Oncolytic vaccinia therapy of squamous cell carcinoma

Analysis of the Biological Properties of Blood Plasma Protein with GcMAF Functional Activity

The main problem related to the studies focusing on group-specific component protein-derived macrophage-activating factor (GcMAF) is the lack of clarity about changes occurring in different types of macrophages and related changes in their properties under the effect of GcMAF in various clinical conditions. We analyzed the antitumor therapeutic properties of GcMAF in a Lewis carcinoma model in two clinical conditions: untreated tumor lesion and tumor resorption after exposure to Karanahan therapy. GcMAF is formed during site-specific deglycosylation of vitamin D3 binding protein (DBP). DBP was obtained from the blood of healthy donors using affinity chromatography on a column with covalently bound actin. GcMAF-related factor (GcMAF-RF) was converted in a mixture with induced lymphocytes through the cellular enzymatic pathway. The obtained GcMAF-RF activates murine peritoneal macrophages (p < 0.05), induces functional properties of dendritic cells (p < 0.05) and promotes in vitro polarization of human M0 macrophages to M1 macrophages (p < 0.01). Treatment of whole blood cells with GcMAF-RF results in active production of both pro- and anti-inflammatory cytokines. It is shown that macrophage activation by GcMAF-RF is inhibited by tumor-secreted factors. In order to identify the specific antitumor effect of GcMAF-RF-activated macrophages, an approach to primary reduction of humoral suppressor activity of the tumor using the Karanahan therapy followed by macrophage activation in the tumor-associated stroma (TAS) was proposed. A prominent additive effect of GcMAF-RF, which enhances the primary immune response activation by the Karanahan therapy, was shown in the model of murine Lewis carcinoma. Inhibition of the suppressive effect of TAS is the main condition required for the manifestation of the antitumor effect of GcMAF-RF. When properly applied in combination with any chemotherapy, significantly reducing the humoral immune response at the advanced tumor site, GcMAF-RF is a promising antitumor therapeutic agent that additively destroys the pro-tumor properties of macrophages of the tumor stroma.

Novel Chimeric Poxvirus CF17 Improves Survival in a Murine Model of Intraperitoneal Ovarian Cancer Metastasis

Despite improvements in surgical techniques and chemotherapy, ovarian cancer remains the most lethal gynecologic cancer. Thus, there is an urgent need for more effective therapeutics, particularly for chemo-resistant peritoneal ovarian cancer metastases. Oncolytic virotherapy represents an innovative treatment paradigm; however, for oncolytic viruses tested from the last generation of genetically engineered viruses, the therapeutic benefits have been modest. To overcome these limitations, we generated a chimeric poxvirus, CF17, through the chimerization of nine species of orthopoxviruses. Compared with its parental viruses, CF17 has demonstrated superior oncolytic characteristics. Here, we report the oncolytic potential of CF17 in ovarian cancer. Replication of CF17 and its resulting cytotoxicity were observed at multiplicities of infection (MOIs) as low as 0.001 in human and mouse cancer cell lines in vitro. Furthermore, CF17 exerted potent antitumor effects in a syngeneic mouse model of ovarian cancer at doses as low as 6 × 10⁶ plaque-forming units. Together, these data merit further investigation of the potential use of this novel chimeric poxvirus as an effective treatment for aggressive intraperitoneal ovarian cancer.

Vaccinia virus injected human tumors: oncolytic virus efficiency predicted by antigen profiling analysis fitted boolean models

Virotherapy on the basis of oncolytic vaccinia virus (VACV) strains is a promising approach for cancer therapy. Recently, we showed that the oncolytic vaccinia virus GLV-1h68 has a therapeutic potential in treating human prostate and hepatocellular carcinomas in xenografted mice. In this study, we describe the use of dynamic boolean modeling for tumor growth prediction of vaccinia virus-injected human tumors. Antigen profiling data of vaccinia virus GLV-1h68-injected human xenografted mice were obtained, analyzed and used to calculate differences in the tumor growth signaling network by tumor type and gender. Our model combines networks for apoptosis, MAPK, p53, WNT, Hedgehog, the T-killer cell mediated cell death, Interferon and Interleukin signaling networks. The in silico findings conform very well with in vivo findings of tumor growth. Similar to a previously published analysis of vaccinia virus-injected canine tumors, we were able to confirm the suitability of our boolean modeling for prediction of human tumor growth after virus infection in the current study as well. In summary, these findings indicate that our boolean models could be a useful tool for testing of the efficacy of VACV-mediated cancer therapy already before its use in human patients.

A chimeric poxvirus with J2R (thymidine kinase) deletion shows safety and anti-tumor activity in lung cancer models

Oncolytic viruses have shown excellent safety profiles in preclinical and clinical studies; however, in most cases therapeutic benefits have been modest. We have previously reported the generation of a chimeric poxvirus (CF33), with significantly improved oncolytic characteristics, through chimerization among different poxviruses. Here we report the sequence analysis of CF33 and oncolytic potential of a GFP-encoding CF33 virus (CF33-GFP) with a J2R deletion in lung cancer models. Replication of CF33-GFP and the resulting cytotoxicity were higher in cancer cell lines compared to a normal cell line, in vitro. After infection with virus, cancer cells expressed markers for immunogenic cell death in vitro. Furthermore, CF33-GFP was safe and exerted potent anti-tumor effects at a dose as low as 1000 plaque forming units in both virus-injected and un-injected distant tumors in A549 tumor xenograft model in mice. Likewise, in a syngeneic model of lung cancer in mice, the virus showed significant anti-tumor effect and was found to increase tumor infiltration by CD8+ T cells. Collectively, these data warrant further investigation of this novel chimeric poxvirus for its potential use as a cancer bio-therapeutic.

Virus and tumor microenvironment induced ER stress and unfolded protein response: from complexity to therapeutics

Endoplasmic reticulum (ER) stress can be activated by various pathological and physiological conditions including the unfolded protein response (UPR) to restore homeostasis. The UPR signaling pathways initiated by double-stranded RNA-activated protein kinase (PKR) like ER kinase (PERK), inositol requiring enzyme 1 α (IRE1α), and activating transcription factor 6 (ATF6) are vital for tumor growth, aggressiveness, microenvironment remodeling, and resistance to cancer therapeutics. This review focuses on the role of ER stress and activity of UPR signaling pathways involved in tumor formation and uncontrolled cell proliferation during various cancers and viral malignancies.

