Breaking Therapy Resistance: An Update on Oncolytic Newcastle Disease Virus for Improvements of Cancer Therapy

Hyperacute rejection-engineered oncolytic virus for interventional clinical trial in refractory cancer patients

Recently, oncolytic virus (OV) therapy has shown great promise in treating malignancies. However, intravenous safety and inherent lack of immunity are two significant limitations in clinical practice. Herein, we successfully developed a recombinant Newcastle disease virus with porcine α1,3GT gene (NDV-GT) triggering hyperacute rejection. We demonstrated its feasibility in preclinical studies. The intravenous NDV-GT showed superior ability to eradicate tumor cells in our innovative CRISPR-mediated primary hepatocellular carcinoma monkeys. Importantly, the interventional clinical trial treating 20 patients with relapsed/refractory metastatic cancer (Chinese Clinical Trial Registry of WHO, ChiCTR2000031980) showed a high rate (90.00%) of disease control and durable responses, without serious adverse events and clinically functional neutralizing antibodies, further suggesting that immunogenicity is minimal under these conditions and demonstrating the feasibility of NDV-GT for immunovirotherapy. Collectively, our results demonstrate the high safety and efficacy of intravenous NDV-GT, thus providing an innovative technology for OV therapy in oncological therapeutics and beyond.

Synergistic Anti-Tumor Effects of Newcastle Disease Virus and Doxorubicin: Evidence from A Murine Breast Cancer Model

BACKGROUND

Despite the recent advances in the diagnosis and treatment of breast cancer, triple-negative breast cancer (TNBC) remains a clinical challenge due to its aggressive nature and resistance to conventional therapies. Virotherapy has emerged as a promising cancer treatment strategy, leveraging the ability of viruses to specifically target and replicate in cancerous cells. This study evaluated the oncolytic potential of a combined therapeutic strategy, utilizing Newcastle disease virus (NDV) and Doxorubicin hydrochloride (Dox) both in vitro and in vivo.

METHODS

The in vitro experiments involved exposing human and mouse TNBC cell lines (MDA-MB-231 and 4T1, respectively) to NDV and Dox, individually or in combination. Cell viability assays and flow cytometry analyses were conducted to assess the synergistic effects of NDV and Dox on regulating breast cancer cell behavior in vitro. Furthermore, the immune-stimulating potential of NDV was investigated by examining its effects on dendritic cell (DC) maturation using flow cytometry and T cell proliferation. The in vitro anti-tumor effects of NDV were examined in both parental and tamoxifen-resistant cancer cells to assess its efficacy against chemoresistance. Animal models of breast cancer were treated with NDV in combination with Dox. The body weight changes, tumor volume, and survival rates of the mice were monitored throughout the study. Histopathological analyses were conducted to evaluate the potential toxic effects of the treatments.

RESULTS

Based on the MTT results, NDV at optimal concentrations synergized the effect of Dox to reduce the viability of both MDA-MB231 and 4T1 cell lines (Isobologram combination index of less than 1). Additionally, individual treatment with NDV was able to significantly reduce the viability of patient-derived breast cancer cells, compared to the untreated control (P < 0.05) without affecting the cells of normal adjacent tissue. Furthermore, a combination of NDV and Dox significantly enhanced the percentage of early and late apoptotic cells in MDA-MB-231 (P < 0.0001) and late apoptotic cells in 4T1 (P < 0.0001), in comparison with individual treatment with these agents. Flow cytometry results showed that, compared to wild type MDA-MB-231 cells, NDV-infected MDA-MB-231 cells were better inducers of T cell proliferation and DC maturation as evidenced by increased proliferation index (P < 0.05) and elevated expression of CD1a, CD83, and CD86 (P < 0.0001), respectively. Moreover, co-treatment of both wild-type and (tamoxifen) TAM-resistant MCF-7/TAMR-1 cells with TAM and NDV significantly reduce the viability of the cancer cells (P < 0.0001). In tumor-bearing mice locally engrafted with 4T1 cells, combined treatment of NDV and Dox exhibited a marked reduction in median tumor volume compared to the control group, validating our in vitro findings on their synergistic anti-tumor effects. These findings suggest that combining NDV with Dox can effectively inhibit tumor progression and has the potential to reduce the dose, and consequently the toxic side-effects, of Dox in breast cancer therapy.

Combination of Diosmetin With Chrysin Against Hepatocellular Carcinoma Through Inhibiting PI3K/AKT/mTOR/NF-кB Signaling Pathway: TCGA Analysis, Molecular Docking, Molecular Dynamics, In Vitro Experiment

Hepatocellular carcinoma (HCC) is the sixth most prevalent malignant tumor. Hepatocellular carcinogenesis is closely linked to apoptosis, autophagy, and inflammation. Diosmetin and chrysin, are two flavonoid compounds, exhibit anti-inflammatory and anticancer properties. In this study, the TCGA database was utilized to identify differentially expressed genes between normal subjects and HCC patients. Molecular docking and molecular dynamics analyses were employed to assess the binding affinity of chrysin and diosmetin to key proteins in the PI3K/AKT/mTOR/NF-κB signaling pathway. Western blotting and RT-qPCR were used to measure the protein and gene expression within this pathway. The results indicated that HCC patients had elevated levels of PI3K, AKT, mTOR, and P65 proteins compared to normal subjects, which adversely affected patient survival. Molecular docking and dynamics studies demonstrated that diosmetin and chrysin are effectively bound to these four proteins. In vitro experiments revealed that the combination of diosmetin and chrysin could induce apoptosis, enhance autophagy, reduce inflammatory mediator production, and improve the tumor cell microenvironment by inhibiting the PI3K/AKT/mTOR/NF-κB signaling pathway. Notably, the synergy score for the combination of diosmetin (25 μM) and chrysin (10 μM) was 16. Thus, the diosmetin-chrysin combination shows promise as an effective therapeutic approach for hepatocellular carcinoma due to its strong synergistic effect.

Harnessing the Therapeutic Potential of Mesenchymal Stem Cells in Cancer Treatment

Cancer, as a complicated disease, is considered to be one of the major leading causes of death globally. Although various cancer therapeutic strategies have been established, however, some issues confine the efficacies of the treatments. In recent decades researchers for finding efficient therapeutic solutions have extensively focused on the abilities of stem cells in cancer inhibition. Mesenchymal stem cells (MSCs) are multipotent stromal cells that can the most widely extracted from various sources such as the bone marrow (BM), placenta, umbilical cord (UC), menses blood, Wharton's jelly (WJ), adipose tissue and dental pulp (DP). These cells are capable of differentiating into the osteoblasts, chondrocytes, and adipocytes. Due to the unique characteristics of MSCs such as paracrine effects, immunomodulation, tumor-tropism, and migration, they are considered promising candidates for cancer therapeutics. Currently, MSCs are an excellent living carrier for delivery of therapeutic genes and chemical agents to target tumor sites. Also, exosomes, the most important extracellular vesicle released from MSCs, act as a strong cell-free tool for cancer therapeutics. MSCs can prevent cancer progression by inhibiting several signaling pathways, such as wnt/β-catenin and PI3K/AKT/mTOR. However, there are several challenges associated with the use of MSCs and their exosomes in the field of therapy that need to be considered. This review explores the significance of MSCs in cell-based therapy, focusing on their homing properties and immunomodulatory characteristics. It also examines the potential of using MSCs as carriers for delivery of anticancer agents and their role in modulating the signal transduction pathways of cancer cells.

