Oncolytic measles virus encoding thyroidal sodium iodide symporter for squamous cell cancer of the head and neck radiovirotherapy

Vaccinia virus and peptide-receptor radiotherapy synergize to improve treatment of peritoneal carcinomatosis

Tumor-specific overexpression of receptors enables a variety of targeted cancer therapies, exemplified by peptide-receptor radiotherapy (PRRT) for somatostatin receptor (SSTR)-positive neuroendocrine tumors. While effective, PRRT is restricted to tumors with SSTR overexpression. To overcome this limitation, we propose using oncolytic vaccinia virus (vvDD)-mediated receptor gene transfer to permit molecular imaging and PRRT in tumors without endogenous SSTR overexpression, a strategy termed radiovirotherapy. We hypothesized that vvDD-SSTR combined with a radiolabeled somatostatin analog could be deployed as radiovirotherapy in a colorectal cancer peritoneal carcinomatosis model, producing tumor-specific radiopeptide accumulation. Following vvDD-SSTR and ¹⁷⁷Lu-DOTATOC treatment, viral replication and cytotoxicity, as well as biodistribution, tumor uptake, and survival, were evaluated. Radiovirotherapy did not alter virus replication or biodistribution, but synergistically improved vvDD-SSTR-induced cell killing in a receptor-dependent manner and significantly increased the tumor-specific accumulation and tumor-to-blood ratio of ¹⁷⁷Lu-DOTATOC, making tumors imageable by microSPECT/CT and causing no significant toxicity. ¹⁷⁷Lu-DOTATOC significantly improved survival over virus alone when combined with vvDD-SSTR but not control virus. We have therefore demonstrated that vvDD-SSTR can convert receptor-negative tumors into receptor-positive tumors and facilitate molecular imaging and PRRT using radiolabeled somatostatin analogs. Radiovirotherapy represents a promising treatment strategy with potential applications in a wide range of cancers.

Nectins and Nectin-like Molecules in Colorectal Cancer: Role in Diagnostics, Prognostic Values, and Emerging Treatment Options: A Literature Review

In 2020, colorectal cancer was the third most common type of cancer worldwide with a clearly visible increase in the number of cases each year. With relatively high mortality rates and an uncertain prognosis, colorectal cancer is a serious health problem. There is an urgent need to investigate its specific mechanism of carcinogenesis and progression in order to develop new strategies of action against this cancer. Nectins and Nectin-like molecules are cell adhesion molecules that take part in a plethora of essential processes in healthy tissues as well as mediating substantial actions for tumor initiation and evolution. Our understanding of their role and a viable application of this in anti-cancer therapy has rapidly improved in recent years. This review summarizes the current data on the role nectins and Nectin-like molecules play in colorectal cancer.

Nectin cell adhesion molecule-4 (NECTIN-4): A potential target for cancer therapy

NECTIN-4 [a poliovirus receptor-related-4 (pvrl-4) encoded protein] is a Ca²⁺ independent immunoglobulin-like protein. Along with other Nectins (Nectin-1, -2 and -3), it is primarily involved in cell-cell adhesion. In contrast to other Nectins, Nectin-4 is specifically enriched in the embryonic and placental tissues but its expression significantly declines in adult life. In recent years, it has been found that Nectin-4 is especially overexpressed and served as a tumor associated inducer in various malignant tumors including breast, lung, colorectal, pancreatic, ovarian cancers etc. Over-expression of Nectin-4 is associated with various aspects of tumor progression like proliferation, angiogenesis, epithelial to mesenchymal transition, metastasis, DNA repair, tumor relapse, poor prognosis in several types of cancer. This review systematically highlights the implications of Nectin-4 in every possible aspect of cancer and the molecular mechanism of Nectin-4 mediated cancer progression. We have further emphasized on the therapeutic strategies that are being proposed to specifically target Nectin-4.

Role of Nectin‑4 protein in cancer (Review)

The Nectin cell adhesion molecule (Nectin) family members are Ca2+‑independent immunoglobulin‑like cellular adhesion molecules (including Nectins 1‑4), involved in cell adhesion via homophilic/heterophilic interplay. In addition, the Nectin family plays a significant role in enhancing cellular viability and movement ability. In contrast to enrichment of Nectins 1‑3 in normal tissues, Nectin‑4 is particularly overexpressed in a number of tumor types, including breast, lung, urothelial, colorectal, pancreatic and ovarian cancer. Moreover, the upregulation of Nectin‑4 is an independent biomarker for overall survival in numerous cancer types. A large number of studies have revealed that high expression of Nectin‑4 is closely related to tumor occurrence and development in various cancer types, but the manner in which Nectin‑4 protein contributes to the onset and development of these malignancies is yet unknown. The present review summarizes the molecular mechanisms and functions of Nectin‑4 protein in the biological processes and current advances with regard to its expression and regulation in various cancer types.