Recombinant viruses with other anti-cancer therapeutics: a step towards advancement of oncolytic virotherapy

Cancer as a disease is a multifaceted foe which sometimes succumbs to the prescribed treatment and sometimes develops resistance against various therapies. Conventional cancer therapies suffer from many limitations, the least of which is their specificity and systemic side effects. In a majority of cases, acquired mutations render the cancer cells resistant to therapy and lower the prognostic outcome. In the constant effort to devise a therapeutic moiety which can comprehensively eliminate cancer cells, oncolytic viruses provide an attractive avenue as they selectively infect and lyse cancer cells sparing normal cells from their effects. Viruses can be engineered for their host specificity and toxicity as a promising anti-cancer tool. As it is essential to devise a strategy to address all targets involved in cancer development and progression, the idea of using oncolytic viruses with enhanced anti-cancer activity through arming with foreign genes gained merit and is showing promising advent in clinical studies. The use of oncolytic viruses as an agent of combination therapy for cancer treatment also gained much attention in the recent past. This review focuses on the emerging role of oncolytic viruses as vital components of anti-cancer regimen presenting a new dimension in an ever-changing cancer therapy scenario.

Phase I Trial of Intravenous Oncolytic Vaccinia Virus (GL-ONC1) with Cisplatin and Radiotherapy in Patients with Locoregionally Advanced Head and Neck Carcinoma

Purpose: Preclinical models have shown that the effectiveness of GL-ONC1, a modified oncolytic vaccinia virus, is enhanced by radiation and chemotherapy. The purpose of this study was to determine the safety of GL-ONC1 when delivered intravenously with chemoradiotherapy to patients with primary, nonmetastatic head and neck cancer.Experimental Design: Patients with locoregionally advanced unresected, nonmetastatic carcinoma of the head/neck, excluding stage III-IVA p16-positive oropharyngeal cancers, were treated with escalating doses and cycles of intravenous GL-ONC1, along with radiotherapy and chemotherapy. The primary aims were to define the MTD and dose-limiting toxicities, and to recommend a dose for phase II trials.Results: Between May 2012 and December 2014, 19 patients were enrolled. The most frequent adverse reactions included grade 1-2 rigors, fever, fatigue, and rash. Grade 3 adverse reactions included hypotension, mucositis, nausea, and vomiting. In 2 patients, the rash was confirmed as viral in origin by fluorescence imaging and viral plaque assay. In 4 patients, viral presence in tumor was confirmed on midtreatment biopsy by quantitative PCR. In 1 patient, live virus was confirmed in a tongue tumor 7 days after receiving the first dose of virus. The MTD was not reached. With median follow-up of 30 months, 1-year (2-year) progression-free survival and overall survival were 74.4% (64.1%) and 84.6% (69.2%), respectively.Conclusions: Delivery of GL-ONC1 is safe and feasible in patients with locoregionally advanced head/neck cancer undergoing standard chemoradiotherapy. A phase II study is warranted to further investigate this novel treatment strategy. Clin Cancer Res; 23(19); 5696-702. ©2017 AACR.

Genetically Engineered Vaccinia Viruses As Agents for Cancer Treatment, Imaging, and Transgene Delivery

Despite advances in technology, the formidable challenge of treating cancer, especially if advanced, still remains with no significant improvement in survival rates, even with the most common forms of cancer. Oncolytic viral therapies have shown great promise for the treatment of various cancers, with the possible advantages of stronger treatment efficacy compared to conventional therapy due to higher tumor selectivity, and less toxicity. They are able to preferentially and selectively propagate in cancer cells, consequently destroying tumor tissue mainly via cell lysis, while leaving non-cancerous tissues unharmed. Several wild-type and genetically engineered vaccinia virus (VACV) strains have been tested in both preclinical and clinical trials with promising results. Greater understanding and advancements in molecular biology have enabled the generation of genetically engineered oncolytic viruses for safer and more efficacious treatment, including arming VACVs with cytokines and immunostimulatory molecules, anti-angiogenic agents, and enzyme prodrug therapy, in addition to combining VACVs with conventional external and systemic radiotherapy, chemotherapy, immunotherapy, and other virus strains. Furthermore, novel oncolytic vaccinia virus strains have been generated that express reporter genes for the tracking and imaging of viral therapy and monitoring of therapeutic response. Further study is needed to unlock VACVs’ full potential as part of the future of cancer therapy.

Features of the Antitumor Effect of Vaccinia Virus Lister Strain

Oncolytic abilities of vaccinia virus (VACV) served as a basis for the development of various recombinants for treating cancer; however, "natural" oncolytic properties of the virus are not examined in detail. Our study was conducted to know how the genetically unmodified L-IVP strain of VACV produces its antitumor effect. Human A431 carcinoma xenografts in nude mice and murine Ehrlich carcinoma in C57Bl mice were used as targets for VACV, which was injected intratumorally. A set of virological methods, immunohistochemistry, light and electron microscopy was used in the study. We found that in mice bearing A431 carcinoma, the L-IVP strain was observed in visceral organs within two weeks, but rapidly disappeared from the blood. The L-IVP strain caused decrease of sizes in both tumors, however, in different ways. Direct cell destruction by replicating virus plays a main role in regression of A431 carcinoma xenografts, while in Ehrlich carcinoma, which poorly supported VACV replication, the virus induced decrease of mitoses by pushing tumor cells into S-phase of cell cycle. Our study showed that genetically unmodified VACV possesses at least two mechanisms of antitumor effect: direct destruction of tumor cells and suppression of mitoses in tumor cells.

Oncolytic virotherapy for head and neck cancer: current research and future developments

Head and neck cancer (HNC) is the sixth most common malignancy worldwide. Despite recent advancements in surgical, chemotherapy, and radiation treatments, HNC remains a highly morbid and fatal disease. Unlike many other cancers, local control rather than systemic control is important for HNC survival. Therefore, novel local therapy in addition to systemic therapy is urgently needed. Oncolytic virotherapy holds promise in this regard as viruses can be injected intratumorally as well as intravenously with excellent safety profiles. This review will discuss the recent advancements in oncolytic virotherapy, highlighting some of the most promising candidates and modifications to date.

Silk-elastin-like protein polymer matrix for intraoperative delivery of an oncolytic vaccinia virus

BACKGROUND

Oncolytic viral efficacy may be limited by the penetration of the virus into tumors. This may be enhanced by intraoperative application of virus immediately after surgical resection.

