Oncolytic adenoviruses targeted to Human Papilloma Virus-positive head and neck squamous cell carcinomas

Viral Shedding in Mice following Intravenous Adenovirus Injection: Impact on Biosafety Classification

There have been numerous advances in gene therapy and oncolytic virotherapy in recent years, especially with respect to cutting-edge animal models to test these novel therapeutics. With all of these advances, it is important to understand the biosafety risks of testing these vectors in animals. We performed adenovirus-based viral shedding studies in murine models to ascertain when it is appropriate to downgrade the animals from Biosafety Level (BSL) 2 to BSL 1 for experimental handling and transport. We utilized intravenous injections of a replication-competent adenovirus and analyzed viral shedding via the collection of buccal and dermal swabs from each animal, in addition to obtaining urine and stool samples. The adenovirus hexon copy number was determined by qPCR, and plaque formation was analyzed to assess the biologic activity of viral particles. Our results demonstrate that after 72 h following viral inoculation, there is no significant quantity of biologically active virus shedding from the animals. This observation suggests that on day 4 following adenovirus injection, mice can be safely downgraded to BSL 1 for the remainder of the experiment with no concern for hazardous exposure to laboratory personnel.

Evaluation of Human Mesenchymal Stromal Cells as Carriers for the Delivery of Oncolytic HAdV-5 to Head and Neck Squamous Cell Carcinomas

Human multipotent mesenchymal stromal cells (hMSCs) are of significant therapeutic interest due to their ability to deliver oncolytic adenoviruses to tumors. This approach is also investigated for targeting head and neck squamous cell carcinomas (HNSCCs). HAdV-5-HexPos3, a recently reported capsid-modified vector based on human adenovirus type 5 (HAdV-5), showed strongly improved infection of both hMSCs and the HNSCC cell line UM-SCC-11B. Given that, we generated life cycle-unmodified and -modified replication-competent HAdV-5-HexPos3 vector variants and analyzed their replication within bone marrow- and adipose tissue-derived hMSCs. Efficient replication was detected for both life cycle-unmodified and -modified vectors. Moreover, we analyzed the migration of vector-carrying hMSCs toward different HNSCCs. Although migration of hMSCs to HNSCC cell lines was confirmed in vitro, no homing of hMSCs to HNSCC xenografts was observed in vivo in mice and in ovo in a chorioallantoic membrane model. Taken together, our data suggest that HAdV-5-HexPos3 is a potent candidate for hMSC-based oncolytic therapy of HNSCCs. However, it also emphasizes the importance of generating optimized in vivo models for the evaluation of hMSC as carrier cells.

Interferon Alpha-Expressing Oncolytic Adenovirus for Treatment of Esophageal Adenocarcinoma

INTRODUCTION

Esophageal adenocarcinoma (EAC) has increased in incidence in Western countries, and its poor prognosis necessitates the development of novel therapeutics. We previously reported the potential of conditionally replicative adenoviruses (CRAd) as a novel therapeutic treatment for this disease. To further augment the therapeutic effectiveness of our cyclooxygenase-2 (Cox2) controlled CRAd in EAC, we inserted an interferon alpha (IFN) transgene into the viral genome that is expressed upon viral replication. In this manuscript, we analyze the cytotoxic and oncolytic effects of an IFN-expressing oncolytic adenovirus in EAC and the role of the Cox2 promoter in providing for selective replication in human tissues.

METHODS

An infectivity-enhanced IFN-expressing CRAd (5/3 Cox2 CRAd ΔE3 ADP IFN) and other control viruses were first tested in vitro with cell lines. For the in vivo study, EAC xenografts in nude mice were treated with a single intratumoral dose of virus. An ex vivo analysis with live tissue slices was conducted using surgically resected EAC patient specimens.

RESULTS

Expression of IFN significantly enhanced the cytotoxic and oncolytic effect of a Cox2-promoter controlled CRAd. This virus showed significant tumor growth suppression in a xenograft model. Furthermore, in human EAC samples, the promoter-controlled virus demonstrated selective replication in cancerous tissues, leaving normal esophageal tissue unaffected.

CONCLUSION

An IFN-expressing CRAd driven by the Cox2 promoter has strong oncolytic effects as well as cancer-specific replication. Our novel vector possesses critical characteristics that make it a potential candidate for clinical translation to treat EAC.

Oncolytic Adenoviruses: Strategies for Improved Targeting and Specificity

Cancer is a major health problem. Most of the treatments exhibit systemic toxicity, as they are not targeted or specific to cancerous cells and tumors. Adenoviruses are very promising gene delivery vectors and have immense potential to deliver targeted therapy. Here, we review a wide range of strategies that have been tried, tested, and demonstrated to enhance the specificity of oncolytic viruses towards specific cancer cells. A combination of these strategies and other conventional therapies may be more effective than any of those strategies alone.

Immunotherapy in the management of squamous cell carcinoma of the head and neck

Despite many advances in surgery, radiotherapy, and systemic treatments, only modest improvements in survival, function, and quality of life have been achieved after treatment of squamous cell carcinoma (SCC) of the head and neck. With a better understanding of the biology and genetics of tumours, the emergence of a paradigm shift towards the further development of non-surgical treatments may result in less morbidity and better outcomes than are seen currently. SCC of the head and neck is known to be a complex disease that has a sophisticated interaction with the human immune system. At the forefront of emerging treatments is immunotherapy, which has already been established in many other areas of oncology. The rapidly evolving nature of immunotherapeutic agents and, sometimes, their complex mechanisms can make the understanding of these concepts challenging, and could discourage clinicians from engaging in clinical trials. The aim of this paper therefore was to review the current premise for immunotherapeutic approaches, and to provide a contemporary evidence-based rationale for their use.