Engineering and combining oncolytic measles virus for cancer therapy

Cancer immunotherapy using tumor-selective, oncolytic viruses is an emerging therapeutic option for solid and hematologic malignancies. A considerable variety of viruses ranging from small picornaviruses to large poxviruses are currently being investigated as potential candidates. In the early days of virotherapy, non-engineered wild-type or vaccine-strain viruses were employed. However, these viruses often did not fully satisfy the major criteria of safety and efficacy. Since the advent of reverse genetics systems for manipulating various classes of viruses, the field has shifted to developing genetically engineered viruses with an improved therapeutic index. In this review, we will summarize the concepts and strategies of multi-level genetic engineering of oncolytic measles virus, a prime candidate for cancer immunovirotherapy. Furthermore, we will provide a brief overview of measles virus-based multimodal combination therapies for improved tumor control and clinical efficacy.

New viral vectors for infectious diseases and cancer

Since the discovery in 1796 by Edward Jenner of vaccinia virus as a way to prevent and finally eradicate smallpox, the concept of using a virus to fight another virus has evolved into the current approaches of viral vectored genetic vaccines. In recent years, key improvements to the vaccinia virus leading to a safer version (Modified Vaccinia Ankara, MVA) and the discovery that some viruses can be used as carriers of heterologous genes encoding for pathological antigens of other infectious agents (the concept of 'viral vectors') has spurred a new wave of clinical research potentially providing for a solution for the long sought after vaccines against major diseases such as HIV, TB, RSV and Malaria, or emerging infectious diseases including those caused by filoviruses and coronaviruses. The unique ability of some of these viral vectors to stimulate the cellular arm of the immune response and, most importantly, T lymphocytes with cell killing activity, has also reawakened the interest toward developing therapeutic vaccines against chronic infectious diseases and cancer. To this end, existing vectors such as those based on Adenoviruses have been improved in immunogenicity and efficacy. Along the same line, new vectors that exploit viruses such as Vesicular Stomatitis Virus (VSV), Measles Virus (MV), Lymphocytic choriomeningitis virus (LCMV), cytomegalovirus (CMV), and Herpes Simplex Virus (HSV), have emerged. Furthermore, technological progress toward modifying their genome to render some of these vectors incompetent for replication has increased confidence toward their use in infant and elderly populations. Lastly, their production process being the same for every product has made viral vectored vaccines the technology of choice for rapid development of vaccines against emerging diseases and for 'personalised' cancer vaccines where there is an absolute need to reduce time to the patient from months to weeks or days. Here we review the recent developments in viral vector technologies, focusing on novel vectors based on primate derived Adenoviruses and Poxviruses, Rhabdoviruses, Paramixoviruses, Arenaviruses and Herpesviruses. We describe the rationale for, immunologic mechanisms involved in, and design of viral vectored gene vaccines under development and discuss the potential utility of these novel genetic vaccine approaches in eliciting protection against infectious diseases and cancer.

Efficient Delivery and Replication of Oncolytic Virus for Successful Treatment of Head and Neck Cancer

Head and neck cancer has been treated by a combination of surgery, radiation, and chemotherapy. In recent years, the development of immune checkpoint inhibitors (ICIs) has made immunotherapy a new treatment method. Oncolytic virus (OV) therapy selectively infects tumor cells with a low-pathogenic virus, lyses tumor cells by the cytopathic effects of the virus, and induces anti-tumor immunity to destroy tumors by the action of immune cells. In OV therapy for head and neck squamous cell carcinoma (HNSCC), viruses, such as herpes simplex virus type 1 (HSV-1), vaccinia virus, adenovirus, reovirus, measles virus, and vesicular stomatitis virus (VSV), are mainly used. As the combined use of mutant HSV-1 and ICI was successful for the treatment of melanoma, studies are underway to combine OV therapy with radiation, chemotherapy, and other types of immunotherapy. In such therapy, it is important for the virus to selectively replicate in tumor cells, and to express the viral gene and the introduced foreign gene in the tumor cells. In OV therapy for HNSCC, it may be useful to combine systemic and local treatments that improve the delivery and replication of the inoculated oncolytic virus in the tumor cells.