METHODS

Oncolytic vaccinia virus GLV-1h68 was delivered in silk-elastin-like protein polymer (SELP) in vitro and in vivo in anaplastic thyroid carcinoma cell line 8505c in nude mice.

RESULTS

GLV-1h68 in SELP infected and lysed anaplastic thyroid cancer cells in vitro equally as effectively as in phosphate-buffered saline (PBS), and at 1 week retains a thousand fold greater infectious plaque-forming units. In surgical resection models of residual tumor, GLV-1h68 in SELP improves tumor control and shows increased viral β-galactosidase expression as compared to PBS.

CONCLUSION

The use of SELP matrix for intraoperative oncolytic viral delivery protects infectious viral particles from degradation, facilitates sustained viral delivery and transgene expression, and improves tumor control. Such optimization of methods of oncolytic viral delivery may enhance therapeutic outcomes.

8th international conference on oncolytic virus therapeutics

The 8th International Conference on Oncolytic Virus Therapeutics meeting was held from April 10-13, 2014, in Oxford, United Kingdom. It brought together experts in the field of oncolytics from Europe, Asia, Australasia, and the Americas and provided a unique opportunity to hear the latest research findings in oncolytic virotherapy. Presentations of recent work were delivered in an informal and intimate setting afforded by a small group of attendees and an exquisitely focused conference topic. Here we describe the oral presentations and enable the reader to share in the benefits of bringing together experts to share their findings.

Progress in oncolytic virotherapy for the treatment of thyroid malignant neoplasm

Thyroid malignant neoplasm develops from follicular or parafollicular thyroid cells. A higher proportion of anaplastic thyroid cancer has an adverse prognosis. New drugs are being used in clinical treatment. However, for advanced thyroid malignant neoplasm such as anaplastic thyroid carcinoma, the major impediment to successful control of the disease is the absence of effective therapies. Oncolytic virotherapy has significantly progressed as therapeutics in recent years. The advance is that oncolytic viruses can be designed with biological specificity to infect, replicate and lyse tumor cells. Significant advances in virotherapy have being achieved to improve the accessibility, safety and efficacy of the treatment. Therefore, it is necessary to summarize and bring together the main areas covered by these investigations for the virotherapy of thyroid malignant neoplasm. We provide an overview of the progress in virotherapy research and clinical trials, which employ virotherapy for thyroid malignant neoplasm as well as the future prospect for virotherapy of thyroid malignant neoplasms.

Inducible gene expression in tumors colonized by modified oncolytic vaccinia virus strains

Exogenous gene induction of therapeutic, diagnostic, and safety mechanisms could be a considerable improvement in oncolytic virotherapy. Here, we introduced a doxycycline-inducible promoter system (comprised of a tetracycline repressor, several promoter constructs, and a tet operator sequence) into oncolytic recombinant vaccinia viruses (rVACV), which were further characterized in detail. Experiments in cell cultures as well as in tumor-bearing mice were analyzed to determine the role of the inducible-system components. To accomplish this, we took advantage of the optical reporter construct, which resulted in the production of click-beetle luciferase as well as a red fluorescent protein. The results indicated that each of the system components could be used to optimize the induction rates and had an influence on the background expression levels. Depending on the given gene to be induced in rVACV-colonized tumors of patients, we discuss the doxycycline-inducible promoter system adjustment and further optimization.

IMPORTANCE

Oncolytic virotherapy of cancer can greatly benefit from the expression of heterologous genes. It is reasonable that some of those heterologous gene products could have detrimental effects either on the cancer patient or on the oncolytic virus itself if they are expressed at the wrong time or if the expression levels are too high. Therefore, exogenous control of gene expression levels by administration of a nontoxic inducer will have positive effects on the safety as well as the therapeutic outcome of oncolytic virotherapy. In addition, it paves the way for the introduction of new therapeutic genes into the genome of oncolytic viruses that could not have been tested otherwise.

Oncolytic Poxviruses

Current standard treatments of cancer can prolong survival of many cancer patients but usually do not effectively cure the disease. Oncolytic virotherapy is an emerging therapeutic for the treatment of cancer that exploits replication-competent viruses to selectively infect and destroy cancerous cells while sparing normal cells and tissues. Clinical and/or preclinical studies on oncolytic viruses have revealed that the candidate viruses being tested in trials are remarkably safe and offer potential for treating many classes of currently incurable cancers. Among these candidates are vaccinia and myxoma viruses, which belong to the family Poxviridae and possess promising oncolytic features. This article describes poxviruses that are being developed for oncolytic virotherapy and summarizes the outcomes of both clinical and preclinical studies. Additionally, studies demonstrating superior efficacy when poxvirus oncolytic virotherapy is combined with conventional therapies are described.

Combination treatment with oncolytic Vaccinia virus and cyclophosphamide results in synergistic antitumor effects in human lung adenocarcinoma bearing mice

Background

The capacity of the recombinant Vaccinia virus GLV-1h68 as a single agent to efficiently treat different human or canine cancers has been shown in several preclinical studies. Currently, its human safety and efficacy are investigated in phase I/II clinical trials. In this study we set out to evaluate the oncolytic activity of GLV-1h68 in the human lung adenocarcinoma cell line PC14PE6-RFP in cell cultures and analyzed the antitumor potency of a combined treatment strategy consisting of GLV-1h68 and cyclophosphamide (CPA) in a mouse model of PC14PE6-RFP lung adenocarcinoma.

Methods

PC14PE6-RFP cells were treated in cell culture with GLV-1h68. Viral replication and cell survival were determined by plaque assays and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, respectively. Subcutaneously implanted PC14PE6-RFP xenografts were treated by systemic injection of GLV-1h68, CPA or a combination of both. Tumor growth and viral biodistribution were monitored and immune-related antigen profiling of tumor lysates was performed.

Results

GLV-1h68 efficiently infected, replicated in and lysed human PC14PE6-RFP cells in cell cultures. PC14PE6-RFP tumors were efficiently colonized by GLV-1h68 leading to much delayed tumor growth in PC14PE6-RFP tumor-bearing nude mice. Combination treatment with GLV-1h68 and CPA significantly improved the antitumor efficacy of GLV-1h68 and led to an increased viral distribution within the tumors. Pro-inflammatory cytokines and chemokines were distinctly elevated in tumors of GLV-1h68-treated mice. Factors expressed by endothelial cells or present in the blood were decreased after combination treatment. A complete loss in the hemorrhagic phenotype of the PC14PE6-RFP tumors and a decrease in the number of blood vessels after combination treatment could be observed.

