The biological roles of CD47 in ovarian cancer progression

Ovarian cancer is one of the most lethal malignant tumors, characterized by high incidence and poor prognosis. Patients relapse occurred in 65-80% after initial treatment. To date, no effective treatment has been established for these patients. Recently, CD47 has been considered as a promising immunotherapy target. In this paper, we reviewed the biological roles of CD47 in ovarian cancer and summarized the related mechanisms. For most types of cancers, the CD47/Sirpα immune checkpoint has attracted the most attention in immunotherapy. Notably, CD47 monoclonal antibodies and related molecules are promising in the immunotherapy of ovarian cancer, and further research is needed. In the future, new immunotherapy regimens targeting CD47 can be applied to the clinical treatment of ovarian cancer patients.

Replication-incompetent influenza A viruses armed with IFN-γ effectively mediate immune modulation and tumor destruction in mice harboring lung cancer

Low pathogenic influenza A viruses (IAVs) have shown promising oncolytic potential in lung cancer-bearing mice. However, as replication-competent pathogens, they may cause side effects in immunocompromised cancer patients. To circumvent this problem, we genetically engineered nonreplicating IAVs lacking the hemagglutinin (HA) gene (ΔHA IAVs), but reconstituted the viral envelope with recombinant HA proteins to allow a single infection cycle. To optimize the therapeutic potential and improve immunomodulatory properties, these replication-incompetent IAVs were complemented with a murine interferon-gamma (mIFN-γ) gene. After intratracheal administration to transgenic mice that develop non-small cell lung cancer (NSCLC), the ΔHA IAVs induced potent tumor destruction. However, ΔHA IAVs armed with mIFN-γ exhibited an even stronger and more sustained effect, achieving 85% tumor reduction at day 12 postinfection. In addition, ΔHA-mIFN-γ viruses were proven to be efficient in recruiting and activating natural killer cells and macrophages from the periphery and in inducing cytotoxic T lymphocytes. Most important, both viruses, and particularly IFN-γ-encoding viruses, activated tumor-associated alveolar macrophages toward a proinflammatory M1-like phenotype. Therefore, replication-incompetent ΔHA-mIFN-γ-IAVs are safe and efficient oncolytic viruses that additionally exhibit immune cell activating properties and thus represent a promising innovative therapeutic option in the fight against NSCLC.

Oncolytic Viral Therapy for Glioma by Recombinant Sindbis Virus

BACKGROUND

The characteristics of glioblastoma, such as drug resistance during treatment, short patient survival, and high recurrence rates, have made patients with glioblastoma more likely to benefit from oncolytic therapy.

METHODS

In this study, we investigated the safety of the sindbis virus by injecting virus intravenously and intracranially in mice and evaluated the therapeutic effect of the virus carrying different combinations of IL-12, IL-7, and GM-CSF on glioma in a glioma-bearing mouse model.

RESULTS

SINV was autologously eliminated from the serum and organs as well as from neural networks after entering mice. Furthermore, SINV was restricted to the injection site in the tree shrew brain and did not spread throughout the whole brain. In addition, we found that SINV-induced apoptosis in conjunction with the stimulation of the immune system by tumor-killing cytokines substantially suppressed tumor development. It is worth mentioning that SINV carrying IL-7 and IL-12 had the most notable glioma-killing effect. Furthermore, in an intracranial glioma model, SINV containing IL-7 and IL-12 effectively prolonged the survival time of mice and inhibited glioma progression.

CONCLUSIONS

These results suggest that SINV has a significant safety profile as an oncolytic virus and that combining SINV with cytokines is an efficient treatment option for malignant gliomas.