Measles virus in cancer therapy

Over the last years, the development of viruses to treat cancer patients has re-gained considerable attention. A genetically modified herpesvirus, Talimogene laherparepvec, has already been authorized for the treatment of melanoma patients. Also recombinant measles virus (MeV) is developed as an oncolytic virus. Because of its high genetic flexibility, a number of different MeV strains have been the basis for the generation of targeted, armed, or shielded viruses that are highly specific for a given tumor target, more effective, or protected against serum neutralization. Such MeV have been extensively tested in vitro and in vivo, whereby remarkable oncolytic potency is accompanied by safety also in non-human primates. Therefore, MeV has been introduced into 19 different clinical trials and has reached phase II against two different tumor entities, multiple myeloma and ovarian carcinoma. Remarkably, one patient with advanced stage myeloma experienced long-term remission after treatment, visualizing the potency of this approach.

Virotheranostics, a double-barreled viral gun pointed toward cancer; ready to shoot?

Compared with conventional cancer treatments, the main advantage of oncolytic virotherapy is its tumor-selective replication followed by the destruction of malignant cells without damaging healthy cells. Accordingly, this kind of biological therapy can potentially be used as a promising approach in the field of cancer management. Given the failure of traditional monitoring strategies (such as immunohistochemical analysis (in providing sufficient safety and efficacy necessary for virotherapy and continual pharmacologic monitoring to track pharmacokinetics in real-time, the development of alternative strategies for ongoing monitoring of oncolytic treatment in a live animal model seems inevitable. Three-dimensional molecular imaging methods have recently been considered as an attractive approach to overcome the limitations of oncolytic therapy. These noninvasive visualization systems provide real-time follow-up of viral progression within the cancer tissue by the ability of engineered oncolytic viruses (OVs) to encode reporter transgenes based on recombinant technology. Human sodium/iodide symporter (hNIS) is considered as one of the most prevalent nuclear imaging reporter transgenes that provides precise information regarding the kinetics of gene expression, viral biodistribution, toxicity, and therapeutic outcomes using the accumulation of radiotracers at the site of transgene expression. Here, we provide an overview of pre-clinical and clinical applications of hNIS-based molecular imaging to evaluate virotherapy efficacy. Moreover, we describe different types of reporter genes and their potency in the clinical trials.

Oncolytic measles virus therapy enhances tumor antigen-specific T-cell responses in patients with multiple myeloma

Oncolytic virus therapy leads to immunogenic death of virus-infected tumor cells and this has been shown in preclinical models to enhance the cytotoxic T-lymphocyte response against tumor-associated antigens (TAAs), leading to killing of uninfected tumor cells. To investigate whether oncolytic virotherapy can increase immune responses to tumor antigens in human subjects, we studied T-cell responses against a panel of known myeloma TAAs using PBMC samples obtained from ten myeloma patients before and after systemic administration of an oncolytic measles virus encoding sodium iodide symporter (MV-NIS). Despite their prior exposures to multiple immunosuppressive antimyeloma treatment regimens, T-cell responses to some of the TAAs were detectable even before measles virotherapy. Measurable baseline T-cell responses against MAGE-C1 and hTERT were present. Furthermore, MV-NIS treatment significantly (P < 0.05) increased T-cell responses against MAGE-C1 and MAGE-A3. Interestingly, one patient who achieved complete remission after MV-NIS therapy had strong baseline T-cell responses both to measles virus proteins and to eight of the ten tested TAAs. Our data demonstrate that oncolytic virotherapy can function as an antigen agnostic vaccine, increasing cytotoxic T-lymphocyte responses against TAAs in patients with multiple myeloma, providing a basis for continued exploration of this modality in combination with immune checkpoint blockade.

Mathematical Modeling of Oncolytic Virotherapy

Mathematical modeling in biology has a long history as it allows the analysis and simulation of complex dynamic biological systems at little cost. A mathematical model trained on experimental or clinical data can be used to generate and evaluate hypotheses, to ask "what if" questions, and to perform in silico experiments to guide future experimentation and validation. Such models may help identify and provide insights into the mechanisms that drive changes in dynamic systems. While a mathematical model may never replace actual experiments, it can synergize with experiments to save time and resources by identifying experimental conditions that are unlikely to yield favorable outcomes, and by using optimization principles to identify experiments that are most likely to be successful. Over the past decade, numerous models have also been developed for oncolytic virotherapy, ranging from merely theoretic frameworks to fully integrated studies that utilize experimental data to generate actionable hypotheses. Here we describe how to develop such models for specific oncolytic virotherapy experimental setups, and which questions can and cannot be answered using integrated mathematical oncology.

