Vaccinia virus GLV-1h153 in combination with 131I shows increased efficiency in treating triple-negative breast cancer

Oncolytic vaccinia virus immunotherapy antagonizes image-guided radiotherapy in mouse mammary tumor models

Ionizing radiation (IR) and oncolytic viruses are both used to treat cancer, and the effectiveness of both agents depends upon stimulating an immune response against the tumor. In this study we tested whether combining image guided ionizing radiation (IG-IR) with an oncolytic vaccinia virus (VACV) could yield a better therapeutic response than either treatment alone. ΔF4LΔJ2R VACV grew well on irradiated human and mouse breast cancer cells, and the virus can be combined with 4 or 8 Gy of IR to kill cells in an additive or weakly synergistic manner. To test efficacy in vivo we used immune competent mice bearing orthotopic TUBO mammary tumors. IG-IR worked well with 10 Gy producing 80% complete responses, but this was halved when the tumors were treated with VACV starting 2 days after IG-IR. VACV monotherapy was ineffective in this model. The antagonism was time dependent as waiting for 21 days after IG-IR eliminated the inhibitory effect but without yielding any further benefits over IR alone. In irradiated tumors, VACV replication was also lower, suggesting that irradiation created an environment that did not support infection as well in vivo as in vitro. A study of how four different treatment regimens affected the immune composition of the tumor microenvironment showed that treating irradiated tumors with VACV altered the immunological profiles in tumors exposed to IR or VACV alone. We detected more PD-1 and PD-L1 expression in tumors exposed to IR+VACV but adding an αPD-1 antibody to the protocol did not change the way VACV interferes with IG-IR therapy. VACV encodes many immunosuppressive gene products that may interfere with the ability of radiotherapy to induce an effective anti-tumor immune response through the release of danger-associated molecular patterns. These data suggest that infecting irradiated tumors with VACV, too soon after exposure, may interfere in the innate and linked adaptive immune responses that are triggered by radiotherapy to achieve a beneficial impact.

Triple-Negative Breast Cancer: Basic Biology and Immuno-Oncolytic Viruses

Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer. TNBC diagnoses account for approximately one-fifth of all breast cancer cases globally. The lack of receptors for estrogen, progesterone, and human epidermal growth factor 2 (HER-2, CD340) results in a lack of available molecular-based therapeutics. This increases the difficulty of treatment and leaves more traditional as well as toxic therapies as the only available standards of care in many cases. Recurrence is an additional serious problem, contributing substantially to its higher mortality rate as compared to other breast cancers. Tumor heterogeneity also poses a large obstacle to treatment approaches. No driver of tumor development has been identified for TNBC, and large variations in mutational burden between tumors have been described previously. Here, we describe the biology of six different subtypes of TNBC, based on differential gene expression. Subtype differences can have a large impact on metastatic potential and resistance to treatment. Emerging antibody-based therapeutics, such as immune checkpoint inhibitors, have available targets for small subsets of TNBC patients, leading to partial responses and relatively low overall efficacy. Immuno-oncolytic viruses (OVs) have recently become significant in the pursuit of effective treatments for TNBC. OVs generally share the ability to ignore the heterogeneous nature of TNBC cells and allow infection throughout a treated tumor. Recent genetic engineering has allowed for the enhancement of efficacy against certain tumor types while avoiding the most common side effects in non-cancerous tissues. In this review, TNBC is described in order to address the challenges it presents to potential treatments. The OVs currently described preclinically and in various stages of clinical trials are also summarized, as are their strategies to enhance therapeutic potential.

