Prime-boost using separate oncolytic viruses in combination with checkpoint blockade improves anti-tumour therapy.

The anti-tumour effects associated with oncolytic virus therapy are mediated significantly through immune-mediated mechanisms, which depend both on the type of virus and the route of delivery. Here, we show that intra-tumoral oncolysis by Reovirus induced the priming of a CD8+, Th1-type anti-tumour response. By contrast, systemically delivered Vesicular Stomatitis Virus expressing a cDNA library of melanoma antigens (VSV-ASMEL) promoted a potent anti-tumour CD4+ Th17 response. Therefore, we hypothesised that combining the Reovirus-induced CD8+ T cell response, with the VSV-ASMEL CD4+ Th17 helper response, would produce enhanced anti-tumour activity. Consistent with this, priming with intra-tumoral Reovirus, followed by an intra-venous VSV-ASMEL Th17 boost, significantly improved survival of mice bearing established subcutaneous B16 melanoma tumours. We also show that combination of either therapy alone with anti-PD-1 immune checkpoint blockade augmented both the Th1 response induced by systemically delivered Reovirus in combination with GM-CSF, and also the Th17 response induced by VSV-ASMEL. Significantly, anti-PD-1 also uncovered an anti-tumour Th1 response following VSV-ASMEL treatment that was not seen in the absence of checkpoint blockade. Finally, the combination of all three treatments (priming with systemically delivered Reovirus, followed by double boosting with systemic VSV-ASMEL and anti-PD-1) significantly enhanced survival, with long-term cures, compared to any individual, or double, combination therapies, associated with strong Th1 and Th17 responses to tumour antigens. Our data show that it is possible to generate fully systemic, highly effective anti-tumour immunovirotherapy by combining oncolytic viruses, along with immune checkpoint blockade, to induce complementary mechanisms of anti-tumour immune responses.

Oncolytic vaccinia virus as a vector for therapeutic sodium iodide symporter gene therapy in prostate cancer.

Oncolytic strains of vaccinia virus are currently in clinical development with clear evidence of safety and promising signs of efficacy. Addition of therapeutic genes to the viral genome may increase the therapeutic efficacy of vaccinia. We evaluated the therapeutic potential of vaccinia virus expressing the sodium iodide symporter (NIS) in prostate cancer models, combining oncolysis, external beam radiotherapy and NIS-mediated radioiodide therapy. The NIS-expressing vaccinia virus (VV-NIS), GLV-1h153, was tested in in vitro analyzes of viral cell killing, combination with radiotherapy, NIS expression, cellular radioiodide uptake and apoptotic cell death in PC3, DU145, LNCaP and WPMY-1 human prostate cell lines. In vivo experiments were carried out in PC3 xenografts in CD1 nude mice to assess NIS expression and tumor radioiodide uptake. In addition, the therapeutic benefit of radioiodide treatment in combination with viral oncolysis and external beam radiotherapy was measured. In vitro viral cell killing of prostate cancers was dose- and time-dependent and was through apoptotic mechanisms. Importantly, combined virus therapy and iodizing radiation did not adversely affect oncolysis. NIS gene expression in infected cells was functional and mediated uptake of radioiodide both in vitro and in vivo. Therapy experiments with both xenograft and immunocompetent Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP) mouse models showed that the addition of radioiodide to VV-NIS-infected tumors was more effective than each single-agent therapy, restricting tumor growth and increasing survival. In conclusion, VV-NIS is effective in prostate cancer models. This treatment modality would be an attractive complement to existing clinical radiotherapy practice.

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.

Lymphokine-activated killer and dendritic cell carriage enhances oncolytic reovirus therapy for ovarian cancer by overcoming antibody neutralization in ascites.

Reovirus is an oncolytic virus (OV), which acts by both direct tumor cell killing and priming of antitumor immunity. A major obstacle for effective oncolytic virotherapy is effective delivery of OV to tumor cells. Ovarian cancer is often confined to the peritoneal cavity and therefore i.p. delivery of reovirus may provide the ideal locoregional delivery, avoiding systemic dissemination. However, ovarian cancer is associated with an accumulation of ascitic fluid, which may interfere with oncolytic viral therapy. Here, we investigated the effect of ascites on reovirus-induced oncolysis against primary ovarian cancer cells and ovarian cancer cell lines. In the absence of ascites, reovirus was cytotoxic against ovarian cancer cells; however, cytotoxicity was abrogated in the presence of ascitic fluid. Neutralizing antibodies (NAb) were identified as the cause of this inhibition. Loading OV onto cell carriers may facilitate virus delivery in the presence of NAb and immune cells which have their own antitumor effector activity are particularly appealing. Immature dendritic cells (iDC), Lymphokine-activated killer (LAK) cells and LAKDC cocultures were tested as potential carriers for reovirus for tumor cell killing and immune cell priming. Reovirus-loaded LAKDC, and to a lesser degree iDC, were able to: (i) protect from NAb and hand-off reovirus for tumor cell killing; (ii) induce a proinflammatory cytokine milieu (IFNÉ£, IL-12, IFNα and TNFα) and (iii) generate an innate and specific antitumor adaptive immune response. Hence, LAKDC pulsed with reovirus represent a novel, clinically practical treatment for ovarian cancer to maximise both direct and innate/adaptive immune-mediated tumor cell killing.

