Newcastle disease virus: A promising agent for tumour immunotherapy

Therapeutic Applications for Oncolytic Self-Replicating RNA Viruses

Self-replicating RNA viruses have become attractive delivery vehicles for therapeutic applications. They are easy to handle, can be rapidly produced in large quantities, and can be delivered as recombinant viral particles, naked or nanoparticle-encapsulated RNA, or plasmid DNA-based vectors. The self-replication of RNA in infected host cells provides the means for generating much higher transgene expression levels and the possibility to apply substantially reduced amounts of RNA to achieve similar expression levels or immune responses compared to conventional synthetic mRNA. Alphaviruses and flaviviruses, possessing a single-stranded RNA genome of positive polarity, as well as measles viruses and rhabdoviruses with a negative-stranded RNA genome, have frequently been utilized for therapeutic applications. Both naturally and engineered oncolytic self-replicating RNA viruses providing specific replication in tumor cells have been evaluated for cancer therapy. Therapeutic efficacy has been demonstrated in animal models. Furthermore, the safe application of oncolytic viruses has been confirmed in clinical trials. Multiple myeloma patients treated with an oncolytic measles virus (MV-NIS) resulted in increased T-cell responses against the measles virus and several tumor-associated antigen responses and complete remission in one patient. Furthermore, MV-CEA administration to patients with ovarian cancer resulted in a stable disease and more than doubled the median overall survival.

Engineering strategies to enhance oncolytic viruses in cancer immunotherapy

Oncolytic viruses (OVs) are emerging as potentially useful platforms in treatment methods for patients with tumors. They preferentially target and kill tumor cells, leaving healthy cells unharmed. In addition to direct oncolysis, the essential and attractive aspect of oncolytic virotherapy is based on the intrinsic induction of both innate and adaptive immune responses. To further augment this efficacious response, OVs have been genetically engineered to express immune regulators that enhance or restore antitumor immunity. Recently, combinations of OVs with other immunotherapies, such as immune checkpoint inhibitors (ICIs), chimeric antigen receptors (CARs), antigen-specific T-cell receptors (TCRs) and autologous tumor-infiltrating lymphocytes (TILs), have led to promising progress in cancer treatment. This review summarizes the intrinsic mechanisms of OVs, describes the optimization strategies for using armed OVs to enhance the effects of antitumor immunity and highlights rational combinations of OVs with other immunotherapies in recent preclinical and clinical studies.

Differential microRNA Expression in Newcastle Disease Virus-Infected HeLa Cells and Its Role in Regulating Virus Replication

As an oncolytic virus, Newcastle disease virus (NDV) can specifically kill tumor cells and has been tested as an attractive oncolytic agent for cancer virotherapy. Virus infection can trigger the changes of the cellular microRNA (miRNA) expression profile, which can greatly influence viral replication and pathogenesis. However, the interplay between NDV replication and cellular miRNA expression in tumor cells is still largely unknown. In the present study, we compared the profiles of cellular miRNAs in uninfected and NDV-infected HeLa cells by small RNA deep sequencing. Here we report that NDV infection in HeLa cells significantly changed the levels of 40 miRNAs at 6 h post-infection (hpi) and 62 miRNAs at 12 hpi. Among 23 highly differentially expressed miRNAs, NDV infection greatly promoted the levels of 3 miRNAs and suppressed the levels of 20 miRNAs at both time points. These 23 miRNAs are predicted to target various genes involved in virus replication and antiviral immunity such as ErbB, Jak-STAT, NF-kB and RIG-I-like receptor. Verification of deep sequencing results by quantitative RT-PCR showed that 9 out of 10 randomly selected miRNAs chosen from this 23-miRNA pool were consistent with deep sequencing data, including 6 down-regulated and 3 up-regulated. Further functional research revealed that hsa-miR-4521, a constituent in this 23-miRNA pool, inhibited NDV replication in HeLa cells. Moreover, dual-luciferase and gene expression array uncovered that the member A of family with sequence similarity 129 (FAM129A) was directly targeted by hsa-miR-4521 and positively regulated NDV replication in HeLa cells, indicating that hsa-miR-4521 may regulate NDV replication via interaction with FAM129A. To our knowledge, this is the first report of the dynamic cellular miRNA expression profile in tumor cells after NDV infection and may provide a valuable basis for further investigation on the roles of miRNAs in NDV-mediated oncolysis.