Attenuated Dengue virus PV001-DV induces oncolytic tumor cell death and potent immune responses

BACKGROUND

Viral therapies developed for cancer treatment have classically prioritized direct oncolytic effects over their immune activating properties. However, recent clinical insights have challenged this longstanding prioritization and have shifted the focus to more immune-based mechanisms. Through the potential utilization of novel, inherently immune-stimulating, oncotropic viruses there is a therapeutic opportunity to improve anti-tumor outcomes through virus-mediated immune activation. PV001-DV is an attenuated strain of Dengue virus (DEN-1 #45AZ5) with a favorable clinical safety profile that also maintains the potent immune stimulatory properties characterstic of Dengue virus infection.

METHODS

In this study, we utilized in vitro tumor killing and immune multiplex assays to examine the anti-tumor effects of PV001-DV as a potential novel cancer immunotherapy.

RESULTS

In vitro assays demonstrated that PV001-DV possesses the ability to directly kill human melanoma cells lines as well as patient melanoma tissue ex vivo. Importantly, further work demonstrated that, when patient peripheral blood mononuclear cells (PBMCs) were exposed to PV001-DV, a substantial induction in the production of apoptotic factors and immunostimulatory cytokines was detected. When tumor cells were cultured with the resulting soluble mediators from these PBMCs, rapid cell death of melanoma and breast cancer cell lines was observed. These soluble mediators also increased dengue virus binding ligands and immune checkpoint receptor, PD-L1 expression.

CONCLUSIONS

The direct in vitro tumor-killing and immune-mediated tumor cytotoxicity facilitated by PV001-DV contributes support of its upcoming clinical evaluation in patients with advanced melanoma who have failed prior therapy.

Modulation of Reoviral Cytolysis (II): Cellular Stemness

Oncolytic viruses (OVs) are an emerging cancer therapeutic that are intended to act by selectively targeting and lysing cancerous cells and by stimulating anti-tumour immune responses, while leaving normal cells mainly unaffected. Reovirus is a well-studied OV that is undergoing advanced clinical trials and has received FDA approval in selected circumstances. However, the mechanisms governing reoviral selectivity are not well characterised despite many years of effort, including those in our accompanying paper where we characterize pathways that do not consistently modulate reoviral cytolysis. We have earlier shown that reovirus is capable of infecting and lysing both certain types of cancer cells and also cancer stem cells, and here we demonstrate its ability to also infect and kill healthy pluripotent stem cells (PSCs). This led us to hypothesize that pathways responsible for stemness may constitute a novel route for the modulation of reoviral tropism. We find that reovirus is capable of killing both murine and human embryonic and induced pluripotent stem cells. Differentiation of PSCs alters the cells' reoviral-permissive state to a resistant one. In a breast cancer cell line that was resistant to reoviral oncolysis, induction of pluripotency programming rendered the cells permissive to cytolysis. Bioinformatic analysis indicates that expression of the Yamanaka pluripotency factors may be associated with regulating reoviral selectivity. Mechanistic insights from these studies will be useful for the advancement of reoviral oncolytic therapy.

Coxsackievirus A11 is an immunostimulatory oncolytic virus that induces complete tumor regression in a human non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related mortality worldwide. Innovative treatment is required to improve overall survival rates for advanced NSCLC. Oncolytic virotherapy using enteroviruses has emerged as a promising anticancer strategy. To identify a novel, potent virotherapy with an improved safety profile, we assessed the oncolytic activity of 28 enteroviral strains and focused on coxsackievirus A11 (CVA11). CVA11 infection caused extensive oncolytic activity in all three of the examined human NSCLC cell lines, with high intercellular adhesion molecule-1 (ICAM-1) expression associated with greater CVA11-induced cytotoxicity. In vitro inhibition analysis using a pan-caspase inhibitor and western blot detection of cleaved poly (ADP-ribose) polymerase (PARP) indicated that apoptosis partly contributed to CVA11-driven cytotoxicity. CVA11 infection-induced immunogenic cell death in vitro was strongly suggested by substantial calreticulin expression and release of high mobility group box-1 protein (HMGB1). Moreover, in vivo treatment of human NSCLC xenografts with intratumoral CVA11 injection caused complete tumor regression in all treated mice, without significant weight loss. Our findings indicate that novel oncolytic virotherapy utilizing CVA11 may be less toxic and more effective than current treatments for human NSCLC, thus warranting further investigation in clinical trial settings, especially in combination with immunotherapy.