Dermal and conjunctival melanocytic proliferations in diffuse uveal melanocytic proliferation.

AIM: The goal of this case report is to describe the dermatologic and conjunctival findings in a case of bilateral diffuse uveal melanocytic proliferation (BDUMP), a paraneoplastic syndrome usually associated with gynecologic cancers. There is little information about other dermatologic melanocytic findings in these patients. METHODS: Histologic and fluorescent in situ hybridization (FISH) analysis of three separate skin biopsies, one of which was separated by 21 months from the others, were performed in a 71-year-old patient with BDUMP to assess for histologic and chromosomal abnormality. Conjunctival histologic evaluation was also done. RESULTS: Dermal melanocytic proliferation was seen in each specimen. The cells were spindle type with mitotic activity. FISH analysis showed a normal copy of chromosomes. The conjunctival sample also showed normal FISH analysis. CONCLUSION: BDUMP is associated with multifocal dermal and conjunctival melanocytic proliferation.

Oncolytic Vaccinia virus and radiotherapy in head and neck cancer.

OBJECTIVE: Oncolytic forms of attenuated Vaccinia virus are now in clinical development, assessing the compatibility of this novel treatment with radiotherapy may reveal exploitable synergistic relationships. MATERIALS AND METHODS: In vitro analyses of cell killing, cell cycle effects and caspase activation were carried out on HN3, HN5, CAL27, Detroit, SIHN5B, and PJ41 cells. In vivo studies of the virus and X-radiation were performed on H&N xenografts in CD1 nude mice. RESULTS: Cell killing in vitro was demonstrated to be dose- and time-dependent. Infection causes an increase in S-phase and sub-G1 cells. A dose dependent increase in active caspase-3 indicated induction of apoptosis. Xenografts injected with Vaccinia stabilised and frequently completely regressed. Combination with radiation generated additional cell death, induction of caspase activity and in vivo further improved long term regression rates. CONCLUSIONS: These data support continued exploration of this therapy combination and indicates potential for clinical trials in head and neck cancer.

Measles virus causes immunogenic cell death in human melanoma.

Oncolytic viruses (OV) are promising treatments for cancer, with several currently undergoing testing in randomised clinical trials. Measles virus (MV) has not yet been tested in models of human melanoma. This study demonstrates the efficacy of MV against human melanoma. It is increasingly recognised that an essential component of therapy with OV is the recruitment of host antitumour immune responses, both innate and adaptive. MV-mediated melanoma cell death is an inflammatory process, causing the release of inflammatory cytokines including type-1 interferons and the potent danger signal HMGB1. Here, using human in vitro models, we demonstrate that MV enhances innate antitumour activity, and that MV-mediated melanoma cell death is capable of stimulating a melanoma-specific adaptive immune response.

Synergistic cytotoxicity of oncolytic reovirus in combination with cisplatin-paclitaxel doublet chemotherapy.

Oncolytic reovirus is currently under active investigation in a range of tumour types. Early phase studies have shown that this agent has modest monotherapy efficacy and its future development is likely to focus on combination regimens with cytotoxic chemotherapy. Indeed, phase I/II clinical trials have confirmed that reovirus can be safely combined with cytotoxic drugs, including a platin-taxane doublet regimen, which is currently being tested in a phase III clinical trial in patients with relapsed/metastatic head and neck cancer. Therefore, we have tested this triple (reovirus, cisplatin, paclitaxel) combination therapy in a panel of four head and neck cancer cell lines. Using the combination index (CI) method, the triple therapy demonstrated synergistic cytotoxicity in vitro in both malignant and non-malignant cell lines. In head and neck cancer cell lines, this was associated with enhanced caspase 3 and 7 cleavage, but no increase in viral replication. In vitro analyses confirmed colocalisation of markers of reovirus infection and caspase 3. Triple therapy was significantly more effective than reovirus or cisplatin-paclitaxel in athymic nude mice. These data suggest that the combination of reovirus plus platin-taxane doublet chemotherapy has significant activity in head and neck cancer and underpin the current phase III study in this indication.