Conclusions

CPA and GLV-1h68 have synergistic antitumor effects on PC14PE6-RFP xenografts. We strongly suppose that in the PC14PE6-RFP model the enhanced tumor growth inhibition achieved by combining GLV-1h68 with CPA is due to an effect on the vasculature rather than an immunosuppressive action of CPA. These results provide evidence to support further preclinical studies of combining GLV-1h68 and CPA in other highly angiogenic tumor models. Moreover, data presented here demonstrate that CPA can be combined successfully with GLV-1h68 based oncolytic virus therapy and therefore might be promising as combination therapy in human clinical trials.

Cellular unfolded protein response against viruses used in gene therapy

Viruses are excellent vehicles for gene therapy due to their natural ability to infect and deliver the cargo to specific tissues with high efficiency. Although such vectors are usually "gutted" and are replication defective, they are subjected to clearance by the host cells by immune recognition and destruction. Unfolded protein response (UPR) is a naturally evolved cyto-protective signaling pathway which is triggered due to endoplasmic reticulum (ER) stress caused by accumulation of unfolded/misfolded proteins in its lumen. The UPR signaling consists of three signaling pathways, namely PKR-like ER kinase, activating transcription factor 6, and inositol-requiring protein-1. Once activated, UPR triggers the production of ER molecular chaperones and stress response proteins to help reduce the protein load within the ER. This occurs by degradation of the misfolded proteins and ensues in the arrest of protein translation machinery. If the burden of protein load in ER is beyond its processing capacity, UPR can activate pro-apoptotic pathways or autophagy leading to cell death. Viruses are naturally evolved in hijacking the host cellular translation machinery to generate a large amount of proteins. This phenomenon disrupts ER homeostasis and leads to ER stress. Alternatively, in the case of gutted vectors used in gene therapy, the excess load of recombinant vectors administered and encountered by the cell can trigger UPR. Thus, in the context of gene therapy, UPR becomes a major roadblock that can potentially trigger inflammatory responses against the vectors and reduce the efficiency of gene transfer.

Vaccinia virus outperforms a panel of other poxviruses as a potent oncolytic agent for the control of head and neck squamous cell carcinoma cell lines

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is the fifth most common cancer worldwide. Existing therapies for advanced tumors have high failure rates and can have severe consequences in terms of pain, disfigurement, and poor speech and swallowing function. New treatment strategies are needed to improve outcomes for patients suffering with this disease and oncolytic viruses represent a promising approach.

METHODS

We infected six well-characterized HNSCC cell lines (Cal27, Detroit562, FaDu, SCC4, SCC15, SCC25), with increasing doses of a panel of poxviruses (including myxoma, vaccinia, raccoonpox and tanapox viruses) modified to express green fluorescence protein to determine which virus was the most effective oncolytic agent in cell-based assays.

RESULTS

While myxoma, raccoonpox and tanapox displayed differing efficacy in the panel of cell lines, vaccinia virus was the most potent of the tested poxviruses and was highly effective in controlling cell growth in all cell lines.

CONCLUSION

Oncolytic poxviruses, particularly vaccinia virus, were effective in killing HNSCC in vitro and hold promise as potential treatments for patients with HNSCC.

Protein kinase C overexpression does not enhance immune-stimulatory surface markers of vaccinia-infected dendritic cells and DC cell lines

One of the shortcomings of vaccinia virus (VACV) as immunization vector is the down-regulation of HLA and costimulatory molecules in antigen presenting cells. To overcome this problem we investigated the use of protein kinase C (PKC) as immune stimulatory agent. Thus several classical and atypical PKCs were inserted into wild-type or attenuated VACV using recombination into the hemagglutinin gene and the expression driven by the VACV 7,5K-IE gene promoter. Recombinant constructs expressing PKC-alpha, -beta, -theta as well as wild-type, constitutive active or dominant negative PKC-zeta constructs were generated. Additional constructs expressing PKB/Akt1 and ICAM-1 were used for comparison. Immature and mature peripheral blood derived-dendritic cells (DC) as well as lymphoid cell lines capable of obtaining a DC-like phenotype upon mitogen stimulation were infected. Disappointingly, VACV-driven PKC overexpression did not significantly enhance expression of various activation markers or costimulatory molecules tested. Neither CD86 nor HLA-DR expression was upregulated and also no influence on the maturation of DC, as measured by DC-SIGN and CD83, was observed. However, VACV did not interfere with LPS induced up-regulation of CD83 and did not lead to substantial apoptosis of infected DC within the first 24 hours.

Vaccinia virus-mediated expression of human erythropoietin in tumors enhances virotherapy and alleviates cancer-related anemia in mice

Recombinant human erythropoietin (rhEPO), a glycoprotein hormone regulating red blood cell (RBC) formation, is used for the treatment of cancer-related anemia. The effect of rhEPO on tumor growth, however, remains controversial. Here, we report the construction and characterization of the recombinant vaccinia virus (VACV) GLV-1h210, expressing hEPO. GLV-1h210 was shown to replicate in and kill A549 lung cancer cells in culture efficiently. In mice bearing A549 lung cancer xenografts, treatment with a single intravenous dose of GLV-1h210 resulted in tumor-specific production and secretion of functional hEPO, which exerted an effect on RBC progenitors and precursors in the mouse bone marrow, leading to a significant increase in the number of RBCs and in the level of hemoglobin. Furthermore, virally expressed hEPO, but not exogenously added rhEPO, enhanced virus-mediated green fluorescent protein (GFP) expression in tumors and subsequently accelerated tumor regression when compared with the treatment with the parental virus GLV-1h68 or GLV-1h209 that expressed a nonfunctional hEPO protein. Moreover, intratumorally expressed hEPO caused enlarged tumoral microvessels, likely facilitating virus spreading. Taken together, VACV-mediated intratumorally expressed hEPO not only enhanced oncolytic virotherapy but also simultaneously alleviated cancer-related anemia.

Oncolytic vaccinia virus therapy of salivary gland carcinoma

OBJECTIVE

To examine the therapeutic effects of an attenuated, replication-competent vaccinia virus (GLV-1h68) against a panel of 5 human salivary gland carcinoma cell lines.

