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ABSTRACTTigilanol tiglate is an oncolytic small molecule that is undergoing clinical trials. A recent study revealed the capacity of this pyroptosis inducer to elicit hallmarks of immunogenic cell death. In addition, intratumoral injection of tigilanol tiglate can sensitize subcutaneous cancers to subsequent immune checkpoint inhibitors targeting CTLA-4 alone or in combination with PD-1.

In recent years, our understanding of the importance of microorganisms on and within our bodies has been revolutionized by the ability to characterize entire microbial communities. No more so is this true than in cases of disease. Community studies have revealed strong associations between microbial populations and disease states where such concomitance was previously absent from aetiology: including in cancers. The study of viruses, in particular, has benefited from the development of new community profiling techniques and we are now realising that their prominence within our physiology is nearly as broad as the diversity of the organisms themselves. Here, we examine the relationship between viruses and colorectal cancer (CRC), the leading cause of gastrointestinal cancer-related death worldwide. In CRC, viruses have been suggested to be involved in oncogenesis both directly, through infection of our cells, and indirectly, through modulating the composition of bacterial communities. Interestingly though, these characteristics have also led to their examination from another perspective-as options for treatment. Advances in our understanding of molecular and viral biology have caused many to look at viruses as potential modular biotherapeutics, where deleterious characteristics can be tamed and desirable characteristics exploited. In this article, we will explore both of these perspectives, covering how viral infections and involvement in microbiome dynamics may contribute to CRC, and examine ways in which viruses themselves could be harnessed to treat the very condition their contemporaries may have had a hand in creating.

Spontaneous canine mammary carcinomas (CMCs) have been widely considered a good research model for human breast cancers, which brings much attention to CMCs. In recent years, the oncolytic effect of Newcastle disease virus (NDV) on cancer cells has been widely studied, but its effect on CMCs is still unclear. This study aims to investigate the oncolytic effect of NDV LaSota strain on canine mammary carcinoma cell line (CMT‐U27) in vivo and in vitro. The in vitro cytotoxicity and immunocytochemistry experiments showed that NDV selectively replicated in CMT‐U27 cells, and inhibited cell proliferation and migration but not in MDCK cells. KEGG analysis of transcriptome sequencing indicated the importance of the TNFα and NF‐κB signalling pathways in the anti‐tumour effect of NDV. Subsequently, the significantly increased expression of TNFα, p65, phospho‐p65, caspase‐8, caspase‐3 and cleaved‐PARP proteins in the NDV group suggested that NDV induced CMT‐U27 cells apoptosis by activating the caspase‐8/caspase‐3 pathway and the TNFα/NF‐κB signalling pathway. Nude mice tumour‐bearing experiments showed that NDV could significantly decrease the growth rate of CMC in vivo. In conclusion, our study demonstrates the effective oncolytic effects of NDV on CMT‐U27 cells in vivo and in vitro, and suggests NDV as a promising candidate for oncolytic therapy. [ABSTRACT FROM AUTHOR]

Vesiculoviruses are widely used in various fields of biotechnology. This article analyzes the results of published experimental works devoted to the development of oncolytic and recombinant vaccines against emergent viral infections based on vesiculoviruses. The use of genetic engineering methods makes it possible to strengthen their immunogenicity and oncolytic potential. Aim. Analysis and summarization of available information devoted to the development of oncolytic and other vaccines based on vesiculoviruses. Materials and methods. Publications were selected based on the PubMed (https://pubmed.ncbi.nlm. nih.gov/) and Google Scholar (https://scholar.google.com/) databases published in 2010–2023. They include information on development of oncolytic and other vaccines based on vesiculoviruses. Results. The article describes in detail the use of vesiculoviruses as a tool for creating highly active recombinant viral vaccines. These vaccines are able to protect people from emergent viral infections in various countries and may find application in anticancer therapy. [ABSTRACT FROM AUTHOR]

Glioblastoma (GBM) is the most common aggressive malignant brain cancer and is chemo- and radioresistant, with poor therapeutic outcomes. The “double-edged sword” of virus-induced cell death could be a potential solution if the oncolytic virus specifically kills cancer cells but spares normal ones. Zika virus (ZIKV) has been defined as a prospective oncolytic virus by selectively targeting GBM cells, but unclear understanding of how ZIKV kills GBM and the consequences hinders its application. Here, we found that the cellular gasdermin D (GSDMD) is required for the efficient death of a human GBM cell line caused by ZIKV infection. The ZIKV protease specifically cleaves human GSDMD to activate caspase-independent pyroptosis, harming both viral protease-harboring and naive neighboring cells. Analyzing human GSDMD variants showed that most people were susceptible to ZIKV-induced cytotoxicity, except for those with variants that resisted ZIKV cleavage or were defective in oligomerizing the N terminus GSDMD cleavage product. Consistently, ZIKV-induced secretion of the pro-inflammatory cytokine interleukin-1β and cytolytic activity were both stopped by a small-molecule inhibitor targeting GSDMD oligomerization. Thus, potential ZIKV oncolytic therapy for GBM would depend on the patient’s GSDMD genetic background and could be abolished by GSDMD inhibitors if required.

