Fighting Cancer with Viruses: Oncolytic Virus Therapy in China

Targeting Cancers with oHSV-Based Oncolytic Viral Immunotherapy

The recent success of cancer immunotherapies, such as immune checkpoint inhibitor (ICIs), monoclonal antibodies (mAbs), cancer vaccines, and adoptive cellular therapies (ACTs), has revolutionized traditional cancer treatment. However, these immunotherapeutic modalities have variable efficacies, and many of them exhibit adverse effects. Oncolytic viral Immunotherapy (OViT), whereby viruses are used to directly or indirectly induce anti-cancer immune responses, is emerging as a novel immunotherapy for treating patients with different types of cancer. The herpes simplex virus type-1 (HSV-1) possesses many characteristics that inform its use as an effective OViT agents and remains a leading candidate. Its recent clinical success resulted in the Food and Drug Administration (FDA) approval of Talimogene laherparevec (T-VEC or Imlygic) in 2015 for the treatment of advanced melanoma. In this review, we discuss recent advances in the development of oncolytic HSV-1-based OViTs, their anti-tumor mechanism of action, and efficacy data from recent clinical trials. We envision this knowledge may be used to inform the rational design and application of future oHSV in cancer treatment.

Nanotechnology and nano-sized tools: Newer approaches to circumvent oncolytic adenovirus limitations

Oncolytic adenoviruses (OAds), engineered Ads preferentially infect and lyse tumor cells, have attracted remarkable attention as immunotherapy weapons for the treatment of various malignancies. Despite hopeful successes in preclinical investigations and translation into clinical phases, they face some challenges that thwart their therapeutic effectiveness, including low infectivity of cancer cells, liver sequestration, pre-existing neutralizing antibodies, physical barriers to the spread of Ads, and immunosuppressive TME. Nanotechnology and nano-sized tools provide several advantages to overcome these limitations of OAds. Nano-sized tools could improve the therapeutic efficacy of OAds by enhancing infectivity and cellular uptake, targeting and protecting from pre-existing immune responses, masking and preventing liver tropism, and co-delivery with other therapeutic agents. Herein, we reviewed the constructs of various OAds and their application in clinical trials, as well as the limitations they have faced. Furthermore, we emphasized the potential applications of nanotechnology to solve the constraints of OAds to improve their anti-tumor activities.

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.

Cancer immunotherapies: advances and bottlenecks

Immunotherapy has ushered in a new era in cancer treatment, and cancer immunotherapy continues to be rejuvenated. The clinical goal of cancer immunotherapy is to prime host immune system to provide passive or active immunity against malignant tumors. Tumor infiltrating leukocytes (TILs) play an immunomodulatory role in tumor microenvironment (TME) which is closely related to immune escape of tumor cells, thus influence tumor progress. Several cancer immunotherapies, include immune checkpoint inhibitors (ICIs), cancer vaccine, adoptive cell transfer (ACT), have shown great efficacy and promise. In this review, we will summarize the recent research advances in tumor immunotherapy, including the molecular mechanisms and clinical effects as well as limitations of immunotherapy.

Oncolytic viruses against cancer, promising or delusion?

Cancer treatment is one of the most challenging topics in medical sciences. Different methods such as chemotherapy, tumor surgery, and immune checkpoint inhibitors therapy (ICIs) are potential approaches to treating cancer and killing tumor cells, but clinical studies have shown that they have been successful for a limited group of patients. Using viruses as a treatment can be considered as an effective treatment in the field of medicine. This is considered as a potential treatment, especially in comparison to chemotherapy, which has severe side effects related to the immune system. Most oncolytic viruses (OVs) have the potential to multiply in cancer cells, which are more than normal cells in malignant tissue and can induce immune responses. Therefore, tons of efforts and research have been started on the utilization of OVs as a treatment for cancer and have shown promising in treating cancers with less side effects. In this article, we have gathered studies about oncolytic viruses and their effectiveness in cancer treatment.Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 1 Given name: [Omid Salahi] Last name [Ardekani], Author 2 Given name: [Mohammad Mehdi] Last name [Fazeli], Author 3 Given name: [Nillofar Asadi] Last name [Jemezghani]. Also, kindly confirm the details in the metadata are correct.Confirmed.

Development and application of oncolytic viruses as the nemesis of tumor cells

Viruses and tumors are two pathologies that negatively impact human health, but what occurs when a virus encounters a tumor? A global consensus among cancer patients suggests that surgical resection, chemotherapy, radiotherapy, and other methods are the primary means to combat cancer. However, with the innovation and development of biomedical technology, tumor biotherapy (immunotherapy, molecular targeted therapy, gene therapy, oncolytic virus therapy, etc.) has emerged as an alternative treatment for malignant tumors. Oncolytic viruses possess numerous anti-tumor properties, such as directly lysing tumor cells, activating anti-tumor immune responses, and improving the tumor microenvironment. Compared to traditional immunotherapy, oncolytic virus therapy offers advantages including high killing efficiency, precise targeting, and minimal side effects. Although oncolytic virus (OV) therapy was introduced as a novel approach to tumor treatment in the 19th century, its efficacy was suboptimal, limiting its widespread application. However, since the U.S. Food and Drug Administration (FDA) approved the first OV therapy drug, T-VEC, in 2015, interest in OV has grown significantly. In recent years, oncolytic virus therapy has shown increasingly promising application prospects and has become a major research focus in the field of cancer treatment. This article reviews the development, classification, and research progress of oncolytic viruses, as well as their mechanisms of action, therapeutic methods, and routes of administration.