Improving cancer immunotherapy by rationally combining oncolytic virus with modulators targeting key signaling pathways

Oncolytic viruses (OVs) represent a new class of multi-modal immunotherapies for cancer, with OV-elicited antitumor immunity being key to their overall therapeutic efficacy. Currently, the clinical effectiveness of OV as monotherapy remains limited, and thus investigators have been exploring various combinations with other anti-cancer agents and demonstrated improved therapeutic efficacy. As cancer cells have evolved to alter key signaling pathways for enhanced cell proliferation, cancer progression and metastasis, these cellular and molecular changes offer promising targets for rational cancer therapy design. In this regard, key molecules in relevant signaling pathways for cancer cells or/and immune cells, such as EGFR-KRAS (e.g., KRAS^G12C), PI3K-AKT-mTOR, ERK-MEK, JAK-STAT, p53, PD-1-PD-L1, and epigenetic, or immune pathways (e.g., histone deacetylases, cGAS-STING) are currently under investigation and have the potential to synergize with OV to modulate the immune milieu of the tumor microenvironment (TME), thereby improving and sustaining antitumor immunity. As many small molecule modulators of these signaling pathways have been developed and have shown strong therapeutic potential, here we review key findings related to both OV-mediated immunotherapy and the utility of small molecule modulators of signaling pathways in immuno-oncology. Then, we focus on discussion of the rationales and potential strategies for combining OV with selected modulators targeting key cellular signaling pathways in cancer or/and immune cells to modulate the TME and enhance antitumor immunity and therapeutic efficacy. Finally, we provide perspectives and viewpoints on the application of novel experimental systems and technologies that can propel this exciting branch of medicine into a bright future.

Reporter Transgenes for Monitoring the Antitumor Efficacy of Recombinant Oncolytic Viruses

Accurate measurement of tumor size and margins is crucial for successful oncotherapy. In the last decade, non-invasive imaging modalities, including optical imaging using non-radioactive substrates, deep-tissue imaging with radioactive substrates, and magnetic resonance imaging have been developed. Reporter genes play the most important role among visualization tools; their expression in tumors and metastases makes it possible to track changes in the tumor growth and gauge therapy effectiveness. Oncolytic viruses are often chosen as a vector for delivering reporter genes into tumor cells, since oncolytic viruses are tumor-specific, meaning that they infect and lyse tumor cells without damaging normal cells. The choice of reporter transgenes for genetic modification of oncolytic viruses depends on the study objectives and imaging methods used. Optical imaging techniques are suitable for in vitro studies and small animal models, while deep-tissue imaging techniques are used to evaluate virotherapy in large animals and humans. For optical imaging, transgenes of fluorescent proteins, luciferases, and tyrosinases are used; for deep-tissue imaging, the most promising transgene is the sodium/iodide symporter (NIS), which ensures an accumulation of radioactive isotopes in virus-infected tumor cells. Currently, NIS is the only reporter transgene that has been shown to be effective in monitoring tumor virotherapy not only in preclinical but also in clinical studies.

Development of oncolytic viruses for cancer therapy

Oncolytic virotherapy is a therapeutic approach that uses replication-competent viruses to kill cancers. The ability of oncolytic viruses to selectively replicate in cancer cells leads to direct cell lysis and induction of anticancer immune response. Like other anticancer therapies, oncolytic virotherapy has several limitations such as viral delivery to the target, penetration into the tumor mass, and antiviral immune responses. This review provides an insight into the different characteristics of oncolytic viruses (natural and genetically modified) that contribute to effective applications of oncolytic virotherapy in preclinical and clinical trials, and strategies to overcome the limitations. The potential of oncolytic virotherapy combining with other conventional treatments or cancer immunotherapies involving immune checkpoint inhibitors and CAR-T therapy could form part of future multimodality treatment strategies.