Together with an anti-tumor immune response, oncolysis using a recombinant viral vector promises to eliminate cancer cells by both gene transfer and host-mediated functions. In this study we explore oncolysis induced by nonreplicating adenoviral vectors used for p14ARF and interferon-β (hIFNβ) gene transfer in human melanoma cell lines, revealing an unexpected role for p14ARF in promoting cellular responses predictive of immune stimulation. Oncolysis was confirmed when UACC-62 (p53 wild-type) cells succumbed upon p14ARF gene transfer in vitro, whereas SK-Mel-29 (p53-mutant) benefitted from its combination with hIFNβ. In the case of UACC-62, in situ gene therapy in nude mice yielded reduced tumor progression in response to the p14ARF and hIFNβ combination. Potential for immune stimulation was revealed where p14ARF gene transfer in vitro was sufficient to induce emission of immunogenic cell death factors in UACC-62 and upregulate pro-immune genes, including IRF1, IRF7, IRF9, ISG15, TAP-1, and B2M. In SK-Mel-29, p14ARF gene transfer induced a subset of these factors. hIFNβ was, as expected, sufficient to induce these immune-stimulating genes in both cell lines. This work is a significant advancement for our melanoma gene therapy strategy because we revealed not only the induction of oncolysis, but also the potential contribution of p14ARF to immune stimulation. [ABSTRACT FROM AUTHOR]

Simple Summary: Current cancer therapies are insufficient to cure advanced malignancies and cause off-target toxicity. Scientists have focused on developing new, more efficacious, and selective therapies to overcome these issues. This review describes a modern approach based on oncotherapy, a type of cancer treatment that helps the immune system fight cancer. Thus, genetic modifications of adenoviruses to increase the anticancer properties of the therapy (benefits, critical points, and risk assessment) were reviewed. We analyzed clinical trial databases and highlighted significant achievements in adenovirus oncotherapy in recent years. In clinical trials, adenovirus vectors (AdVs) are commonly used platforms for human gene delivery therapy. High genome capacity and flexibility in gene organization make HAdVs suitable for cloning. Recent advancements in molecular techniques have influenced the development of genetically engineered adenovirus vectors showing therapeutic potential. Increased molecular understanding of the benefits and limitations of HAdVs in preclinical research and clinical studies is a crucial point in the engineering of refined oncolytic vectors. This review presents HAdV species (A–G) used in oncotherapy. We describe the adenovirus genome organizations and modifications, the possibilities oncolytic viruses offer, and their current limitations. Ongoing and ended clinical trials based on oncolytic adenoviruses are presented. This review provides a broad overview of the current knowledge of oncolytic therapy. HAdV-based strategies targeting tumors by employing variable immune modifiers or delivering immune stimulatory factors are of great promise in the field of immune oncologyy This approach can change the face of the fight against cancer, supplying the medical tools to defeat tumors more selectively and safely. [ABSTRACT FROM AUTHOR]

Intratumoral injection of oncolytic agents such as modified herpes simplex virus T-VEC or local administration of non-viral oncolytic therapies (such as radiofrequency, chemoembolization, cryoablation, or radiotherapy) can activate an anticancer immune response and hence trigger abscopal effects reducing secondary lesions. Preliminary data suggested that oncolytic treatments modulate tumor-infiltrating immune effectors and can be advantageously combined with the immune checkpoint inhibitors. Recent findings indicate that local anesthetics, which are usually used in the clinics to control surgical pain, also possess antineoplastic effects mimicking oncolytic treatments if they are injected into malignant lesions. Moreover, the association of local anesthetics with systemic immune checkpoint inhibition significantly improved overall survival in several preclinical tumor models. This may be explained by direct cytotoxic activity of local anesthetics and additional immune-related abscopal effects. We also summarize the molecular and cellular mechanisms by which the combination of local anesthetics and immunotherapy improves tumor control by the immune system. [ABSTRACT FROM AUTHOR]

Herpes simplex virus 1 (HSV-1) has been widely used to treat various cancers, but its efficacy is limited. Studies indicated that combining HSV-1 and chemotherapy drugs can effectively improve the lethality of HSV-1 in tumor cells, which has a synergistic effect. Here, we explored the oncolytic effect and mechanism of bortezomib and HSV-1 on colorectal cancer cells, HCT116 and Caco-2. First, we selected four drugs to detect cell viability and found that the strongest HSV-1-promoting effect was achieved using bortezomib + HSV-1 treatment. Bortezomib combined with HSV-1 treatment significantly upregulated the expression of heat shock proteins, endoplasmic reticulum stress-related proteins and apoptosis-related proteins, while Bcl-2 was downregulated. JC-1 staining revealed that combining bortezomib and HSV-1 promotes cell apoptosis. In addition, bortezomib + oHSV-1 treatment effectively inhibit tumor growth. These results indicate that bortezomib combined with HSV-1 induce intense endoplasmic reticulum stress and activate the caspase-12 apoptosis pathway, killing tumor cells. • Bortezomib + oHSV-1 combined therapy can significantly improve the therapeutic effect of colorectal cancer. • The combined treatment of protease inhibitors and oHSV-1 with traditional cancer therapy enhanced the colorectal cancer efficacy. • BTZ + oHSV-1 combined therapy is controllable and less toxic. [ABSTRACT FROM AUTHOR]