Recombinant measles virus vaccine rMV-Hu191 exerts an oncolytic effect on esophageal squamous cell carcinoma via caspase-3/GSDME-mediated pyroptosis

Oncolytic viruses have recently been proven to be an effective and promising cancer therapeutic strategy, but there is rare data about oncolytic therapy in esophageal squamous cell carcinoma (ESCC), especially oncolytic measles virotherapy. Therefore, this study aimed to explore whether the recombinant measles virus vaccine strain rMV-Hu191 has an oncolytic effect against ESCC cells in vitro and in vivo and elucidate the underlying mechanisms. Our results showed that rMV-Hu191 could efficiently replicate in and kill ESCC cells through caspase-3/GSDME-mediated pyroptosis. Mechanistically, rMV-Hu191 triggers mitochondrial dysfunction to induce pyroptosis, which is mediated by BAK (BCL2 antagonist/killer 1) or BAX (BCL2 associated X). Further analysis revealed that rMV-Hu191 activates inflammatory signaling in ESCC cells, which may enhance the oncolytic efficiency. Moreover, intratumoral injection of rMV-Hu191 induced dramatic tumor regression in an ESCC xenograft model. Collectively, these findings imply that rMV-Hu191 exhibits an antitumor effect through BAK/BAX-dependent caspase-3/GSDME-mediated pyroptosis and provides a potentially promising new therapy for ESCC treatment.

Evaluation of the in vitro and in vivo effect of liposomal doxorubicin along with oncolytic Newcastle disease virus on 4T1 cell line: Animal preclinical research

BACKGROUND

Breast cancer is one of the most common malignancies in women, with one in 20 globally. Oncolytic viruses have recently been the first step in the biological treatment of cancer, either genetically engineered or naturally occurring. They increase specifically inside cancer cells and destroy them without damaging normal tissues or producing a host immune response against tumour cells or expressing transgenes. One of the most known members of this family is the Newcastle disease virus (NDV), a natural oncolytic virus that selectively induces apoptosis and DNA fragmentation in human cancer cells.

METHODS

This study performed biochemical and molecular investigations with variable doses of NDV (32, 64, 128 HAU) and liposomal doxorubicin (9 mg/kg) on mouse triple-negative mammary carcinoma cell line 4T1 and BALB/c models tumours for the first time.

RESULTS

Real-time quantitative PCR analysis in NDV-treated animal tumours showed increased expression of P21, P27 and P53 genes and decreased expression of CD34, integrin Alpha 5, VEGF and VEGF-R genes. Additional assessments in treated mouse models also showed that NDV increased ROS production, induced apoptosis, reduced tumour size and significantly improved prognosis, with no adverse effect on normal tissues.

CONCLUSIONS

These findings all together might indicate that NDV in combination with chemotherapy drugs could improve prognosis in cancer patients although many more conditions should be considered.

Advances in Intralesional Therapy for Locoregionally Advanced and Metastatic Melanoma: Five Years of Progress

Locoregionally advanced and metastatic melanoma are complex diagnoses with a variety of available treatment options. Intralesional therapy for melanoma has been under investigation for decades; however, it has advanced precipitously in recent years. In 2015, the Food and Drug Administration (FDA) approved talimogene laherparepvec (T-VEC), the only FDA-approved intralesional therapy for advanced melanoma. There has been significant progress since that time with other oncolytic viruses, toll-like receptor agonists, cytokines, xanthene dyes, and immune checkpoint inhibitors all under investigation as intralesional agents. Further to this, there has been exploration of numerous combinations of intralesional therapies and systemic therapies as various lines of therapy. Several of these combinations have been abandoned due to their lack of efficacy or safety concerns. This manuscript presents the various types of intralesional therapies that have reached phase 2 or later clinical trials in the past 5 years, including their mechanism of action, therapeutic combinations under investigation, and published results. The intention is to provide an overview of the progress that has been made, discuss ongoing trials worth following, and share our opinions on opportunities for further advancement.

Chloroquine Inhibition of Autophagy Enhanced the Anticancer Effects of Listeria monocytogenes in Melanoma

Listeria monocytogenes has been shown to exhibit antitumor effects. However, the mechanism remains unclear. Autophagy is a cellular catabolic process that mediates the degradation of unfolded proteins and damaged organelles in the cytosol, which is a double-edged sword in tumorigenesis and treatment outcome. Tumor cells display lower levels of basal autophagic activity than normal cells. This study examined the role and molecular mechanism of autophagy in the antitumor effects induced by LM, as well as the combined antitumor effect of LM and the autophagy inhibitor chloroquine (CQ). We investigated LM-induced autophagy in B16F10 melanoma cells by real-time PCR, immunofluorescence, Western blotting, and transmission electron microscopy and found that autophagic markers were increased following the infection of tumor cells with LM. The autophagy pathway in B16F10 cells was blocked with the pharmacological autophagy inhibitor chloroquine, which led to a significant increase in intracellular bacterial multiplication in tumor cells. The combination of CQ and LM enhanced LM-mediated cancer cell death and apoptosis compared with LM infection alone. Furthermore, the combination of LM and CQ significantly inhibited tumor growth and prolonged the survival time of mice in vivo, which was associated with the increased colonization and accumulation of LM and induced more cell apoptosis in primary tumors. The data indicated that the inhibition of autophagy by CQ enhanced LM-mediated antitumor activity in vitro and in vivo and provided a novel strategy to improving the anticancer efficacy of bacterial treatment.

Multiple potential recombination events among Newcastle disease virus genomes in China between 1946 and 2020

Introduction

Newcastle Disease Virus (NDV) is a highly adaptable virus with large genetic diversity that has been widely studied for its oncolytic activities and potential as a vector vaccine. This study investigated the molecular characteristics of 517 complete NDV strains collected from 26 provinces across China between 1946-2020.

Methods

Herein, phylogenetic, phylogeographic network, recombination, and amino acid variability analyses were performed to reveal the evolutionary characteristics of NDV in China.