Cancer therapy with the viral and bacterial pathogens: The past enemies can be considered the present allies

Cancer continues to be one of the leading causes of mortality worldwide despite significant advancements in cancer treatment. Many difficulties have arisen as a result of the detrimental consequences of chemotherapy and radiotherapy as a common cancer therapy, such as drug inability to penetrate deep tumor tissue, and also the drug resistance in tumor cells continues to be a major concern. These obstacles have increased the need for the development of new techniques that are more selective and effective against cancer cells. Bacterial-based therapies and the use of oncolytic viruses can suppress cancer in comparison to other cancer medications. The tumor microenvironment is susceptible to bacterial accumulation and proliferation, which can trigger immune responses against the tumor. Oncolytic viruses (OVs) have also gained considerable attention in recent years because of their potential capability to selectively target and induce apoptosis in cancer cells. This review aims to provide a comprehensive summary of the latest literature on the role of bacteria and viruses in cancer treatment, discusses the limitations and challenges, outlines various strategies, summarizes recent preclinical and clinical trials, and emphasizes the importance of optimizing current strategies for better clinical outcomes.

Oncolytic virotherapy for hepatocellular carcinoma: A potent immunotherapeutic landscape

Hepatocellular carcinoma (HCC) is a systemic disease with augmented malignant degree, high mortality and poor prognosis. Since the establishment of the immune mechanism of tumor therapy, people have realized that immunotherapy is an effective means for improvement of HCC patient prognosis. Oncolytic virus is a novel immunotherapy drug, which kills tumor cells and exempts normal cells by directly lysing tumor and inducing anti-tumor immune response, and it has been extensively examined as an HCC therapy. This editorial discusses oncolytic viruses for the treatment of HCC, emphasizing viral immunotherapy strategies and clinical applications related to HCC.

The Application of Newcastle Disease Virus (NDV): Vaccine Vectors and Tumor Therapy

Newcastle disease virus (NDV) is an avian pathogen with an unsegmented negative-strand RNA genome that belongs to the Paramyxoviridae family. While primarily pathogenic in birds, NDV presents no threat to human health, rendering it a safe candidate for various biomedical applications. Extensive research has highlighted the potential of NDV as a vector for vaccine development and gene therapy, owing to its transcriptional modularity, low recombination rate, and lack of a DNA phase during replication. Furthermore, NDV exhibits oncolytic capabilities, efficiently eliciting antitumor immune responses, thereby positioning it as a promising therapeutic agent for cancer treatment. This article comprehensively reviews the biological characteristics of NDV, elucidates the molecular mechanisms underlying its oncolytic properties, and discusses its applications in the fields of vaccine vector development and tumor therapy.

Individualized Multimodal Immunotherapy (IMI): Scientific Rationale and Clinical Experience from a Single Institution

Oncolytic viruses and combinatorial immunotherapy for cancer (this Special Issue) are both part of cancer treatment at IOZK. This review focusses on an individual multimodal cancer immunotherapy concept developed by IOZK, Cologne, Germany. The scientific rationale for employing three main components is explained: (i) oncolytic Newcastle disease virus, (ii) modulated electrohyperthermia and (iii) individual tumor antigen and oncolytic virus modified dendritic cell vaccine (IO-VACR). The strategy involves repeated cancer-immunity cycles evoked in cancer patients by systemic oncolytic virus exposure plus hyperthermia pretreatment to induce immunogenic cell death followed by intradermal IO-VACR vaccination. As an example of the experience at IOZK, we present the latest results from combining the immunotherapy with standard treatment of patients suffering from glioblastoma multiforme. The promising clinical results in terms of overall survival benefit of additional individualized multimodal immunotherapy are presented. The cancer-immunity cycle, as introduced 10 years ago, describes key important steps occurring locally at the sites of both tumor and draining lymph nodes. This view is extended here towards systemic events occuring in blood where immunogenic cell death-induced tumor antigens are transported into the bone marrow. For 20 years it has been known that bone marrow is an antigen-responsive organ in which dendritic cells present tumor antigens to T cells leading to immunological synapse formation, tumor antigen-specific T cell activation and memory T cell formation. Bone marrow is known to be the most prominent source of de novo cellular generation in the body and to play an important role for the storage and maintenance of immunological memory. Its systemic activation is recommended to augment cancer-immunity cycles.

Oncolytic Virotherapy: A New Paradigm in Cancer Immunotherapy

Oncolytic viruses (OVs) are emerging as potential treatment options for cancer. Natural and genetically engineered viruses exhibit various antitumor mechanisms. OVs act by direct cytolysis, the potentiation of the immune system through antigen release, and the activation of inflammatory responses or indirectly by interference with different types of elements in the tumor microenvironment, modification of energy metabolism in tumor cells, and antiangiogenic action. The action of OVs is pleiotropic, and they show varied interactions with the host and tumor cells. An important impediment in oncolytic virotherapy is the journey of the virus into the tumor cells and the possibility of its binding to different biological and nonbiological vectors. OVs have been demonstrated to eliminate cancer cells that are resistant to standard treatments in many clinical trials for various cancers (melanoma, lung, and hepatic); however, there are several elements of resistance to the action of viruses per se. Therefore, it is necessary to evaluate the combination of OVs with other standard treatment modalities, such as chemotherapy, immunotherapy, targeted therapies, and cellular therapies, to increase the response rate. This review provides a comprehensive update on OVs, their use in oncolytic virotherapy, and the future prospects of this therapy alongside the standard therapies currently used in cancer treatment.

Cell and gene therapy in neuro-oncology

The majority of primary brain tumors are gliomas, among which glioblastoma multiforme (GBM) is the most common malignant brain tumor in adults. GBM has a median survival of 18-24 months, and despite extensive research it remains incurable, thus novel therapies are urgently needed. The current standard of care is a combination of surgery, radiation, and chemotherapy, but still remains ineffective due to the invasive nature and high recurrence of gliomas. Gene therapy is a versatile treatment strategy investigated for multiple tumor types including GBM. In gene therapy, a variety of vectors are employed to deliver genes designed for different antitumoral effects. Also, over the past decades, stem cell biology has provided a new approach to cancer therapies. Stem cells can be used as regenerative medicine, therapeutic carriers, drug targeting, and generation of immune cells. Stem cell-based therapy allows targeted therapy that spares healthy brain tissue as well as establishes a long-term antitumor response by stimulating the immune system and delivering prodrug, metabolizing genes, or even oncolytic viruses. This chapter describes the latest developments and the current trends in gene and cell-based therapy against GBM from both preclinical and clinical perspectives, including different gene therapy delivery systems, molecular targets, and stem cell therapies.

A promising future in cancer immunotherapy: Oncolytic viruses

Alongside the conventional methods, attention has been drawn to the use of immunotherapy-based methods for cancer treatment. Immunotherapy has developed as a therapeutic option that can be more specific with better outcomes in tumor treatment. It can boost or regulate the immune system behind the targeted virotherapy. Virotherapy is a kind of oncolytic immunotherapy that investigated broadly in cancer treatment in recent decades, due to its several advantages. According to recent advance in the field of understanding cancer cell biology and its occurrence, as well as increasing the knowledge about conditionally replicating oncolytic viruses and their destructive function in the tumor cells, nowadays, it is possible to apply this strategy in the treatment of malignancies. Relying on achievements in clinical trials of oncolytic viruses, we can certainly expect that this therapeutic perception can play a more central role in cancer treatment. In cancer treatment, combination therapy using oncolytic viruses alongside standard cancer treatment methods and other immunotherapy-based treatments can expect more promising results in the future.