Abstract Background Glioblastoma is one of the most serious brain cancer. Previous studies have demonstrated that PTEN function disorder affects the causing and exacerbation of glioblastoma. Newcastle disease virus (NDV) has been studied as a cancer virotherapeutics. In this study, PTEN gene was delivered to glioblastoma by recombinant NDV (rNDV) and translated into protein at the cytoplasm of the glioblastoma. Methods We did comparison tests PTEN protein expression efficiency and oncolytic effect depend on the PTEN gene insertion site at the between NP and P genes and the between P and M gene. PTEN protein mRNA transcription, translation in glioblastoma cell, and functional PTEN protein effect of the rNDV in vitro and in vivo test performed using western blotting, RT-qPCR, MTT assay, and Glioblastoma xenograft animal model test. Results The result of this study demonstrates that rNDV-PTEN kills glioblastoma cells and reduces cancer tissue better than rNDV without the PTEN gene. In molecular immunological and cytological assays, PTEN expression level was high at located in the between NP and P gene, and PTEN gene was successfully delivered to the glioblastoma cell using rNDV and PTEN gene translated to functional protein and inhibits hTERT and AKT gene. Conclusions PTEN gene enhances the oncolytic effect of the rNDV. And our study demonstrated that NP and P gene site is better than P and M gene site which is commonly and conventionally used. PTEN gene containing rNDV is a good candidate virotherapeutics for glioblastoma.

Mammalian orthoreoviruses (ReoV) are non-enveloped viruses with segmented double-stranded RNA genomes. In humans, ReoV are generally considered non-pathogenic, although members of this family have been proven to cause mild gastroenteritis in young children and may contribute to the development of inflammatory conditions, including Celiac disease. Because of its low pathogenic potential and its ability to efficiently infect and kill transformed cells, the ReoV strain Type 3 Dearing (T3D) is clinical trials as an oncolytic agent. ReoV manifests its oncolytic effects in large part by infecting tumor cells and activating programmed cell death pathways (PCDs). It was previously believed that apoptosis was the dominant PCD pathway triggered by ReoV infection. However, new studies suggest that ReoV also activates other PCD pathways, such as autophagy, pyroptosis, and necroptosis. Necroptosis is a caspase-independent form of PCD reliant on receptor-interacting serine/threonine-protein kinase 3 (RIPK3) and its substrate, the pseudokinase mixed-lineage kinase domain-like protein (MLKL). As necroptosis is highly inflammatory, ReoV-induced necroptosis may contribute to the oncolytic potential of this virus, not only by promoting necrotic lysis of the infected cell, but also by inflaming the surrounding tumor microenvironment and provoking beneficial anti-tumor immune responses. In this review, we summarize our current understanding of the ReoV replication cycle, the known and potential mechanisms by which ReoV induces PCD, and discuss the consequences of non-apoptotic cell death—particularly necroptosis—to ReoV pathogenesis and oncolysis. [ABSTRACT FROM AUTHOR]

Background: Glioblastoma is one of the most serious brain cancer. Previous studies have demonstrated that PTEN function disorder affects the causing and exacerbation of glioblastoma. Newcastle disease virus (NDV) has been studied as a cancer virotherapeutics. In this study, PTEN gene was delivered to glioblastoma by recombinant NDV (rNDV) and translated into protein at the cytoplasm of the glioblastoma. Methods: We did comparison tests PTEN protein expression efficiency and oncolytic effect depend on the PTEN gene insertion site at the between NP and P genes and the between P and M gene. PTEN protein mRNA transcription, translation in glioblastoma cell, and functional PTEN protein effect of the rNDV in vitro and in vivo test performed using western blotting, RT-qPCR, MTT assay, and Glioblastoma xenograft animal model test. Results: The result of this study demonstrates that rNDV-PTEN kills glioblastoma cells and reduces cancer tissue better than rNDV without the PTEN gene. In molecular immunological and cytological assays, PTEN expression level was high at located in the between NP and P gene, and PTEN gene was successfully delivered to the glioblastoma cell using rNDV and PTEN gene translated to functional protein and inhibits hTERT and AKT gene. Conclusions: PTEN gene enhances the oncolytic effect of the rNDV. And our study demonstrated that NP and P gene site is better than P and M gene site which is commonly and conventionally used. PTEN gene containing rNDV is a good candidate virotherapeutics for glioblastoma. [ABSTRACT FROM AUTHOR]