Results and discussions

Phylogenetic analysis revealed the existence of two major groups: GI, which comprises a single genotype Ib, and GII group encompassing eight genotypes (I, II, III, VI. VII. VIII, IX and XII). The Ib genotype is found to dominate China (34%), particularly South and East China, followed by VII (24%) and VI (22%). NDV strains from the two identified groups exhibited great dissimilarities at the nucleotide level of phosphoprotein (P), matrix protein (M), fusion protein (F), and haemagglutinin-neuraminidase (HN) genes. Consistently, the phylogeographic network analysis revealed two main Network Clusters linked to a possible ancestral node from Hunan (strain MH289846.1). Importantly, we identified 34 potential recombination events that involved mostly strains from VII and Ib genotypes. A recombinant of genotype XII isolated in 2019 seems to emerge newly in Southern China. Further, the vaccine strains are found to be highly involved in potential recombination. Therefore, since the influence of recombination on NDV virulence cannot be predicted, this report's findings need to be considered for the security of NDV oncolytic application and the safety of NDV live attenuated vaccines.

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.

A Biflavonoid-Rich Extract from Selaginella doederleinii Hieron. against Throat Carcinoma via Akt/Bad and IKKβ/NF-κB/COX-2 Pathways

Selaginella doederleinii Hieron. is a common pharmacological plant, and this folk herbal medicine and its complex preparations have been widely used for the treatment of throat carcinoma (TC) and several associated complications in traditional Chinese medicine. This study was aimed at investigating the specific anti-throat carcinoma impacts and potential mechanisms of a biflavonoid-rich extract from S. doederleinii (SD-BFRE). The phytochemical profiling of SD-BFRE was performed by HPLC-ESI-QTOF-MS and UPLC-PDA, and the detailed pharmacological effects and mechanisms were respectively evaluated in vitro and in vivo. MTT assay, the Transwell assay and flow cytometry were performed to evaluate the abilities of SD-BFRE on inhibiting cell infiltrative growth in TC cells (Hep-2 and FaDu) in in vitro experiments. In vivo experiments used Hep-2 tumor-bearing nude mice to evaluate the anti-TC effect of SD-BFRE. Western blotting was used to explore the potential apoptotic pathway of TC cells. Here, we found that SD-BFRE exhibited anti-proliferation and pro-apoptotic effects in TC cells. Mechanistic studies have identified that SD-BFRE can suppress the activity of IKKβ and IκB-α kinase and then down-regulate the effector proteins of NF-κB/COX-2 signaling. Moreover, SD-BFRE induced apoptosis partly by regulating the Akt/Bad/caspase signaling pathway. Taken together, this study firstly demonstrated that SD-BFRE exerted its anti-TC effects by way of IKKβ/NF-κB/COX-2 and Akt/Bad pathways and might represent a potential chemotherapeutic agent for throat carcinoma.

Oncolytic Viruses for the Treatment of Bladder Cancer: Advances, Challenges, and Prospects

Bladder cancer is one of the most prevalent cancers. Despite recent advancements in bladder cancer therapy, new strategies are still required for improving patient outcomes, particularly for those who experienced Bacille Calmette-Guerin failure and those with locally advanced or metastatic bladder cancer. Oncolytic viruses are either naturally occurring or purposefully engineered viruses that have the ability to selectively infect and lyse tumor cells while avoiding harming healthy cells. In light of this, oncolytic viruses serve as a novel and promising immunotherapeutic strategy for bladder cancer. A wide diversity of viruses, including adenoviruses, herpes simplex virus, coxsackievirus, Newcastle disease virus, vesicular stomatitis virus, alphavirus, and vaccinia virus, have been studied in many preclinical and clinical studies for their potential as oncolytic agents for bladder cancer. This review aims to provide an overview of the advances in oncolytic viruses for the treatment of bladder cancer and highlights the challenges and research directions for the future.

2-Deoxyglucose, an Inhibitor of Glycolysis, Enhances the Oncolytic Effect of Coxsackievirus

Glioblastoma multiforme (GBM) is one of the most common types of brain tumor. Despite intensive research, patients with GBM have a poor prognosis due to a very high rate of relapse and significant side effects of the treatment, with a median survival of 14.6 months. Oncolytic viruses are considered a promising strategy to eliminate GBM and other types of cancer, and several viruses have already been introduced into clinical practice. However, identification of the factors that underly the sensitivity of tumor species to oncolytic viruses or that modulate their clinical efficacy remains an important target. Here, we show that Coxsackievirus B5 (CVB5) demonstrates high oncolytic potential towards GBM primary cell species and cell lines. Moreover, 2-deoxyglucose (2DG), an inhibitor of glycolysis, potentiates the cytopathic effects of CVB5 in most of the cancer cell lines tested. The cells in which the inhibition of glycolysis enhanced oncolysis are characterized by high mitochondrial respiratory activity and glycolytic capacity, as determined by Seahorse analysis. Thus, 2-deoxyglucose and other analogs should be considered as adjuvants for oncolytic therapy of glioblastoma multiforme.

Current landscape and perspective of oncolytic viruses and their combination therapies

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Oncolytic virotherapy has become an important branch of cancer immunotherapy in clinical practice.

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Multiple viruses can be engineered to be OVs and armed with anticancer genes to enhance their efficacy.

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OVs can reshape TME and produce synergistic anticancer efficacy when combined with other therapies.

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Safety and effectiveness are the main direction of future research and development of OVs.

Oncolytic virotherapy has become an important strategy in cancer immunotherapy. Oncolytic virus (OV) can reshape the tumor microenvironment (TME) through its replication-mediated oncolysis and transgene-produced anticancer effect, inducing an antitumor immune response and creating favorable conditions for the combination of other therapeutic measures. Extensive preclinical and clinical data have suggested that OV-based combination therapy has definite efficacy and promising prospects. Recently, several clinical trials of oncolytic virotherapy combined with immunotherapy have made breakthroughs. This review comprehensively elaborates the OV types and their targeting mechanisms, the selection of anticancer genes armed in OVs, and the therapeutic modes of action and strategies of OVs to provide a theoretical basis for the better design and construction of OVs and the optimization of OV-based therapeutic strategies.

