ABSTRACT
Oncolytic viruses (OVs) have shown promising clinical activity when administered by direct intratumoral injection. However, natural barriers in the blood, including antibodies and complement, are likely to limit the ability to repeatedly administer OVs by the intravenous route. We demonstrate here that for a prototype of the clinical vaccinia virus based product Pexa-Vec, the neutralizing activity of antibodies elicited by smallpox vaccination, as well as the anamnestic response in hyperimmune virus treated cancer patients, is strictly dependent on the activation of complement. In immunized rats, complement depletion stabilized vaccinia virus in the blood and led to improved delivery to tumors. Complement depletion also enhanced tumor infection when virus was directly injected into tumors in immunized animals. The feasibility and safety of using a complement inhibitor, CP40, in combination with vaccinia virus was tested in cynomolgus macaques. CP40 pretreatment elicited an average 10-fold increase in infectious titer in the blood early after the infusion and prolonged the time during which infectious virus was detectable in the blood of animals with preexisting immunity. Capitalizing on the complement dependence of antivaccinia antibody with adjunct complement inhibitors may increase the infectious dose of oncolytic vaccinia virus delivered to tumors in virus in immune hosts.
Subject(s)
Oncolytic Virotherapy/methods , Oncolytic Viruses/immunology , Vaccinia virus/immunology , Animals , Antibodies, Viral/blood , Antibodies, Viral/immunology , Cell Line, Tumor , Chlorocebus aethiops , Disease Models, Animal , Drug Delivery Systems , Feasibility Studies , Female , HeLa Cells , Humans , Injections, Intralesional , Macaca fascicularis/immunology , Male , Neoplasms/blood , Neoplasms/therapy , Neutralization Tests , Pyridones/immunology , Pyridones/pharmacology , Rats , Rats, Inbred F344 , Smallpox Vaccine/blood , Smallpox Vaccine/immunology , Vaccination , Vero CellsABSTRACT
Attenuated Semliki Forest virus (SFV) may be suitable for targeting malignant glioma due to its natural neurotropism, but its replication in brain tumor cells may be restricted by innate antiviral defenses. We attempted to facilitate SFV replication in glioma cells by combining it with vaccinia virus, which is capable of antagonizing such defenses. Surprisingly, we found parenchymal mouse brain tumors to be refractory to both viruses. Also, vaccinia virus appears to be sensitive to SFV-induced antiviral interference.
Subject(s)
Glioma/therapy , Oncolytic Viruses/growth & development , Oncolytic Viruses/immunology , Semliki forest virus/growth & development , Semliki forest virus/immunology , Vaccinia virus/growth & development , Vaccinia virus/immunology , Animals , Disease Models, Animal , MiceABSTRACT
Histone deacetylase inhibitors (HDACi) can modulate innate antiviral responses and render tumors more susceptible to oncolytic viruses (OVs); however, their effects on adaptive immunity in this context are largely unknown. Our present study reveals an unexpected property of the HDACi MS-275 that enhances viral vector-induced lymphopenia leading to selective depletion of bystander lymphocytes and regulatory T cells while allowing expansion of antigen-specific secondary responses. Coadministration of vaccine plus drug during the boosting phase focuses the immune response on the tumor by suppressing the primary immune response against the vaccine vector and enhancing the secondary response against the tumor antigen. Furthermore, improvement of T cell functionality was evident suggesting that MS-275 can orchestrate a complex array of effects that synergize immunotherapy and viral oncolysis. Surprisingly, while MS-275 dramatically enhanced efficacy, it suppressed autoimmune pathology, profoundly improving the therapeutic index.