Background: Glioblastoma is one of the most serious brain cancer. Previous studies have demonstrated that PTEN function disorder affects the causing and exacerbation of glioblastoma. Newcastle disease virus (NDV) has been studied as a cancer virotherapeutics. In this study, PTEN gene was delivered to glioblastoma by recombinant NDV (rNDV) and translated into protein at the cytoplasm of the glioblastoma. Methods: We did comparison tests PTEN protein expression efficiency and oncolytic effect depend on the PTEN gene insertion site at the between NP and P genes and the between P and M gene. PTEN protein mRNA transcription, translation in glioblastoma cell, and functional PTEN protein effect of the rNDV in vitro and in vivo test performed using western blotting, RT-qPCR, MTT assay, and Glioblastoma xenograft animal model test. Results: The result of this study demonstrates that rNDV-PTEN kills glioblastoma cells and reduces cancer tissue better than rNDV without the PTEN gene. In molecular immunological and cytological assays, PTEN expression level was high at located in the between NP and P gene, and PTEN gene was successfully delivered to the glioblastoma cell using rNDV and PTEN gene translated to functional protein and inhibits hTERT and AKT gene. Conclusions: PTEN gene enhances the oncolytic effect of the rNDV. And our study demonstrated that NP and P gene site is better than P and M gene site which is commonly and conventionally used. PTEN gene containing rNDV is a good candidate virotherapeutics for glioblastoma. [ABSTRACT FROM AUTHOR]

Abstract As a promising therapeutic strategy, oncolytic virotherapy has shown potent anticancer efficacy in numerous pre-clinical and clinical trials. Oncolytic viruses have the capacity for conditional-replication within carcinoma cells leading to cell death via multiple mechanisms, including direct lysis of neoplasms, induction of immunogenic cell death, and elicitation of innate and adaptive immunity. In addition, these viruses can be engineered to express cytokines or chemokines to alter tumor microenvironments. Combination of oncolytic virotherapy with other antitumor therapeutic modalities, such as chemotherapy and radiation therapy as well as cancer immunotherapy can be used to target a wider range of tumors and promote therapeutic efficacy. In this review, we outline the basic biological characteristics of oncolytic viruses and the underlying mechanisms that support their use as promising antitumor drugs. We also describe the enhanced efficacy attributed to virotherapy combined with other drugs for the treatment of cancer.

In recent years, advancements in microbial sequencing technology have sparked an increasing interest in the bacteria residing within solid tumors and its distribution and functions in various tumors. Intratumoral bacteria critically modulate tumor oncogenesis and development through DNA damage induction, chronic inflammation, epigenetic alterations, and metabolic and immune regulation, while also influencing cancer treatment efficacy by affecting drug metabolism. In response to these discoveries, a variety of anti-cancer therapies targeting these microorganisms have emerged. These approaches encompass oncolytic therapy utilizing tumor-associated bacteria, the design of biomaterials based on intratumoral bacteria, the use of intratumoral bacterial components for drug delivery systems, and comprehensive strategies aimed at the eradication of tumor-promoting bacteria. Herein, this review article summarizes the distribution patterns of bacteria in different solid tumors, examines their impact on tumors, and evaluates current therapeutic strategies centered on tumor-associated bacteria. Furthermore, the challenges and prospects for developing drugs that target these bacterial communities are also explored, promising new directions for cancer treatment., (© 2024 Wiley‐VCH GmbH.)

Abstract Background Previous studies have identified IFNγ as an important early barrier to oncolytic viruses including vaccinia. The existing innate and adaptive immune barriers restricting oncolytic virotherapy, however, can be overcome using autologous or allogeneic mesenchymal stem cells as carrier cells with unique immunosuppressive properties. Methods To test the ability of mesenchymal stem cells to overcome innate and adaptive immune barriers and to successfully deliver oncolytic vaccinia virus to tumor cells, we performed flow cytometry and virus plaque assay analysis of ex vivo co-cultures of stem cells infected with vaccinia virus in the presence of peripheral blood mononuclear cells from healthy donors. Comparative analysis was performed to establish statistically significant correlations and to evaluate the effect of stem cells on the activity of key immune cell populations. Results Here, we demonstrate that adipose-derived stem cells (ADSCs) have the potential to eradicate resistant tumor cells through a combination of potent virus amplification and sensitization of the tumor cells to virus infection. Moreover, the ADSCs demonstrate ability to function as a virus-amplifying Trojan horse in the presence of both autologous and allogeneic human PBMCs, which can be linked to the intrinsic immunosuppressive properties of stem cells and their unique potential to overcome innate and adaptive immune barriers. The clinical application of ready-to-use ex vivo expanded allogeneic stem cell lines, however, appears significantly restricted by patient-specific allogeneic differences associated with the induction of potent anti-stem cell cytotoxic and IFNγ responses. These allogeneic responses originate from both innate (NK)- and adaptive (T)- immune cells and might compromise therapeutic efficacy through direct elimination of the stem cells or the induction of an anti-viral state, which can block the potential of the Trojan horse to amplify and deliver vaccinia virus to the tumor. Conclusions Overall, our findings and data indicate the feasibility to establish simple and informative assays that capture critically important patient-specific differences in the immune responses to the virus and stem cells, which allows for proper patient-stem cell matching and enables the effective use of off-the-shelf allogeneic cell-based delivery platforms, thus providing a more practical and commercially viable alternative to the autologous stem cell approach.