Delivery of cancer therapies by synthetic and bio-inspired nanovectors

BACKGROUND

As a complement to the clinical development of new anticancer molecules, innovations in therapeutic vectorization aim at solving issues related to tumor specificity and associated toxicities. Nanomedicine is a rapidly evolving field that offers various solutions to increase clinical efficacy and safety. MAIN: Here are presented the recent advances for different types of nanovectors of chemical and biological nature, to identify the best suited for translational research projects. These nanovectors include different types of chemically engineered nanoparticles that now come in many different flavors of 'smart' drug delivery systems. Alternatives with enhanced biocompatibility and a better adaptability to new types of therapeutic molecules are the cell-derived extracellular vesicles and micro-organism-derived oncolytic viruses, virus-like particles and bacterial minicells. In the first part of the review, we describe their main physical, chemical and biological properties and their potential for personalized modifications. The second part focuses on presenting the recent literature on the use of the different families of nanovectors to deliver anticancer molecules for chemotherapy, radiotherapy, nucleic acid-based therapy, modulation of the tumor microenvironment and immunotherapy.

CONCLUSION

This review will help the readers to better appreciate the complexity of available nanovectors and to identify the most fitting "type" for efficient and specific delivery of diverse anticancer therapies.

A Novel Chimeric Poxvirus Encoding hNIS Is Tumor-Tropic, Imageable, and Synergistic with Radioiodine to Sustain Colon Cancer Regression

Colon cancer has a high rate of recurrence even with good response to modern therapies. Novel curative adjuncts are needed. Oncolytic viral therapy has shown preclinical promise against colon cancer but lacks robust efficacy in clinical trials and raises regulatory concerns without real-time tracking of viral replication. Novel potent vectors are needed with adjunctive features to enhance clinical efficacy. We have thus used homologous recombination and high-throughput screening to create a novel chimeric poxvirus encoding a human sodium iodide symporter (hNIS) at a redundant tk locus. The resulting virus (CF33-hNIS) consistently expresses hNIS and demonstrates replication efficiency and immunogenic cell death in colon cancer cells in vitro. Tumor-specific CF33-hNIS efficacy against colon cancer results in tumor regression in vivo in colon cancer xenograft models. Early expression of hNIS by infected cells makes viral replication reliably imageable via positron emission tomography (PET) of I-124 uptake. The intensity of I-124 uptake mirrors viral replication and tumor regression. Finally, systemic delivery of radiotherapeutic I-131 isotope following CF33-hNIS infection of colon cancer xenografts enhances and sustains tumor regression compared with virus treatment alone in HCT116 xenografts, demonstrating synergy of oncolytic viral therapy with radioablation in vivo.

Poxvirus oncolytic virotherapy

INTRODUCTION

Over the last decade, advances in biological therapies have resulted in remarkable clinical responses for the treatment of some previously incurable cancers. Oncolytic virotherapy is one of these promising novel strategies for cancer therapy. A successful oncolytic virus promotes tumor cell oncolysis and elicits a robust long-term anti-tumor immunity.

AREAS COVERED

Oncolytic poxviruses (Vaccinia virus and Myxoma virus) demonstrated encouraging results in multiple pre-clinical tumor models and some clinical trials for the treatment of various cancers. This review summarizes the advances made on poxvirus oncolytic virotherapy in the last five years.

EXPERT OPINION

Many challenges remain in poxvirus oncolytic virotherapy. Two key goals to achieve are enhancing the efficiency of viral delivery to tumor sites and overcoming local tumor immune-evasion. Additional efforts are necessary to explore the best combination of virotherapy with standard available treatments, particularly immunotherapies. By addressing these issues, this new modality will continue to improve as an adjunct biotherapy to treat malignant diseases.

Therapeutic potency of oncolytic virotherapy in breast cancer targeting, current status and perspective

Breast cancer is the most common cause of cancer death in women and presents a serious therapeutic challenge worldwide. Traditional treatments are less successful at targeting cancer tumors, leading to recurrent treatment-resistant secondary malignancies. Oncolytic virotherapy (OV) is a novel anticancer strategy with therapeutic implications at targeting cancer cells by using mechanisms that differ from conventional therapies. Administration of OVs either alone or in combination with standard therapies provide new insights regarding the effectiveness and improvement of treatment responses for breast cancer patients. This review summarizes cellular, animal and clinical studies investigating therapeutic potency of oncolytic virotherapy in breast cancer treatment for a better understanding and hence a better management of this disease.