Refined control of CRISPR-Cas9 gene editing in Clostridium sporogenes: the creation of recombinant strains for therapeutic applications

Despite considerable clinical success, the potential of cancer immunotherapy is restricted by a lack of tumour-targeting strategies. Treatment requires systemic delivery of cytokines or antibodies at high levels to achieve clinically effective doses at malignant sites. This is exacerbated by poor penetration of tumour tissue by therapeutic antibodies. High-grade immune-related adverse events (irAEs) occur in a significant number of patients (5-15%, cancer- and therapeutic-dependent) that can lead to lifelong issues and can exclude from treatment patients with pre-existing autoimmune diseases. Tumour-homing bacteria, genetically engineered to produce therapeutics, is one of the approaches that seeks to mitigate these drawbacks. The ability of Clostridium sporogenes to form spores that are unable to germinate in the presence of oxygen (typical of healthy tissue) offers a unique advantage over other vectors. However, the limited utility of existing gene editing tools hinders the development of therapeutic strains. To overcome the limitations of previous systems, expression of the Cas9 protein and the gRNA was controlled using tetracycline inducible promoters. Furthermore, the components of the system were divided across two plasmids, improving the efficiency of cloning and conjugation. Genome integrated therapeutic genes were assayed biochemically and in cell-based functional assays. The potency of these strains was further improved through rationally-conceived gene knock-outs. The new system was validated by demonstrating the efficient addition and deletion of large sequences from the genome. This included the creation of recombinant strains expressing two pro-inflammatory cytokines, interleukin-2 (IL-2) and granulocyte macrophage-colony stimulating factor (GM-CSF), and a pro-drug converting enzyme (PCE). A comparative, temporal in vitro analysis of the integrant strains and their plasmid-based equivalents revealed a substantial reduction of cytokine activity in chromosome-based constructs. To compensate for this loss, a 7.6 kb operon of proteolytic genes was deleted from the genome. The resultant knock-out strains showed an 8- to 10-fold increase in cytokine activity compared to parental strains.

Oncolytic Viruses: An Inventory of Shedding Data from Clinical Trials and Elements for the Environmental Risk Assessment

Attenuated and/or genetically modified oncolytic viruses (OV) gain increasing interest as a promising approach for cancer therapy. Beside the assessment of subject safety, quality and efficacy aspects of medicinal products for human use, genetically modified viruses are also governed by EU regulatory frameworks requiring an environmental risk assessment (ERA). An important element to be assessed as part of the ERA is the incidence of exposure to OV of individuals, other than the trial subjects, and the environment. The evidence-based evaluation of shedding data is considered to be decisive in that context, as it may impact the OV capacity to be transmitted. This is particularly true for OV still able to (conditionally) replicate as opposed to replication-defective viral vectors commonly used in gene therapy or vaccination. To our knowledge, this article presents the most extensive and up-to-date review of shedding data reported with OV employed in clinics. Besides the identification of a topical need for improving the collection of shedding data, this article aims at providing an aid to the design of an appropriate shedding study, thereby relying on and further complementing principles described in existing guidelines issued by European and international institutions.

The Viral Knock: Ameliorating Cancer Treatment with Oncolytic Newcastle Disease Virus

The prospect of cancer treatment has drastically transformed over the last four decades. The side effects caused by the traditional methods of cancer treatment like surgery, chemotherapy, and radiotherapy through the years highlight the prospect for a novel, complementary, and alternative cancer therapy. Oncolytic virotherapy is an evolving treatment modality that utilizes oncolytic viruses (OVs) to selectively attack cancer cells by direct lysis and can also elicit a strong anti-cancer immune response. Newcastle disease virus (NDV) provides a very high safety profile compared to other oncolytic viruses. Extensive research worldwide concentrates on experimenting with and better understanding the underlying mechanisms by which oncolytic NDV can be effectively applied to intercept cancer. This review encapsulates the potential of NDV to be explored as an oncolytic agent and discusses current preclinical and clinical research scenarios involving various NDV strains.

Glioblastoma Multiforme: The Latest Diagnostics and Treatment Techniques

BACKGROUND

Glioblastoma multiforme (GBM) is a WHO grade 4 glioma and the most common malignant primary brain tumour. Recently, there has been outstanding progress in the treatment of GBM. In addition to the newest form of GBM removal using fluorescence, three-dimensional (3D) imaging, tomoradiotherapy, moderate electro-hyperthermia, and adjuvant temozolomide (post-operative chemotherapy), new developments have been made in the fields of immunology, molecular biology, and virotherapy. An unusual and modern treatment has been created, especially for stage 4 GBM, using the latest therapeutic techniques, including immunotherapy and virotherapy. Modern oncological medicine is producing extraordinary and progressive therapeutic methods. Oncological therapy includes individual analysis of the properties of a tumour and targeted therapy using small-molecule inhibitors. Individualised medicine covers the entire patient (tumour and host) in the context of immunotherapy. An example is individualised multimodal immunotherapy (IMI), which relies on individual immunological tumour-host interactions. In addition, IMI is based on the concept of oncolytic virus-induced immunogenic tumour cell death.

SUMMARY

In this review, we outline current knowledge of the various available treatment options used in the therapy of GBM including both traditional therapeutic strategy and modern therapies, such as tomotherapy, electro-hyperthermia, and oncolytic virotherapy, which are promising treatment strategies with the potential to improve prognosis in patients with GBM.

KEY MESSAGES

This newest therapy, immunotherapy combined with virotherapy (oncolytic viruses and cancer vaccines), is displaying encouraging signs for combating GBM. Additionally, the latest 3D imaging is compared to conventional two-dimensional imaging.

The Clinical Advances of Oncolytic Viruses in Cancer Immunotherapy

A promising future for oncology treatment has been brought about by the emergence of a novel approach utilizing oncolytic viruses in cancer immunotherapy. Oncolytic viruses are viruses that have been exploited genetically to assault malignant cells and activate a robust immune response. Several techniques have been developed to endow viruses with an oncolytic activity through genetic engineering. For instance, redirection capsid modification, stimulation of anti-neoplastic immune response, and genetically arming viruses with cytokines such as IL-12. Oncolytic viral clinical outcomes are sought after, particularly in more advanced cancers. The effectiveness and safety profile of the oncolytic virus in clinical studies with or without the combination of standard treatment (chemotherapy, radiotherapy, or primary excision) has been assessed using response evaluation criteria in solid tumors (RECIST). This review will comprehensively outline the most recent clinical applications and provide the results from various phases of clinical trials in a variety of cancers in the latest published literature.

Oncolytic Rodent Protoparvoviruses Evade a TLR- and RLR-Independent Antiviral Response in Transformed Cells

The oncolytic rodent protoparvoviruses (PVs) minute virus of mice (MVMp) and H-1 parvovirus (H-1PV) are promising cancer viro-immunotherapy candidates capable of both exhibiting direct oncolytic activities and inducing anticancer immune responses (AIRs). Type-I interferon (IFN) production is instrumental for the activation of an efficient AIR. The present study aims at characterizing the molecular mechanisms underlying PV modulation of IFN induction in host cells. MVMp and H-1PV triggered IFN production in semi-permissive normal mouse embryonic fibroblasts (MEFs) and human peripheral blood mononuclear cells (PBMCs), but not in permissive transformed/tumor cells. IFN production triggered by MVMp in primary MEFs required PV replication and was independent of the pattern recognition receptors (PRRs) Toll-like (TLR) and RIG-like (RLR) receptors. PV infection of (semi-)permissive cells, whether transformed or not, led to nuclear translocation of the transcription factors NFĸB and IRF3, hallmarks of PRR signaling activation. Further evidence showed that PV replication in (semi-)permissive cells resulted in nuclear accumulation of dsRNAs capable of activating mitochondrial antiviral signaling (MAVS)-dependent cytosolic RLR signaling upon transfection into naïve cells. This PRR signaling was aborted in PV-infected neoplastic cells, in which no IFN production was detected. Furthermore, MEF immortalization was sufficient to strongly reduce PV-induced IFN production. Pre-infection of transformed/tumor but not of normal cells with MVMp or H-1PV prevented IFN production by classical RLR ligands. Altogether, our data indicate that natural rodent PVs regulate the antiviral innate immune machinery in infected host cells through a complex mechanism. In particular, while rodent PV replication in (semi-)permissive cells engages a TLR-/RLR-independent PRR pathway, in transformed/tumor cells this process is arrested prior to IFN production. This virus-triggered evasion mechanism involves a viral factor(s), which exert(s) an inhibitory action on IFN production, particularly in transformed/tumor cells. These findings pave the way for the development of second-generation PVs that are defective in this evasion mechanism and therefore endowed with increased immunostimulatory potential through their ability to induce IFN production in infected tumor cells.