DESIGN

The susceptibility of 5 salivary gland carcinoma cell lines to infection and oncolysis by GLV-1h68 was assessed in vitro and in vivo.

RESULTS

All 5 cell lines were susceptible to viral infection, transgene expression, and cytotoxic reactions. Three cell lines were exquisitely sensitive to infection by very low doses of GLV-1h68. Orthotopic parotid tumors exhibited more aggressive behavior compared with flank tumors. A single intratumoral injection of GLV-1h68 induced significant tumor regression without observed toxic effects in flank and parotid tumor models; controls demonstrated rapid tumor progression.

CONCLUSION

These promising results demonstrate significant oncolytic activity by an attenuated vaccinia virus for infecting and lysing salivary gland carcinomas, supporting future clinical trials.

Treatment of malignant effusion by oncolytic virotherapy in an experimental subcutaneous xenograft model of lung cancer

Background

Malignant pleural effusion (MPE) is associated with advanced stages of lung cancer and is mainly dependent on invasion of the pleura and expression of vascular endothelial growth factor (VEGF) by cancer cells. As MPE indicates an incurable disease with limited palliative treatment options and poor outcome, there is an urgent need for new and efficient treatment options.

Methods

In this study, we used subcutaneously generated PC14PE6 lung adenocarcinoma xenografts in athymic mice that developed subcutaneous malignant effusions (ME) which mimic pleural effusions of the orthotopic model. Using this approach monitoring of therapeutic intervention was facilitated by direct observation of subcutaneous ME formation without the need of sacrificing mice or special imaging equipment as in case of MPE. Further, we tested oncolytic virotherapy using Vaccinia virus as a novel treatment modality against ME in this subcutaneous PC14PE6 xenograft model of advanced lung adenocarcinoma.

Results

We demonstrated significant therapeutic efficacy of Vaccinia virus treatment of both advanced lung adenocarcinoma and tumor-associated ME. We attribute the efficacy to the virus-mediated reduction of tumor cell-derived VEGF levels in tumors, decreased invasion of tumor cells into the peritumoral tissue, and to viral infection of the blood vessel-invading tumor cells. Moreover, we showed that the use of oncolytic Vaccinia virus encoding for a single-chain antibody (scAb) against VEGF (GLAF-1) significantly enhanced mono-therapy of oncolytic treatment.

Conclusions

Here, we demonstrate for the first time that oncolytic virotherapy using tumor-specific Vaccinia virus represents a novel and promising treatment modality for therapy of ME associated with advanced lung cancer.

Synergistic cytotoxicity of radiation and oncolytic Lister strain vaccinia in (V600D/E)BRAF mutant melanoma depends on JNK and TNF-α signaling

Melanoma is an aggressive skin cancer that carries an extremely poor prognosis when local invasion, nodal spread or systemic metastasis has occurred. Recent advances in melanoma biology have revealed that RAS-RAF-MEK-ERK signaling has a pivotal role in governing disease progression and treatment resistance. Proof-of-concept clinical studies have shown that direct BRAF inhibition yields impressive responses in advanced disease but these are short-lived as treatment resistance rapidly emerges. Therefore, there is a pressing need to develop new targeted strategies for BRAF mutant melanoma. As such, oncolytic viruses represent a promising cancer-specific approach with significant activity in melanoma. This study investigated interactions between genetically-modified vaccinia virus (GLV-1h68) and radiotherapy in melanoma cell lines with BRAF mutant, Ras mutant or wild-type genotype. Preclinical studies revealed that GLV-1h68 combined with radiotherapy significantly increased cytotoxicity and apoptosis relative to either single agent in (V600D)BRAF/(V600E)BRAF mutant melanoma in vitro and in vivo. The mechanism of enhanced cytotoxicity with GLV-1h68/radiation (RT) was independent of viral replication and due to attenuation of JNK, p38 and ERK MAPK phosphorylation specifically in BRAF mutant cells. Further studies showed that JNK pathway inhibition sensitized BRAF mutant cells to GLV-1h68-mediated cell death, mimicking the effect of RT. GLV-1h68 infection activated MAPK signaling in (V600D)BRAF/(V600E)BRAF mutant cell lines and this was associated with TNF-α secretion which, in turn, provided a prosurvival signal. Combination GLV-1h68/RT (or GLV-1h68/JNK inhibition) caused abrogation of TNF-α secretion. These data provide a strong rationale for combining GLV-1h68 with irradiation in (V600D/E)BRAF mutant tumors.

Growth inhibition of different human colorectal cancer xenografts after a single intravenous injection of oncolytic vaccinia virus GLV-1h68

Background

Despite availability of efficient treatment regimens for early stage colorectal cancer, treatment regimens for late stage colorectal cancer are generally not effective and thus need improvement. Oncolytic virotherapy using replication-competent vaccinia virus (VACV) strains is a promising new strategy for therapy of a variety of human cancers.

Methods

Oncolytic efficacy of replication-competent vaccinia virus GLV-1h68 was analyzed in both, cell cultures and subcutaneous xenograft tumor models.

Results

In this study we demonstrated for the first time that the replication-competent recombinant VACV GLV-1h68 efficiently infected, replicated in, and subsequently lysed various human colorectal cancer lines (Colo 205, HCT-15, HCT-116, HT-29, and SW-620) derived from patients at all four stages of disease. Additionally, in tumor xenograft models in athymic nude mice, a single injection of intravenously administered GLV-1h68 significantly inhibited tumor growth of two different human colorectal cell line tumors (Duke’s type A-stage HCT-116 and Duke’s type C-stage SW-620), significantly improving survival compared to untreated mice. Expression of the viral marker gene ruc-gfp allowed for real-time analysis of the virus infection in cell cultures and in mice. GLV-1h68 treatment was well-tolerated in all animals and viral replication was confined to the tumor. GLV-1h68 treatment elicited a significant up-regulation of murine immune-related antigens like IFN-γ, IP-10, MCP-1, MCP-3, MCP-5, RANTES and TNF-γ and a greater infiltration of macrophages and NK cells in tumors as compared to untreated controls.

Conclusion

The anti-tumor activity observed against colorectal cancer cells in these studies was a result of direct viral oncolysis by GLV-1h68 and inflammation-mediated innate immune responses. The therapeutic effects occurred in tumors regardless of the stage of disease from which the cells were derived. Thus, the recombinant vaccinia virus GLV-1h68 has the potential to treat colorectal cancers independently of the stage of progression.

