Oncolytic Sendai virus-based virotherapy for cancer: recent advances

Viral vectors: design and delivery for small RNA

RNA interference regulates gene expression by selectively silencing target genes through the introduction of small RNA molecules, such as microRNA, small interfering RNA and short hairpin RNA. These molecules offer significant therapeutic potential for diverse human ailments like cancer, viral infections and neurodegenerative disorders. Whilst non-viral vectors like nanoparticles have been extensively explored for delivering these RNAs, viral vectors, with superior specificity and delivery efficiency, remain less studied. This review examines current viral vectors for small RNA delivery, focusing on design strategies and characteristics. It compares the advantages and drawbacks of each vector, aiding readers in selecting the optimal one for small RNA delivery.

Local treatment of HVJ-E with T cell costimulatory molecule stimulation elicits systemic anti-tumor effects

The tumor-infiltrating lymphocyte (TIL) is a crucial factor in controlling tumor growth. A therapeutic method activating TIL is desired for treating patients with metastatic tumors. Here, we show that treating a local tumor with a combination therapy of UV-irradiated hemagglutinating virus of Japan envelope (HVJ-E) plus agonist antibodies, including OX40, against T cell costimulatory molecules induces systemic anti-tumor effects in a T cell-dependent manner in multiple cancer cell lines. Transcriptome and T cell receptor repertoire analyses revealed that HVJ-E + anti-OX40 antibody treatment activates CD4 and CD8 T cells and promotes T cell trafficking between tumors. These systemic anti-tumor effects required an association between Nkg2d and Nkg2d ligands. Our findings provide insights into how systemic anti-tumor effects are induced and may help the development of therapeutic strategies for eliciting such effects.

Tutorial: design, production and testing of oncolytic viruses for cancer immunotherapy

Oncolytic viruses (OVs) represent a novel class of cancer immunotherapy agents that preferentially infect and kill cancer cells and promote protective antitumor immunity. Furthermore, OVs can be used in combination with established or upcoming immunotherapeutic agents, especially immune checkpoint inhibitors, to efficiently target a wide range of malignancies. The development of OV-based therapy involves three major steps before clinical evaluation: design, production and preclinical testing. OVs can be designed as natural or engineered strains and subsequently selected for their ability to kill a broad spectrum of cancer cells rather than normal, healthy cells. OV selection is further influenced by multiple factors, such as the availability of a specific viral platform, cancer cell permissivity, the need for genetic engineering to render the virus non-pathogenic and/or more effective and logistical considerations around the use of OVs within the laboratory or clinical setting. Selected OVs are then produced and tested for their anticancer potential by using syngeneic, xenograft or humanized preclinical models wherein immunocompromised and immunocompetent setups are used to elucidate their direct oncolytic ability as well as indirect immunotherapeutic potential in vivo. Finally, OVs demonstrating the desired anticancer potential progress toward translation in patients with cancer. This tutorial provides guidelines for the design, production and preclinical testing of OVs, emphasizing considerations specific to OV technology that determine their clinical utility as cancer immunotherapy agents.

Immune responses elicited by ssRNA(-) oncolytic viruses in the host and in the tumor microenvironment

Oncolytic viruses (OVs) are at the forefront of biologicals for cancer treatment. They represent a diverse landscape of naturally occurring viral strains and genetically modified viruses that, either as single agents or as part of combination therapies, are being evaluated in preclinical and clinical settings. As the field gains momentum, the research on OVs has been shifting efforts to expand our understanding of the complex interplay between the virus, the tumor and the immune system, with the aim of rationally designing more efficient therapeutic interventions. Nowadays, the potential of an OV platform is no longer defined exclusively by the targeted replication and cancer cell killing capacities of the virus, but by its contribution as an immunostimulator, triggering the transformation of the immunosuppressive tumor microenvironment (TME) into a place where innate and adaptive immunity players can efficiently engage and lead the development of tumor-specific long-term memory responses. Here we review the immune mechanisms and host responses induced by ssRNA(-) (negative-sense single-stranded RNA) viruses as OV platforms. We focus on two ssRNA(-) OV candidates: Newcastle disease virus (NDV), an avian paramyxovirus with one of the longest histories of utilization as an OV, and influenza A (IAV) virus, a well-characterized human pathogen with extraordinary immunostimulatory capacities that is steadily advancing as an OV candidate through the development of recombinant IAV attenuated platforms.