Mammalian orthoreoviruses (ReoV) are non-enveloped viruses with segmented double-stranded RNA genomes. In humans, ReoV are generally considered non-pathogenic, although members of this family have been proven to cause mild gastroenteritis in young children and may contribute to the development of inflammatory conditions, including Celiac disease. Because of its low pathogenic potential and its ability to efficiently infect and kill transformed cells, the ReoV strain Type 3 Dearing (T3D) is clinical trials as an oncolytic agent. ReoV manifests its oncolytic effects in large part by infecting tumor cells and activating programmed cell death pathways (PCDs). It was previously believed that apoptosis was the dominant PCD pathway triggered by ReoV infection. However, new studies suggest that ReoV also activates other PCD pathways, such as autophagy, pyroptosis, and necroptosis. Necroptosis is a caspase-independent form of PCD reliant on receptor-interacting serine/threonine-protein kinase 3 (RIPK3) and its substrate, the pseudokinase mixed-lineage kinase domain-like protein (MLKL). As necroptosis is highly inflammatory, ReoV-induced necroptosis may contribute to the oncolytic potential of this virus, not only by promoting necrotic lysis of the infected cell, but also by inflaming the surrounding tumor microenvironment and provoking beneficial anti-tumor immune responses. In this review, we summarize our current understanding of the ReoV replication cycle, the known and potential mechanisms by which ReoV induces PCD, and discuss the consequences of non-apoptotic cell death—particularly necroptosis—to ReoV pathogenesis and oncolysis.

In recent years, our understanding of the importance of microorganisms on and within our bodies has been revolutionized by the ability to characterize entire microbial communities. No more so is this true than in cases of disease. Community studies have revealed strong associations between microbial populations and disease states where such concomitance was previously absent from aetiology: including in cancers. The study of viruses, in particular, has benefited from the development of new community profiling techniques and we are now realising that their prominence within our physiology is nearly as broad as the diversity of the organisms themselves. Here, we examine the relationship between viruses and colorectal cancer (CRC), the leading cause of gastrointestinal cancer-related death worldwide. In CRC, viruses have been suggested to be involved in oncogenesis both directly, through infection of our cells, and indirectly, through modulating the composition of bacterial communities. Interestingly though, these characteristics have also led to their examination from another perspective—as options for treatment. Advances in our understanding of molecular and viral biology have caused many to look at viruses as potential modular biotherapeutics, where deleterious characteristics can be tamed and desirable characteristics exploited. In this article, we will explore both of these perspectives, covering how viral infections and involvement in microbiome dynamics may contribute to CRC, and examine ways in which viruses themselves could be harnessed to treat the very condition their contemporaries may have had a hand in creating. [ABSTRACT FROM AUTHOR]

Tigilanol tiglate is an oncolytic small molecule that is undergoing clinical trials. A recent study revealed the capacity of this pyroptosis inducer to elicit hallmarks of immunogenic cell death. In addition, intratumoral injection of tigilanol tiglate can sensitize subcutaneous cancers to subsequent immune checkpoint inhibitors targeting CTLA-4 alone or in combination with PD-1., Competing Interests: J.G.P. is the inventor of patents covering the diagnosis, prognosis, and treatment of cancers, including patents licensed to Turstone Biologics and Therafast Bio. GK has been holding research contracts with Daiichi Sankyo, Eleor, Kaleido, Lytix Pharma, PharmaMar, Osasuna Therapeutics, Samsara Therapeutics, Sanofi, Sutro, Tollys, and Vascage. GK is on the Board of Directors of the Bristol Myers Squibb Foundation France. GK is a scientific co-founder of everImmune, Osasuna Therapeutics, Samsara Therapeutics and Therafast Bio. GK is in the scientific advisory boards of Hevolution, Institut Servier, Longevity Vision Funds and Rejuveron Life Sciences. GK is the inventor of patents covering therapeutic targeting of aging, cancer, cystic fibrosis and metabolic disorders. GK’s wife, Laurence Zitvogel, has held research contracts with Glaxo Smyth Kline, Incyte, Lytix, Kaleido, Innovate Pharma, Daiichi Sankyo, Pilege, Merus, Transgene, 9 m, Tusk and Roche, was on the on the Board of Directors of Transgene, is a cofounder of everImmune, and holds patents covering the treatment of cancer and the therapeutic manipulation of the microbiota. GK’s brother, Romano Kroemer, was an employee of Sanofi and now consults for Boehringer-Ingelheim. The funders had no role in the design of the study; in the writing of the manuscript or in the decision to publish the results., (© 2024 The Author(s). Published with license by Taylor & Francis Group, LLC.)