Zoonotic potential of Newcastle disease virus: Old and novel perspectives related to public health

Newcastle disease virus (NDV) has a worldwide distribution, causing lethal infection in a wide range of avian species. Affected birds develop respiratory, digestive and neurologic symptoms with profound immunosuppression. Mild systemic Newcastle disease (ND) infection restricted to the respiratory and neurological systems can be observed in humans and other non-avian hosts. Evidence of ND infection and its genome-based detection have been reported in Bovidae (cattle and sheep), Mustelidae (mink), Cercetidae (hamster), Muridae (mice), Leporidae (rabbit), Camelidae (camel), Suidae (pig), Cercophithecidae (monkeys) and Hominidae (humans). Owing to frequent ND outbreaks in poultry workers, individuals engaged in the veterinary field, including poultry production or evisceration and vaccine production units have constantly been at a much higher risk than the general population. A lethal form of infection has been described in immunocompromised humans and non-avian species including mink, pig and cattle demonstrating the capability of NDV to cross species barriers. Therefore, contact with infectious material and/or affected birds can pose a risk of zoonosis and raise public health concerns. The broad and expanding host range of NDV and its maintenance within non-avian species hampers disease control, particularly in disease-endemic settings.

The oncolytic Newcastle disease virus as an effective immunotherapeutic strategy against glioblastoma

Glioblastoma is the most frequent primary brain tumor in adults, with a dismal prognosis despite aggressive resection, chemotherapeutics, and radiotherapy. Although understanding of the molecular pathogenesis of glioblastoma has progressed in recent years, therapeutic options have failed to significantly change overall survival or progression-free survival. Thus, researchers have begun to explore immunomodulation as a potential strategy to improve clinical outcomes. The application of oncolytic virotherapy as a novel biological to target pathogenic signaling in glioblastoma has brought new hope to the field of neuro-oncology. This class of immunotherapeutics combines selective cancer cell lysis prompted by virus induction while promoting a strong inflammatory antitumor response, thereby acting as an effective in situ tumor vaccine. Several investigators have reported the efficacy of experimental oncolytic viruses as demonstrated by improved long-term survival in cancer patients with advanced disease. Newcastle disease virus (NDV) is one of the most well-researched oncolytic viruses known to affect a multitude of human cancers, including glioblastoma. Preclinical in vitro and in vivo studies as well as human clinical trials have demonstrated that NDV exhibits oncolytic activity against glioblastoma, providing a promising avenue of potential treatment. Herein, the authors provide a detailed discussion on NDV as a mode of therapy for glioblastoma. They discuss the potential therapeutic pathways associated with NDV as demonstrated by in vitro and in vivo experiments as well as results from human trials. Moreover, they discuss current challenges, potential solutions, and future perspectives in utilizing NDV in the treatment of glioblastoma.

Interference chromatography: a novel approach to optimizing chromatographic selectivity and separation performance for virus purification

Background

Oncolytic viruses are playing an increasingly important role in cancer immunotherapy applications. Given the preclinical and clinical efficacy of these virus-based therapeutics, there is a need for fast, simple, and inexpensive downstream processing methodologies to purify biologically active viral agents that meet the increasingly higher safety standards stipulated by regulatory authorities like the Food and Drug Administration and the European Agency for the Evaluation of Medicinal Products. However, the production of virus materials for clinical dosing of oncolytic virotherapies is currently limited—in quantity, quality, and timeliness—by current purification technologies. Adsorption of virus particles to solid phases provides a convenient and practical choice for large-scale fractionation and recovery of viruses from cell and media contaminants. Indeed, chromatography has been deemed the most promising technology for large-scale purification of viruses for biomedical applications. The implementation of new chromatography media has improved process performance, but low yields and long processing times required to reach the desired purity are still limiting.

Results

Here we report the development of an interference chromatography-based process for purifying high titer, clinical grade oncolytic Newcastle disease virus using NatriFlo® HD-Q membrane technology. This novel approach to optimizing chromatographic performance utilizes differences in molecular bonding interactions to achieve high purity in a single ion exchange step.

Conclusions

When used in conjunction with membrane chromatography, this high yield method based on interference chromatography has the potential to deliver efficient, scalable processes to enable viable production of oncolytic virotherapies.

Tumor Cells Modified with Newcastle Disease Virus Expressing IL-24 as a Cancer Vaccine

Interleukin-24 (IL-24) is a promising agent for cancer immunotherapy that induces apoptosis of tumor cells and enhances T cell activation and function. In order to improve the antitumor activity induced by Newcastle disease virus (NDV)-modified tumor vaccine, we generated a recombinant NDV expressing IL-24 using reverse genetics. Irradiated tumor cells infected with LX/IL-24 showed stable IL-24 expression. The cytotoxicity assay showed that LX/IL-24-infected murine melanoma cells significantly enhanced the antitumor immune response in vitro. Then, the antitumor effects of virus-infected tumor cells were examined in the murine tumor models. LX/IL-24-infected tumor cells exhibited strong antitumor effects both in prophylaxis and therapeutic models. LX/IL-24-infected tumor cells increased infiltration of CD4⁺ T cells and CD8⁺ T cells in tumor sites, and the antitumor activity of the tumor vaccine modified with LX/IL-24 was dependent on CD8⁺ T cells. Taken together, our data well illustrates that LX/IL-24-modified tumor cells are a promising agent for cancer immunotherapy.