Generation of a Tumor-Specific Chemokine Gradient Using Oncolytic Vesicular Stomatitis Virus Encoding CXCL9

Genetically modified vesicular stomatitis virus (VSV) is an attractive agent for cancer treatment due to rapid intratumoral replication and observed clinical responses. Although VSV selectively kills malignant cells and can boost antitumor immunity, limited induction of intratumoral immune infiltration remains a barrier to efficacy in some cancer models. Here we engineered the oncolytic VSV platform to encode the T cell chemokine CXCL9, which is known to mediate the recruitment of activated CD8⁺ cytotoxic T cells and CD4⁺ T helper cells, and demonstrates conserved protein function between mice and humans. Chemotactic activity of the virally encoded chemokine was confirmed in vitro. Intratumoral concentration of CXCL9 was shown to increase after VSV therapy in three different cancer models, but to a much greater degree after VSV-CXCL9 therapy as compared with VSV control viruses. Despite a steep chemokine gradient from the tumor to the bloodstream, tumor trafficking of adoptively transferred and endogenous T cells was not measurably increased following VSV-CXCL9 therapy. Our results indicate that oncolytic VSV infection promotes release of CXCL9 in the tumor microenvironment, but further boosting of the functional chemokine gradient through virus engineering has little incremental impact on intratumoral immune cell infiltration in mouse and human tumor models.

Oncolytic viruses and checkpoint inhibitors: combination therapy in clinical trials

Advances in the understanding of cancer immunotherapy and the development of multiple checkpoint inhibitors have dramatically changed the current landscape of cancer treatment. Recent large-scale phase III trials (e.g. PHOCUS, OPTiM) are establishing use of oncolytic viruses as another tool in the cancer therapeutics armamentarium. These viruses do not simply lyse cells to achieve their cancer-killing effects, but also cause dramatic changes in the tumor immune microenvironment. This review will highlight the major vector platforms that are currently in development (including adenoviruses, reoviruses, vaccinia viruses, herpesviruses, and coxsackieviruses) and how they are combined with checkpoint inhibitors. These vectors employ a variety of engineered capsid modifications to enhance infectivity, genome deletions or promoter elements to confer selective replication, and encode a variety of transgenes to enhance anti-tumor or immunogenic effects. Pre-clinical and clinical data have shown that oncolytic vectors can induce anti-tumor immunity and markedly increase immune cell infiltration (including cytotoxic CD8⁺ T cells) into the local tumor microenvironment. This "priming" by the viral infection can change a 'cold' tumor microenvironment into a 'hot' one with the influx of a multitude of immune cells and cytokines. This alteration sets the stage for subsequent checkpoint inhibitor delivery, as they are most effective in an environment with a large lymphocytic infiltrate. There are multiple ongoing clinical trials that are currently combining oncolytic viruses with checkpoint inhibitors (e.g. CAPTIVE, CAPRA, and Masterkey-265), and the initial results are encouraging. It is clear that oncolytic viruses and checkpoint inhibitors will continue to evolve together as a combination therapy for multiple types of cancers.

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.

The Sodium/Iodide Symporter (NIS): Molecular Physiology and Preclinical and Clinical Applications

Active iodide (I^-) transport in both the thyroid and some extrathyroidal tissues is mediated by the Na⁺/I^- symporter (NIS). In the thyroid, NIS-mediated I^- uptake plays a pivotal role in thyroid hormone (TH) biosynthesis. THs are key during embryonic and postembryonic development and critical for cell metabolism at all stages of life. The molecular characterization of NIS in 1996 and the use of radioactive I^- isotopes have led to significant advances in the diagnosis and treatment of thyroid cancer and provide the molecular basis for studies aimed at extending the use of radioiodide treatment in extrathyroidal malignancies. This review focuses on the most recent findings on I^- homeostasis and I^- transport deficiency-causing NIS mutations, as well as current knowledge of the structure/function properties of NIS and NIS regulatory mechanisms. We also discuss employing NIS as a reporter gene using viral vectors and stem cells in imaging, diagnostic, and therapeutic procedures.

