immunity by recruiting immune effectors to the tumor site. Thus, combining targeted oncolytic MV with vector-mediated immunomodulation is a promising approach with direct implications for future clinical trials.
406. Oncolytic Herpes Simplex Viruses Encoding an Antibody Retargeted C5a Complement Protein for Multiple Myeloma Therapy Hongtao Li,1 Stephen J. Russell.1 Molecular Medicine, Mayo Clinic Rochester, Rochester, MN.
1
Incorporation of cytokine genes in oncolytic virus genomes can enhance their therapeutic potency. We recently reported that a single intravenous injection of 2 x 108 TCID50 of VSV-IFN-NIS, a recombinant VSV encoding mouse interferon- and the human thyroidal sodium iodide symporter, could eliminate syngeneic plasmacytomas in fully immunocompetent mice. The cross-primed anti-tumor immune response that follows intratumoral virus spread and the elimination of the virus infected cells is critical to prevent the relapse of the tumor in this model (Leukemia. 2012 Aug; 26(8):1870S156
8). Complement C5a is a potent immunomodulator and anaphylatoxin that can elicit a robust influx of innate immune effector cells to generate a strong inflammatory response. Absence of C5a signaling leads to autoinductive TGF-Beta1 signaling and the induction of Foxp3+ regulatory T cells (Nat Immunol. 2012 Dec 23). We therefore hypothesized that an oncolytic herpes simplex virus expressing C5a could break the host immune tolerance to tumors. However C5a is a small protein which is likely to dissipate rapidly from the tumor parenchyma into the bloodstream. In order to enhance the retention of the virally encoded C5a at the tumor site, we made C5a-single chain antibody fragment fusions using scFvs recognizing myeloma antigens CD38 and Wue1, or a control scFv targeting the human EGF receptor. The integrity of each of the expressed fusion proteins was confirmed by ELISA and Western blot analysis. At the time of writing, rescue of the corresponding oncolytic HSVs is underway and it is hoped that they will prove to be potent oncolytics for myeloma therapy.
407.
Mengovirus Therapy for Multiple Myeloma
Autumn Ruiz,1 Elizabeth M. Hadac,1 Stephen J. Russell.1 1 Molecular Medicine, Mayo Clinic, Rochester, MN.
Despite significant advancements in treatment, multiple myeloma, a malignancy of antibody-producing plasma cells, remains largely incurable emphasizing the need for novel therapeutic approaches. Multiple myeloma represents an ideal candidate for oncolytic virotherapy because it is disseminated from the outset, highly vascular, expresses minimal extracellular matrix, is metabolically active and provides an excellent substrate for virus propagation. Oncolytic picornaviruses undergo rapid lytic propagation and extravasate efficiently through tumor vessels allowing widespread dissemination through continuous release of virus progeny into the bloodstream from the primary intratumoral (IT) injection site. We previously demonstrated the utility of picornaviruses as oncolytic agents using Coxsackievirus A21 (CVA21). MicroRNA targeting was used to eliminate the undesirable muscle toxicity of this virus and the targeted virus resulted in rapid destruction of subcutaneous myeloma xenografts following intravenous (IV) administration. However, similar to the majority of currently studied oncolytic viruses, the CVA21 system lacks a relevant immunocompetent animal model hindering the preclinical evaluation of this virus. The importance of performing preclinical evaluation in the presence of an immune system is becoming increasingly apparent with the emerging trend of oncolytic viruses demonstrating potent activity in the absence of an immune system while proving inadequate in clinical trials. Mengo encephalomyocarditis virus (Mengo-EMCV) is a well-studied zoonotic picornaviral pathogen of low human seroprevalence with a broad species tropism. Mengovirus causes encephalitis and/or myocarditis but can be attenuated by shortening the poly(C) tract in the 5’ noncoding region (NCR). The attenuated Mengovirus is potently oncolytic for a wide range of mouse and human tumor cell lines and when administered by IT or IV routes exhibits moderate oncolytic activity against syngeneic mouse plasmacytomas in immunocompetent mice providing a better model for preclinical evaluation. The goal of this study was to improve the utility of Mengovirus as an oncolytic agent by eliminating the CNS and cardiac toxicities of the virus through microRNA targeting for future optimization as an anti-cancer therapy. Insertion of microRNA target sequences into both the 5’ and 3’ NCRs resulted in diminished replication of the virus in the presence of the corresponding miRNAs.
Molecular Therapy Volume 21, Supplement 1, May 2013 Copyright © The American Society of Gene & Cell Therapy