Non-replicating Newcastle Disease Virus as an adjuvant for DNA vaccine enhances antitumor efficacy through the induction of TRAIL and granzyme B expression

The potential of non-replicating Newcastle Disease Virus (NDV) as an adjuvant for DNA vaccination remains to be elucidated. To assess the therapeutic effects of DNA vaccine (HPV-16 E7 gene) adjuvanted with NDV, female C57/BL6 mice were inoculated with murine TC-1 cells of human papillomavirus (HPV)-related carcinoma, expressing human papillomavirus 16 (HPV-16) E6/E7 antigens, and immunized with DNA vaccine alone or pretreated with NDV. One week after third immunization, Cytotoxic T lymphocytes (CTLs), splenocyte proliferation, cytokine balance (IFN-γ, IL-4 and IL-12 secretions) and intratumoral expression of cytotoxicity related proteins in tumor lysates were investigated. The results showed that treatment with non-replicating NDV prior to DNA vaccine induced tumor-specific cytolytic and splenocyte proliferation responses. The levels of cytokines IL-12, IL-4 and IFN-γ after treating with combined E7-DNA -non-replicating NDV (NDV-DNA Vaccine) were significantly higher than those of control groups. The intratumoral granzyme B and Tumor Necrosis Factor Related Apoptosis Inducing Ligand (TRAIL)-mediated apoptosis was also significantly increased. Tumor therapeutic experiments showed that the NDV pretreatment could reduce the tumor progression of established E7-expressing TC-tumors. Taken together these data suggest that the significant antitumor responses evidenced during treatment with non-replicating NDV prior to DNA vaccine are due, in part, to strong E7-induced cellular immunity and enhanced expression of cytotoxicity related proteins in the tumor microenvironment. These observations indicated the potential of non-replicating NDV as an adjuvant for enhancing therapeutic DNA vaccines -induced immunity and antitumor responses.

Combining Tumor Vaccination and Oncolytic Viral Approaches with Checkpoint Inhibitors: Rationale, Pre-Clinical Experience, and Current Clinical Trials in Malignant Melanoma

The field of tumor immunology has faced many complex challenges over the last century, but the approval of immune checkpoint inhibitors (anti-cytotoxic T-lymphocyte-associated protein 4 [CTLA4] and anti-programmed cell death-1 [PD-1]/PD-ligand 1 [PD-L1]) and talimogene laherparepvec (T-VEC) for the treatment of metastatic melanoma have awakened a new wave of interest in cancer immunotherapy. Additionally, combinations of vaccines and oncolytic viral therapies with immune checkpoint inhibitors and other systemic agents seem to be promising synergistic strategies to further boost the immune response against cancer. These combinations are undergoing clinical investigation, and if successful, will hopefully soon become available to patients. Here, we review key basic concepts of tumor-induced immune suppression in malignant melanoma, the historical perspective around vaccine development in melanoma, and advances in oncolytic viral therapies. We also discuss the emerging role for combination approaches with different immunomodulatory agents as well as new developments in personalized immunization approaches.

New frontiers in oncolytic viruses: optimizing and selecting for virus strains with improved efficacy

Oncolytic viruses have demonstrated selective replication and killing of tumor cells. Different types of oncolytic viruses – adenoviruses, alphaviruses, herpes simplex viruses, Newcastle disease viruses, rhabdoviruses, Coxsackie viruses, and vaccinia viruses – have been applied as either naturally occurring or engineered vectors. Numerous studies in animal-tumor models have demonstrated substantial tumor regression and prolonged survival rates. Moreover, clinical trials have confirmed good safety profiles and therapeutic efficacy for oncolytic viruses. Most encouragingly, the first cancer gene-therapy drug – Gendicine, based on oncolytic adenovirus type 5 – was approved in China. Likewise, a second-generation oncolytic herpes simplex virus-based drug for the treatment of melanoma has been registered in the US and Europe as talimogene laherparepvec.