Microorganisms in chemotherapy for pancreatic cancer: An overview of current research and future directions

Pancreatic cancer is a malignant tumor of the digestive system with a very high mortality rate. While gemcitabine-based chemotherapy is the predominant treatment for terminal pancreatic cancer, its therapeutic effect is not satisfactory. Recently, many studies have found that microorganisms not only play a consequential role in the occurrence and progression of pancreatic cancer but also modulate the effect of chemotherapy to some extent. Moreover, microorganisms may become an important biomarker for predicting pancreatic carcinogenesis and detecting the prognosis of pancreatic cancer. However, the existing experimental literature is not sufficient or convincing. Therefore, further exploration and experiments are imperative to understanding the mechanism underlying the interaction between microorganisms and pancreatic cancer. In this review, we primarily summarize and discuss the influences of oncolytic viruses and bacteria on pancreatic cancer chemotherapy because these are the two types of microorganisms that are most often studied. We focus on some potential methods specific to these two types of microorganisms that can be used to improve the efficacy of chemotherapy in pancreatic cancer therapy.

Structure and assembly of double-headed Sendai virus nucleocapsids

Paramyxoviruses, including the mumps virus, measles virus, Nipah virus and Sendai virus (SeV), have non-segmented single-stranded negative-sense RNA genomes which are encapsidated by nucleoproteins into helical nucleocapsids. Here, we reported a double-headed SeV nucleocapsid assembled in a tail-to-tail manner, and resolved its helical stems and clam-shaped joint at the respective resolutions of 2.9 and 3.9 Å, via cryo-electron microscopy. Our structures offer important insights into the mechanism of the helical polymerization, in particular via an unnoticed exchange of a N-terminal hole formed by three loops of nucleoproteins, and unveil the clam-shaped joint in a hyper-closed state for nucleocapsid dimerization. Direct visualization of the loop from the disordered C-terminal tail provides structural evidence that C-terminal tail is correlated to the curvature of nucleocapsid and links nucleocapsid condensation and genome replication and transcription with different assembly forms.

Virus-Intrinsic Differences and Heterogeneous IRF3 Activation Influence IFN-Independent Antiviral Protection

Type 1 interferon (IFN) plays a critical role in early antiviral defense and priming of adaptive immunity by signaling upregulation of host antiviral IFN-stimulated genes (ISGs). Certain stimuli trigger strong activation of IFN regulatory factor 3 (IRF3) and direct upregulation of ISGs in addition to IFN. It remains unclear why some stimuli are stronger activators of IRF3 and how this leads to IFN-independent antiviral protection. We found that UV-inactivated human cytomegalovirus (HCMV) particles triggered an IFN-independent ISG signature that was absent in cells infected with UV-inactivated Sendai virus particles. HCMV particles triggered mostly uniform activation of IRF3 and low-level IFN-β production within the population while SeV particles triggered a small fraction of cells producing abundant IFN-β. These findings suggest that population-level activation of IRF3 and antiviral protection emerges from a diversity of responses occurring simultaneously in single cells. Moreover, this occurs in the absence of virus replication.

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The antiviral response to virus particles requires low levels of interferon

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Cells respond differently to HCMV or SeV particles

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Heterogeneous IRF3 activation influences the response to virus

The Innate Immune Signalling Pathways: Turning RIG-I Sensor Activation Against Cancer