Mesenchymal stem cell-released oncolytic virus: an innovative strategy for cancer treatment

Oncolytic viruses (OVs) infect, multiply, and finally remove tumor cells selectively, causing no damage to normal cells in the process. Because of their specific features, such as, the ability to induce immunogenic cell death and to contain curative transgenes in their genomes, OVs have attracted attention as candidates to be utilized in cooperation with immunotherapies for cancer treatment. This treatment takes advantage of most tumor cells' inherent tendency to be infected by certain OVs and both innate and adaptive immune responses are elicited by OV infection and oncolysis. OVs can also modulate tumor microenvironment and boost anti-tumor immune responses. Mesenchymal stem cells (MSC) are gathering interest as promising anti-cancer treatments with the ability to address a wide range of cancers. MSCs exhibit tumor-trophic migration characteristics, allowing them to be used as delivery vehicles for successful, targeted treatment of isolated tumors and metastatic malignancies. Preclinical and clinical research were reviewed in this study to discuss using MSC-released OVs as a novel method for the treatment of cancer. Video Abstract.

Gene Therapy for High Grade Glioma: The Clinical Experience

INTRODUCTION

High-grade gliomas (HGG) are the most common malignant primary brain tumors in adults, with a median survival of ~18 months. The standard of care (SOC) is maximal safe surgical resection, and radiation therapy with concurrent and adjuvant temozolomide. This protocol remains unchanged since 2005, even though HGG median survival has marginally improved.

AREAS COVERED

Gene therapy was developed as a promising approach to treat HGG. Here, we review completed and ongoing clinical trials employing viral and non-viral vectors for adult and pediatric HGG, as well as the key supporting preclinical data.

EXPERT OPINION

These therapies have proven safe, and pre- and post-treatment tissue analyses demonstrated tumor cell lysis, increased immune cell infiltration, and increased systemic immune function. Although viral therapy in clinical trials has not yet significantly extended the survival of HGG, promising strategies are being tested. Oncolytic HSV vectors have shown promising results for both adult and pediatric HGG. A recently published study demonstrated that HG47Δ improved survival in recurrent HGG. Likewise, PVSRIPO has shown survival improvement compared to historical controls. It is likely that further analysis of these trials will stimulate the development of new administration protocols, and new therapeutic combinations that will improve HGG prognosis.

Leading Edge: Intratumor Delivery of Monoclonal Antibodies for the Treatment of Solid Tumors

Immunotherapies based on immune checkpoint blockade have shown remarkable clinical outcomes and durable responses in patients with many tumor types. Nevertheless, these therapies lack efficacy in most cancer patients, even causing severe adverse events in a small subset of patients, such as inflammatory disorders and hyper-progressive disease. To diminish the risk of developing serious toxicities, intratumor delivery of monoclonal antibodies could be a solution. Encouraging results have been shown in both preclinical and clinical studies. Thus, intratumor immunotherapy as a new strategy may retain efficacy while increasing safety. This approach is still an exploratory frontier in cancer research and opens up new possibilities for next-generation personalized medicine. Local intratumor delivery can be achieved through many means, but an attractive approach is the use of gene therapy vectors expressing mAbs inside the tumor mass. Here, we summarize basic, translational, and clinical results of intratumor mAb delivery, together with descriptions of non-viral and viral strategies for mAb delivery in preclinical and clinical development. Currently, this is an expanding research subject that will surely play a key role in the future of oncology.

A NEW HYPOTHESIS IN THE TREATMENT OF RECURRENT GLIOBLASTOMA MULTIFORME (GBM). PART 1: INTRODUCTION

Modern treatment of glioblastoma multiforme (GBM) is based on neurosurgical methods combined with radiotherapy and chemotherapy. The prognosis for patients with GBM is extremely poor. Often, complete removal of the tumor is impossible and it often recurs. Therefore, in addition to standard regimens, modern methods such as modulated electrohyperthermia, monoclonal antibodies and individualised multimodal immunotherapy (IMI) based on vaccines and oncolytic viruses are also used in the treatment of GBM. Radioiodine therapy (RIT) also holds out hope for an effective treatment of this extremely aggressive brain tumor. The expression of the sodium iodide symporter (NIS) gene has been proven to have a positive effect on the treatment of selected cancers. Research confirm the presence of expression of this gene in GBM cells, although only in animal studies. Is it possible and therapeutically effective to treat GBM with RIT without the use of an exogenous NIS gene? The safety of therapy is relevant, as the only more serious adverse effect may be hypothyroidism. The use of RIT requires further clinical studies in patients. Perhaps it is worth revolutionizing GBM therapy to give sufferers a "new life".

Oncolytic virus-based hepatocellular carcinoma treatment: Current status, intravenous delivery strategies, and emerging combination therapeutic solutions

Current treatments for advanced hepatocellular carcinoma (HCC) have limited success in improving patients' quality of life and prolonging life expectancy. The clinical need for more efficient and safe therapies has contributed to the exploration of emerging strategies. Recently, there has been increased interest in oncolytic viruses (OVs) as a therapeutic modality for HCC. OVs undergo selective replication in cancerous tissues and kill tumor cells. Strikingly, pexastimogene devacirepvec (Pexa-Vec) was granted an orphan drug status in HCC by the U.S. Food and Drug Administration (FDA) in 2013. Meanwhile, dozens of OVs are being tested in HCC-directed clinical and preclinical trials. In this review, the pathogenesis and current therapies of HCC are outlined. Next, we summarize multiple OVs as single therapeutic agents for the treatment of HCC, which have demonstrated certain efficacy and low toxicity. Emerging carrier cell-, bioengineered cell mimetic- or nonbiological vehicle-mediated OV intravenous delivery systems in HCC therapy are described. In addition, we highlight the combination treatments between oncolytic virotherapy and other modalities. Finally, the clinical challenges and prospects of OV-based biotherapy are discussed, with the aim of continuing to develop a fascinating approach in HCC patients.

Counteracting Immunosuppression in the Tumor Microenvironment by Oncolytic Newcastle Disease Virus and Cellular Immunotherapy

An apparent paradox exists between the evidence for spontaneous systemic T cell- mediated anti-tumor immune responses in cancer patients, observed particularly in their bone marrow, and local tumor growth in the periphery. This phenomenon, known as "concomitant immunity" suggests that the local tumor and its tumor microenvironment (TME) prevent systemic antitumor immunity to become effective. Oncolytic Newcastle disease virus (NDV), an agent with inherent anti-neoplastic and immune stimulatory properties, is capable of breaking therapy resistance and immunosuppression. This review updates latest information about immunosuppression by the TME and discusses mechanisms of how oncolytic viruses, in particular NDV, and cellular immunotherapy can counteract the immunosuppressive effect of the TME. With regard to cellular immunotherapy, the review presents pre-clinical studies of post-operative active-specific immunotherapy and of adoptive T cell-mediated therapy in immunocompetent mice. Memory T cell (MTC) transfer in tumor challenged T cell-deficient nu/nu mice demonstrates longevity and functionality of these cells. Graft-versus-leukemia (GvL) studies in mice demonstrate complete remission of late-stage disease including metastases and cachexia. T cell based immunotherapy studies with human cells in human tumor xenotransplanted NOD/SCID mice demonstrate superiority of bone marrow-derived as compared to blood-derived MTCs. Results from clinical studies presented include vaccination studies using two different types of NDV-modified cancer vaccine and a pilot adoptive T-cell mediated therapy study using re-activated bone marrow-derived cancer-reactive MTCs. As an example for what can be expected from clinical immunotherapy against tumors with an immunosuppressive TME, results from vaccination studies are presented from the aggressive brain tumor glioblastoma multiforme. The last decades of basic research in virology, oncology and immunology can be considered as a success story. Based on discoveries of these research areas, translational research and clinical studies have changed the way of treatment of cancer by introducing and including immunotherapy.