Oncolytic Virus Combination Therapy: Killing One Bird with Two Stones

Over the last 60 years an eclectic collection of microbes has been tested in a variety of pre-clinical models as anti-cancer agents. At the forefront of this research are a number of virus-based platforms that have shown exciting activity in a variety of pre-clinical models and are collectively referred to as oncolytic viruses. Our true understanding of the potential and limitations of this therapeutic modality has been substantially advanced through clinical studies carried out over the last 25 years. Perhaps not surprising, as with all other cancer therapeutics, it has become clear that current oncolytic virus therapeutics on their own are unlikely to be effective in the majority of patients. The greatest therapeutic gains will therefore be made through thoughtful combination strategies built upon an understanding of cancer biology.

The importance of imaging strategies for pre-clinical and clinical in vivo distribution of oncolytic viruses

Oncolytic viruses (OVs) are an emergent and unique therapy for cancer patients. Similar to chemo- and radiation therapy, OV can lyse (kill) cancer cell directly. In general, the advantages of OVs over other treatments are primarily: a higher safety profile (as shown by less adverse effects), ability to replicate, transgene(s) delivery, and stimulation of a host’s immune system against cancer. The latter has prompted successful use of OVs with other immunotherapeutic strategies in a synergistic manner. In spite of extended testing in pre-clinical and clinical setting, using biologically derived therapeutics like virus always raises potential concerns about safety (replication at non-intended locations) and bio-availability of the product. Recent advent in in vivo imaging techniques dramatically improves the convenience of use, quality of pictures, and amount of information acquired. Easy assessing of safety/localization of the biotherapeutics like OVs became a new potential weapon in the physician’s arsenal to improve treatment outcome. Given that OVs are typically replicating, in vivo imaging can also track virus replication and persistence as well as precisely mapping tumor tissues presence. This review discusses the importance of imaging in vivo in evaluating OV efficacy, as well as currently available tools and techniques.

A Novel Oncolytic Chimeric Orthopoxvirus Encoding Luciferase Enables Real-Time View of Colorectal Cancer Cell Infection

This study hypothesizes that a novel oncolytic chimeric orthopoxvirus CF33-Fluc is imageable and targets colorectal cancer cells (CRCs). A novel chimeric orthopoxvirus (CF33) was constructed. The thymidine kinase locus was replaced with firefly luciferase (Fluc) to yield a recombinant virus—CF33-Fluc. In vitro cytotoxicity and viral replication assays were performed. In vivo CRC flank xenografts received single doses of intratumoral or intravenous CF33-Fluc. Viral biodistribution was analyzed via luciferase imaging and organ titers. CF33-Fluc infects, replicates in, and kills CRCs in vitro in a dose-dependent manner. CF33 has superior secretion of extracellular-enveloped virus versus all but one parental strain. Rapid tumor regression or stabilization occurred in vivo at a low dose over a short time period, regardless of the viral delivery method in the HCT-116 colorectal tumor xenograft model. Rapid luciferase expression in virus-infected tumor cells was associated with treatment response. CRC death occurs via necroptotic pathways. CF33-Fluc replicates in and kills colorectal cancer cells in vitro and in vivo regardless of delivery method. Expression of luciferase enables real-time tracking of viral replication. Despite the chimerism, CRC death occurs via standard poxvirus-induced mechanisms. Further studies are warranted in immunocompetent models.

Oncolytic Viruses for Tumor Precision Imaging and Radiotherapy

In 2003 in China, Peng et al. invented the recombinant adenovirus expressing p53 (Gendicine) for clinical tumor virotherapy. This was the first clinically approved gene therapy and tumor virotherapy drug in the world. An oncolytic herpes simplex virus expressing granulocyte-macrophage colony-stimulating factor (Talimogene laherparepvec) was approved for melanoma treatment in the United States in 2015. Since then, oncolytic viruses have been attracting more and more attention in the field of oncology, and may become novel significant modalities of tumor precision imaging and radiotherapy after further improvement. Oncolytic viruses carrying reporter genes can replicate and express genes of interest selectively in tumor cells, thus improving in vivo noninvasive precision molecular imaging and radiotherapy. Here, the latest developments and molecular mechanisms of tumor imaging and radiotherapy using oncolytic viruses are reviewed, and perspectives are given for further research. Various types of tumors are discussed, and special attention is paid to gastrointestinal tumors.