Engineering Cancer Selective Virotherapies: Are the Pieces of the Puzzle Falling into Place?

Advances in gene therapy, synthetic biology, cancer genomics, and patient-derived cancer models have expanded the repertoire of strategies for targeting human cancers using viral vectors. Novel capsids, synthetic promoters, and therapeutic payloads are being developed and assessed through approaches such as rational design, pooled library screening, and directed evolution. Ultimately, the goal is to generate precision-engineered viruses that target different facets of tumor cell biology, without compromising normal tissue and organ function. In this study, we briefly review the opportunities for engineering cancer selectivity into viral vectors at both the cell extrinsic and intrinsic level. Such stringently tumor-targeted vectors can subsequently act as platforms for the delivery of potent therapeutic transgenes, including the exciting prospect of immunotherapeutic payloads. These have the potential to eradicate nontransduced cells through stimulation of systemic anticancer immune responses, thereby side-stepping the inherent challenge of achieving gene delivery to the entire cancer cell population. We discuss the importance of using advanced primary human cellular models, such as patient-derived cultures and organoids, to enable rapid screening and triage of novel candidates using disease-relevant models. We believe this combination of improved delivery and selectivity, through novel capsids and promoters, coupled with more potent choices for the combinations of immunotherapy-based payloads seems capable of finally delivering innovative new gene therapies for oncology. Many pieces of the puzzle of how to build a virus capable of targeting human cancers appear to be falling into place.

Effects of H101 on proliferation, migration, and apoptosis of gastric cancer cells and underlying mechanisms

BACKGROUND

As a new means of cancer treatment, oncolytic virus has the characteristics of rapid efficacy, strong targeting, and no cytotoxicity. H101, as a commercially marketed oncolytic virus, has shown stable anticancer effect, which provides a possibility for the treatment of peritoneal metastasis in patients with advanced gastric cancer.

AIM

To investigate the effects of H101 on proliferation, migration, and apoptosis of gastric cancer cells and the underlying mechanisms.

METHODS

The gastric cancer cell lines BGC-823 and SGC-7901were cultured in 6-well plates, and H101 with multiplicity of infection (MOI) values of 1, 5, 10, and 15 were added, respectively. After treatment for 48 h, MTS method was used to detect the cell survival rate, and Western blot was used to detect the expression of E1A. SGC-7901 cells were then selected and cell mobility was detected by the scratch test. Hoechst33342 dye was used to observe the formation of apoptotic bodies after treatment with H101 for 48 h. The expression of apoptosis-related proteins was detected by Western blot.

RESULTS

Western blot analysis showed that EIA expression in cells treated with H101 was significantly higher than that in the control group (P < 0.05). MTS assay showed that H101 with an MOI value of 15 could more significantly kill BGC-823 and SGC-79012 cells in vitro than in that with an MOI value of 1 (P < 0.05). After 48 h, the migration distance of cells in the MOI = 5, MOI = 10, and MOI = 15 groups was significantly lower than that of the control group and MOI = 1 group (P < 0.05). Compared with the MOI = 1 group, the MOI = 5, MOI = 10, and MOI = 15 groups had significantly more apoptotic bodies (P < 0.05), and the expression levels of Bcl-2, Bax, and Caspase were significantly higher in the MOI = 5, MOI = 5, and MOI = 10 groups than in the control group and MOI = 1 group (P < 0.05).

CONCLUSION

H101 can inhibit the proliferation and migration of gastric cancer cells, increase the expression of apoptosis-related proteins, and accelerate the apoptosis of gastric cancer cells.

Chimeric Oncolytic Adenovirus Armed Chemokine Rantes for Treatment of Breast Cancer

The immunosuppressive state in the tumor microenvironment (TME) of breast cancer makes it difficult to treat with immunotherapy. Oncolytic viruses not only lyse tumor cells but also reshape the TME. Therefore, they can play a multi-mechanism synergistic effect with immunotherapy. In this study, an oncolytic adenovirus Ad5F11bSP-Rantes was constructed and used as a vector to express the chemokine Rantes. The objective of this study was to test the dual mechanisms of the oncolytic effect mediated by virus replication and the enhanced anticancer immune response mediated by Rantes chemotaxis of immune cells. It was found that Ad5F11bSP-Rantes has strong infectivity and effective killing activity against breast cancer cells. In the established triple negative breast cancer (TNBC) xenograft model in NCG mice whose immune system was humanized with human peripheral blood mononuclear cells (PBMCs), Ad5F11bSP-Rantes achieved 88.33% tumor inhibition rate. Rantes expression was high in mouse blood, a large number of CD3+ lymphocytes infiltrated in tumor tissues and E-cadherin was up-regulated in cancer cells, suggesting that Ad5F11bSP-Rantes altered the TME and induced a reversal of cancer cell epithelial-mesenchymal transition (EMT). In conclusion, oncolytic adenovirus can exert the oncolytic effect and the chemotactic effect of immune cells and realize the synergy of multiple anticancer effects. This strategy creates a candidate treatment for the optimization of breast cancer, especially TNBC, combination therapy.

Oncolytic viruses: challenges and considerations in an evolving clinical landscape

Despite advances in treatment, cancer remains a leading cause of death worldwide. Although treatment strategies are continually progressing, cancers have evolved many mechanisms for evading therapies and the host immune system. Oncolytic viruses (OVs) could provide a much-needed option for cancers that are resistant to existing treatments. OVs can be engineered to specifically target and kill cancer cells, while simultaneously triggering an immune response at the site of infection. This review will focus on the challenges of developing a successful OV and translation to clinical practice, discussing the innovative strategies that are being used to optimize the potential of OVs. Here, we will also explore the current clinical landscape and the prospects of OVs in early clinical development.