Correlates between host and viral transcriptional program associated with different oncolytic vaccinia virus isolates

Vaccinia virus (VACV) has emerged as an attractive tool in oncolytic virotherapy. VACV replication efficiency plays a crucial role in the therapeutic outcome. However, little is known about the influence of host factors on viral replication efficiency and permissiveness of a host cell line to infection and oncolysis. In this study, replication of the attenuated VACV GLV-1h68 strain and three wild-type VACV isolates was determined in two autologous human melanoma cell lines (888-MEL and 1936-MEL). Host gene expression and viral gene expression in infected cells were evaluated via respective expression array platforms. Microarray analyses followed by sequential statistical approaches characterized human genes that change specifically due to virus infection. Viral gene transcription correlated with viral replication in a time-dependent manner. A set of human genes revealed strong correlations with the respective viral gene expression. Finally we identified a set of human genes with possible predictive value for viral replication in an independent dataset. The results demonstrate a probable correlation between viral replication, early gene expression, and the respective host response, and thus a possible involvement of human host factors in viral early replication. The characterization of human target genes that influence viral replication could help answer the question of host cell permissiveness to oncolytic virotherapy and provide important information for the development of novel recombinant vaccinia viruses with improved features to enhance replication rate and hence trigger therapeutic outcome.

Vaccinia virus-mediated intra-tumoral expression of matrix metalloproteinase 9 enhances oncolysis of PC-3 xenograft tumors

Background

Oncolytic viruses, including vaccinia virus (VACV), are a promising alternative to classical mono-cancer treatment methods such as surgery, chemo- or radiotherapy. However, combined therapeutic modalities may be more effective than mono-therapies. In this study, we enhanced the effectiveness of oncolytic virotherapy by matrix metalloproteinase (MMP-9)-mediated degradation of proteins of the tumoral extracellular matrix (ECM), leading to increased viral distribution within the tumors.

Methods

For this study, the oncolytic vaccinia virus GLV-1h255, containing the mmp-9 gene, was constructed and used to treat PC-3 tumor-bearing mice, achieving an intra-tumoral over-expression of MMP-9. The intra-tumoral MMP-9 content was quantified by immunohistochemistry in tumor sections. Therapeutic efficacy of GLV-1h255 was evaluated by monitoring tumor growth kinetics and intra-tumoral virus titers. Microenvironmental changes mediated by the intra-tumoral MMP-9 over-expression were investigated by microscopic quantification of the collagen IV content, the blood vessel density (BVD) and the analysis of lymph node metastasis formation.

Results

GLV-1h255-treatment of PC-3 tumors led to a significant over-expression of intra-tumoral MMP-9, accompanied by a marked decrease in collagen IV content in infected tumor areas, when compared to GLV-1h68-infected tumor areas. This led to considerably elevated virus titers in GLV-1h255 infected tumors, and to enhanced tumor regression. The analysis of the BVD, as well as the lumbar and renal lymph node volumes, revealed lower BVD and significantly smaller lymph nodes in both GLV-1h68- and GLV-1h255- injected mice compared to those injected with PBS, indicating that MMP-9 over-expression does not alter the metastasis-reducing effect of oncolytic VACV.

Conclusions

Taken together, these results indicate that a GLV-1h255-mediated intra-tumoral over-expression of MMP-9 leads to a degradation of collagen IV, facilitating intra-tumoral viral dissemination, and resulting in accelerated tumor regression. We propose that approaches which enhance the oncolytic effect by increasing the intra-tumoral viral load, may be an effective way to improve therapeutic outcome.

Real-time imaging of tumors using replication-competent light-emitting microorganisms

Early detection of cancer and metastases is pivotal to the success of subsequent treatment intervention. In recent years, the use of live microorganisms, such as viruses and bacteria, has gained substantial research and clinical interest in both detection and therapy of cancer. Many of these live microorganisms have shown remarkable tumor-specific replication following systemic delivery. With the aid of modern molecular technologies, modified live microorganisms can be engineered to carry additional diagnostic and therapeutic capabilities. We have shown that when armed with light-emitting protein genes, such as genes for luciferase and green fluorescent protein, the entry and specific amplification of systemically-delivered vaccinia virus and bacteria in tumors can be visualized in real time using a low-light imager, or using macro- and micro-fluorescence microscopes. Therefore, through optical imaging, the location of tumors and metastases could be revealed by these light-emitting microorganisms. The tumor-colonization capability has been demonstrated in both immuno-competent as well as immuno-compromised rodent models with syngeneic and allogeneic tumors. Based on their "tumor-finding" nature, bacteria and viruses could be further designed as "vehicles" to carry multiple genes for detection and therapy of cancer.

Preclinical evaluation of oncolytic vaccinia virus for therapy of canine soft tissue sarcoma

Virotherapy using oncolytic vaccinia virus (VACV) strains is one promising new strategy for canine cancer therapy. In this study we describe the establishment of an in vivo model of canine soft tissue sarcoma (CSTS) using the new isolated cell line STSA-1 and the analysis of the virus-mediated oncolytic and immunological effects of two different Lister VACV LIVP1.1.1 and GLV-1h68 strains against CSTS. Cell culture data demonstrated that both tested VACV strains efficiently infected and destroyed cells of the canine soft tissue sarcoma line STSA-1. In addition, in our new canine sarcoma tumor xenograft mouse model, systemic administration of LIVP1.1.1 or GLV-1h68 viruses led to significant inhibition of tumor growth compared to control mice. Furthermore, LIVP1.1.1 mediated therapy resulted in almost complete tumor regression and resulted in long-term survival of sarcoma-bearing mice. The replication of the tested VACV strains in tumor tissues led to strong oncolytic effects accompanied by an intense intratumoral infiltration of host immune cells, mainly neutrophils. These findings suggest that the direct viral oncolysis of tumor cells and the virus-dependent activation of tumor-associated host immune cells could be crucial parts of anti-tumor mechanism in STSA-1 xenografts. In summary, the data showed that both tested vaccinia virus strains and especially LIVP1.1.1 have great potential for effective treatment of CSTS.