Inversion of neurovascular coupling after subarachnoid hemorrhage in vivo

Subarachnoid hemorrhage (SAH) induces acute changes in the cerebral microcirculation. Recent findings ex vivo suggest neurovascular coupling (NVC), the process that increases cerebral blood flow upon neuronal activity, is also impaired after SAH. The aim of the current study was to investigate whether this occurs also in vivo. C57BL/6 mice were subjected to either sham surgery or SAH by filament perforation. Twenty-four hours later NVC was tested by forepaw stimulation and CO₂ reactivity by inhalation of 10% CO₂. Vessel diameter was assessed in vivo by two-photon microscopy. NVC was also investigated ex vivo using brain slices. Cerebral arterioles of sham-operated mice dilated to 130% of baseline upon CO₂ inhalation or forepaw stimulation and cerebral blood flow (CBF) increased. Following SAH, however, CO₂ reactivity was completely lost and the majority of cerebral arterioles showed paradoxical constriction in vivo and ex vivo resulting in a reduced CBF response. As previous results showed intact NVC 3 h after SAH, the current findings indicate that impairment of NVC after cerebral hemorrhage occurs secondarily and is progressive. Since neuronal activity-induced vasoconstriction (inverse NVC) is likely to further aggravate SAH-induced cerebral ischemia and subsequent brain damage, inverse NVC may represent a novel therapeutic target after SAH.

Therapeutic oncolytic viruses: clinical advances and future directions

PURPOSE OF REVIEW

The present review will highlight recent advances in the clinical application of oncolytic viral therapy.

RECENT FINDINGS

Until recently, oncolytic viral researchers saw the immune system as an enemy that would clear the virus from the bloodstream. However, researchers now understand that sustained responses are seen in those patients with more robust antitumor immune responses. Much of the current focus in oncolytic viral research is trained on manipulation of the immune system to affect cancer cell killing in the tumor microenvironment and to facilitate durable systemic antitumor immunity. Many investigators have demonstrated synergistic effects of checkpoint inhibition and other immune therapies with viral administration. At the same time, insertion of various markers enables noninvasive deep tissue imaging. Finally, following regulatory approval in the United States and Europe, unbridled clinical use of T-VEC for patients with metastatic melanoma is also generating large volumes of patient data that will help elucidate strengths and weaknesses of oncolytic viral therapy. Perhaps the most telling sign of the field's future is a seismic shift in clinical trials with more investigators combining virus and immunotherapies.

SUMMARY

This article reviews the current state of therapeutic oncolytic viruses in clinical use, and explores future directions of the field.

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.

Acute changes in neurovascular reactivity after subarachnoid hemorrhage in vivo

Subarachnoid hemorrhage causes acute and long-lasting constrictions of pial arterioles. Whether these vessels dilate normally to neuronal activity is of great interest since a mismatch between delivery and consumption of glucose and oxygen may cause additional neuronal damage. Therefore, we investigated neurovascular reactivity of pial and parenchymal arterioles after experimental subarachnoid hemorrhage. C57BL/6 mice were subjected to subarachnoid hemorrhage by filament perforation or sham surgery. Neurovascular reactivity was assessed 3 h later by forepaw stimulation or inhalation of 10% CO₂ Diameters of cerebral arterioles were assessed using two-photon microscopy. Neurovascular coupling and astrocytic endfoot Ca²⁺ were measured in brain slices using two-photon and infrared-differential interference contrast microscopy. Vessels of sham-operated mice dilated normally to CO₂ and forepaw stimulation. Three hours after subarachnoid hemorrhage, CO₂ reactivity was completely lost in both pial and parenchymal arterioles, while neurovascular coupling was not affected. Brain slices studies also showed normal neurovascular coupling and a normal increase in astrocytic endfoot Ca²⁺ acutely after subarachnoid hemorrhage. These findings suggest that communication between neurons, astrocytes, and parenchymal arterioles is not affected in the first few hours after subarachnoid hemorrhage, while CO₂ reactivity, which is dependent on NO signaling, is completely lost.