Subject(s)
Histone Deacetylase Inhibitors/therapeutic use , Immunotherapy/methods , Neoplasms/therapy , Animals , Autoimmunity/drug effects , Cell Line, Tumor , Female , Melanoma/drug therapy , Melanoma/therapy , Mice , Mice, Inbred C57BL , Neoplasms/drug therapyABSTRACT
Replicating viruses for the treatment of cancer have a number of advantages over traditional therapeutic modalities. They are highly targeted, self-amplifying, and have the added potential to act as both gene-therapy delivery vehicles and oncolytic agents. Parapoxvirus ovis or Orf virus (ORFV) is the prototypic species of the Parapoxvirus genus, causing a benign disease in its natural ungulate host. ORFV possesses a number of unique properties that make it an ideal viral backbone for the development of a cancer therapeutic: it is safe in humans, has the ability to cause repeat infections even in the presence of antibody, and it induces a potent T(h)-1-dominated immune response. Here, we show that live replicating ORFV induces an antitumor immune response in multiple syngeneic mouse models of cancer that is mediated largely by the potent activation of both cytokine-secreting, and tumoricidal natural killer (NK) cells. We have also highlighted the clinical potential of the virus by demonstration of human cancer cell oncolysis including efficacy in an A549 xenograft model of cancer.
Subject(s)
Genetic Vectors/administration & dosage , Neoplasms/immunology , Neoplasms/therapy , Oncolytic Virotherapy , Oncolytic Viruses/immunology , Orf virus/immunology , Animals , Cell Line, Tumor , Cytokines/immunology , Cytokines/metabolism , Disease Models, Animal , Female , Genetic Therapy , Genetic Vectors/adverse effects , Humans , Immunity, Innate , Killer Cells, Natural/immunology , Lung/immunology , Lung/metabolism , Lung Neoplasms/secondary , Melanoma, Experimental/genetics , Melanoma, Experimental/immunology , Melanoma, Experimental/therapy , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Neoplasms/genetics , Oncolytic Viruses/genetics , Orf virus/genetics , Spleen/immunology , Spleen/metabolism , Tumor Burden , Virus Replication , Xenograft Model Antitumor AssaysABSTRACT
Treatment of permissive tumors with the oncolytic virus (OV) VSV-Δ51 leads to a robust antitumor T-cell response, which contributes to efficacy; however, many tumors are not permissive to in vivo treatment with VSV-Δ51. In an attempt to channel the immune stimulatory properties of VSV-Δ51 and broaden the scope of tumors that can be treated by an OV, we have developed a potent oncolytic vaccine platform, consisting of tumor cells infected with VSV-Δ51. We demonstrate that prophylactic immunization with this infected cell vaccine (ICV) protected mice from subsequent tumor challenge, and expression of granulocyte-monocyte colony stimulating factor (GM-CSF) by the virus (VSVgm-ICV) increased efficacy. Immunization with VSVgm-ICV in the VSV-resistant B16-F10 model induced maturation of dendritic and natural killer (NK) cell populations. The challenge tumor is rapidly infiltrated by a large number of interferon γ (IFNγ)-producing T and NK cells. Finally, we demonstrate that this approach is robust enough to control the growth of established tumors. This strategy is broadly applicable because of VSV's extremely broad tropism, allowing nearly all cell types to be infected at high multiplicities of infection in vitro, where the virus replication kinetics outpace the cellular IFN response. It is also personalized to the unique tumor antigen(s) displayed by the cancer cell.