Triple-serotype chimeric oncolytic adenovirus exerts multiple synergistic mechanisms against solid tumors

Background

Oncolytic virotherapy has become an important branch of cancer immunotherapy. This study investigated the efficacy of an oncolytic adenovirus (OAV), OncoViron, with synergistic mechanisms in the treatment of multiple solid tumors.

Methods

An OAV, OncoViron, was constructed and investigated by cytological experiments and implanted tumor models of multiple solid tumor cell lines to certify its anticancer efficacy, the synergistic effects of viral oncolysis and transgene anticancer activity of OncoViron, as well as oncolytic virotherapy combined with immunotherapy, were also verified.

Results

The selective replication of OncoViron mediated high expression of anticancer factors, specifically targeted a variety of solid tumors and significantly inhibited cancer cell proliferation. On a variety of implanted solid tumor models in immunodeficient mice, immunocompetent mice, and humanized mice, OncoViron showed great anticancer effects on its own and in combination with programmed death 1 (PD-1) antibody and chimeric antigen receptor (CAR) T cells. Pathological examination, single-cell sequencing, and spatial transcriptome analysis of animal implanted tumor specimens confirmed that OncoViron significantly altered the gene expression profile of infected cancer cells, not only recruiting a large number of lymphocytes, natural killer cells, and mononuclear macrophages into tumor microenvironment (TME) and activated immune cells, especially T cells but also inducing M1 polarization of macrophages and promoting the release of more immune cytokines, thereby remodeling the TME for coordinating PD-1 antibody or CAR T therapy.

Conclusions

The chimeric OncoViron is a novel broad-spectrum anticancer product with multiple mechanisms of synergistic and potentiated immunotherapy, creating a good opportunity for combined immunotherapy against solid tumors.

Gospel of malignant Glioma: Oncolytic virus therapy

Glioma accounts for nearly 80% of all intracranial malignant tumors. It is a major challenge to society as it is causes to impaired brain function in many patients. Currently, gliomas are mainly treated with surgery, postoperative radiotherapy, and chemotherapy. However, the curative effects of these treatments are not satisfactory. Oncolytic virus (OV) is a novel treatment which works by activating the immune functions and inducing apoptosis of tumor cells. The OV propagates indefinitely in the host cell, eventually leading to the death of host cell. Subsequently, a large number of antigens and signal molecules are released which exert antitumor immunity. Several preclinical and clinical studies have shown that G207, DNX2401, Zika and other viruses have important roles in malignant tumors. For example, these viruses can reduce the growth of tumor cells without causing severe complications. However, the known OVs have not been clearly classified. Herein, we divided OVs into neurotropic and non-neurophilic OVs based on whether the OVs are naturally neurotropic or not. The therapeutic effects of each group were compared. Finally, challenges encountered in the clinical application of OVs in the treatment of malignant gliomas were summarized.

Perspectives for Combining Viral Oncolysis With Additional Immunotherapies for the Treatment of Melanoma

Melanoma is the deadliest type of skin cancer with steadily increasing incidence worldwide during the last few decades. In addition to its tumor associated antigens (TAAs), melanoma has a high mutation rate compared to other tumors, which promotes the appearance of tumor specific antigens (TSAs) as well as increased lymphocytic infiltration, inviting the use of therapeutic tools that evoke new or restore pre-existing immune responses. Innovative therapeutic proposals, such as immune checkpoint inhibitors (ICIs), have emerged as effective options for melanoma. However, a significant portion of these patients relapse and become refractory to treatment. Likewise, strategies using viral vectors, replicative or not, have garnered confidence and approval by different regulatory agencies around the world. It is possible that further success of immune therapies against melanoma will come from synergistic combinations of different approaches. In this review we outline molecular features inherent to melanoma and how this supports the use of viral oncolysis and immunotherapies when used as monotherapies or in combination.

Oncolytic Viruses: Newest Frontier for Cancer Immunotherapy

Cancer remains a leading cause of death worldwide. Despite many signs of progress, currently available cancer treatments often do not provide desired outcomes for too many cancers. Therefore, newer and more effective therapeutic approaches are needed. Oncolytic viruses (OVs) have emerged as a novel cancer treatment modality, which selectively targets and kills cancer cells while sparing normal ones. In the past several decades, many different OV candidates have been developed and tested in both laboratory settings as well as in cancer patient clinical trials. Many approaches have been taken to overcome the limitations of OVs, including engineering OVs to selectively activate anti-tumor immune responses. However, newer approaches like the combination of OVs with current immunotherapies to convert "immune-cold" tumors to "immune-hot" will almost certainly improve the potency of OVs. Here, we discuss strategies that are explored to further improve oncolytic virotherapy.

Oncolytic viruses for triple negative breast cancer and beyond

Biological therapy is considered an alternative treatment capable of eliciting the same effects on tumors as surgery, radiotherapy, and chemotherapy. As a major player in biological therapy, oncolytic viruses (OVs) have attracted great attention and achieved good results. Specifically, the successful application of OVs in head and neck cancer, as well as melanoma, promoted its research in triple negative breast cancer (TNBC). TNBC is a high-risk molecular type of breast cancer, characterized by strong invasion, easy recurrence, and metastasis. Due to the absence of estrogen and progesterone receptors, as well as the absence of overexpression or gene amplification of human epidermal growth factor receptor 2 (HER2), endocrine therapy and anti HER-2 targeted therapy have proven ineffective. Although chemotherapy has shown substantial efficacy in some TNBC patients, the occurrence of drug resistance and poor prognosis have prompted the exploration of new and effective treatment methods. The emerging concept of OVs provides a new platform to treat TNBC. Indeed, several studies have confirmed the therapeutic effects of OVs in TNBC. Numerous studies have also investigated the efficacy of OVs in other malignances, including solid tumor clinical trials, thus further demonstrating the promising application of oncolytic virotherapy for TNBC. The primary focus of the current review is the examination of OV mechanisms underlying their antitumor properties, while also summarizing the ongoing progress in OV research regarding TNBC treatment, as well as the various combinatorial strategies comprising OVs and other therapies. We also briefly introduce specific relevant clinical trials and discuss some of the progress in the research of novel OVs for the treatment of other malignancies, thereby affirming the significant therapeutic potential of OVs for the treatment of TNBC, as well as other cancers.