Viruses as nanomedicine for cancer

Oncolytic virotherapy, a type of nanomedicine in which oncolytic viruses (OVs) are used to selectively infect and lyse cancer cells, is an emerging field in cancer therapy. Some OVs exhibit a specific tropism for cancer cells, whereas others require genetic modification to enhance their binding with and entry into cancer cells. OVs both kill tumor cells and induce the host’s immune response against tumor cells. Armed with antitumor cellular molecules, antibodies, and/or in combination with anticancer drugs, OVs can accelerate the lysis of cancer cells. Among the OVs, vaccinia virus has been the focus of preclinical and clinical research because of its many favorable properties. In this review, the basic mechanisms of action of OVs are presented, including their entry, survival, tumor lysis, and immune activation, and the latest research in vaccinia virus-based virotherapy and its status as an anticancer nanomedicine in prospective clinical trials are discussed.

Oncolytic virus efficiency inhibited growth of tumour cells with multiple drug resistant phenotype in vivo and in vitro

Background

Tumour resistance to a wide range of drugs (multiple drug resistant, MDR) acquired after intensive chemotherapy is considered to be the main obstacle of the curative treatment of cancer patients. Recent work has shown that oncolytic viruses demonstrated prominent potential for effective treatment of diverse cancers. Here, we evaluated whether genetically modified vaccinia virus (LIVP-GFP) may be effective in treatment of cancers displaying MDR phenotype.

Methods

LIVP-GFP replication, transgene expression and cytopathic effects were analysed in human cervical carcinomas KB-3-1 (MDR−), KB-8-5 (MDR+) and in murine melanoma B-16 (MDR−), murine lymphosarcomas RLS and RLS-40 (MDR+). To investigate the efficacy of this therapy in vivo, we treated immunocompetent mice bearing murine lymphosarcoma RLS-40 (MDR+) (6- to 8-week-old female CBA mice; n = 10/group) or melanoma B-16 (MDR−) (6- to 8-week-old female C57Bl mice; n = 6/group) with LIVP-GFP (5 × 10⁷ PFU of virus in 0.1 mL of IMDM immediately and 4 days after tumour implantation).

Results

We demonstrated that LIVP-GFP replication was effective in human cervical carcinomas KB-3-1 (MDR−) and KB-8-5 (MDR+) and in murine melanoma B-16 (MDR−), whereas active viral production was not detected in murine lymphosarcomas RLS and RLS-40 (MDR+). Additionally, it was found that in tumour models in immunocompetent mice under the optimized regimen intratumoural injections of LIVP-GFP significantly inhibited melanoma B16 (33 % of mice were with complete response after 90 days) and RLS-40 tumour growth (fourfold increase in tumour doubling time) as well as metastasis.

Conclusion

The anti-tumour activity of LIVP-GFP is a result of direct oncolysis of tumour cells in case of melanoma B-16 because the virus effectively replicates and destroys these cells, and virus-mediated activation of the host immune system followed by immunologically mediated destruction of of tumour cells in case of lymphosarcoma RLS-40. Thus, the recombinant vaccinia virus LIVP-GFP is able to inhibit the growth of malignant cells with the MDR phenotype and tumour metastasis when administered in the early stages of tumour development.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1002-x) contains supplementary material, which is available to authorized users.