Oncolytic virus therapy for malignant gliomas: entering the new era

INTRODUCTION

To overcome the challenge of treating malignant brain tumors, oncolytic viruses (OVs) represent an innovative therapeutic approach, featuring unique mechanisms of action. The recent conditional approval of the oncolytic herpes simplex virus G47Δ as a therapeutic for malignant brain tumors marked a significant milestone in the long history of OV development in neuro-oncology.

AREAS COVERED

This review summarizes the results of recently completed and active clinical studies that investigate the safety and efficacy of different OV types in patients with malignant gliomas. The changing landscape of the OV trial design includes expansion of subjects to newly diagnosed tumors and pediatric populations. A variety of delivery methods and new routes of administration are vigorously tested to optimize tumor infection and overall efficacy. New therapeutic strategies such as combination with immunotherapies are proposed that take advantage of the characteristics of OV therapy as an immunotherapy. Preclinical studies of OV have been active and aim to translate new OV strategies to the clinic.

EXPERT OPINION

For the next decade, clinical trials and preclinical and translational research will continue to drive the development of innovative OV treatments for malignant gliomas and benefit patients and define new OV biomarkers.

Application of cation exchange chromatography in bind and elute and flowthrough mode for the purification of enteroviruses

Members of the enterovirus genus are promising oncolytic agents. Their morphogenesis involves the generation of both genome-packed infectious capsids and empty capsids. The latter are typically considered as an impurity in need of removal from the final product. The separation of empty and full capsids can take place with centrifugation methods, which are of low throughput and poorly scalable, or scalable chromatographic processes, which typically require peak cutting and a significant trade-off between purity and yield. Here we demonstrate the application of packed bed cation exchange (CEX) column chromatography for the separation of empty capsids from infectious virions for a prototype strain of Coxsackievirus A21. This separation was developed using high throughput chromatography techniques and scaled up as a bind and elute polishing step. The separation was robust over a wide range of operating conditions and returned highly resolved empty and full capsids. The CEX step could be operated in bind and elute or flowthrough mode with similar selectivity and returned yields greater than 70% for full mature virus particles. Similar performance was also achieved using a selection of other bead based CEX chromatography media, demonstrating general applicability of this type of chromatography for Coxsackievirus A21 purification. These results highlight the wide applicability and excellent performance of CEX chromatography for the purification of enteroviruses, such as Coxsackievirus A21.

Efficient delivery of oncolytic enterovirus by carrier cell line NK-92

Many members of the enterovirus family are considered as promising oncolytic agents; however, their systemic administration is largely inefficient due to the rapid neutralization of the virus in the circulation and the barrier functions of the endothelium. We aimed to evaluate natural killer cells as carriers for the delivery of oncolytic enteroviruses, which would combine the effects of cell immunotherapy with virotherapy. We tested four strains of nonpathogenic enteroviruses against the glioblastoma cell line panel and evaluated the produced infectious titers. Next, we explored whether these virus strains could be delivered to the tumor by natural killer cell line NK-92, which is being actively evaluated as a clinically acceptable therapeutic. Several strains of enteroviruses demonstrated oncolytic properties, but only coxsackievirus A7 (CVA7) could replicate in NK-92 cells efficiently. We compared the delivery efficiency of CVA7 in vivo, using NK-92 cells and direct intravenous administration, and found significant advantages of cell delivery even after a single injection. This suggests that the NK-92 cell line can be utilized as a vehicle for the delivery of the oncolytic strain of CVA7, which would improve the clinical potential of this viral oncolytic for the treatment of glioblastoma multiforme and other forms of cancer.