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.

Current status of intralesional agents in treatment of malignant melanoma

Prognosis of metastatic melanoma has undergone substantial improvement with the discovery of checkpoint inhibitors. Immunotherapies and targeted therapies have improved the median overall survival (OS) of metastatic melanoma from 6 months to more than 3 years. However, still about half of the patients die due to uncontrolled disease. Therefore, multiple strategies are currently being investigated to improve outcomes. One such strategy is intralesional/intratumoral (IT) therapies which can either directly kill the tumor cells or make the tumor more immunogenic to be recognized by the immune system. Talimogene laherparepvec (T-VEC), an oncolytic virus, is the first FDA approved IT therapy. This review focuses on the current status of IT agents currently under clinical trials in melanoma. Reviewed therapies include T-VEC, T-VEC with immune checkpoint inhibitors including ipilimumab and pembrolizumab or other agents, RP1, OrienX010, Canerpaturev (C-REV, HF10), CAVATAK (coxsackievirus A21, CVA21) alone or in combination with checkpoint inhibitors, oncolytic polio/rhinovirus recombinant (PVSRIPO), MAGE-A3-expressing MG1 Maraba virus, VSV-IFNbetaTYRP1, suicide gene therapy, ONCOS-102, OBP-301 (Telomelysin), Stimulation of Interferon Genes Pathway (STING agonists) including DMXAA, MIW815 (ADU-S100) and MK-1454, PV-10, toll-like receptors (TLRs) agonists including TLR-9 agonists (SD-101, CMP-001, IMO-2125 or tilsotolimod, AST-008 or cavrotolimod, MGN1703 or lefitolimod), CV8102, NKTR-262 plus NKTR-214, LHC165, G100, intralesional interleukin-2, Daromun (L19IL2 plus L19TNF), Hiltonol (poly-ICLC), electroporation including calcium electroporation and plasmid interleukin-12 electroporation (pIL-12 EP), IT ipilimumab, INT230-6 (cisplatin and vinblastine with an amphiphilic penetration enhancer), TTI-621 (SIRPαFc), CD-40 agonistic antibodies (ABBV-927 and APX005M), antimicrobial peptide LL37 and other miscellaneous agents.

A bibliometric review of oncolytic virus research as a novel approach for cancer therapy

Background

In recent years, oncolytic viruses (OVs) have drawn attention as a novel therapy to various types of cancers, both in clinical and preclinical cancer studies all around the world. Consequently, researchers have been actively working on enhancing cancer therapy since the early twentieth century. This study presents a systematic review of the literature on OVs, discusses underlying research clusters and, presents future directions of OVs research.

Methods

A total of 1626 published articles related to OVs as cancer therapy were obtained from the Web of Science (WoS) database published between January 2000 and March 2020. Various aspects of OVs research, including the countries/territories, institutions, journals, authors, citations, research areas, and content analysis to find trending and emerging topics, were analysed using the bibliometrix package in the R-software.

Results

In terms of the number of publications, the USA based researchers were the most productive (n = 611) followed by Chinese (n = 197), and Canadian (n = 153) researchers. The Molecular Therapy journal ranked first both in terms of the number of publications (n = 133) and local citations (n = 1384). The most prominent institution was Mayo Clinic from the USA (n = 117) followed by the University of Ottawa from Canada (n = 72), and the University of Helsinki from Finland (n = 63). The most impactful author was Bell J.C with the highest number of articles (n = 67) and total local citations (n = 885). The most impactful article was published in the Cell journal. In addition, the latest OVs research mainly builds on four research clusters.

Conclusion

The domain of OVs research has increased at a rapid rate from 2000 to 2020. Based on the synthesis of reviewed studies, adenovirus, herpes simplex virus, reovirus, and Newcastle disease virus have shown potent anti-cancer activity. Developed countries such as the USA, Canada, the UK, and Finland were the most productive, hence, contributed most to this field. Further collaboration will help improve the clinical research translation of this therapy and bring benefits to cancer patients worldwide.

Delivery of cancer therapies by synthetic and bio-inspired nanovectors

BACKGROUND

As a complement to the clinical development of new anticancer molecules, innovations in therapeutic vectorization aim at solving issues related to tumor specificity and associated toxicities. Nanomedicine is a rapidly evolving field that offers various solutions to increase clinical efficacy and safety. MAIN: Here are presented the recent advances for different types of nanovectors of chemical and biological nature, to identify the best suited for translational research projects. These nanovectors include different types of chemically engineered nanoparticles that now come in many different flavors of 'smart' drug delivery systems. Alternatives with enhanced biocompatibility and a better adaptability to new types of therapeutic molecules are the cell-derived extracellular vesicles and micro-organism-derived oncolytic viruses, virus-like particles and bacterial minicells. In the first part of the review, we describe their main physical, chemical and biological properties and their potential for personalized modifications. The second part focuses on presenting the recent literature on the use of the different families of nanovectors to deliver anticancer molecules for chemotherapy, radiotherapy, nucleic acid-based therapy, modulation of the tumor microenvironment and immunotherapy.

CONCLUSION

This review will help the readers to better appreciate the complexity of available nanovectors and to identify the most fitting "type" for efficient and specific delivery of diverse anticancer therapies.