Over the last 15 years, the ability to harness a patient's own immune system has led to significant progress in cancer therapy. For instance, immunotherapeutic strategies, including checkpoint inhibitors or adoptive cell therapy using chimeric antigen receptor T-cell (CAR-T), are specifically aimed at enhancing adaptive anti-tumour immunity. Several research groups demonstrated that adaptive anti-tumour immunity is highly sustained by innate immune responses. Host innate immunity provides the first line of defence and mediates recognition of danger signals through pattern recognition receptors (PRRs), such as cytosolic sensors of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular pattern (DAMP) signals. The retinoic acid-inducible gene I (RIG-I) is a cytosolic RNA helicase, which detects viral double-strand RNA and, once activated, triggers signalling pathways, converging on the production of type I interferons, proinflammatory cytokines, and programmed cell death. Approaches aimed at activating RIG-I within cancers are being explored as novel therapeutic treatments to generate an inflammatory tumour microenvironment and to facilitate cytotoxic T-cell cross-priming and infiltration. Here, we provide an overview of studies regarding the role of RIG-I signalling in the tumour microenvironment, and the most recent preclinical studies that employ RIG-I agonists. Lastly, we present a selection of clinical trials designed to prove the antitumour role of RIG I and that may result in improved therapeutic outcomes for cancer patients.

Efficient photodynamic therapy against drug-resistant prostate cancer using replication-deficient virus particles and talaporfin sodium

To enhance the potency of photosensitizer, we developed a novel photosensitizer, Laserphyrin®-HVJ-E (L-HVJ-E), by incorporating talaporfin sodium (Laserphyrin®, Meiji Seika Pharma) into hemagglutinating virus of Japan envelope (HVJ-E). In this study, we examined the optimal Laserphyrin® concentration for preparation of Laserphyrin®-HVJ-E which had photocytotoxicity and maintained direct cytotoxicity derived from HVJ-E. Then, potency of Laserphyrin®-HVJ-E and Laserphyrin® were compared in vitro using castration-resistant prostate cancer cell line (PC-3). A laser diode (L660P120, Thorlabs, USA) with a wavelength of 664 nm was used for light activation of Laserphyrin®, which corresponds to an absorption peak of Laserphyrin® and provides a high therapeutic efficiency. The photocytotoxicity and direct cytotoxicity of Laserphyrin®-HVJ-E prepared using various Laserphyrin® concentrations were evaluated using PC-3 cell in vitro. We categorized the treatment groups as Group 1: 50 μL of D-MEM treatment group, Group 2: HVJ-E treatment group, Group 3: Laserphyrin®-HVJ-E treatment group, and Group 4: Laserphyrin® treatment group. Group 3 was subjected to different concentrations of Laserphyrin®-HVJ-E suspension, and all groups were subjected to different incubation periods (24, 48 h), (30 min, 1 h, or 3 h,) respectively, without and after PDT. Laserphyrin®-HVJ-E prepared using 15 mM Laserphyrin® had high photocytotoxicity and maintained HVJ-E's ability to induce direct cytotoxicity. Therapeutic effect of Laserphyrin®-HVJ-E was substantially equivalent to that of Laserphyrin® alone even at half Laserphyrin® concentration. By utilizing Laserphyrin®-HVJ-E, PDT could be performed with lower Laserphyrin® concentration. In addition, Laserphyrin®-HVJ-E showed higher potency than Laserphyrin® by combining cytotoxicities of HVJ-E and PDT.

Photodynamic therapy by lysosomal-targeted drug delivery using talaporfin sodium incorporated into inactivated virus particles

BACKGROUND

Photodynamic therapy (PDT), a minimally invasive cancer treatment involving the activation of photosensitizer by a specific wavelength of light, is considered to be a promising treatment option for drug-resistant prostate cancer. Hemagglutinating virus of Japan envelope (HVJ-E) has the potential to serve as a highly effective cancer therapy through selective drug delivery and enhancement of the anti-tumor immune response.

OBJECTIVES

To improve therapeutic efficacy and selective accumulation of photosensitizer into tumor cells, we developed a novel photosensitizer, Laserphyrin®-HVJ-E (L-HVJ-E), by incorporating talaporfin sodium (Laserphyrin®, Meiji Seika Pharma) into HVJ-E.