Histological findings of birdshot chorioretinopathy in an eye with ciliochoroidal melanoma.

PURPOSE: To describe the histological findings of birdshot chorioretinopathy. DESIGN/PARTICIPANT: This is a case study of a single patient who has both birdshot chorioretinopathy and ciliochoroidal melanoma. METHODS: A 55-year-old woman who was HLA-A29 positive and had birdshot chorioretinopathy had a large ciliochoroidal melanoma (T4b N0 M0) and underwent enucleation. OUTCOME MEASURES: Using histopathology, we hope to further define the pathological findings in an eye with both birdshot chorioretinopathy and coexistant ciliochoroidal melanomas. RESULTS: The eye showed a ciliochoroidal melanoma. In addition, elsewhere, there were multiple choroidal nodules of lymphocytes that showed the presence of CD3-positive cells, which also stained for CD4 or CD8. There were only a few CD20-positive B cells and rare CD68-positive histiocytes. No granulomas were present. DISCUSSION: To our knowledge, there are only two previous reports describing the histological findings in birdshot chorioretinopathy: one that was HLA-A29 negative showing choroidal granulomas and another that was HLA-A29 positive exhibiting histological findings similar to our case. Incidentally, the latter case had a history of cutaneous melanoma. CONCLUSION: Birdshot chorioretinopathy is a nongranulomatous nodular infiltration of the choroid.

Dynamics of melanoma tumor therapy with vesicular stomatitis virus: explaining the variability in outcomes using mathematical modeling.

Tumor selective, replication competent viruses are being tested for cancer gene therapy. This approach introduces a new therapeutic paradigm due to potential replication of the therapeutic agent and induction of a tumor-specific immune response. However, the experimental outcomes are quite variable, even when studies utilize highly inbred strains of mice and the same cell line and virus. Recognizing that virotherapy is an exercise in population dynamics, we utilize mathematical modeling to understand the variable outcomes observed when B16ova malignant melanoma tumors are treated with vesicular stomatitis virus in syngeneic, fully immunocompetent mice. We show how variability in the initial tumor size and the actual amount of virus delivered to the tumor have critical roles on the outcome of therapy. Virotherapy works best when tumors are small, and a robust innate immune response can lead to superior tumor control. Strategies that reduce tumor burden without suppressing the immune response and methods that maximize the amount of virus delivered to the tumor should optimize tumor control in this model system.

GALV expression enhances the therapeutic efficacy of an oncolytic adenovirus by inducing cell fusion and enhancing virus distribution.

The limitations of the current oncolytic adenoviruses for cancer therapy include insufficient potency and poor distribution of the virus throughout the tumor mass. To address these problems, we generated an oncolytic adenovirus expressing the hyperfusogenic form of the gibbon-ape leukemia virus (GALV) envelope glycoprotein under the control of the adenovirus major late promoter. The oncolytic properties of the new fusogenic adenovirus, ICOVIR16, were analyzed both in vitro and in vivo, and compared with that of its non-fusogenic counterpart, ICOVIR15. Our results indicate that GALV expression by ICOVIR16 induced extensive syncytia formation and enhanced tumor cell killing in a variety of tumor cell types. When injected intratumorally or intravenously into mice with large pre-established melanoma or pancreatic tumors, ICOVIR16 rapidly reduced tumor burden, and in some cases, resulted in complete eradication of the tumors. Importantly, GALV expression induced tumor cell fusion in vivo and enhanced the spreading of the virus throughout the tumor. Taken together, these results indicate that GALV expression can improve the antitumoral potency of an oncolytic adenovirus and suggest that ICOVIR16 is a promising candidate for clinical evaluation in patients with cancer.

Recent clinical experience with oncolytic viruses.

There has been interest in using viruses to treat cancer for over a century. Recent clinical efforts, driven on by significant preclinical advances, have focussed on the safety of using replication-competent viruses. Recently published clinical trials of six oncolytic viruses (adenovirus, reovirus, measles, herpes simplex, Newcastle disease virus and vaccinia) have added to the accumulating data that endorse oncolytic viruses as a safe and well tolerated treatment approach. Conclusive evidence of efficacy remains to be demonstrated, but randomised clinical trials are now underway.

Locoregional intravascular viral therapy of cancer: precision guidance for Paris's arrow?