Immune evasion is an important cancer hallmark and the understanding of its mechanisms has generated successful therapeutic approaches. Induction of immunogenic cell death (ICD) is expected to attract immune cell populations that promote innate and adaptive immune responses. Here, we present a critical advance for our adenovirus-mediated gene therapy approach, where the combined p14ARF and human interferon-β (IFNβ) gene transfer to human melanoma cells led to oncolysis, ICD and subsequent activation of immune cells. Our results indicate that IFNβ alone or in combination with p14ARF was able to induce massive cell death in the human melanoma cell line SK-MEL-147, though caspase 3/7 activation was not essential. In situ gene therapy of s.c. SK-MEL-147 tumors in Nod-Scid mice revealed inhibition of tumor growth and increased survival in response to IFNβ alone or in combination with p14ARF. Emission of critical markers of ICD (exposition of calreticulin, secretion of ATP and IFNβ) was stronger when cells were treated with combined p14ARF and IFNβ gene transfer. Co-culture of previously transduced SK-MEL-147 cells with monocyte-derived dendritic cells (Mo-DCs) derived from healthy donors resulted in increased levels of activation markers HLA-DR, CD80, and CD86. Activated Mo-DCs were able to prime autologous and allogeneic T cells, resulting in increased secretion of IFNγ, TNF-α, and IL-10. Preliminary data showed that T cells primed by Mo-DCs activated with p14ARF+IFNβ-transduced SK-MEL-147 cells were able to induce the loss of viability of fresh non-transduced SK-MEL-147 cells, suggesting the induction of a specific cytotoxic population that recognized and killed SK-MEL-147 cells. Collectively, our results indicate that p14ARF and IFNβ delivered by our adenoviral system induced oncolysis in human melanoma cells accompanied by adaptive immune response activation and regulation.

BackgroundAlthough the naturally occurring reovirus causes only mild symptoms in humans, it shows considerable potential as an oncolytic agent because of its innate ability to target cancer cells. In immunocompromised hosts, however, wild-type reovirus can target healthy tissues, including heart, liver, pancreas and neural structures.MethodsWe characterized an attenuated form of reovirus (AV) derived from a persistently infected cell line through sequence analysis, as well as western blot and in vitro transcription and translation techniques. To examine its pathogenesis and oncolytic potential, AV reovirus was tested on healthy embryonic stem cells, various non-transformed and transformed cell lines, and in severe combined immunodeficiency (SCID) mice with tumour xenografts.ResultsSequence analysis of AV reovirus revealed a premature STOP codon in its sigma 1 attachment protein. Western blot and in vitro translation confirmed the presence of a truncated σ1. In comparison to wild-type reovirus, AV reovirus did not kill healthy stem cells or induce black tail formation in SCID mice. However, it did retain its ability to target cancer cells and reduce tumour size.ConclusionDespite containing a truncated attachment protein, AV reovirus still preferentially targets cancer cells, and compared with wild-type reovirus it shows reduced toxicity when administered to immunodeficient hosts, suggesting the potential use of AV reovirus in combination cancer therapy.

Local immunotherapies such as the intratumoral injection of oncolytic compounds aim at reinstating and enhancing systemic anticancer immune responses. LTX-315 is a first-in-class, clinically evaluated oncolytic peptide-based local immunotherapy that meets these criteria. Here, we show that LTX-401, yet another oncolytic compound designed for local immunotherapy, depicts a similar safety profile and that sequential local inoculation of LTX-401 was able to cure immunocompetent host from subcutaneous MCA205 and TC-1 cancers. Cured animals exhibited long-term immune memory effects that rendered them resistant to rechallenge with syngeneic tumors. Nevertheless, the local treatment with LTX-401 alone had only limited abscopal effects on secondary contralateral lesions. Anticancer effects resulting from single as well as sequential injections of LTX-401 were boosted in combination with PD-1 and CTLA-4 immune checkpoint blockade (ICB), and sequential LTX-401 treatment combined with double ICB exhibited strong abscopal antineoplastic effects on contralateral tumors underlining the potency of this combination therapy.

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

Canine distemper virus (CDV), bearing a close resemblance to measles virus, represents a promising candidate for oncolytic therapy; however, its application and underlying oncolytic mechanisms in canine mammary carcinoma cells remain to be explored. Here, we found that an attenuated canine distemper vaccine strain, CDV‐L, efficiently infected and inhibited the growth of canine mammary tubular adenocarcinoma CIPp cells but not MDCK cells in vitro. Transcriptomic analysis of CDV‐L‐infected CIPp cells revealed substantially differentially expressed genes in apoptotic and NF‐κB signalling pathways. Subsequent validations confirmed that CDV‐L‐induced apoptosis of CIPp cells through the caspase‐8 and caspase‐3 pathway. Identification of phosphorylated‐IκBα, phosphorylated‐p65 and the nuclear translocation of p65 confirmed the activation of the NF‐κB signalling pathway. Inhibition of the NF‐κB pathway abrogated CDV‐L‐induced cleaved‐caspase‐3 and cleaved‐PARP. In a CIPp subcutaneous xenograft mouse model, intratumoural injections of CDV‐L significantly restricted tumour growth without apparent pathology, and virus remained localized within the tumour. Taken altogether, these findings indicate that CDV‐L exerts an antitumour effect in CIPp cells, and that apoptosis and the NF‐κB pathway play essential roles in this process. [ABSTRACT FROM AUTHOR]