Shell disorder and the HIV vaccine mystery: lessons from the legendary Oswald Avery

The search for a human immunodeficiency virus (HIV) vaccine has spanned nearly four decades without much success. A much needed paradigm shift can be found in the abnormally high levels of intrinsic disorder in the outer shells of HIVs, the hepatitis C virus (HCV), and herpes simplex viruses (HSVs), for which successful vaccines have not been established. On the other hand, this feature (high levels of intrinsic disorder in the outer shells) is completely absent in classic viruses for which effective vaccines are found, such as the rabies virus. The motions arising from the disordered outer shell result in the inability of antibodies to bind tightly to the polysaccharides on the viral surface proteins, and, therefore, induce inadequate immune response. Experiments conducted by the legendary Avery Oswald in the 1920s form the theoretical underpinning of this new model. Failures of the vaccines based on the HIV glycoprotein Gp120 and other vaccines can be traced back to the lack of understanding of the important roles of shell disorder in a "Trojan-horse" immune evasion mechanism utilized by the virus.Communicated by Ramaswamy H. Sarma.

A Tumor-Targeted Replicating Oncolytic Adenovirus Ad-TD-nsIL12 as a Promising Therapeutic Agent for Human Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal cancers in China and existing therapies have been unable to significantly improve prognosis. Oncolytic adenoviruses (OAds) are novel promising anti-tumor drugs and have been evaluated in several cancers including ESCC. However, the antitumour efficacy of the first generation OAds (H101) as single agent is limited. Therefore, more effective OAds are needed. Our previous studies demonstrated that the novel oncolytic adenovirus Ad-TD-nsIL12 (human adenovirus type 5 with E1ACR2, E1B19K, E3gp19K-triple deletions)harboring human non-secretory IL-12 had significant anti-tumor effect, with no toxicity, in a Syrian hamster pancreatic cancer model. In this study, we evaluated the anti-tumor effect of Ad-TD-nsIL12 in human ESCC. The cytotoxicity of Ad-TD-nsIL12, H101 and cisplatin were investigated in two newly established patient-derived tumor cells (PDCs) and a panel of ESCC cell lines in vitro. A novel adenovirus-permissive, immune-deficient Syrian hamster model of PDCs subcutaneous xenograft was established for in vivo analysis of efficacy. The results showed that Ad-TD-nsIL12 was more cytotixic to and replicated more effectively in human ESCC cell lines than H101. Compared with cisplatin and H101, Ad-TD-nsIL12 could significantly inhibit tumor growth and tumor angiogenesis as well as enhance survival rate of animals with no side effects. These findings suggest that Ad-TD-nsIL12 has superior anti-tumor potency against human ESCC with a good safety profile.

Delivery and Biosafety of Oncolytic Virotherapy

In recent years, oncolytic virotherapy has emerged as a promising anticancer therapy. Oncolytic viruses destroy cancer cells, without damaging normal tissues, through virus self-replication and antitumor immunity responses, showing great potential for cancer treatment. However, the clinical guidelines for administering oncolytic virotherapy remain unclear. Delivery routes for oncolytic virotherapy to patients vary in existing studies, depending on the tumor sites and the objective of studies. Moreover, the biosafety of oncolytic virotherapy, including mainly uncontrolled adverse events and long-term complications, remains a serious concern that needs to be accurately measured. This review provides a comprehensive and detailed overview of the delivery and biosafety of oncolytic virotherapy.

Development of oncolytic virotherapy: from genetic modification to combination therapy

Oncolytic virotherapy (OVT) is a novel form of immunotherapy using natural or genetically modified viruses to selectively replicate in and kill malignant cells. Many genetically modified oncolytic viruses (OVs) with enhanced tumor targeting, antitumor efficacy, and safety have been generated, and some of which have been assessed in clinical trials. Combining OVT with other immunotherapies can remarkably enhance the antitumor efficacy. In this work, we review the use of wild-type viruses in OVT and the strategies for OV genetic modification. We also review and discuss the combinations of OVT with other immunotherapies.

Oncolytic Virotherapy with Myxoma Virus

Oncolytic viruses are one of the most promising novel therapeutics for malignant cancers. They selectively infect and kill cancer cells while sparing the normal counterparts, expose cancer- specific antigens and activate the host immune system against both viral and tumor determinants. Oncolytic viruses can be used as monotherapy or combined with existing cancer therapies to become more potent. Among the many types of oncolytic viruses that have been developed thus far, members of poxviruses are the most promising candidates against diverse cancer types. This review summarizes recent advances that are made with oncolytic myxoma virus (MYXV), a member of the Leporipoxvirus genus. Unlike other oncolytic viruses, MYXV infects only rabbits in nature and causes no harm to humans or any other non-leporid animals. However, MYXV can selectively infect and kill cancer cells originating from human, mouse and other host species. This selective cancer tropism and safety profile have led to the testing of MYXV in various types of preclinical cancer models. The next stage will be successful GMP manufacturing and clinical trials that will bring MYXV from bench to bedside for the treatment of currently intractable malignancies.

Zika and Flavivirus Shell Disorder: Virulence and Fetal Morbidity

Zika virus (ZIKV) was first discovered in 1947 in Africa. Since then, sporadic ZIKV infections of humans have been reported in Africa and Asia. For a long time, this virus was mostly unnoticed due to its mild symptoms and low fatality rates. However, during the 2015-2016 epidemic in Central and South America, when millions of people were infected, it was discovered that ZIKV causes microcephaly in the babies of mothers infected during pregnancy. An examination of the M and C proteins of the ZIKV shell using the disorder predictor PONDR VLXT revealed that the M protein contains relatively high disorder levels comparable only to those of the yellow fever virus (YFV). On the other hand, the disorder levels in the C protein are relatively low, which can account for the low case fatality rate (CFR) of this virus in contrast to the more virulent YFV, which is characterized by high disorder in its C protein. A larger variation was found in the percentage of intrinsic disorder (PID) in the C protein of various ZIKV strains. Strains of African lineage are characterized by higher PIDs. Using both in vivo and in vitro experiments, laboratories have also previously shown that strains of African origin have a greater potential to inflict higher fetal morbidity than do strains of Asian lineage, with dengue-2 virus (DENV-2) having the least potential. Strong correlations were found between the potential to inflict fetal morbidity and shell disorder in ZIKV (r² = 0.9) and DENV-2 (DENV-2 + ZIKV, r² = 0.8). A strong correlation between CFR and PID was also observed when ZIKV was included in an analysis of sets of shell proteins from a variety of flaviviruses (r² = 0.8). These observations have potential implications for antiviral vaccine development and for the design of cancer therapeutics in terms of developing therapeutic viruses that penetrate hard-to-reach organs.