MATERIALS AND METHODS

The therapeutic effect of PDT with Laserphyrin® or L-HVJ-E was evaluated in the human prostate cancer cell line PC-3 in vitro. The subcellular localizations of Laserphyrin® and L-HVJ-E were observed by confocal microscopy. Apoptosis or necrosis following PDT was detected by annexin V-fluorescein/propidium iodide double staining.

RESULTS

The cytotoxic effect of Laserphyrin®- and L-HVJ-E-mediated PDT were determined by evaluating cell survival rate and production of reactive oxygen species. The cytotoxicity of L-HVJ-E-mediated PDT was dependent on drug concentration and light dose. Laserphyrin® and L-HVJ-E gradually entered cells as incubation time increased, and both agents tended to be distributed in lysosomes rather than mitochondria. Time and dose dependent increase in ROS production was observed, and induction of both apoptotic and necrotic cell death was confirmed.

CONCLUSIONS

Laserphyrin® and L-HVJ-E were distributed mainly in lysosomes and induced cell death by both apoptosis and necrosis. Furthermore, L-HVJ-E-mediated PDT effectively killed cultured PC-3 cells and exerted higher photocytotoxicity than Laserphyrin®-mediated PDT.

Cancer Immunotherapies and Humanized Mouse Drug Testing Platforms

Cancer immunotherapy is a type of treatment that restores and stimulates human immune system to inhibit cancer growth or eradicate cancer. It serves as one of the latest systemic therapies, which has been approved to treat different types of cancer in patients. Nevertheless, the clinical response rate is unsatisfactory and the response observed is mostly a partial response in patients. Despite the continuous improvement and identification of novel cancer immunotherapy, there is a pressing need to establish a robust platform to evaluate the efficacy and safety of pre-clinical drugs, simulate the interaction between patients’ tumor and immune system, and predict patients’ responses to the treatment. In this review, we summarize the pros and cons of existing immuno-oncology assay platforms, especially the humanized mouse models for the screening of cancer immunotherapy drugs. In addition, various emerging trends and progress of utilizing humanized mouse models as the screening tool are discussed. Of note, humanized mouse models can also be used for further development of personalized precision medicines to treat cancer. Collectively, these highlight the significance of humanized mouse models as the important platform for the screening of next generation cancer immunotherapy in vivo.

Oncolytic viruses: how "lytic" must they be for therapeutic efficacy?

Oncolytic viruses (OVs) preferentially target and kill cancer cells without affecting healthy cells through a multi-modal mechanism of action. While historically the direct killing activity of OVs was considered the primary mode of action, initiation or augmentation of a host antitumor immune response is now considered an essential aspect of oncolytic virotherapy. To improve oncolytic virotherapy, many studies focus on increasing virus replication and spread. In this article, we open for discussion the traditional dogma that correlates replication with the efficacy of OVs, pointing out several examples that oppose this principle.

Salmonella mediated the hemagglutinating virus of Japan-envelope transfer suppresses tumor growth

Salmonella can target to tumor microenvironments after systemic treatment. The hemagglutinating virus of Japan-envelope (HVJ-E) induced apoptosis in tumor cells without toxicity in normal cells. Current HVJ-E therapeutic strategies, aimed at using HVJ-E for intratumor treatment, have shown great promise in animal models but have achieved only limited systemic treatment. The purpose of this study was to investigate the modulation of the anti-tumor efficiency of HVJ-E by coating the particles with poly (allylamine hydrochloride) (PAH), designated as P-HVJ-E. Treatment with P-HVJ-E resulted in decreased hemagglutinating activity and maintained tumor cell-selective apoptosis and anti-tumor immunity. The use of Salmonella as a coating for P-HVJ-E (PHS) enhanced the antitumor activity and maintained the tumor-targeting activity. Treatment with PHS resulted in delayed tumor growth in tumor-bearing mice. Furthermore, a Western blot assay of the tumors revealed that HVJ-E targeted to the tumor after systemic treatment with PHS. These results indicate that Salmonella coating viral particles may provide a new approach for tumor therapy.