Newcastle disease virus (NDV) have shown oncolytic therapeutic efficacy in preclinical study and are currently approved for clinical trials. NDV Anhinga strain which is a mesogenic strain should be classified as lytic strain and has a therapeutic efficacy in hepatocellular cancer. In this study, we evaluated the capacity of NDV Anhinga strain to elicit immune reaction in vivo and the possibility for using as a vaccine vector for expressing tumor therapeutic factors. Interleukin-2 (IL-2) could boost the immune response against the tumor cells. Therefore, we use NDV Anhinga strain as backbone to construct a recombinant virus (NDV/Anh-IL-2) expressing IL-2. The virus growth curve showed that the production of recombinant NDV/Anh-IL-2 was slightly delayed compared to the wild type. The NDV/Anh-IL-2 strain could express soluble IL-2 and effectively inhibit the growth of hepatocellular carcinoma in vivo. 60 days post-treatment, mice which were completely cured by previous treatment were well protected when rechallenged with the same tumor cell. From the H&E-stained sections, intense infiltration of lymphocyte was observed in the NDV Anhinga strain treated group, especially in NDV/Anh-IL-2 group. The NDV Anhinga strain could not only kill the tumor directly, but could also elicit immune reaction and a potent immunological memory when killing tumor in vivo. In conclusion, the Anhinga strain could be an effective vector for tumor therapy; the recombinant NDV/Anh-IL-2 strain expressing soluble IL-2 is a promising candidate for hepatoma therapy.

Over the past century, treatment of malignant tumors of the brain has remained a challenge. Refinements in neurosurgical techniques, discovery of powerful chemotherapeutic agents, advances in radiotherapy, applications of biotechnology, and improvements in methods of targeted delivery have led to some extension of length of survival of glioblastoma patients. Refinements in surgery are mentioned because most of the patients with glioblastoma undergo surgery and many of the other innovative therapies are combined with surgery. However, cure of glioblastoma has remained elusive because it requires complete destruction of the tumor. Radical surgical ablation is not possible in the brain and even a small residual tumor leads to rapid recurrence that eventually kills the patient. Blood-brain barrier (BBB) comprising brain endothelial cells lining the cerebral microvasculature, limits delivery of drugs to the brain. Even though opening of the BBB in tumor core occurs locally, BBB limits systemic chemotherapy especially at the tumor periphery, where tumor cells invade normal brain structure comprising intact BBB. Comprehensive approaches are necessary to gain maximally from promising targeted therapies. Common methods used for critical evaluation of targeted therapies for glioblastoma include: (1) novel methods for targeted delivery of chemotherapy; (2) strategies for delivery through BBB and blood-tumor barriers; (3) innovations in radiotherapy for selective destruction of tumor; (4) techniques for local destruction of tumor; (5) tumor growth inhibitors; (6) immunotherapy; and (7) cell/gene therapies. Suggestions for improvements in glioblastoma therapy include: (1) controlled targeted delivery of anticancer therapy to glioblastoma through the BBB using nanoparticles and monoclonal antibodies; (2) direct introduction of genetically modified bacteria that selectively destroy cancer cells but spare the normal brain into the remaining tumor after resection; (3) use of better animal models for preclinical testing; and (4) personalized/precision medicine approaches to therapy in clinical trials and translation into practice of neurosurgery and neurooncology. Advances in these techniques suggest optimism for the future management of glioblastoma.

Oncolytic adenoviruses (Ads) are cancer selective tumoricidal agents; however their mechanism of Ad-mediated cancer cell lysis, or oncolysis, remains undefined. This report focuses upon the autophagy mediator c-JUN n-terminal kinase (JNK) and its effects upon Ad oncolysis and replication. Previously, E1b-deleted Ads have been used to treat several hundred cancer patients with limited clinical efficacy. We hypothesize that by studying the potential interactions between E1b and JNK, mechanisms to improve oncolytic Ad design and cancer therapeutic efficacy may be elucidated. To test this hypothesis, E1b was selectively deleted from the Ad genome. These studies indicated that Ads encoding E1b induced JNK phosphorylation predominately occurred via E1b-19K. The expression of another crucial Ad gene E1a was then overexpressed by the CMV promoter via the replication competent Ad vector Adhz69; these data indicated that E1A also induced JNK phosphorylation. To assess the effects of host cell JNK expression upon Ad oncolysis and replication, siRNA targeting JNK1 and JNK2 (JNK1/2) were utilized. The oncolysis and replication of the E1b-19K wild-type Ads Ad5 and Adhz63 were significantly attenuated following JNK1/2 siRNA transfection. However the oncolytic effects and replication of the E1b-19K deleted Ad Adhz60 were not altered by JNK1/2 siRNA transfection, further implicating the crucial role of E1b-19K for Ad oncolysis and replication via JNK phosphorylation. This study has demonstrated for the first time that JNK is an intriguing molecular marker associated with enhanced Ad virotherapy efficacy, influencing future Ad vector design. [ABSTRACT FROM AUTHOR]