Immunovirotherapy: The role of antibody based therapeutics combination with oncolytic viruses

Despite the fact that the new drugs and targeted therapies have been approved for cancer therapy during the past 30 years, the majority of cancer types are still remain challenging to be treated. Due to the tumor heterogeneity, immune system evasion and the complex interaction between the tumor microenvironment and immune cells, the great majority of malignancies need multimodal therapy. Unfortunately, tumors frequently develop treatment resistance, so it is important to have a variety of therapeutic choices available for the treatment of neoplastic diseases. Immunotherapy has lately shown clinical responses in malignancies with unfavorable outcomes. Oncolytic virus (OV) immunotherapy is a cancer treatment strategy that employs naturally occurring or genetically-modified viruses that multiply preferentially within cancer cells. OVs have the ability to not only induce oncolysis but also activate cells of the immune system, which in turn activates innate and adaptive anticancer responses. Despite the fact that OVs were translated into clinical trials, with T-VECs receiving FDA approval for melanoma, their use in fighting cancer faced some challenges, including off-target side effects, immune system clearance, non-specific uptake, and intratumoral spread of OVs in solid tumors. Although various strategies have been used to overcome the challenges, these strategies have not provided promising outcomes in monotherapy with OVs. In this situation, it is increasingly common to use rational combinations of immunotherapies to improve patient benefit. With the development of other aspects of cancer immunotherapy strategies, combinational therapy has been proposed to improve the anti-tumor activities of OVs. In this regard, OVs were combined with other biotherapeutic platforms, including various forms of antibodies, nanobodies, chimeric antigen receptor (CAR) T cells, and dendritic cells, to reduce the side effects of OVs and enhance their efficacy. This article reviews the promising outcomes of OVs in cancer therapy, the challenges OVs face and solutions, and their combination with other biotherapeutic agents.

Development of immunotherapy for high-grade gliomas: Overcoming the immunosuppressive tumor microenvironment

The preclinical and clinical development of novel immunotherapies for the treatment of central nervous system (CNS) tumors is advancing at a rapid pace. High-grade gliomas (HGG) are aggressive tumors with poor prognoses in both adult and pediatric patients, and innovative and effective therapies are greatly needed. The use of cytotoxic chemotherapies has marginally improved survival in some HGG patient populations. Although several challenges exist for the successful development of immunotherapies for CNS tumors, recent insights into the genetic alterations that define the pathogenesis of HGG and their direct effects on the tumor microenvironment (TME) may allow for a more refined and targeted therapeutic approach. This review will focus on the TME in HGG, the genetic drivers frequently found in these tumors and their effect on the TME, the development of immunotherapy for HGG, and the practical challenges in clinical trials employing immunotherapy for HGG. Herein, we will discuss broadly the TME and immunotherapy development in HGG, with a specific focus on glioblastoma multiforme (GBM) as well as additional discussion in the context of the pediatric HGG diagnoses of diffuse midline glioma (DMG) and diffuse hemispheric glioma (DHG).

Recent Advances in Glioma Cancer Treatment: Conventional and Epigenetic Realms

Glioblastoma (GBM) is the most typical and aggressive form of primary brain tumor in adults, with a poor prognosis. Successful glioma treatment is hampered by ineffective medication distribution across the blood-brain barrier (BBB) and the emergence of drug resistance. Although a few FDA-approved multimodal treatments are available for glioblastoma, most patients still have poor prognoses. Targeting epigenetic variables, immunotherapy, gene therapy, and different vaccine- and peptide-based treatments are some innovative approaches to improve anti-glioma treatment efficacy. Following the identification of lymphatics in the central nervous system, immunotherapy offers a potential method with the potency to permeate the blood-brain barrier. This review will discuss the rationale, tactics, benefits, and drawbacks of current glioma therapy options in clinical and preclinical investigations.

Oncolytic viral vectors in the era of diversified cancer therapy: from preclinical to clinical

With the in-depth research and wide application of immunotherapy recently, new therapies based on oncolytic viruses are expected to create new prospects for cancer treatment via eliminating the suppression of the immune system by tumors. Currently, an increasing number of viruses are developed and engineered, and various virus vectors based on effectively stimulating human immune system to kill tumor cells have been approved for clinical treatment. Although the virus can retard the proliferation of tumor cells, the choice of oncolytic viruses in biological cancer therapy is equally critical given their therapeutic efficacy, safety and adverse effects. Moreover, previously known oncolytic viruses have not been systematically classified. Therefore, in this review, we summarized and distinguished the characteristics of several common types of oncolytic viruses: herpes simplex virus, adenovirus, measles virus, Newcastle disease virus, reovirus and respiratory syncytial virus. Subsequently, we outlined that these oncolytic viral vectors have been transformed from preclinical studies in combination with immunotherapy, radiotherapy, chemotherapy, and nanoparticles into clinical therapeutic strategies for various advanced solid malignancies or circulatory system cancers.

Avian Paramyxovirus 4 Antitumor Activity Leads to Complete Remissions and Long-term Protective Memory in Preclinical Melanoma and Colon Carcinoma Models

Avulaviruses represent a diverse subfamily of non-segmented negative strand RNA viruses infecting avian species worldwide. To date, 22 different serotypes have been identified in a variety of avian hosts, including wild and domestic birds. APMV-1, also known as Newcastle disease virus (NDV), is the only avulavirus that has been extensively characterized due to its relevance for the poultry industry and, more recently, its inherent oncolytic activity and potential as a cancer therapeutic. An array of both naturally-occurring and recombinant APMV-1 strains has been tested in different preclinical models and clinical trials, highlighting NDV as a promising viral agent for human cancer therapy. To date, the oncolytic potential of other closely related avulaviruses remains unknown. Here, we have examined the in vivo anti-tumor capability of prototype strains of APMV serotypes -2, -3, -4, -6, -7, -8 and -9 in syngeneic murine colon carcinoma and melanoma tumor models. Our studies have identified APMV-4 Duck/Hong Kong/D3/1975 virus as a novel oncolytic agent with greater therapeutic potential than one of the NDV clinical candidate strains, La Sota. Intratumoral administration of the naturally-occurring APMV-4 virus significantly extends survival, promotes complete remission, and confers protection against re-challenge in both murine colon carcinoma and melanoma tumor models. Furthermore, we have designed a plasmid rescue strategy that allows us to develop recombinant APMV-4-based viruses. The infectious clone rAPMV-4 preserves the extraordinary antitumor capacity of its natural counterpart, paving the way to a promising next generation of viral therapeutics.

Viruses as tools in gene therapy, vaccine development, and cancer treatment

Using viruses to our advantage has been a huge leap for humanity. Their ability to mediate horizontal gene transfer has made them useful tools for gene therapy, vaccine development, and cancer treatment. Adenoviruses, adeno-associated viruses, retroviruses, lentiviruses, alphaviruses, and herpesviruses are a few of the most common candidates for use as therapeutic agents or efficient gene delivery systems. Efforts are being made to improve and perfect viral-vector-based therapies to overcome potential or reported drawbacks. Some preclinical trials of viral vector vaccines have yielded positive results, indicating their potential as prophylactic or therapeutic vaccine candidates. Utilization of the oncolytic activity of viruses is the future of cancer therapy, as patients will then be free from the harmful effects of chemo- or radiotherapy. This review discusses in vitro and in vivo studies showing the brilliant therapeutic potential of viruses.