From Benchtop to Bedside: A Review of Oncolytic Virotherapy

Oncolytic viruses (OVs) demonstrate the ability to replicate selectively in cancer cells, resulting in antitumor effects by a variety of mechanisms, including direct cell lysis and indirect cell death through immune-mediate host responses. Although the mechanisms of action of OVs are still not fully understood, major advances have been made in our understanding of how OVs function and interact with the host immune system, resulting in the recent FDA approval of the first OV for cancer therapy in the USA. This review provides an overview of the history of OVs, their selectivity for cancer cells, and their multifaceted mechanism of antitumor action, as well as strategies employed to augment selectivity and efficacy of OVs. OVs in combination with standard cancer therapies are also discussed, as well as a review of ongoing human clinical trials.

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.

The use of the NIS reporter gene for optimizing oncolytic virotherapy

Introduction: Oncolytic viruses are experimental cancer therapies being translated to the clinic. They are unique in their ability to amplify within the body, therefore requiring careful monitoring of viral replication and biodistribution. Traditional monitoring strategies fail to recapitulate the dynamic nature of oncolytic virotherapy. Consequently, clinically relevant, noninvasive, high resolution strategies are needed to effectively track virotherapy in real time.

Areas covered: The expression of the sodium iodide symporter (NIS) reporter gene is tightly coupled to viral genome replication and mediates radioisotope concentration, allowing noninvasive molecular nuclear imaging of active viral infection with high resolution. This provides insight into replication kinetics, biodistribution, the impact of vector design, administration, and dosing on therapeutic outcomes, and highlights the heterogeneity of spatial distribution and temporal evolution of infection. NIS-mediated imaging in clinical trials confirms the feasibility of this technology to noninvasively and longitudinally observe oncolytic virus infection, replication, and distribution.

Expert opinion: NIS-mediated imaging provides detailed functional and molecular information on the evolution of oncolytic virus infection in living animals. The use of NIS reporter gene imaging has rapidly advanced to provide unparalleled insight into the spatial and temporal context of oncolytic infection which will be integral to optimization of oncolytic treatment strategies.

Iodide transport and breast cancer

Breast cancer is the second most common cancer worldwide and the leading cause of cancer death in women, with incidence rates that continue to rise. The heterogeneity of the disease makes breast cancer exceptionally difficult to treat, particularly for those patients with triple-negative disease. To address the therapeutic complexity of these tumours, new strategies for diagnosis and treatment are urgently required. The ability of lactating and malignant breast cells to uptake and transport iodide has led to the hypothesis that radioiodide therapy could be a potentially viable treatment for many breast cancer patients. Understanding how iodide is transported, and the factors regulating the expression and function of the proteins responsible for iodide transport, is critical for translating this hypothesis into reality. This review covers the three known iodide transporters - the sodium iodide symporter, pendrin and the sodium-coupled monocarboxylate transporter - and their role in iodide transport in breast cells, along with efforts to manipulate them to increase the potential for radioiodide therapy as a treatment for breast cancer.

Promising oncolytic agents for metastatic breast cancer treatment

New therapies for metastatic breast cancer patients are urgently needed. The long-term survival rates remain unacceptably low for patients with recurrent disease or disseminated metastases. In addition, existing therapies often cause a variety of debilitating side effects that severely impact quality of life. Oncolytic viruses constitute a developing therapeutic modality in which interest continues to build due to their ability to spare normal tissue while selectively destroying tumor cells. A number of different viruses have been used to develop oncolytic agents for breast cancer, including herpes simplex virus, adenovirus, vaccinia virus, measles virus, reovirus, and others. In general, clinical trials for several cancers have demonstrated excellent safety records and evidence of efficacy. However, the impressive tumor responses often observed in preclinical studies have yet to be realized in the clinic. In order for the promise of oncolytic virotherapy to be fully realized for breast cancer patients, effectiveness must be demonstrated in metastatic disease. This review provides a summary of oncolytic virotherapy strategies being developed to target metastatic breast cancer.