miR-375- and miR-1-Regulated Coxsackievirus B3 Has No Pancreas and Heart Toxicity But Strong Antitumor Efficiency in Colorectal Carcinomas

Coxsackievirus B3 (CVB3) has strong oncolytic activity in colorectal carcinoma but it also infects the pancreas and the heart. To improve the safety of the virus, here we investigated whether pancreas and cardiac toxicity can be prevented by insertion of target sites (TS), which are complementary to miR-375 and miR-1 into the viral genome. Although miR-375 and miR-1 are abundantly expressed in the pancreas and in the heart, respectively, their expression levels are low in colorectal carcinomas, which allows the carcinomas to be selectively attacked. To investigate the importance of the microRNAs, two viruses were engineered, H3N-375TS containing only miR-375TS and H3N-375/1TS containing miR-375TS and miR-1TS. In vitro, both viruses replicated in and lysed colorectal carcinoma cells, similar to a nontargeted control virus H3N-39TS, whereas they were strongly attenuated in cell lines transiently or endogenously expressing the corresponding microRNAs. In vivo, the control virus H3N-39TS induced strong infection of the pancreas and the heart, which led to fatal disease within 4 days after a single intratumoral virus injection in mice xenografted with colorectal DLD-1 cell tumors. In contrast, three intratumoral injections of H3N-375TS or H3N-375/1TS failed to induce virus-induced sickness. In the animals, both viruses were completely ablated from the pancreas and H3N-375/1TS was also ablated from the heart, whereas the cardiac titers of H3N-375TS were strongly reduced. Long-term investigations of the DLD-1 tumor model confirmed lack of virus-induced adverse effects in H3N-375TS- and H3N-375/1TS-treated mice. There was no mortality, and the pancreas and the heart were free of pathological alterations. Regarding the therapeutic efficiency, the treated animals showed high and long-lasting H3N-375TS and H3N-375/1TS persistence in the tumor and significantly slower tumor growth. These data demonstrate that miR-375- and miR-1-mediated virus detargeting from the pancreas and heart is a highly effective strategy to prevent toxicity of oncolytic CVB3.

Improving antitumor efficacy via combinatorial regimens of oncolytic virotherapy

As a promising therapeutic strategy, oncolytic virotherapy has shown potent anticancer efficacy in numerous pre-clinical and clinical trials. Oncolytic viruses have the capacity for conditional-replication within carcinoma cells leading to cell death via multiple mechanisms, including direct lysis of neoplasms, induction of immunogenic cell death, and elicitation of innate and adaptive immunity. In addition, these viruses can be engineered to express cytokines or chemokines to alter tumor microenvironments. Combination of oncolytic virotherapy with other antitumor therapeutic modalities, such as chemotherapy and radiation therapy as well as cancer immunotherapy can be used to target a wider range of tumors and promote therapeutic efficacy. In this review, we outline the basic biological characteristics of oncolytic viruses and the underlying mechanisms that support their use as promising antitumor drugs. We also describe the enhanced efficacy attributed to virotherapy combined with other drugs for the treatment of cancer.

PD-1 IC Inhibition Synergistically Improves Influenza A Virus-Mediated Oncolysis of Metastatic Pulmonary Melanoma

Recently, we showed that infection of primary lung tumor-bearing mice with oncolytic influenza A viruses (IAVs) led to strong virus-induced tumor cell lysis but also to restoration of immune competence of innate immune cells. Murine B16-F10 melanoma cells are known for their high lung tropism and progressive growth. As these cells are also highly permissive for IAVs, we analyzed their oncolytic and immunomodulatory efficiency against pulmonary B16-F10 lung metastases in vivo. IAV infection abrogated the melanoma-mediated immune suppression in the lung and induced a more than 50% cancer cell lysis. The oncolytic effect reached maximal efficacy 3 days post-infection, but it was not sustained over time. In order to maintain the virus-induced anti-tumor effect, mice with melanoma-derived lung cancers were treated in addition to influenza virus infection with an immune checkpoint inhibitor against programmed death-1 receptor (PD-1). The combined IAV and immune checkpoint inhibition (ICI) therapy resulted in a sustained anti-tumor efficacy, keeping the lung melanoma mass at day 12 of IAV infection still reduced by 50% over the control mice. In conclusion, ICI treatment strongly enhanced the oncolytic effect of influenza virus infection, suggesting that combined treatment is a promising approach against metastatic pulmonary melanoma.