Development and Scalable Production of Newcastle Disease Virus-Vectored Vaccines for Human and Veterinary Use

The COVID-19 pandemic has highlighted the need for efficient vaccine platforms that can rapidly be developed and manufactured on a large scale to immunize the population against emerging viruses. Viral-vectored vaccines are prominent vaccine platforms that have been approved for use against the Ebola virus and SARS-CoV-2. The Newcastle Disease Virus is a promising viral vector, as an avian paramyxovirus that infects poultry but is safe for use in humans and other animals. NDV has been extensively studied not only as an oncolytic virus but also a vector for human and veterinary vaccines, with currently ongoing clinical trials for use against SARS-CoV-2. However, there is a gap in NDV research when it comes to process development and scalable manufacturing, which are critical for future approved vaccines. In this review, we summarize the advantages of NDV as a viral vector, describe the steps and limitations to generating recombinant NDV constructs, review the advances in human and veterinary vaccine candidates in pre-clinical and clinical tests, and elaborate on production in embryonated chicken eggs and cell culture. Mainly, we discuss the existing data on NDV propagation from a process development perspective and provide prospects for the next steps necessary to potentially achieve large-scale NDV-vectored vaccine manufacturing.

Oncolytic Activity of Wild-type Newcastle Disease Virus HK84 Against Hepatocellular Carcinoma Associated with Activation of Type I Interferon Signaling

BACKGROUND AND AIMS

Hepatocellular carcinoma (HCC) is listed as one of the most common causes of cancer-related death. Oncolytic therapy has become a promising treatment because of novel immunotherapies and gene editing technology, but biosafety concerns remain the biggest limitation for clinical application. We studied the the antitumor activity and biosafety of the wild-type Newcastle disease virus HK84 strain (NDV/HK84) and 10 other NDV strains.

METHODS

Cell proliferation and apoptosis were determined by cell counting Kit-8 and fluorescein isothiocyanate Annexin V apoptosis assays. Colony formation, wound healing, and a xenograft mouse model were used to evaluate in vivo and in vitro oncolytic effectiveness. The safety of NDV/HK84 was tested in nude mice by an in vivo luciferase imaging system. The replication kinetics of NDV/HK84 in normal tissues and tumors were evaluated by infectious-dose assays in eggs. RNA sequencing analysis was performed to explore NDV/HK84 activity and was validated by quantitative real-time PCR.

RESULTS

The cell counting Kit-8 assays of viability found that the oncolytic activity of the NDV strains differed with the multiplicity of infection (MOI). At an MOI of 20, the oncolytic activity of all NDV strains except the DK/JX/21358/08 strain was >80%. The oncolytic activities of the NDV/HK84 and DK/JX/8224/04 strains were >80% at both MOI=20 and MOI=2. Only NDV/HK84 had >80% oncolytic activities at both MOI=20 and MOI=2. We chose NDV/HK84 as the candidate virus to test the oncolytic effect of NDV in HCC in the in vitro and in vivo experiments. NDV/HK84 killed human SK-HEP-1 HCC cells without affecting healthy cells.

CONCLUSIONS

Intratumor infection with NDV/HK84 strains compared with vehicle controls or positive controls indicated that NDV/HK84 strain specifically inhibited HCC without affecting healthy mice. High-throughput RNA sequencing showed that the oncolytic activity of NDV/HK84 was dependent on the activation of type I interferon signaling.

Protein Cages: From Fundamentals to Advanced Applications

Proteins that self-assemble into polyhedral shell-like structures are useful molecular containers both in nature and in the laboratory. Here we review efforts to repurpose diverse protein cages, including viral capsids, ferritins, bacterial microcompartments, and designed capsules, as vaccines, drug delivery vehicles, targeted imaging agents, nanoreactors, templates for controlled materials synthesis, building blocks for higher-order architectures, and more. A deep understanding of the principles underlying the construction, function, and evolution of natural systems has been key to tailoring selective cargo encapsulation and interactions with both biological systems and synthetic materials through protein engineering and directed evolution. The ability to adapt and design increasingly sophisticated capsid structures and functions stands to benefit the fields of catalysis, materials science, and medicine.

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.

Newcastle disease virus expressing an angiogenic inhibitor exerts an enhanced therapeutic efficacy in colon cancer model

Newcastle disease virus (NDV)-mediated gene therapy is a promising new approach for treatment of cancer but shows limited anti-angiogenesis. VEGF-Trap plays a vital role in anti-angiogenesis. To enhance the anti-tumor effect of NDV, VEGF-Trap gene was incorporated into the genome of rNDV in this study (named rNDV-VEGF-Trap). Results showed that rNDV-VEGF-Trap reduced cell growth ratio by 85.37% and migration ratio by 87.9% in EA.hy926 cells. In vivo studies, rNDV-VEGF-Trap reduced tumor volume and weight of CT26-bearing mice by more than 3 folds. Immunohistochemistry analysis of CD34 showed rNDV-VEGF-Trap significantly decreased the number of vascular endothelial cells in the tumor tissues. Moreover, Western blot analysis demonstrated that treatment with rNDV-VEGF-Trap significantly decreased the phosphorylation levels of AKT, ERK1/2 and STAT3 and increased the expression levels of P53, BAX and cleaved caspase-3 in the tumor tissue. In addition, to evaluate the toxicity of rNDV-VEGF-Trap, serum chemistries were analyzed. The results showed that rNDV-VEGF-Trap caused insignificant changes of creatinine levels, alanine aminotransferase and aspartate transaminase. Furthermore, administration of rNDV-VEGF-Trap did not cause the diarrhoea, decreased appetite, weight decrease and haemorrhage of the experimental mice. These data suggest that rNDV-VEGF-Trap exhibits an enhanced inhibition of CT26-bearing mice by enhancing anti-angiogenesis and apoptosis and may be a potential candidate for carcinoma therapy especially for colon cancer.

Molecular Mechanisms of Anti-Neoplastic and Immune Stimulatory Properties of Oncolytic Newcastle Disease Virus

Oncolytic viruses represent interesting anti-cancer agents with high tumor selectivity and immune stimulatory potential. The present review provides an update of the molecular mechanisms of the anti-neoplastic and immune stimulatory properties of the avian paramyxovirus, Newcastle Disease Virus (NDV). The anti-neoplastic activities of NDV include (i) the endocytic targeting of the GTPase Rac1 in Ras-transformed human tumorigenic cells; (ii) the switch from cellular protein to viral protein synthesis and the induction of autophagy mediated by viral nucleoprotein NP; (iii) the virus replication mediated by viral RNA polymerase (large protein (L), associated with phosphoprotein (P)); (iv) the facilitation of NDV spread in tumors via the membrane budding of the virus progeny with the help of matrix protein (M) and fusion protein (F); and (v) the oncolysis via apoptosis, necroptosis, pyroptosis, or ferroptosis associated with immunogenic cell death. A special property of this oncolytic virus consists of its potential for breaking therapy resistance in human cancer cells. Eight examples of this important property are presented and explained. In healthy human cells, NDV infection activates the RIG-MAVs immune signaling pathway and establishes an anti-viral state based on a strong and uninhibited interferon α,ß response. The review also describes the molecular determinants and mechanisms of the NDV-mediated immune stimulatory effects, in which the viral hemagglutinin-neuraminidase (HN) protein plays a prominent role. The six viral proteins provide oncolytic NDV with a special profile in the treatment of cancer.

Optimization of oncolytic effect of Newcastle disease virus Clone30 by selecting sensitive tumor host and constructing more oncolytic viruses

The direct oncolytic effect of Newcastle disease virus (NDV) depends on the following two aspects: the susceptibility of cancer cells to virus infection and the ability of virus itself to lyse cancer cells. First, we investigate the susceptibility of cancer cells to NDV infection, HepG2, MDA-MB-231, and SH-SY5Y cells were susceptible, A549, MCF7, and LoVo cells were less susceptible. To investigate the molecular mechanism responsible for cancer cell susceptibility, transcriptome sequencing was carried out. We found that the levels of alpha-sialic acid acyltransferase were upregulated in MDA-MB-231 cells compared with MCF7 cells, and the interferon was downregulated. Second, to optimize the oncolytic capacity of the wild-type rClone30, a series of chimeric viruses rClone30-Anh(HN), rClone30-Anh(F), and rClone30-Anh(HN-F) were constructed by exchanging the HN gene, F gene or both of non-lytic rClone30 strain with lytic strain Anhinga. rClone30-Anh(F) and rClone30-Anh(HN-F) enhanced the oncolytic effect of the rClone30, and this enhancement is more obvious in the susceptible cells. The oncolytic mechanism of rClone30-Anh(F) was analyzed by transcriptome analyses, in comparison with rClone30, rClone30-Anh(F) upregulated the expression of ATG5, Beclin 1, and MAP1LC3B, thus activating autophagy and promoting the production of syncytia. In conclusion, our study provides a strategy to enhance the oncolytic effect of rClone30.