Potential and clinical translation of oncolytic measles viruses

INTRODUCTION

Oncolytic viruses represent a novel treatment modality that is unencumbered by the standard resistance mechanisms limiting the therapeutic efficacy of conventional antineoplastic agents. Attenuated engineered measles virus strains derived from the Edmonston vaccine lineage have undergone extensive preclinical evaluation with significant antitumor activity observed in a broad range of preclinical tumoral models. These have laid the foundation for several clinical trials in both solid and hematologic malignancies, which have demonstrated safety, biologic activity and the ability to elicit antitumor immune responses. Areas covered: This review examines the published preclinical data which supported the clinical translation of this therapeutic platform, reviews the available clinical trial data and expands on ongoing phase II testing. It also looks at approaches to optimize clinical applicability and offers future perspectives. Expert opinion: Reverse genetic engineering has allowed the generation of oncolytic MV strains retargeted to increase viral tumor specificity, or armed with therapeutic and immunomodulatory genes in order to enhance anti-tumor efficacy. Continuous efforts focusing on exploring methods to overcome resistance pathways and determining optimal combinatorial strategies will facilitate further development of this encouraging antitumor strategy.

Measles to the Rescue: A Review of Oncolytic Measles Virus

Oncolytic virotherapeutic agents are likely to become serious contenders in cancer treatment. The vaccine strain of measles virus is an agent with an impressive range of oncolytic activity in pre-clinical trials with increasing evidence of safety and efficacy in early clinical trials. This paramyxovirus vaccine has a proven safety record and is amenable to careful genetic modification in the laboratory. Overexpression of the measles virus (MV) receptor CD46 in many tumour cells may direct the virus to preferentially enter transformed cells and there is increasing awareness of the importance of nectin-4 and signaling lymphocytic activation molecule (SLAM) in oncolysis. Successful attempts to retarget MV by inserting genes for tumour-specific ligands to antigens such as carcinoembryonic antigen (CEA), CD20, CD38, and by engineering the virus to express synthetic microRNA targeting sequences, and "blinding" the virus to the natural viral receptors are exciting measures to increase viral specificity and enhance the oncolytic effect. Sodium iodine symporter (NIS) can also be expressed by MV, which enables in vivo tracking of MV infection. Radiovirotherapy using MV-NIS, chemo-virotherapy to convert prodrugs to their toxic metabolites, and immune-virotherapy including incorporating antibodies against immune checkpoint inhibitors can also increase the oncolytic potential. Anti-viral host immune responses are a recognized barrier to the success of MV, and approaches such as transporting MV to the tumour sites by carrier cells, are showing promise. MV Clinical trials are producing encouraging preliminary results in ovarian cancer, myeloma and cutaneous non-Hodgkin lymphoma, and the outcome of currently open trials in glioblastoma multiforme, mesothelioma and squamous cell carcinoma are eagerly anticipated.

The current status of oncolytic viral therapy for head and neck cancer

Objective

Cancer affects the head and neck region frequently and leads to significant morbidity and mortality. Oncolytic viral therapy has the potential to make a big impact in cancers that affect the head and neck. We intend to review the current state of oncolytic viruses in the treatment of cancers that affect the head and neck region.

Method

Data sources are from National clinical trials database, literature, and current research.

Results

There are many past and active trials for oncolytic viruses that show promise for treating cancers of the head and neck. The first oncolytic virus was approved by the FDA October 2015 (T-VEC, Amgen) for the treatment of melanoma. Active translational research continues for this and many other oncolytic viruses.

Conclusion

The evolving field of oncolytic viruses is impacting the treatment of head and neck cancer and further trials and agents are moving forward in the coming years.

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.

Advances in the design and development of oncolytic measles viruses

A successful oncolytic virus is one that selectively propagates and destroys cancerous tissue without causing excessive damage to the normal surrounding tissue. Oncolytic measles virus (MV) is one such virus that exhibits this characteristic and thus has rapidly emerged as a potentially useful anticancer modality. Derivatives of the Edmonston MV vaccine strain possess a remarkable safety record in humans. Promising results in preclinical animal models and evidence of biological activity in early phase trials contribute to the enthusiasm. Genetic modifications have enabled MV to evolve from a vaccine agent to a potential anticancer therapy. Specifically, alterations of the MV genome have led to improved tumor selectivity and delivery, therapeutic potency, and immune system modulation. In this article, we will review the advancements that have been made in the design and development of MV that have led to its use as a cancer therapy. In addition, we will discuss the evidence supporting its use, as well as the challenges associated with MV as a potential cancer therapeutic.

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.