Optimizing oncolytic virotherapy in cancer treatment

In the wake of the success of modern immunotherapy, oncolytic viruses (OVs) are currently seen as a potential therapeutic option for patients with cancer who do not respond or fail to achieve durable responses following treatment with immune checkpoint inhibitors. OVs offer a multifaceted therapeutic platform because they preferentially replicate in tumour cells, can be engineered to express transgenes that augment their cytotoxic and immunostimulatory activities, and modulate the tumour microenvironment to optimize immune-mediated tumour eradication, both at locoregional and systemic sites of disease. Lysis of tumour cells releases tumour-specific antigens that trigger both the innate and adaptive immune systems. OVs also represent attractive combination partners with other systemically delivered agents by virtue of their highly favourable safety profiles. Rational combinations of OVs with different immune modifiers and/or antitumour agents, based on mechanisms of tumour resistance to immune-mediated attack, may benefit the large, currently underserved, population of patients who respond poorly to immune checkpoint inhibition.

Multimodality Treatment of a Colorectal Cancer Stage IV Patient with FOLFOX-4, Bevacizumab, Rigvir Oncolytic Virus, and Surgery

Colorectal cancer is one of the most commonly diagnosed cancers worldwide. The treatment consists of surgical resection, systemic chemotherapy, and new biological agents. One more recently emerging treatment option is oncolytic virotherapy. Although the use of the new treatment methods shows improved overall and progression-free survival, in general, even with the new treatments, mortality remains high and combinations of treatments should be sought to treat patients with colorectal cancer. Here we report a stage IV colorectal cancer patient who received multimodality treatment including bevacizumab, FOLFOX-4, surgery, and the oncolytic virus Rigvir. The patient shows complete pathological remission and remains stable 7.7 years after initial diagnosis. The possible benefits of combining Rigvir oncolytic virus and bevacizumab should be investigated since in vitro research suggests that anti-angiogenesis agents improve viral distribution by altering the microenvironment of the tumor.

Gene therapy clinical trials worldwide to 2017: An update

To date, almost 2600 gene therapy clinical trials have been completed, are ongoing or have been approved worldwide. Our database brings together global information on gene therapy clinical activity from trial databases, official agency sources, published literature, conference presentations and posters kindly provided to us by individual investigators or trial sponsors. This review presents our analysis of clinical trials that, to the best of our knowledge, have been or are being performed worldwide. As of our November 2017 update, we have entries on 2597 trials undertaken in 38 countries. We have analysed the geographical distribution of trials, the disease indications (or other reasons) for trials, the proportions to which different vector types are used, and the genes that have been transferred. Details of the analyses presented, and our searchable database are available via The Journal of Gene Medicine Gene Therapy Clinical Trials Worldwide website at: http://www.wiley.co.uk/genmed/clinical. We also provide an overview of the progress being made in gene therapy clinical trials around the world, and discuss key trends since the previous review, namely the use of chimeric antigen receptor T cells for the treatment of cancer and advancements in genome editing technologies, which have the potential to transform the field moving forward.

