21 research outputs found

    Oncolytic Virotherapy as Emerging Immunotherapeutic Modality: Potential of Parvovirus H-1

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    Human tumors develop multiple strategies to evade recognition and efficient suppression by the immune system. Therefore, a variety of immunotherapeutic strategies have been developed to reactivate and reorganize the human immune system. The recent development of new antibodies against immune check points may help to overcome the immune silencing induced by human tumors. Some of these antibodies have already been approved for treatment of various solid tumor entities. Interestingly, targeting antibodies may be combined with standard chemotherapy or radiation protocols. Furthermore, recent evidence indicates that intratumoral (it) or intravenous (iv) injections of replicative oncolytic viruses such as herpes simplex-, pox-, parvo- or adenoviruses may also reactivate the human immune system. By generating tumor cell lysates in situ, oncolytic viruses overcome cellular tumor resistance mechanisms and induce immunogenic tumor cell death resulting in the recognition of newly released tumor antigens.This is in particular the case of the oncolytic parvovirus H-1 (H-1PV) which is able to kill human tumor cells and stimulate an antitumor immune response through increased presentation of tumor-associated antigens, maturation of dendritic cells and release of proinflammatory cytokines. Current research and clinical studies aim to assess the potential of oncolytic virotherapy and its combination with immunotherapeutic agents or conventional treatments to further induce effective antitumoral immune responses

    Enhancement of Vaccinia Virus Based Oncolysis with Histone Deacetylase Inhibitors

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    Histone deacetylase inhibitors (HDI) dampen cellular innate immune response by decreasing interferon production and have been shown to increase the growth of vesicular stomatitis virus and HSV. As attenuated tumour-selective oncolytic vaccinia viruses (VV) are already undergoing clinical evaluation, the goal of this study is to determine whether HDI can also enhance the potency of these poxviruses in infection-resistant cancer cell lines. Multiple HDIs were tested and Trichostatin A (TSA) was found to potently enhance the spread and replication of a tumour selective vaccinia virus in several infection-resistant cancer cell lines. TSA significantly decreased the number of lung metastases in a syngeneic B16F10LacZ lung metastasis model yet did not increase the replication of vaccinia in normal tissues. The combination of TSA and VV increased survival of mice harbouring human HCT116 colon tumour xenografts as compared to mice treated with either agent alone. We conclude that TSA can selectively and effectively enhance the replication and spread of oncolytic vaccinia virus in cancer cells

    Sequential Therapy With JX-594, A Targeted Oncolytic Poxvirus, Followed by Sorafenib in Hepatocellular Carcinoma: Preclinical and Clinical Demonstration of Combination Efficacy

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    JX-594 is a targeted and granulocyte-macrophage colony stimulating factor (GM-CSF) expressing oncolytic poxvirus designed to selectively replicate in and destroy cancer cells through viral oncolysis and tumor-specific immunity. In a phase 1 trial, JX-594 injection into hepatocellular carcinoma (HCC) was well-tolerated and associated with viral replication, decreased tumor perfusion, and tumor necrosis. We hypothesized that JX-594 and sorafenib, a small molecule inhibitor of B-raf and vascular endothelial growth factor receptor (VEGFR) approved for HCC, would have clinical benefit in combination given their demonstrated efficacy in HCC patients and their complementary mechanisms-of-action. HCC cell lines were uniformly sensitive to JX-594. Anti-raf kinase effects of concurrent sorafenib inhibited JX-594 replication in vitro, whereas sequential therapy was superior to either agent alone in murine tumor models. We therefore explored pilot safety and efficacy of JX-594 followed by sorafenib in three HCC patients. In all three patients, sequential treatment was (i) well-tolerated, (ii) associated with significantly decreased tumor perfusion, and (iii) associated with objective tumor responses (Choi criteria; up to 100% necrosis). HCC historical control patients on sorafenib alone at the same institutions had no objective tumor responses (0 of 15). Treatment of HCC with JX-594 followed by sorafenib has antitumoral activity, and JX-594 may sensitize tumors to subsequent therapy with VEGF/VEGFR inhibitors

    Targeting Tumor Vasculature With an Oncolytic Virus

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    Oncolytic viruses (OVs) have been engineered or selected for cancer cell-specific infection however, we have found that following intravenous administration of vesicular stomatitis virus (VSV), tumor cell killing rapidly extends far beyond the initial sites of infection. We show here for the first time that VSV directly infects and destroys tumor vasculature in vivo but leaves normal vasculature intact. Three-dimensional (3D) reconstruction of infected tumors revealed that the majority of the tumor mass lacks significant blood flow in contrast to uninfected tumors, which exhibit relatively uniform perfusion. VSV replication in tumor neovasculature and spread within the tumor mass, initiates an inflammatory reaction including a neutrophil-dependent initiation of microclots within tumor blood vessels. Within 6 hours of intravenous administration of VSV and continuing for at least 24 hours, we observed the initiation of blood clots within the tumor vasculature whereas normal vasculature remained clot free. Blocking blood clot formation with thrombin inhibitors prevented tumor vascular collapse. Our results demonstrate that the therapeutic activity of an OV can go far beyond simple infection and lysis of malignant cells