Oncolytic measles virus as a novel therapy for malignant peripheral nerve sheath tumors

Malignant peripheral nerve sheath tumors (MPNSTs) are devastating soft tissue sarcomas that can arise sporadically or in association with neurofibromatosis type I, have a poor prognosis, and have limited treatment options. Oncolytic measles virus therapy has been demonstrated to have significant antitumor properties in a number of different cancers, but the oncolytic potential of a MV Edmonston (MVEdm) vaccine strain engineered to express the human sodium iodide symporter (MV-NIS) on MPNST has not previously been evaluated. MPNST cell lines were found to highly express CD46, a cellular receptor required for measles viral entry, on their cell surface. After in vitro MV-NIS infection, MPNST cell lines showed significant cytopathic effect (CPE), while normal Schwann cells were less susceptible to CPE. Virus localization and distribution could be monitored by imaging of I-125 uptake. Local administration of MV-NIS into MPNST-derived tumors resulted in significant regression of tumor and improved survival. These results demonstrate feasibility of oncolytic measles virus therapy for MPNST patients and the possibility of a novel treatment for patients with NF1 tumors.

Reporter gene imaging identifies intratumoral infection voids as a critical barrier to systemic oncolytic virus efficacy

Systemically administered oncolytic viruses have the ability to cause tumor destruction through the expansion and coalescence of intratumoral infectious centers. Efficacy is therefore dependent upon both the density and intratumoral distribution of virus-infected cells achieved after initial virus infusion, and delivery methods are being developed to enhance these critical parameters. However, the three-dimensional (3D) mapping of intratumoral infectious centers is difficult using conventional immunohistochemical methodology, requiring painstaking 3D reconstruction of numerous sequential stained tumor sections, with no ability to study the temporal evolution of spreading infection in a single animal. We therefore developed a system using very high-resolution noninvasive in vivo micro single-photon emitted computed tomography/computed tomography (microSPECT/CT) imaging to determine the intratumoral distribution of thyroid radiotracers in tumors infected with an oncolytic virus encoding the thyroidal sodium–iodide symporter (NIS). This imaging system was used for longitudinal analysis of the density, distribution, and evolution of intratumoral infectious centers after systemic administration of oncolytic vesicular stomatitis virus in tumor-bearing mice and revealed heterogeneous delivery of virus particles both within and between tumors in animals receiving identical therapy. This study provides compelling validation of high resolution in vivo reporter gene mapping as a convenient method for serial monitoring of intratumoral virus spread that will be necessary to address critical barriers to systemic oncolytic virus efficacy such as intratumoral delivery.

Combination of vaccine-strain measles and mumps virus synergistically kills a wide range of human hematological cancer cells: Special focus on acute myeloid leukemia

Through combining vaccine-derived measles and mumps viruses (MM), we efficiently targeted a wide range of hematopoietic cancer cell lines. MM synergistically killed many cell lines including acute myeloid leukemia (AML) cell lines. Further investigation suggested that enhanced oncolytic effect of MM was due to increased apoptosis induction. In an U937 xenograft AML mouse model, MM displayed greater tumor suppression and prolonged survival. Furthermore, MM efficiently killed blasts from 16 out of 20 AML patients and elicited more efficient killing effect on 11 patients when co-administered with Ara-C. Our results demonstrate that MM is a promising therapeutic candidate for hematological malignancies.

Viral oncolysis - can insights from measles be transferred to canine distemper virus?

Neoplastic diseases represent one of the most common causes of death among humans and animals. Currently available and applied therapeutic options often remain insufficient and unsatisfactory, therefore new and innovative strategies and approaches are highly needed. Periodically, oncolytic viruses have been in the center of interest since the first anecdotal description of their potential usefulness as an anti-tumor treatment concept. Though first reports referred to an incidental measles virus infection causing tumor regression in a patient suffering from lymphoma several decades ago, no final treatment concept has been developed since then. However, numerous viruses, such as herpes-, adeno- and paramyxoviruses, have been investigated, characterized, and modified with the aim to generate a new anti-cancer treatment option. Among the different viruses, measles virus still represents a highly interesting candidate for such an approach. Numerous different tumors of humans including malignant lymphoma, lung and colorectal adenocarcinoma, mesothelioma, and ovarian cancer, have been studied in vitro and in vivo as potential targets. Moreover, several concepts using different virus preparations are now in clinical trials in humans and may proceed to a new treatment option. Surprisingly, only few studies have investigated viral oncolysis in veterinary medicine. The close relationship between measles virus (MV) and canine distemper virus (CDV), both are morbilliviruses, and the fact that numerous tumors in dogs exhibit similarities to their human counterpart, indicates that both the virus and species dog represent a highly interesting translational model for future research in viral oncolysis. Several recent studies support such an assumption. It is therefore the aim of the present communication to outline the mechanisms of morbillivirus-mediated oncolysis and to stimulate further research in this potentially expanding field of viral oncolysis in a highly suitable translational animal model for the benefit of humans and dogs.