Viral therapy of cancer includes strategies such as viral transduction of tumour cells with 'suicide genes', using viral infection to trigger immune-mediated tumour cell death and using oncolytic viruses for their direct anti-tumour action. However, problems still remain in terms of adequate viral delivery to tumours. A role is also emerging for single-organ isolation and perfusion. Having begun with the advent of isolated limb perfusion for extremity malignancy, experimental systems have been developed for the perfusion of other organs, particularly the liver, kidneys and lungs. These are beginning to be adopted into clinical treatment pathways. The combination of these two modalities is potentially significant. Locoregional perfusion increases the exposure of tumour cells to viral agents. In addition, the avoidance of systemic elimination through the immune and reticulo-endothelial systems should provide a mechanism for increased transduction/infection of target cells. The translation of laboratory research to clinical practice would occur within the context of perfusion programmes, which are already established in the clinic. Many of these programmes include the use of vasoactive cytokines such as tumour necrosis factor-alpha, which may have an effect on viral uptake. Evidence of activation of specific anti-tumour immunological responses by intratumoural and other existing methods of viral administration raises the intriguing possibility of a locoregional therapy, with the ability to affect distant sites of disease. In this review, we examined the state of the literature in this area and summarized current findings before indicating likely areas of continuing interest.

Retargeted adenoviral cancer gene therapy for tumour cells overexpressing epidermal growth factor receptor or urokinase-type plasminogen activator receptor.

We have assessed the ability of bispecific fusion proteins to improve adenovirus-mediated transfer of therapeutic and marker transgenes. We constructed an expression vector that can be easily modified to synthesize a variety of fusion proteins for retargeting adenoviral gene therapy vectors to cell surface markers, which are differentially expressed between normal and cancer cells. Adenoviral transduction can be improved in a number of tumour cell lines which overexpress EGFR (epidermal growth factor receptor) or uPAR (urokinase-type plasminogen activator receptor), but which have only low levels of endogenous hCAR (human coxsackie B and adenovirus receptor) expression. Up to 40-fold improvement in beta-galactosidase transgene expression was seen using an EGFR retargeting protein, and up to 16-fold using a second fusion protein targeting uPAR. In vitro, our uPAR retargeting fusion protein improved the sensitivity to adenoviral herpes simplex virus thymidine kinase/ganciclovir by an order of magnitude, whereas in vivo, our EGFR retargeting protein is able to significantly delay tumour growth in rodent animal models in a dose-dependent manner. The 'cassette' design of our fusion protein constructs offers a flexible method for the straightforward synthesis of multiple adenoviral retargeting proteins, directed against a variety of tumour-associated antigens, for use in clinical trials.

Clinical trials with oncolytic reovirus: moving beyond phase I into combinations with standard therapeutics.

It is time for those working on oncolytic viruses to take stock of the status of the field. We now have at our disposal an array of potential therapeutic agents, and are beginning to conduct early-phase clinical trials in patients with relapsed/metastatic cancers. By drawing on lessons learned during the development of other biological therapies, such as monoclonal antibodies and targeted small molecule inhibitors, we are now in a position to chart the course of the next wave of trials that will go beyond the phase I studies of safety and feasibility. In this article we review our approach to the development of oncolytic viruses as cancer therapeutics. In doing so, we emphasise the fact that this process is modular and involves multiple iterative steps between the laboratory and the clinic. Ultimately, at least in the medium term, the future of oncolytic virotherapy lies in combination regimens with standard anti-cancer agents such as radiation and chemotherapy.

Single-cycle viral gene expression, rather than progressive replication and oncolysis, is required for VSV therapy of B16 melanoma.

A fully intact immune system would be expected to hinder the efficacy of oncolytic virotherapy by inhibiting viral replication. Simultaneously, however, it may also enhance antitumor therapy through initiation of proinflammatory, antiviral cytokine responses at the tumor site. The aim of this study was to investigate the role of a fully intact immune system on the antitumor efficacy of an oncolytic virus. In this respect, injection of oncolytic vesicular stomatitis virus (VSV) into subcutaneous B16ova melanomas in C57Bl/6 mice leads to tumor regression, but it is not associated with viral replicative burst in the tumor. In contrast, intratumoral delivery of VSV induces an acute proinflammatory reaction, which quickly resolves concomitantly with virus clearance. Consistent with the hypothesis that therapy may not be dependent on the ability of VSV to undergo progressive rounds of replication, a single-cycle VSV is equally effective as a fully replication-competent VSV, whereas inactivated viruses do not generate therapy. Even though therapy is dependent on host CD8+ and natural killer cells, these effects are not associated with interferon-gamma-dependent responses against either the virus or tumor. There is, however, a strong correlation between viral gene expression, induction of proinflammatory reaction in the tumor and in vivo therapy. Overall, our results suggest that acute innate antiviral immune response, which rapidly clears VSV from B16ova tumors, is associated with the therapy observed in this model. Therefore, the antiviral immune response to an oncolytic virus mediates an intricate balance between safety, restriction of oncolysis and, potentially, significant immune-mediated antitumor therapy.