Synergistic combination of oncolytic virotherapy with CAR T-cell therapy

For patients with advanced hematological malignancies the therapeutic landscape has been transformed by the emergence of adoptive cell transfer utilizing autologous chimeric antigen receptor (CAR)-redirected T-cells. However, solid tumors have proved far more resistant to this approach. Here, we summarize the numerous challenges faced by CAR T-cells designed to target solid tumors, highlighting, in particular, issues related to impaired trafficking, expansion, and persistence. In parallel, we draw attention to exciting developments in the burgeoning field of oncolytic virotherapy and posit strategies for the synergistic combination of oncolytic viruses with CAR T-cells to improve outcomes for patients with advanced solid tumors.

HIV Vaccine Mystery and Viral Shell Disorder

Hundreds of billions of dollars have been spent for over three decades in the search for an effective human immunodeficiency virus (HIV) vaccine with no success. There are also at least two other sexually transmitted viruses, for which no vaccine is available, the herpes simplex virus (HSV) and the hepatitis C virus (HCV). Traditional textbook explanatory paradigm of rapid mutation of retroviruses cannot adequately address the unavailability of vaccine for many sexually transmissible viruses, since HSV and HCV are DNA and non-retroviral RNA viruses, respectively, whereas effective vaccine for the horsefly-transmitted retroviral cousin of HIV, equine infectious anemia virus (EIAV), was found in 1973. We reported earlier the highly disordered nature of proteins in outer shells of the HIV, HCV, and HSV. Such levels of disorder are completely absent among the classical viruses, such as smallpox, rabies, yellow fever, and polio viruses, for which efficient vaccines were discovered. This review analyzes the physiology and shell disorder of the various related and non-related viruses to argue that EIAV and the classical viruses need harder shells to survive during harsher conditions of non-sexual transmissions, thus making them vulnerable to antibody detection and neutralization. In contrast, the outer shell of the HIV-1 (with its preferential sexual transmission) is highly disordered, thereby allowing large scale motions of its surface glycoproteins and making it difficult for antibodies to bind to them. The theoretical underpinning of this concept is retrospectively traced to a classical 1920s experiment by the legendary scientist, Oswald Avery. This concept of viral shapeshifting has implications for improved treatment of cancer and infections via immune evasion.

Oncolytic Newcastle disease virus reduces growth of cervical cancer cell by inducing apoptosis

Although Oncolytic viruses have been regarded as a promising tool for targeted therapy of cancer, accomplishing high efficacy and specificity with this strategy is challenging. Oncolytic virotherapy is one of the novel therapeutic methods recently used for the therapy of human malignancies. Cervical cancer is on the major public health problem and the second most common cause of cancer death among females in less developed countries. The aim of this study was mainly to determine the apoptosis effect of oncolytic Newcastle disease virus (NDV) in TC-1 cell line.

In the current study, the oncolytic NDV, vaccine strain LaSota, was used to infect murine TC-1 cells of human papillomavirus (HPV)-associated carcinoma which expressing human papillomavirus 16 (HPV-16) E6/E7 antigens in vitro. The effectiveness of NDV for cervical cancer cell line was investigated by evaluating the antitumor activity of oncolytic NDV and the involved mechanisms. Antitumor activities of oncolytic NDV were assessed by cell proliferation (MTT) and lactate dehydrogenase (LDH) release analysis. In addition, molecular changes of early stage of apoptosis and the role of reactive oxygen species (ROS) were analyzed by flow cytometry and Western Blot in NDV-treated TC-1 cells.

The results showed that NDV treatment significantly decreased the viability of a TC-1 cell line and suppressed the growth by inducing apoptotic cell death. In addition, we demonstrated that NDV-induced apoptosis of TC-1 cells is mediated by ROS production. In summary, our findings suggest that oncolytic NDV is a possible therapeutic candidate as a selective antitumor agent for the treatment of cervical cancer.

The viral approach to breast cancer immunotherapy

Despite years of intensive research, breast cancer remains the leading cause of death in women worldwide. New technologies including oncolytic virus therapies, virus, and phage display are among the most powerful and advanced methods that have emerged in recent years with potential applications in cancer prevention and treatment. Oncolytic virus therapy is an interesting strategy for cancer treatment. Presently, a number of viruses from different virus families are under laboratory and clinical investigation as oncolytic therapeutics. Oncolytic viruses (OVs) have been shown to be able to induce and initiate a systemic antitumor immune response. The possibility of application of a multimodal therapy using a combination of the OV therapy with immune checkpoint inhibitors and cancer antigen vaccination holds a great promise in the future of cancer immunotherapy. Display of immunologic peptides on bacterial viruses (bacteriophages) is also increasingly being considered as a new and strong cancer vaccine delivery strategy. In phage display immunotherapy, a peptide or protein antigen is presented by genetic fusions to the phage coat proteins, and the phage construct formulation acts as a protective or preventive vaccine against cancer. In our laboratory, we have recently tested a few peptides (E75, AE37, and GP2) derived from HER2/neu proto-oncogene as vaccine delivery modalities for the treatment of TUBO breast cancer xenograft tumors of BALB/c mice. Here, in this paper, we discuss the latest advancements in the applications of OVs and bacterial viruses display systems as new and advanced modalities in cancer immune therapeutics.