The evolution of poxvirus vaccines

After Edward Jenner established human vaccination over 200 years ago, attenuated poxviruses became key players to contain the deadliest virus of its own family: Variola virus (VARV), the causative agent of smallpox. Cowpox virus (CPXV) and horsepox virus (HSPV) were extensively used to this end, passaged in cattle and humans until the appearance of vaccinia virus (VACV), which was used in the final campaigns aimed to eradicate the disease, an endeavor that was accomplished by the World Health Organization (WHO) in 1980. Ever since, naturally evolved strains used for vaccination were introduced into research laboratories where VACV and other poxviruses with improved safety profiles were generated. Recombinant DNA technology along with the DNA genome features of this virus family allowed the generation of vaccines against heterologous diseases, and the specific insertion and deletion of poxvirus genes generated an even broader spectrum of modified viruses with new properties that increase their immunogenicity and safety profile as vaccine vectors. In this review, we highlight the evolution of poxvirus vaccines, from first generation to the current status, pointing out how different vaccines have emerged and approaches that are being followed up in the development of more rational vaccines against a wide range of diseases.

Molecular imaging of oncolytic viral therapy

Oncolytic viruses have made their mark on the cancer world as a potential therapeutic option, with the possible advantages of reduced side effects and strengthened treatment efficacy due to higher tumor selectivity. Results have been so promising, that oncolytic viral treatments have now been approved for clinical trials in several countries. However, clinical studies may benefit from the ability to noninvasively and serially identify sites of viral targeting via molecular imaging in order to provide safety, efficacy, and toxicity information. Furthermore, molecular imaging of oncolytic viral therapy may provide a more sensitive and specific diagnostic technique to detect tumor origin and, more importantly, presence of metastases. Several strategies have been investigated for molecular imaging of viral replication broadly categorized into optical and deep tissue imaging, utilizing several reporter genes encoding for fluorescence proteins, conditional enzymes, and membrane protein and transporters. Various imaging methods facilitate molecular imaging, including computer tomography, magnetic resonance imaging, positron emission tomography, single photon emission CT, gamma-scintigraphy, and photoacoustic imaging. In addition, several molecular probes are used for medical imaging, which act as targeting moieties or signaling agents. This review will explore the preclinical and clinical use of in vivo molecular imaging of replication-competent oncolytic viral therapy.

Oncolytic vaccinia virotherapy for endometrial cancer

OBJECTIVE

Oncolytic virotherapy is a promising modality in endometrial cancer (EC) therapy. In this study, we compared the efficacy of the Copenhagen and Wyeth strains of oncolytic vaccinia virus (VV) incorporating the human thyroidal sodium iodide symporter (hNIS) as a reporter gene (VVNIS-C and VVNIS-W) in EC.

METHODS

Infectivity of VVNIS-C and VVNIS-W in type I (HEC1A, Ishikawa, KLE, RL95-2, and AN3 CA) and type II (ARK-1, ARK-2, and SPEC-2) human EC cell lines was evaluated. Athymic mice with ARK-2 or AN3 CA xenografts were treated with one intravenous dose of VVNIS-C or VVNIS-W. Tumor regression and in vivo infectivity were monitored via NIS expression using SPECT-CT imaging.

RESULTS

All EC cell lines except KLE were susceptible to infection and killing by VVNIS-C and VVNIS-W in vitro. VVNIS-C had higher infectivity and oncolytic activity than VVNIS-W in all cell lines, most notably in AN3 CA. Intravenous VVNIS-C was more effective at controlling AN3 CA xenograft growth than VVNIS-W, while both VVNIS-C and VVNIS-W ceased tumor growth and induced tumor regression in 100% of mice bearing ARK-2 xenografts.

CONCLUSION

Overall, VVNIS-C has more potent oncolytic viral activity than VVSIN-W in EC. VV appears to be most active in type II EC. Novel therapies are needed for the highly lethal type II EC histologies and further development of a VV clinical trial in type II EC is warranted.