Effective oncolytic vaccinia therapy for human sarcomas

BACKGROUND

Approximately one fourth of bone and soft-tissue sarcomas recur after prior treatment. GLV-1h68 is a recombinant, replication-competent vaccinia virus that has been shown to have oncolytic effects against many human cancer types. We sought to determine whether GLV-1h68 could selectively target and lyse a panel of human bone and soft-tissue sarcoma cell lines in vitro and in vivo.

METHODS

GLV-1h68 was tested in a panel of four cell lines including: fibrosarcoma HT-1080, osteosarcoma U-2OS, fibrohistiocytoma M-805, and rhabdomyosarcoma HTB-82. Gene expression, infectivity, viral proliferation, and cytotoxicity were characterized in vitro. HT-1080 xenograft flank tumors grown in vivo were injected intratumorally with a single dose of GLV-1h68.

RESULTS

All four cell lines supported robust viral transgene expression in vitro. At a multiplicity of infection (MOI) of five, GLV-1h68 was cytotoxic to three cell lines, resulting in >80% cytotoxicity over 7 d. In vivo, a single injection of GLV-1h68 into HT-1080 xenografts exhibited localized intratumoral luciferase activity peaking at d 2-4, with gradual resolution over 8 d and no evidence of spread to normal tissues. Treated animals exhibited near-complete tumor regression over a 28-d period without observed toxicity.

CONCLUSION

GLV-1h68 has potent direct oncolytic effects against human sarcoma in vitro and in vivo. Recombinant vaccinia oncolytic virotherapy could provide a new platform for the treatment of patients with bone and soft tissue sarcomas. Future clinical trials investigating oncolytic vaccinia as a therapy for sarcomas are warranted.

Permissivity of the NCI-60 cancer cell lines to oncolytic Vaccinia Virus GLV-1h68

Background

Oncolytic viral therapy represents an alternative therapeutic strategy for the treatment of cancer. We previously described GLV-1h68, a modified Vaccinia Virus with exclusive tropism for tumor cells, and we observed a cell line-specific relationship between the ability of GLV-1h68 to replicate in vitro and its ability to colonize and eliminate tumor in vivo.

Methods

In the current study we surveyed the in vitro permissivity to GLV-1h68 replication of the NCI-60 panel of cell lines. Selected cell lines were also tested for permissivity to another Vaccinia Virus and a vesicular stomatitis virus (VSV) strain. In order to identify correlates of permissity to viral infection, we measured transcriptional profiles of the cell lines prior infection.

Results

We observed highly heterogeneous permissivity to VACV infection amongst the cell lines. The heterogeneity of permissivity was independent of tissue with the exception of B cell derivation. Cell lines were also tested for permissivity to another Vaccinia Virus and a vesicular stomatitis virus (VSV) strain and a significant correlation was found suggesting a common permissive phenotype. While no clear transcriptional pattern could be identified as predictor of permissivity to infection, some associations were observed suggesting multifactorial basis permissivity to viral infection.

Conclusions

Our findings have implications for the design of oncolytic therapies for cancer and offer insights into the nature of permissivity of tumor cells to viral infection.

Replication efficiency of oncolytic vaccinia virus in cell cultures prognosticates the virulence and antitumor efficacy in mice

Background

We have shown that insertion of the three vaccinia virus (VACV) promoter-driven foreign gene expression cassettes encoding Renilla luciferase-Aequorea GFP fusion protein, β-galactosidase, and β-glucuronidase into the F14.5L, J2R, and A56R loci of the VACV LIVP genome, respectively, results in a highly attenuated mutant strain GLV-1h68. This strain shows tumor-specific replication and is capable of eradicating tumors with little or no virulence in mice. This study aimed to distinguish the contribution of added VACV promoter-driven transcriptional units as inserts from the effects of insertional inactivation of three viral genes, and to determine the correlation between replication efficiency of oncolytic vaccinia virus in cell cultures and the virulence and antitumor efficacy in mice

Methods

A series of recombinant VACV strains was generated by replacing one, two, or all three of the expression cassettes in GLV-1h68 with short non-coding DNA sequences. The replication efficiency and tumor cell killing capacity of these newly generated VACV strains were compared with those of the parent virus GLV-1h68 in cell cultures. The virus replication efficiency in tumors and antitumor efficacy as well as the virulence were evaluated in nu/nu (nude) mice bearing human breast tumor xenografts.

Results

we found that virus replication efficiency increased with removal of each of the expression cassettes. The increase in virus replication efficiency was proportionate to the strength of removed VACV promoters linked to foreign genes. The replication efficiency of the new VACV strains paralleled their cytotoxicity in cell cultures. The increased replication efficiency in tumor xenografts resulted in enhanced antitumor efficacy in nude mice. Similarly, the enhanced virus replication efficiency was indicative of increased virulence in nude mice.

Conclusions

These data demonstrated that insertion of VACV promoter-driven transcriptional units into the viral genome for the purpose of insertional mutagenesis did modulate the efficiency of virus replication together with antitumor efficacy as well as virulence. Replication efficiency of oncolytic VACV in cell cultures can predict the virulence and therapeutic efficacy in nude mice. These findings may be essential for rational design of safe and potent VACV strains for vaccination and virotherapy of cancer in humans and animals.

Efficient colonization and therapy of human hepatocellular carcinoma (HCC) using the oncolytic vaccinia virus strain GLV-1h68

Virotherapy using oncolytic vaccinia virus strains is one of the most promising new strategies for cancer therapy. In this study, we analyzed for the first time the therapeutic efficacy of the oncolytic vaccinia virus GLV-1h68 in two human hepatocellular carcinoma cell lines HuH7 and PLC/PRF/5 (PLC) in cell culture and in tumor xenograft models. By viral proliferation assays and cell survival tests, we demonstrated that GLV-1h68 efficiently colonized, replicated in, and did lyse these cancer cells in culture. Experiments with HuH7 and PLC xenografts have revealed that a single intravenous injection (i.v.) of mice with GLV-1h68 resulted in a significant reduction of primary tumor sizes compared to uninjected controls. In addition, replication of GLV-1h68 in tumor cells led to strong inflammatory and oncolytic effects resulting in intense infiltration of MHC class II-positive cells like neutrophils, macrophages, B cells and dendritic cells and in up-regulation of 13 pro-inflammatory cytokines. Furthermore, GLV-1h68 infection of PLC tumors inhibited the formation of hemorrhagic structures which occur naturally in PLC tumors. Interestingly, we found a strongly reduced vascular density in infected PLC tumors only, but not in the non-hemorrhagic HuH7 tumor model. These data demonstrate that the GLV-1h68 vaccinia virus may have an enormous potential for treatment of human hepatocellular carcinoma in man.