Trial Watch:: Oncolytic viruses for cancer therapy

Oncolytic viruses are natural or genetically modified viral species that selectively infect and kill neoplastic cells. Such an innate or exogenously conferred specificity has generated considerable interest around the possibility to employ oncolytic viruses as highly targeted agents that would mediate cancer cell-autonomous anticancer effects. Accumulating evidence, however, suggests that the therapeutic potential of oncolytic virotherapy is not a simple consequence of the cytopathic effect, but strongly relies on the induction of an endogenous immune response against transformed cells. In line with this notion, superior anticancer effects are being observed when oncolytic viruses are engineered to express (or co-administered with) immunostimulatory molecules. Although multiple studies have shown that oncolytic viruses are well tolerated by cancer patients, the full-blown therapeutic potential of oncolytic virotherapy, especially when implemented in the absence of immunostimulatory interventions, remains unclear. Here, we cover the latest advances in this active area of translational investigation, summarizing high-impact studies that have been published during the last 12 months and discussing clinical trials that have been initiated in the same period to assess the therapeutic potential of oncolytic virotherapy in oncological indications.

Genetically engineered Newcastle disease virus expressing interleukin 2 is a potential drug candidate for cancer immunotherapy

Newcastle disease virus (NDV) is an intrinsically tumor-specific virus, several clinical trials have reported that mesogenic NDV is a safe and effective agent for human cancer therapy. Interleukin 2 (IL2) is a cytokine that stimulates T cell propagation to trigger innate and adaptive immunity. IL2 has been used for cancer therapy and has achieved curative effects. In this study, a recombinant NDV LaSota strain expressing human interleukin 2 (rLaSota/IL2) was generated. The ability of rLaSota/IL2 to express human IL2 was detected in the infected tumor cells. In addition, the activity of IL2 was analyzed. The antitumor potential of rLaSota/IL2 was studied by xenograph mice carrying H22 and B16-F10 cells. Tumor-specific CD4(+) and CD8(+) T cells and MHC II were also analyzed in the two tumor-bearing models. Our study showed that rLaSota/IL2 significantly stimulated tumor-specific cytotoxic T-lymphocyte (CTL) responses and increased regulatory CD4(+) and cytotoxic CD8(+) T cells proliferation. The treatment with rLaSota/IL2 led to tumor regression in tumor-bearing mice and prolonged the survival of tumor-bearing mice. Furthermore, tumor challenging experiments demonstrated that rLaSota/IL2 invoked mice a unique capacity to remember a pathogen through the generation of memory T cells, which protect the host in the event of reinfection and form adaptive immune system. The result indicates that tumor-infiltrating CD4(+) T regulatory cells may denote the effective regression of tumors. Taken together, rLaSota/IL2 has potential for immunotherapy and oncolytic therapy of cancers and may be an ideal candidate for clinical application in future cancer therapy.

Armed therapeutic viruses - a disruptive therapy on the horizon of cancer immunotherapy

For the past 150 years cancer immunotherapy has been largely a theoretical hope that recently has begun to show potential as a highly impactful treatment for various cancers. In particular, the identification and targeting of immune checkpoints have given rise to exciting data suggesting that this strategy has the potential to activate sustained antitumor immunity. It is likely that this approach, like other anti-cancer strategies before it, will benefit from co-administration with an additional therapeutic and that it is this combination therapy that may generate the greatest clinical outcome for the patient. In this regard, oncolytic viruses are a therapeutic moiety that is well suited to deliver and augment these immune-modulating therapies in a highly targeted and economically advantageous way over current treatment. In this review, we discuss the blockade of immune checkpoints, how oncolytic viruses complement and extend these therapies, and speculate on how this combination will uniquely impact the future of cancer immunotherapy.