Sendai Virus Propagation Using Chicken Eggs

Sendai virus is a member of the family Paramyxoviridae, and an enveloped virus with a negative-stranded RNA genome. Sendai virus is not pathogenic to humans, but for mice and can cause pneumonia in mice. Easy and efficient techniques for propagating Sendai virus are required for studying virus replication, virus-induced innate- and adaptive-immunity, Sendai-virus-based virotherapy and IgA nephropathy. Here, we describe a protocol for Sendai virus propagation using chicken eggs. This traditional protocol enables us to generate a large amount of virus enough for animal experiments as well as cell culture experiments in a relatively inexpensive way.

Efficacy and Safety of the Immunization with DNA for Alzheimer's Disease in Animal Models: A Systematic Review from Literature

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disease that does not have a proven cure; however, one of the most promising strategies for its treatment has been DNA vaccines.

OBJECTIVE

The present review is aimed to report the new developments of the efficacy and safety of DNA vaccines for AD in animal models.

METHOD

The method PRISMA was used for this review. The article search was made in the electronic databases PubMed, LILACS, and Scopus using the descriptors ''Alzheimer disease" and ''Vaccine, DNA". Articles published between January 2001 and September 2017 in English, Portuguese, and Spanish were included.

RESULTS

Upon the consensus, the researchers identified 28 original articles. The studies showed satisfying results as for the decrease of amyloid plaques in mouse, rabbits, and monkeys brains using mostly the DNA Aβ42 vaccine, AV-1955, and AdPEDI-(Aβ1-6)11, mainly with a gene gun. In addition to a reduction in tau by the first DNA vaccine (AV-1980D) targeting this protein. The use of adjuvants and boosters also had positive results as they increased the destruction of the amyloid plaques and induced an anti-inflammatory response profile without side effects.

CONCLUSION

The results of DNA vaccines targeting the amyloid-β and the tau protein with or without adjuvants and boosters were promising in reducing amyloid plaques and tau protein without side effects in animals. Although there are many vaccines being tested in animals, few reach clinical trials. Thus, as a future perspective, we suggest that clinical studies should be conducted with vaccines that have been promising in animal models (e.g., DNA Aβ42 vaccine, AV-1955, and AdPEDI-(Aβ1-6)11).

Immunogenicity of oncolytic vaccinia viruses JX-GFP and TG6002 in a human melanoma in vitro model: studying immunogenic cell death, dendritic cell maturation and interaction with cytotoxic T lymphocytes

Oncolytic virotherapy is an emerging immunotherapeutic modality for cancer treatment. Oncolytic viruses with genetic modifications can further enhance the oncolytic effects on tumor cells and stimulate antitumor immunity. The oncolytic vaccinia viruses JX-594-GFP+/hGM-CSF (JX-GFP) and TG6002 are genetically modified by secreting granulocyte-macrophage colony-stimulating factor (GM-CSF) or transforming 5-fluorocytosine (5-FC) into 5-fluorouracil (5-FU). We compared their properties to kill tumor cells and induce an immunogenic type of cell death in a human melanoma cell model using SK29-MEL melanoma cells. Their influence on human immune cells, specifically regarding the activation of dendritic cells (DCs) and the interaction with the autologous cytotoxic T lymphocyte (CTL) clone, was investigated. Melanoma cells were infected with either JX-GFP or TG6002 alone or in combination with 5-FC and 5-FU. The influence of viral infection on cell viability followed a time- and multiplicity of infection dependent manner. Combination of virus treatment with 5-FU resulted in stronger reduction of cell viability. TG6002 in combination with 5-FC did not significantly strengthen the reduction of cell viability in this setting. Expression of calreticulin and high mobility group 1 protein (HMGB1), markers of immunogenic cell death (ICD), could be detected after viral infection. Accordingly, DC maturation was noted after viral oncolysis. DCs presented stronger expression of activation and maturation markers. The autologous CTL clone IVSB expressed the activation marker CD69, but viral treatment failed to enhance cytotoxicity marker. In summary, vaccinia viruses JX-GFP and TG6002 lyse melanoma cells and induce additional immunostimulatory effects to promote antitumor immune response. Further investigation in vivo is needed to consolidate the data.