The Development of Oncolytic Adenovirus Therapy in the Past and Future - For the Case of Pancreatic Cancer

Pancreatic cancer is an aggressive malignant disease and the efficacy of current treatments for unresectable diseases is quite limited despite recent advances. Gene therapy /virotherapy strategies may provide new options for the treatment of various cancers including pancreatic cancer. Oncolytic adenovirus shows an antitumoral effect via its intratumoral amplification and strong cytocidal effect in a variety of cancers and it has been employed for the development of potent oncolytic virotherapy agents for pancreatic cancer. Our ultimate goal is to develop an oncolytic adenovirus enabling the treatment of patients with advanced or spread diseases by systemic injection. Systemic application of oncolytic therapy mandates more efficient and selective gene delivery and needs to embody sufficient antitumor effect even with limited initial delivery to the tumor location. In this review, the current status of oncolytic adenoviruses from the viewpoints of vector design and potential strategies to overcome current obstacles for its clinical application will be described. We will also discuss the efforts to improve the antitumor activity of oncolytic adenovirus, in in vivo animal models, and the combination therapy of oncolytic adenovirus with radiation and chemotherapy.

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.

A New Role for Vitamin D: The Enhancement of Oncolytic Viral Therapy in Pancreatic Cancer

Oncolytic viruses have emerged as a novel class of anti-cancer therapeutics with one virus already receiving United States Food and Drug Administration (FDA) approval (talimogene laherparepvec) and many others undergoing testing in clinical trials. These viruses have direct lytic effects on tumor cells as well as immunomodulatory functions to increase inflammatory cell infiltrates in the tumor microenvironment. Despite all of the advances in cancer care, pancreatic cancer remains a highly lethal malignancy. One of the main barriers to successful systemic treatment of the disease is the fibrotic tumor stroma, as the unique extracellular matrix creates an environment that promotes tumor growth and is resistant to chemotherapy and other anti-cancer agents. The pleiotropic effects of Vitamin D have been widely studied, but recent research has now demonstrated it to be an effective agent in modulating pancreatic cancer stroma to facilitate the enhanced delivery of cytotoxic chemotherapy and immunogenicity in response to treatment. This review will explore the combination of Vitamin D with oncolytic viruses and how this novel application of Vitamin D's ability to modulate pancreatic tumor stroma may result in a potential mechanism for increasing the efficacy of oncolytic virotherapy in pancreatic cancer.

Oncolytic Adenovirus Harboring Interleukin-24 Improves Chemotherapy for Advanced Prostate Cancer

PURPOSE

Oncolytic adenoviruses emerge as new agents for cancer therapy. This study aimed to investigate the synergistic anti-tumor activity of oncolytic adenovirus armed with IL-24 (ZD55-IL-24) and docetaxel (DTX) on advanced prostate cancer in vitro and in vivo.

METHODS

DU145 prostate cancer cells or nude mice xenografted with DU145 prostate cancer cells were treated by ZD55-IL-24 and DTX alone or in combination.

RESULTS

DTX did not affect ZD55-IL-24 replication and IL-24 expression in DU145 cells. In vitro, the combination of ZD55-IL-24 and DTX showed synergistic inhibitory effects on prostate cancer cell viability and invasion. In vivo, ZD55-IL-24 and DTX synergistically inhibited the growth and activated the apoptosis of DU145 xenografts, accompanied by significantly decreased PARP-1 levels and increased caspase-3 and caspase-8 levels as well as decreased CD31 expression.

CONCLUSION

We reported the synergistic anti-tumor efficacy of ZD55-IL-24 and DTX on prostate cancer. Our results suggest that chemotherapy combined with oncolytic adenovirus mediated gene therapy is a promising strategy for the treatment of advanced prostate cancer.

Trial Watch: Oncolytic viro-immunotherapy of hematologic and solid tumors

Oncolytic viruses selectively target and kill cancer cells in an immunogenic fashion, thus supporting the establishment of therapeutically relevant tumor-specific immune responses. In 2015, the US Food and Drug Administration (FDA) approved the oncolytic herpes simplex virus T-VEC for use in advanced melanoma patients. Since then, a plethora of trials has been initiated to assess the safety and efficacy of multiple oncolytic viruses in patients affected with various malignancies. Here, we summarize recent preclinical and clinical progress in the field of oncolytic virotherapy.

Role of Gene Therapy in Pancreatic Cancer-A Review

Mortality from pancreatic ductal adenocarcinoma (PDAC) has remained essentially unchanged for decades and its relative contribution to overall cancer death is projected to only increase in the coming years. Current treatment for PDAC includes aggressive chemotherapy and surgical resection in a limited number of patients, with median survival of optimal treatment rather dismal. Recent advances in gene therapies offer novel opportunities for treatment, even in those with locally advanced disease. In this review, we summarize emerging techniques to the design and administration of virotherapy, synthetic vectors, and gene-editing technology. Despite these promising advances, shortcomings continue to exist and here will also be highlighted those approaches to overcoming obstacles in current laboratory and clinical research.