HSV-NIS, an oncolytic herpes simplex virus type 1 encoding human sodium iodide symporter for preclinical prostate cancer radiovirotherapy

Several clinical trials have shown that oncolytic herpes simplex virus type 1 (oHSV-1) can be safely administered to patients. However, virus replication in tumor tissue has generally not been monitored in these oHSV clinical trials, and the data suggest that its oncolytic potency needs to be improved. To facilitate noninvasive monitoring of the in vivo spread of an oHSV and to increase its antitumor efficacy, the gene coding for human sodium iodide symporter (NIS) was incorporated into a recombinant oHSV genome and the corresponding virus (oHSV-NIS) rescued in our laboratory. Our data demonstrate that a human prostate cancer cell line, LNCap, efficiently concentrates radioactive iodine after the cells have been infected in vitro or in vivo. In vivo replication of oHSV-NIS in tumors was noninvasively monitored by computed tomography/single-photon emission computed tomography imaging of the biodistribution of pertechnetate and was confirmed. LNCap xenografts in nude mice were eradicated by intratumoral administration of oHSV-NIS. Systemic administration of oHSV-NIS prolonged the survival of tumor-bearing mice, and the therapeutic effect was further enhanced by administration of ¹³¹I after the intratumoral spread of the virus had peaked. oHSV-NIS has the potential to substantially enhance the outcomes of standard therapy for patients with prostate cancer.

Oncolytic measles virus strains as novel anticancer agents

INTRODUCTION

Replication-competent oncolytic measles virus (MV) strains preferentially infect and destroy a wide variety of cancer tissues. Clinical translation of engineered attenuated MV vaccine derivatives is demonstrating the therapeutic potential and negligible pathogenicity of these strains in humans.

AREAS COVERED

The present review summarizes the mechanisms of MV tumor selectivity and cytopathic activity as well as the current data on the oncolytic efficacy and preclinical testing of MV strains. Investigational strategies to reprogram MV selectivity, escape antiviral immunity and modulate the immune system to enhance viral delivery and tumor oncolysis are also discussed.

EXPERT OPINION

Clinical viral kinetic data derived from noninvasive monitoring of reporter transgene expression will guide future protocols to enhance oncolytic MV efficacy. Anti-measles immunity is a major challenge of measles-based therapeutics and various strategies are being investigated to modulate immunity. These include the combination of MV therapy with immunosuppressive drugs, such as cyclophosphamide, the use of cell carriers and the introduction of immunomodulatory transgenes and wild-type virulence genes. Available MV retargeting technologies can address safety considerations that may arise as more potent oncolytic MV vectors are being developed.

Nectin 4 is the epithelial cell receptor for measles virus

Measles virus (MV) causes acute respiratory disease, infects lymphocytes and multiple organs, and produces immune suppression leading to secondary infections. In rare instances it can also cause persistent infections in the brain and central nervous system. Vaccine and laboratory-adapted strains of MV use CD46 as a receptor, whereas wild-type strains of MV (wtMV) cannot. Both vaccine and wtMV strains infect lymphocytes, monocytes, and dendritic cells (DCs) using the signaling lymphocyte activation molecule (CD150/SLAM). In addition, MV can infect the airway epithelial cells of the host. Nectin 4 (PVRL4) was recently identified as the epithelial cell receptor for MV. Coupled with recent observations made in MV-infected macaques, this discovery has led to a new paradigm for how the virus accesses the respiratory tract and exits the host. Nectin 4 is also a tumor cell marker which is highly expressed on the apical surface of many adenocarcinoma cell lines, making it a potential target for MV oncolytic therapy.

Preclinical efficacy of the oncolytic measles virus expressing the sodium iodide symporter in iodine non-avid anaplastic thyroid cancer: a novel therapeutic agent allowing noninvasive imaging and radioiodine therapy

Anaplastic thyroid cancer is an extremely aggressive disease resistant to radioiodine treatment because of loss of sodium iodide symporter (NIS) expression. To enhance prognosis of this fatal cancer, we validated the preclinical efficacy of measles virus (MV)-NIS, the vaccine strain of the oncolytic MV (MV-Edm), modified to include the NIS gene. Western blotting analysis confirmed that a panel of eight anaplastic thyroid cancer (ATC)-derived cell lines do not express NIS protein, but do express CD46, the MV receptor. In vitro cell death assays and in vivo xenograft studies demonstrate the oncolytic efficacy of MV-NIS in BHT-101 and KTC-3, ATC-derived cell lines. Radioactive iodine uptake along with single-photon emission computed tomography (SPECT)-computed tomography imaging of KTC-3 xenografts after (99)Tc(m) administration confirmed NIS expression in vitro and in vivo, respectively, after virus treatment. Adjuvant administration of RAI, to MV-NIS-treated KTC-3 tumors showed a trend for increased tumor cell killing. As current treatment for ATC is only palliative, and MV-NIS is currently Food and Drug Administration approved for human clinical trials in myeloma, our data indicate that targeting ATC with MV-NIS could prove to be a novel therapeutic strategy for effective treatment of iodine-resistant ATC and will expedite its testing in clinical trials for this aggressive disease.