Oncolytic Viro-Immunotherapy: An Emerging Option in the Treatment of Gliomas

The prognosis of malignant gliomas remains poor, with median survival fewer than 20 months and a 5-year survival rate merely 5%. Their primary location in the central nervous system (CNS) and its immunosuppressive environment with little T cell infiltration has rendered cancer therapies mostly ineffective, and breakthrough therapies such as immune checkpoint inhibitors (ICIs) have shown limited benefit. However, tumor immunotherapy is developing rapidly and can help overcome these obstacles. But for now, malignant gliomas remain fatal with short survival and limited therapeutic options. Oncolytic virotherapy (OVT) is a unique antitumor immunotherapy wherein viruses selectively or preferentially kill tumor cells, replicate and spread through tumors while inducing antitumor immune responses. OVTs can also recondition the tumor microenvironment and improve the efficacy of other immunotherapies by escalating the infiltration of immune cells into tumors. Some OVTs can penetrate the blood-brain barrier (BBB) and possess tropism for the CNS, enabling intravenous delivery. Despite the therapeutic potential displayed by oncolytic viruses (OVs), optimizing OVT has proved challenging in clinical development, and marketing approvals for OVTs have been rare. In June 2021 however, as a genetically engineered OV based on herpes simplex virus-1 (G47Δ), teserpaturev got conditional and time-limited approval for the treatment of malignant gliomas in Japan. In this review, we summarize the current state of OVT, the synergistic effect of OVT in combination with other immunotherapies as well as the hurdles to successful clinical use. We also provide some suggestions to overcome the challenges in treating of gliomas.

Immunomodulatory Arming Factors-The Current Paradigm for Oncolytic Vectors Relies on Immune Stimulating Molecules

The dogma of engineering oncolytic viral vectors has shifted from emphasizing the viral lysis of individual cancer cells to the recruitment and coordination of the adaptive immune system to clear the tumor. To accomplish this, researchers have been adding several classes of transgenes to their preferred viral platforms. The most prevalent of these include antibodies and targeting moieties, interleukins and cytokines, and genes which rely on small molecule co-administration for tumor killing. Most current vectors rely exclusively on one of these types of transgenes to elicit the desired immune response to clear tumors, but are not mutually exclusive, with several larger OVs armed with several of these factors. The common theme of emerging armed vectors is to simply initiate or enhance infiltration of effector CD8+ T cells to clear the tumor locally at OV infection sites, and systemically throughout the body where the OV has not infected tumor cells. The precision of oncolytic vectors to target a cell type or tissue remains its key advantage over small-molecule drugs. Unlike chemo- and other drug therapies, viral vectors can be made to specifically infect and grow within tumor cells. This ensures localized expression of the therapeutic transgene to the diseased tissue, thereby limiting systemic toxicity. This review will examine the immunomodulating transgenes of current OVs, describe their general effect on the immune system, and provide the rationale for each vector's use in clearing its targeted tumor.

Development of Group B Coxsackievirus as an Oncolytic Virus: Opportunities and Challenges

Oncolytic viruses have emerged as a promising strategy for cancer therapy due to their dual ability to selectively infect and lyse tumor cells and to induce systemic anti-tumor immunity. Among various candidate viruses, coxsackievirus group B (CVBs) have attracted increasing attention in recent years. CVBs are a group of small, non-enveloped, single-stranded, positive-sense RNA viruses, belonging to species human Enterovirus B in the genus Enterovirus of the family Picornaviridae. Preclinical studies have demonstrated potent anti-tumor activities for CVBs, particularly type 3, against multiple cancer types, including lung, breast, and colorectal cancer. Various approaches have been proposed or applied to enhance the safety and specificity of CVBs towards tumor cells and to further increase their anti-tumor efficacy. This review summarizes current knowledge and strategies for developing CVBs as oncolytic viruses for cancer virotherapy. The challenges arising from these studies and future prospects are also discussed in this review.

MicroRNA-204 plays a role as a tumor suppressor in Newcastle disease virus-induced oncolysis in lung cancer A549 cells

Tumor development and progression are closely associated with various microRNAs (miRNAs/miRs). We have previously shown that Newcastle disease virus (NDV) strain 7793 induces oncolysis in lung cancer. However, how NDV exerts its oncolytic effect on lung cancer remains to be investigated. The present study assessed the role of miR-204 in the NDV-induced oncolysis of lung cancer A549 cells by oncolysis induction in vitro. miR-204 was significantly upregulated in NDV-treated A549 cells. Overexpression or inhibition of miR-204 was significantly associated with NDV-induced oncolysis in A549 cells. Caspase-3 and Bax, major regulators of the apoptosis pathway, were regulated by miR-204, and the association between caspase-3-related apoptosis and miR-204 was identified in NDV-mediated oncolysis. These data demonstrated that miR-204 as a tumor suppressor played a role in NDV-induced oncolysis in lung cancer cells. The present study demonstrates the potential of strategies using miRs to improve oncolytic NDV potency, and highlights miR-204 as a tumor suppressor in NDV-induced oncolysis of lung cancer cells.

Mesenchymal stem cell carriers enhance anti-tumor efficacy of oncolytic virotherapy

Oncolytic viruses (OVs) specifically infect, replicate and eventually destroy tumor cells, with no concomitant toxicity to adjacent normal cells. Furthermore, OVs can regulate tumor microenvironments and stimulate anti-tumor immune responses. Mesenchymal stem cells (MSCs) have inherent tumor tropisms and immunosuppressive functions. MSCs carrying OVs not only protect viruses from clearing by the immune system, but they also deliver the virus to tumor lesions. Equally, cytokines released by MSCs enhance anti-tumor immune responses, suggesting that MSCs carrying OVs may be considered as a promising strategy in enhancing the anti-tumor efficacies of virotherapy. In the present review, preclinical and clinical studies were evaluated and discussed, as well as the effectiveness of MSCs carrying OVs for tumor treatment.

Less Can Be More: The Hormesis Theory of Stress Adaptation in the Global Biosphere and Its Implications

A dose-response relationship to stressors, according to the hormesis theory, is characterized by low-dose stimulation and high-dose inhibition. It is non-linear with a low-dose optimum. Stress responses by cells lead to adapted vitality and fitness. Physical stress can be exerted through heat, radiation, or physical exercise. Chemical stressors include reactive species from oxygen (ROS), nitrogen (RNS), and carbon (RCS), carcinogens, elements, such as lithium (Li) and silicon (Si), and metals, such as silver (Ag), cadmium (Cd), and lead (Pb). Anthropogenic chemicals are agrochemicals (phytotoxins, herbicides), industrial chemicals, and pharmaceuticals. Biochemical stress can be exerted through toxins, medical drugs (e.g., cytostatics, psychopharmaceuticals, non-steroidal inhibitors of inflammation), and through fasting (dietary restriction). Key-lock interactions between enzymes and substrates, antigens and antibodies, antigen-presenting cells, and cognate T cells are the basics of biology, biochemistry, and immunology. Their rules do not obey linear dose-response relationships. The review provides examples of biologic stressors: oncolytic viruses (e.g., immuno-virotherapy of cancer) and hormones (e.g., melatonin, stress hormones). Molecular mechanisms of cellular stress adaptation involve the protein quality control system (PQS) and homeostasis of proteasome, endoplasmic reticulum, and mitochondria. Important components are transcription factors (e.g., Nrf2), micro-RNAs, heat shock proteins, ionic calcium, and enzymes (e.g., glutathion redox enzymes, DNA methyltransferases, and DNA repair enzymes). Cellular growth control, intercellular communication, and resistance to stress from microbial infections involve growth factors, cytokines, chemokines, interferons, and their respective receptors. The effects of hormesis during evolution are multifarious: cell protection and survival, evolutionary flexibility, and epigenetic memory. According to the hormesis theory, this is true for the entire biosphere, e.g., archaia, bacteria, fungi, plants, and the animal kingdoms.