Subject(s)
Cancer Vaccines/immunology , Melanoma, Experimental/prevention & control , Melanoma, Experimental/therapy , Skin Neoplasms/prevention & control , Skin Neoplasms/therapy , Vesiculovirus/immunology , Animals , Antigens, Neoplasm/genetics , Antigens, Neoplasm/immunology , Cancer Vaccines/administration & dosage , Cell Line, Tumor , Chlorocebus aethiops , Female , Genetic Therapy/methods , Granulocyte-Macrophage Colony-Stimulating Factor/immunology , Humans , Immunization , Interferon-gamma/biosynthesis , Interferon-gamma/immunology , Killer Cells, Natural/immunology , Killer Cells, Natural/metabolism , Melanoma, Experimental/immunology , Mice , Mice, Inbred C57BL , Oncolytic Virotherapy/methods , Oncolytic Viruses/genetics , Oncolytic Viruses/immunology , Skin Neoplasms/immunology , T-Lymphocytes/immunology , T-Lymphocytes/metabolism , Vero Cells , Vesiculovirus/genetics , Virus ReplicationABSTRACT
Oncolytic viruses constitute a promising therapy against malignant gliomas (MGs). However, virus-induced type I IFN greatly limits its clinical application. The kinase mammalian target of rapamycin (mTOR) stimulates type I IFN production via phosphorylation of its effector proteins, 4E-BPs and S6Ks. Here we show that mouse embryonic fibroblasts and mice lacking S6K1 and S6K2 are more susceptible to vesicular stomatitis virus (VSV) infection than their WT counterparts as a result of an impaired type I IFN response. We used this knowledge to employ a pharmacoviral approach to treat MGs. The highly specific inhibitor of mTOR rapamycin, in combination with an IFN-sensitive VSV-mutant strain (VSV(DeltaM51)), dramatically increased the survival of immunocompetent rats bearing MGs. More importantly, VSV(DeltaM51) selectively killed tumor, but not normal cells, in MG-bearing rats treated with rapamycin. These results demonstrate that reducing type I IFNs through inhibition of mTORC1 is an effective strategy to augment the therapeutic activity of VSV(DeltaM51).
Subject(s)
Glioma/metabolism , Glioma/therapy , Interferon Type I/biosynthesis , Transcription Factors/metabolism , Vesicular Stomatitis/metabolism , Vesiculovirus/physiology , Animals , Cell Line , Cell Line, Tumor , Female , Glioma/genetics , Glioma/virology , Mechanistic Target of Rapamycin Complex 1 , Mice , Mice, Knockout , Multiprotein Complexes , Neoplasm Transplantation , Oncolytic Virotherapy , Proteins , Rats , Rats, Inbred F344 , Ribosomal Protein S6 Kinases/deficiency , Ribosomal Protein S6 Kinases/metabolism , Ribosomal Protein S6 Kinases, 90-kDa/deficiency , Ribosomal Protein S6 Kinases, 90-kDa/metabolism , Sirolimus/pharmacology , TOR Serine-Threonine Kinases , Vesicular Stomatitis/genetics , Vesicular Stomatitis/virology , Vesiculovirus/geneticsABSTRACT
Oncolytic viruses are a promising anti-cancer platform, achieving significant pre-clinical and clinical milestones in recent years. A full arsenal of selective, safe, and effective viruses has been developed with some emerging pre-clinical research focusing on optimizing these therapies in the face of remaining challenges, both in the bloodstream and in the tumour microenvironment. Herein we discuss the recent progress in pre-clinical virotherapy research to address these challenges, with special focus on innovative strategies that seek to complement the current strengths of virotherapy, ensuring an optimal multi-faceted attack on cancer. This review highlights the research areas that we believe provide the most potential to increase the efficacy of this exciting biotherapy platform: cell carriers, tumour vascular destruction, microenvironment modulation, combination therapies, and virus-mediated anti-tumour immune responses.
Subject(s)
Neoplasms/genetics , Neoplasms/therapy , Oncolytic Virotherapy , Oncolytic Viruses/genetics , Animals , HumansABSTRACT
PURPOSE: Acute lymphoblastic leukemia (ALL) remains incurable in most adults. It has been difficult to provide effective immunotherapy to improve outcomes for the majority of patients. Rhabdoviruses induce strong antiviral immune responses. We hypothesized that mice administered ex vivo rhabdovirus-infected ALL cells [immunotherapy by leukemia-oncotropic virus (iLOV)] would develop robust antileukemic immune responses capable of controlling ALL. EXPERIMENTAL DESIGN: Viral protein production, replication, and cytopathy were measured in human and murine ALL cells exposed to attenuated rhabdovirus. Survival following injection of graded amounts of ALL cells was compared between cohorts of mice administered γ-irradiated rhabdovirus-infected ALL cells (iLOV) or multiple control vaccines to determine key immunotherapeutic components and characteristics. Host immune requirements were assessed in immunodeficient and bone marrow-transplanted mice or by adoptive splenocyte transfer from immunized donors. Antileukemic immune memory was ascertained by second leukemic challenge in long-term survivors. RESULTS: Human and murine ALL cells were infected and killed by rhabdovirus; this produced a potent antileukemia vaccine. iLOV protected mice from otherwise lethal ALL by developing durable leukemia-specific immune-mediated responses (P < 0.0001), which required an intact CTL compartment. Preexisting antiviral immunity augmented iLOV potency. Splenocytes from iLOV-vaccinated donors protected 60% of naïve recipients from ALL challenge (P = 0.0001). Injecting leukemia cells activated by, or concurrent with, multiple Toll-like receptor agonists could not reproduce the protective effect of iLOV. Similarly, injecting uninfected irradiated viable, apoptotic, or necrotic leukemia cells with/without concurrent rhabdovirus administration was ineffective. CONCLUSION: Rhabdovirus-infected leukemia cells can be used to produce a vaccine that induces robust specific immunity against aggressive leukemia.