The vaccinia virus A56 protein: a multifunctional transmembrane glycoprotein that anchors two secreted viral proteins

The vaccinia virus A56 protein was one of the earliest-described poxvirus proteins with an identifiable activity. While originally characterized as a haemagglutinin protein, A56 has other functions as well. The A56 protein is capable of binding two viral proteins, a serine protease inhibitor (K2) and the vaccinia virus complement control protein (VCP), and anchoring them to the surface of infected cells. This is important; while both proteins have biologically relevant functions at the cell surface, neither one can locate there on its own. The A56-K2 complex reduces the amount of virus superinfecting an infected cell and also prevents the formation of syncytia by infected cells; the A56-VCP complex can protect infected cells from complement attack. Deletion of the A56R gene results in varying effects on vaccinia virus virulence. In addition, since the gene encoding the A56 protein is non-essential, it can be used as an insertion point for foreign genes and has been deleted in some viruses that are in clinical development as oncolytic agents.

Insertion of the human sodium iodide symporter to facilitate deep tissue imaging does not alter oncolytic or replication capability of a novel vaccinia virus

INTRODUCTION

Oncolytic viruses show promise for treating cancer. However, to assess therapeutic efficacy and potential toxicity, a noninvasive imaging modality is needed. This study aimed to determine if insertion of the human sodium iodide symporter (hNIS) cDNA as a marker for non-invasive imaging of virotherapy alters the replication and oncolytic capability of a novel vaccinia virus, GLV-1h153.

METHODS

GLV-1h153 was modified from parental vaccinia virus GLV-1h68 to carry hNIS via homologous recombination. GLV-1h153 was tested against human pancreatic cancer cell line PANC-1 for replication via viral plaque assays and flow cytometry. Expression and transportation of hNIS in infected cells was evaluated using Westernblot and immunofluorescence. Intracellular uptake of radioiodide was assessed using radiouptake assays. Viral cytotoxicity and tumor regression of treated PANC-1tumor xenografts in nude mice was also determined. Finally, tumor radiouptake in xenografts was assessed via positron emission tomography (PET) utilizing carrier-free 124I radiotracer.

RESULTS

GLV-1h153 infected, replicated within, and killed PANC-1 cells as efficiently as GLV-1h68. GLV-1h153 provided dose-dependent levels of hNIS expression in infected cells. Immunofluorescence detected transport of the protein to the cell membrane prior to cell lysis, enhancing hNIS-specific radiouptake (P < 0.001). In vivo, GLV-1h153 was as safe and effective as GLV-1h68 in regressing pancreatic cancer xenografts (P < 0.001). Finally, intratumoral injection of GLV-1h153 facilitated imaging of virus replication in tumors via 124I-PET.

CONCLUSION

Insertion of the hNIS gene does not hinder replication or oncolytic capability of GLV-1h153, rendering this novel virus a promising new candidate for the noninvasive imaging and tracking of oncolytic viral therapy.

Therapeutic effects of a fusogenic newcastle disease virus in treating head and neck cancer

BACKGROUND

Newcastle disease virus (NDV) is a paramyxovirus that is pathogenic in birds but causes only mild flulike symptoms in human beings. NDV(F3aa)-GFP is a genetically modified, fusogenic NDV. We assessed the utility of NDV(F3aa)-GFP in treating head and neck squamous cell carcinoma.

METHODS AND RESULTS

At a multiplicity of infection (MOI) of 1, NDV(F3aa)-GFP infection of 3 cell lines supported strong GFP expression by 36 hours. Four cell lines were highly sensitivite to viral cytotoxicity, with >75% of cells lysed by day 6 at MOI 0.1, and 2 other cell lines were partially susceptible. Murine SCC25 flank tumors exhibited robust GFP expression after a single intratumoral viral injection and showed near-complete tumor regression over 34 days. There were no adverse effects attributable to therapy.

CONCLUSIONS

We demonstrate that a fusogenic NDV exerts potent oncolytic effects against human head and neck cancer and support its continued investigation for clinical application.

Oncolytic vaccinia virus: a theranostic agent for cancer

Vaccinia virus (VACV) is arguably the most successful live biotherapeutic agent because of its critical role in the eradication of smallpox, one of the most deadly diseases in human history. VACV has been exploited as an oncolytic therapeutic agent for cancer since 1922. This virus selectively infects and destroys tumor cells, while sparing normal cells, both in cell cultures and in animal models. A certain degree of therapeutic efficacy also has been demonstrated in patients with different types of cancer. In recent years, several strategies have been successfully developed to further improve its tumor selectivity and antitumor efficacy. Oncolytic VACVs carrying imaging genes represent a new treatment strategy that combines tumor site-specific therapeutics with diagnostics (theranostics).

The combination of immunosuppression and carrier cells significantly enhances the efficacy of oncolytic poxvirus in the pre-immunized host

Pre-existing antipoxvirus immunity in cancer patients presents a severe barrier to poxvirus-mediated oncolytic virotherapy. We have explored strategies of immunosuppression (IS) and/or immune evasion for efficient delivery of an oncolytic double-deleted vaccinia virus (vvDD) to tumors in the pre-immunized mice. Transient IS using immunosuppressive drugs, including tacrolimus, mycophenolate mofetil and methylprednisolone sodium succinate, have been used successfully in organ transplantation. This drug cocktail alone did not enhance viral recovery from subcutaneous tumor after systemic viral delivery. Using B-cell knockout mice, we confirmed that the neutralizing antibodies had a significant role in preventing poxvirus infection. Using a MC38 peritoneal carcinomatosis model, we found that the combination of IS and tumor cells as carriers led to the most effective viral delivery, viral replication and viral spread inside the tumor mass. We found that our immunosuppressive drug cocktail facilitated recruitment of tumor-associated macrophages and conversion into an immunosuppressive M2 phenotype (interleukin (IL)-10(hi)/IL-12(low)) in the tumor microenvironment. A combination of IS and carrier cells led to significantly prolonged survival in the tumor model. These results showed the feasibility of treating pre-vaccinated patients with peritoneal carcinomatosis using an oncolytic poxvirus and a combined immune intervention strategy.