Oncolytic activity of a coxsackievirus B3 strain in human endometrial cancer cell lines

BACKGROUND

Endometrial cancer (EC) is one of the most common gynecological malignancies globally. Although progress has been made in surgical and other adjuvant therapies, there is still a great need to develop new approaches to further reduce the incidence and mortality of EC. Oncolytic virotherapy offers a novel promising option of cancer treatment and has demonstrated good efficacy in preclinical models and clinical trials. However, only few oncolytic viruses have been tested for EC treatment. In this study, the potential of an oncolytic coxsackievirus B3 (CV-B3) strain 2035A (CV-B3/2035A) was investigated as a novel biotherapeutic agent against EC.

METHODS

Human EC cell lines (Ishikawa, HEC-1-A and HEC-1-B) were infected with CV-B3/2035A, and viral replication and cytotoxic effects were evaluated in vitro. CV-B3/2035A-induced oncolysis was also investigated in nude mice bearing EC xenografts in vivo and in patient-derived EC samples ex vivo.

RESULTS

Human EC cell lines expressing different levels of CAR and DAF were all susceptible to infection by CV-B3/2035A and supported efficient viral replication in vitro. In the EC xenograft/nude mouse model, both intratumoral and intravenous administrations of CV-B3-2035A exerted significant therapeutic effects against pre-established EC tumors without causing significant treatment-related toxicity and mortality in nude mice. Moreover, CV-B3/2035A treatment resulted in decreased viability of patient-derived EC samples ex vivo.

CONCLUSIONS

CV-B3/2035A showed oncolytic activity in human EC cell lines both in vitro and in vivo as well as in patient-derived EC samples ex vivo and thus could be used as an alternative virotherapy agent for the treatment of EC.

Oncolytic influenza virus infection restores immunocompetence of lung tumor-associated alveolar macrophages

Non-small-cell lung cancer (NSCLC) is the most frequent type of lung cancer and demonstrates high resistance to radiation and chemotherapy. These tumors evade immune system detection by promoting an immunosuppressive tumor microenvironment. Genetic analysis has revealed oncogenic activation of the Ras/Raf/MEK/ERK signaling pathway to be a hallmark of NSCLCs, which promotes influenza A virus (IAV) infection and replication in these cells. Thus, we aimed to unravel the oncolytic properties of IAV infection against NSCLCs in an immunocompetent model in vivo. Using Raf-BxB transgenic mice that spontaneously develop NSCLCs, we demonstrated that infection with low-pathogenic IAV leads to rapid and efficient oncolysis, eliminating 70% of the initial tumor mass. Interestingly, IAV infection of Raf-BxB mice caused a functional reversion of immunosuppressed tumor-associated lung macrophages into a M1-like pro-inflammatory active phenotype that additionally supported virus-induced oncolysis of cancer cells. Altogether, our data demonstrate for the first time in an immunocompetent in vivo model that oncolytic IAV infection is capable of restoring and redirecting immune cell functions within the tumor microenvironment of NSCLCs.

How Behavioral Changes Can Indicate Serious Cerebral Pathology: A Case Report of Concomitant Olfactory Neuroblastoma and Distemper Virus Encephalitis in a Swiss Shepherd Dog

Behavioral alterations in dogs are not easy to understand and cure. The situation is more difficult when an encephalitis due to Canine Distemper Virus (CDV) and a concomitant olfactory neuroblastoma are present. This case report deals with the story of a 5-year-old Swiss shepherd dog with behavioral changes, seizures, epistaxis and ataxia. Following clinical and laboratory exams, a suspected diagnosis of CDV infection was hypothesized, and a therapy based on Ω-interferon was administered. Every supporting therapy failed and the worsening of the clinical conditions led to the euthanasia of the patient. A neoformation in the right frontal lobe was found post mortem. Histopathology and immunohistochemistry investigation showed a non-suppurative demyelinating encephalitis, suggestive of CDV infection, and a desmoplastic epithelioid olfactory neuroblastoma. To the best of authors’ knowledge, this is the first clinical pathological report of a non-suppurative encephalitis due to CDV infection and olfactory neuroblastoma in a dog.