Subject(s)
Immunotherapy, Adoptive , Precursor Cell Lymphoblastic Leukemia-Lymphoma/therapy , Rhabdoviridae/physiology , Adoptive Transfer , Animals , Bone Marrow Transplantation , Cancer Vaccines , Cell Line, Tumor , Cell Survival , Chlorocebus aethiops , Humans , Mice , Mice, Inbred C57BL , Mice, Inbred DBA , Mice, Nude , Neoplasm Transplantation , Precision Medicine , Precursor Cell Lymphoblastic Leukemia-Lymphoma/immunology , Vero CellsABSTRACT
Oncolytic viruses are complex biological agents that interact at multiple levels with both tumour and normal tissues. Antiviral pathways induced by interferon are known to have a critical role in determining tumour cell sensitivity and normal cell resistance to infection with oncolytic viruses. Here we pursue a synthetic biology approach to identify methods that enhance antitumour activity of oncolytic viruses through suppression of interferon signalling. On the basis of the mathematical analysis of multiple strategies, we hypothesize that a positive feedback loop, established by virus-mediated expression of a soluble interferon-binding decoy receptor, increases tumour cytotoxicity without compromising normal cells. Oncolytic rhabdoviruses engineered to express a secreted interferon antagonist have improved oncolytic potential in cellular cancer models, and display improved therapeutic potential in tumour-bearing mice. Our results demonstrate the potential of this methodology in evaluating potential caveats of viral immune-evasion strategies and improving the design oncolytic viruses.
Subject(s)
Models, Biological , Oncolytic Virotherapy , Oncolytic Viruses/physiology , Animals , Cell Death , Computer Simulation , Gentian Violet , Immune Evasion , Interferons/metabolism , Mice , Mice, Inbred BALB C , Reproducibility of Results , Rhabdoviridae/physiology , Tissue Distribution , Virus ReplicationABSTRACT
Oncolytic viruses (OVs) are selected or designed to eliminate malignancies by direct infection and lysis of cancer cells. In contrast to this concept of direct tumor lysis by viral infection, we observed that a significant portion of the in vivo tumor killing activity of two OVs, vesicular stomatitis virus (VSV) and vaccinia virus is caused by indirect killing of uninfected tumor cells. Shortly after administering the oncolytic virus we observed limited virus infection, coincident with a loss of blood flow to the interior of the tumor that correlated with induction of apoptosis in tumor cells. Transcript profiling of tumors showed that virus infection resulted in a dramatic transcriptional activation of pro-inflammatory genes including the neutrophil chemoattractants CXCL1 and CXCL5. Immunohistochemical examination of infected tumors revealed infiltration by neutrophils correlating with chemokine induction. Depletion of neutrophils in animals prior to VSV administration eliminated uninfected tumor cell apoptosis and permitted more extensive replication and spreading of the virus throughout the tumor. Taken all together, these results indicate that targeted recruitment of neutrophils to infected tumor beds enhances the killing of malignant cells. We propose that activation of inflammatory cells can be used for enhancing the effectiveness of oncolytic virus therapeutics, and that this approach should influence the planning of therapeutic doses.