Current Approaches for Glioma Gene Therapy and Virotherapy

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in the adult population and it carries a dismal prognosis. Inefficient drug delivery across the blood brain barrier (BBB), an immunosuppressive tumor microenvironment (TME) and development of drug resistance are key barriers to successful glioma treatment. Since gliomas occur through sequential acquisition of genetic alterations, gene therapy, which enables to modification of the genetic make-up of target cells, appears to be a promising approach to overcome the obstacles encountered by current therapeutic strategies. Gene therapy is a rapidly evolving field with the ultimate goal of achieving specific delivery of therapeutic molecules using either viral or non-viral delivery vehicles. Gene therapy can also be used to enhance immune responses to tumor antigens, reprogram the TME aiming at blocking glioma-mediated immunosuppression and normalize angiogenesis. Nano-particles-mediated gene therapy is currently being developed to overcome the BBB for glioma treatment. Another approach to enhance the anti-glioma efficacy is the implementation of viro-immunotherapy using oncolytic viruses, which are immunogenic. Oncolytic viruses kill tumor cells due to cancer cell-specific viral replication, and can also initiate an anti-tumor immunity. However, concerns still remain related to off target effects, and therapeutic and transduction efficiency. In this review, we describe the rationale and strategies as well as advantages and disadvantages of current gene therapy approaches against gliomas in clinical and preclinical studies. This includes different delivery systems comprising of viral, and non-viral delivery platforms along with suicide/prodrug, oncolytic, cytokine, and tumor suppressor-mediated gene therapy approaches. In addition, advances in glioma treatment through BBB-disruptive gene therapy and anti-EGFRvIII/VEGFR gene therapy are also discussed. Finally, we discuss the results of gene therapy-mediated human clinical trials for gliomas. In summary, we highlight the progress, prospects and remaining challenges of gene therapies aiming at broadening our understanding and highlighting the therapeutic arsenal for GBM.

Personalizing Oncolytic Virotherapy for Glioblastoma: In Search of Biomarkers for Response

Simple Summary

Glioblastoma (GBM) is the most frequent and aggressive primary brain tumor. Despite multimodal treatment, the prognosis of GBM patients remains very poor. Oncolytic virotherapy is being evaluated as novel treatment for this patient group and clinical trials testing oncolytic viruses have shown impressive responses, albeit in a small subset of GBM patients. Obtaining insight into specific tumor- or patient-related characteristics of the responding patients, may in the future improve response rates. In this review we discuss factors related to oncolytic activity of the most widely applied oncolytic virus strains as well as potential biomarkers and future assays that may allow us to predict response to these agents. Such biomarkers and tools may in the future enable personalizing oncolytic virotherapy for GBM patients.

Abstract

Oncolytic virus (OV) treatment may offer a new treatment option for the aggressive brain tumor glioblastoma. Clinical trials testing oncolytic viruses in this patient group have shown promising results, with patients achieving impressive long-term clinical responses. However, the number of responders to each OV remains low. This is thought to arise from the large heterogeneity of these tumors, both in terms of molecular make-up and their immune-suppressive microenvironment, leading to variability in responses. An approach that may improve response rates is the personalized utilization of oncolytic viruses against Glioblastoma (GBM), based on specific tumor- or patient-related characteristics. In this review, we discuss potential biomarkers for response to different OVs as well as emerging ex vivo assays that in the future may enable selection of optimal OV for a specific patient and design of stratified clinical OV trials for GBM.

Newcastle Disease Virus at the Forefront of Cancer Immunotherapy

Preclinical and clinical studies dating back to the 1950s have demonstrated that Newcastle disease virus (NDV) has oncolytic properties and can potently stimulate antitumor immune responses. NDV selectively infects, replicates within, and lyses cancer cells by exploiting defective antiviral defenses in cancer cells. Inflammation within the tumor microenvironment in response to NDV leads to the recruitment of innate and adaptive immune effector cells, presentation of tumor antigens, and induction of immune checkpoints. In animal models, intratumoral injection of NDV results in T cell infiltration of both local and distant non-injected tumors, demonstrating the potential of NDV to activate systemic adaptive antitumor immunity. The combination of intratumoral NDV with systemic immune checkpoint blockade leads to regression of both injected and distant tumors, an effect further potentiated by introduction of immunomodulatory transgenes into the viral genome. Clinical trials with naturally occurring NDV administered intravenously demonstrated durable responses across numerous cancer types. Based on these studies, further exploration of NDV is warranted, and clinical studies using recombinant NDV in combination with immune checkpoint blockade have been initiated.

Mitochondria at Work: New Insights into Regulation and Dysregulation of Cellular Energy Supply and Metabolism

Mitochondria are of great relevance to health, and their dysregulation is associated with major chronic diseases. Research on mitochondria-156 brand new publications from 2019 and 2020-have contributed to this review. Mitochondria have been fundamental for the evolution of complex organisms. As important and semi-autonomous organelles in cells, they can adapt their function to the needs of the respective organ. They can program their function to energy supply (e.g., to keep heart muscle cells going, life-long) or to metabolism (e.g., to support hepatocytes and liver function). The capacity of mitochondria to re-program between different options is important for all cell types that are capable of changing between a resting state and cell proliferation, such as stem cells and immune cells. Major chronic diseases are characterized by mitochondrial dysregulation. This will be exemplified by cardiovascular diseases, metabolic syndrome, neurodegenerative diseases, immune system disorders, and cancer. New strategies for intervention in chronic diseases will be presented. The tumor microenvironment can be considered a battlefield between cancer and immune defense, competing for energy supply and metabolism. Cancer cachexia is considered as a final stage of cancer progression. Nevertheless, the review will present an example of complete remission of cachexia via immune cell transfer. These findings should encourage studies along the lines of mitochondria, energy supply, and metabolism.

Genomic Diversity and Evolution of Quasispecies in Newcastle Disease Virus Infections

Newcastle disease virus (NDV) infections are well known to harbour quasispecies, due to the error-prone nature of the RNA polymerase. Quasispecies variants in the fusion cleavage site of the virus are known to significantly change its virulence. However, little is known about the genomic patterns of diversity and selection in NDV viral swarms. We analyse deep sequencing data from in vitro and in vivo NDV infections to uncover the genomic patterns of diversity and the signatures of selection within NDV swarms. Variants in viruses from in vitro samples are mostly localised in non-coding regions and 3′ and 5′ untranslated regions (3′UTRs or 5′UTRs), while in vivo samples contain an order of magnitude more variants. We find different patterns of genomic divergence and diversity among NDV genotypes, as well as differences in the genomic distribution of intra-host variants among in vitro and in vivo infections of the same strain. The frequency spectrum shows clear signatures of intra-host purifying selection in vivo on the matrix protein (M) coding gene and positive or diversifying selection on nucleocapsid (NP) and haemagglutinin-neuraminidase (HN). The comparison between within-host polymorphisms and phylogenetic divergence reveals complex patterns of selective pressure on the NDV genome at between- and within-host level. The M sequence is strongly constrained both between and within hosts, fusion protein (F) coding gene is under intra-host positive selection, and NP and HN show contrasting patterns: HN RNA sequence is positively selected between hosts while its protein sequence is positively selected within hosts, and NP is under intra-host positive selection at the RNA level and negative selection at the protein level.