Dendritic cells and T cells deliver oncolytic reovirus for tumour killing despite pre-existing anti-viral immunity.

Reovirus is a naturally occurring oncolytic virus currently in early clinical trials. However, the rapid induction of neutralizing antibodies represents a major obstacle to successful systemic delivery. This study addresses, for the first time, the ability of cellular carriers in the form of T cells and dendritic cells (DC) to protect reovirus from systemic neutralization. In addition, the ability of these cellular carriers to manipulate the subsequent balance of anti-viral versus anti-tumour immune response is explored. Reovirus, either neat or loaded onto DC or T cells, was delivered intravenously into reovirus-naive or reovirus-immune C57Bl/6 mice bearing lymph node B16tk melanoma metastases. Three and 10 days after treatment, reovirus delivery, carrier cell trafficking, metastatic clearance and priming of anti-tumour/anti-viral immunity were assessed. In naive mice, reovirus delivered either neat or through cell carriage was detectable in the tumour-draining lymph nodes 3 days after treatment, though complete clearance of metastases was only obtained when the virus was delivered on T cells or mature DC (mDC); neat reovirus or loaded immature DC (iDC) gave only partial early tumour clearance. Furthermore, only T cells carrying reovirus generated anti-tumour immune responses and long-term tumour clearance; reovirus-loaded DC, in contrast, generated only an anti-viral immune response. In reovirus-immune mice, however, the results were different. Neat reovirus was completely ineffective as a therapy, whereas mDC--though not iDC--as well as T cells, effectively delivered reovirus to melanoma in vivo for therapy and anti-tumour immune priming. Moreover, mDC were more effective than T cells over a range of viral loads. These data show that systemically administered neat reovirus is not optimal for therapy, and that DC may be an appropriate vehicle for carriage of significant levels of reovirus to tumours. The pre-existing immune status against the virus is critical in determining the balance between anti-viral and anti-tumour immunity elicited when reovirus is delivered by cell carriage, and the viral dose and mode of delivery, as well as the immune status of patients, may profoundly affect the success of any clinical anti-tumour viral therapy. These findings are therefore of direct translational relevance for the future design of clinical trials.

Metastatic malignant melanoma.

Metastatic malignant melanoma is an incurable malignancy with extremely poor prognosis. Patients bearing this diagnosis face a median survival time of approximately 9 months with a probability of surviving 5 years after initial presentation at less than 5%. This is contrasted by the curative nature of surgical resection of early melanoma detected in the skin. To date, no systemic therapy has consistently and predictably impacted the overall survival of patients with metastatic melanoma. However, in recent years, a resurgence of innovative diagnostic and therapeutic developments have broadened our understanding of the natural history of melanoma and identified rational therapeutic targets/strategies that seem poised to significantly change the clinical outcomes in these patients. Herein we review the state-of-the-art in metastatic melanoma diagnostics and therapeutics with particular emphasis on multi-disciplinary clinical management.

Microvascular free tissue transfer for gene delivery: in vivo evaluation of different routes of plasmid and adenoviral delivery.

Transfer of healthy autologous tissue as a microvascular free flap facilitates reconstruction during ablative cancer surgery. In addition to filling surgical defects, free flaps might concentrate viral vectors at the tumour bed and mediate local therapeutic effects. We evaluated the magnitude, topography and duration of luciferase gene expression after plasmid and adenoviral delivery in rat superficial inferior epigastric (SIE) flaps. For plasmid delivery, luciferase expression was significantly increased by all transduction routes (topical, intraflap injection, intravascular) (P<0.01) at day 1, but not at day 7. The spread of luciferase expression was significantly different between the 4 groups at 1 day (P=0.026) and was greatest for flaps transduced by intravascular injection. For adenoviral transduction, total radiance was significantly different between the transduced groups at 1, 14 and 28 days (P<0.05 for all comparisons). The highest levels of radiance were seen in the intravascular group. There was a statistically significant difference in the spread of light emission between the 3 groups at 1 (P=0.009) and 14 (P=0.013) days, but this was no longer evident at 28 days. Intravascular adenoviral delivery yields high-level, diffuse and durable gene expression in rat SIE flaps and is suitable for examination in therapeutic models.