Latest trends in cancer therapy applying viral vectors

Gene therapy based on viral vectors has demonstrated steady progress recently, not only in the area of cancers. A multitude of viral vectors has been engineered for both preventive and therapeutic applications. Two main approaches comprise of viral vector-based delivery of toxic or anticancer genes or immunization with anticancer antigens. Tumor growth inhibition and tumor regression have been observed, providing improved survival rates in animal tumor models. Furthermore, vaccine-based cancer immunotherapy has demonstrated both tumor regression and protection against challenges with lethal doses of tumor cells. Several clinical trials with viral vectors have also been conducted. Additionally, viral vector-based cancer drugs have been approved. This review gives an overview of different viral vector systems and their applications in cancer gene therapy.

Newcastle disease virus mediates pancreatic tumor rejection via NK cell activation and prevents cancer relapse by prompting adaptive immunity

Pancreatic cancer is the 8th most common cause of cancer-related deaths worldwide and the tumor with the poorest prognosis of all solid malignancies. In 1957, it was discovered that Newcastle disease virus (NDV) has oncolytic properties on tumor cells. To study the oncolytic properties of NDV in pancreatic cancer a single dose was administered intravenously in a syngeneic orthotopic tumor model using two different murine pancreatic adenocarcinoma cell lines (DT6606PDA, Panc02). Tumor growth was monitored and immune response was analyzed. A single treatment with NDV inhibited DT6606PDA tumor growth in mice and prevented recurrence for a period of three months. Tumor infiltration and systemic activation of NK cells, cytotoxic and helper T-cells was enhanced. NDV-induced melting of Panc02 tumors until d7 pi, but they recurred displaying unrestricted tumor growth, low immunogenicity and inhibition of tumor-specific immune response. Arrest of DT6606PDA tumor growth and rejection was mediated by activation of NK cells and a specific antitumor immune response via T-cells. Panc02 tumors rapidly decreased until d7 pi, but henceforth tumors characterized by the ability to perform immune-regulatory functions reappeared. Our results demonstrated that NDV-activated immune cells are able to reject tumors provided that an adaptive antitumor immune response can be initiated. However, activated NK cells that are abundant in Panc02 tumors lead to outgrowth of nonimmunogenic tumor cells with inhibitory properties. Our study emphasizes the importance of an adaptive immune response, which is initiated by NDV to mediate long-term tumor surveillance in addition to direct oncolysis.

Autologous tumor vaccine modified with recombinant new castle disease virus expressing IL-7 promotes antitumor immune response

Autologous tumor vaccine modified with nonlytic Newcastle disease virus (ATV-NDV) is a promising vaccine for cancer immunotherapy. IL-7 plays a critical role in lymphocyte development and homeostasis. To improve the efficacy of ATV-NDV, we inserted the murine IL-7 gene into the genome of nonlytic NDV strain LX using reverse genetic system. The insertion of the IL-7 gene neither affected the main features of NDV replication nor its tumor selectivity. The gene product was biologically active and stable. Then we tested the antitumor effects of the autologous tumor vaccine modified with LX/(IL-7) in the murine tumor models. We showed that tumor cells modified with LX/IL-7 induced a strong antitumor activity both in prophylaxis and therapeutic models. The IFN-γ production and the cytotoxicity of tumor-specific CD8(+) T cells were significantly enhanced after immunization with tumor cells modified with LX/(IL-7) in both models. Although the tumor-infiltrating CD4(+) T cells and CD8(+) T cells were both increased and their IFN-γ productions also were upregulated, the antitumor activity of the tumor vaccine modified with LX/(IL-7) was dependent on CD8(+) T cells. Our results demonstrated that the autologous tumor vaccine modified with NDV strain LX/(IL-7) could promote the antitumor immune responses mediated by CD8(+) T cells and significantly improve the efficacy of the ATV-NDV.

Oncolytic virus-mediated reversal of impaired tumor antigen presentation

Anti-tumor immunity can eliminate existing cancer cells and also maintain a constant surveillance against possible relapse. Such an antigen-specific adaptive response begins when tumor-specific T cells become activated. T-cell activation requires two signals on antigen presenting cells (APCs): antigen presentation through major histocombatibility complex (MHC) molecules and co-stimulation. In the absence of one or both these signals, T cells remain inactivated or can even become tolerized. Cancer cells and their associated microenvironment strategically hinder the processing and presentation of tumor antigens and consequently prevent the development of anti-tumor immunity. Many studies, however, demonstrate that interventions that over-turn tumor-associated immune evasion mechanisms can establish anti-tumor immune responses of therapeutic potential. One such intervention is oncolytic virus (OV)-based anti-cancer therapy. Here, we discuss how OV-induced immunological events override tumor-associated antigen presentation impairment and promote appropriate T cell–APC interaction. Detailed understanding of this phenomenon is pivotal for devising the strategies that will enhance the efficacy of OV-based anti-cancer therapy by complementing its inherent oncolytic activities with desired anti-tumor immune responses.

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.