Over the past century, treatment of malignant tumors of the brain has remained a challenge. Refinements in neurosurgical techniques, discovery of powerful chemotherapeutic agents, advances in radiotherapy, applications of biotechnology, and improvements in methods of targeted delivery have led to some extension of length of survival of glioblastoma patients. Refinements in surgery are mentioned because most of the patients with glioblastoma undergo surgery and many of the other innovative therapies are combined with surgery. However, cure of glioblastoma has remained elusive because it requires complete destruction of the tumor. Radical surgical ablation is not possible in the brain and even a small residual tumor leads to rapid recurrence that eventually kills the patient. Blood-brain barrier (BBB) comprising brain endothelial cells lining the cerebral microvasculature, limits delivery of drugs to the brain. Even though opening of the BBB in tumor core occurs locally, BBB limits systemic chemotherapy especially at the tumor periphery, where tumor cells invade normal brain structure comprising intact BBB. Comprehensive approaches are necessary to gain maximally from promising targeted therapies. Common methods used for critical evaluation of targeted therapies for glioblastoma include: (1) novel methods for targeted delivery of chemotherapy; (2) strategies for delivery through BBB and blood-tumor barriers; (3) innovations in radiotherapy for selective destruction of tumor; (4) techniques for local destruction of tumor; (5) tumor growth inhibitors; (6) immunotherapy; and (7) cell/gene therapies. Suggestions for improvements in glioblastoma therapy include: (1) controlled targeted delivery of anticancer therapy to glioblastoma through the BBB using nanoparticles and monoclonal antibodies; (2) direct introduction of genetically modified bacteria that selectively destroy cancer cells but spare the normal brain into the remaining tumor after resection; (3) use of better animal models for preclinical testing; and (4) personalized/precision medicine approaches to therapy in clinical trials and translation into practice of neurosurgery and neurooncology. Advances in these techniques suggest optimism for the future management of glioblastoma. [ABSTRACT FROM AUTHOR]

Genetic replacement of adenoviral fiber knobs by ligands that enable tumor specific targeting of oncolytic adenoviruses is challenging because the fiber knob contributes to virus assembly. Here, we present a novel concept by describing stable recombinant adenoviruses with tumor specific infection mode. The fiber knob was replaced by endosialidaseNF (endoNF), the tailspike protein of bacteriophage K1F. EndoNF recognizes polysialic acid, an oncofetal antigen characteristic for high malignant tumors of neuroendocrine origin. An intramolecular chaperone contained in endoNF warrants folding and compensates for the knob function in virus assembly. Obtained recombinant viruses demonstrated polysialic acid dependent infection modes, strong oncolytic capacity with polysialic acid positive cells in culture and a high potential to inhibit tumor growth in a therapeutic mouse model of subcutaneous neuroblastoma. With a single genetic manipulation we achieved ablation of the fiber knob, introduction of a tumor specific ligand, and folding control over the chimeric fiber construct. [ABSTRACT FROM AUTHOR]

Acute reoviral infection has been extensively studied given the virus's propensity to target malignant cells and activate caspase-3 mediated apoptosis. Reovirus infection of malignant N1E-115 mouse neuroblastoma cells led to significant increased expression of importin-β and exportin-5 mRNAs (qRTPCR) and proteins (immunohistochemistry) which was partially blocked by small interfering LNA oligomers directed against the reoviral genome. Co-expression analysis showed that the N1E-115 cells that contained reoviral capsid protein had accumulated importin-β and exportin-5, as well as activated caspase 3. Reoviral oncolysis using a syngeneic mouse model of multiple myeloma similarly induced a significant increase in importin-β and exportin-5 proteins that were co-expressed with reoviral capsid protein and caspase-3. Apoptotic proteins (BAD, BIM, PUMA, NOXA, BAK, BAX) were increased with infection and co-localized with reoviral capsid protein. Surprisingly the anti-apoptotic MCL1 and bcl2 were also increased and co-localized with the capsid protein suggesting that it was the balance of pro-apoptotic molecules that correlated with activation of caspase-3. In summary, productive reoviral infection is strongly correlated with elevated importin-β and exportin-5 levels which may serve as biomarkers of the disease in clinical specimens. [ABSTRACT FROM AUTHOR]

Conditionally replicative adenoviruses (CRAds) replicate poorly in murine cancer cells; however, E1b-deleted CRAds may replicate effectively in HPV16-E6/E7-positive murine cancer cells (TC-1). The HPV16 E7 open reading frame encodes functions analogous to these deleted adenovirus E1 proteins. In this study, an E1b-deleted CRAd (Adhz60) was evaluated for its ability to replicate and induce oncolysis in TC-1 cells. Adhz60-mediated oncolysis was similar in TC-1 and HeLa cells. Productive viral replication was evident based on expression of E1A and hexon, production of infectious virus progeny, and Adhz60-induced apoptosis. The results suggest that TC-1 murine cancer cells allow Adhz60 replication and oncolysis. [ABSTRACT FROM AUTHOR]

Cancer is the leading cause of disease-related death in companion animals such as dogs and cats. Despite recent progress in the diagnosis and treatment of advanced canine and feline cancer, overall patient treatment outcome has not been substantially improved. Virotherapy using oncolytic viruses is one promising new strategy for cancer therapy. Oncolytic viruses (OVs) preferentially infect and lyse cancer cells, without causing excessive damage to surrounding healthy tissue, and initiate tumor-specific immunity. The current review describes the use of different oncolytic viruses for cancer therapy and their application to canine and feline cancer.

Starvation sensitizes tumor cells to chemotherapy while protecting normal cells at the same time, a phenomenon defined as differential stress resistance. In this study, we analyzed if starvation would also increase the oncolytic potential of an oncolytic measles vaccine virus (MeV-GFP) while protecting normal cells against off-target lysis. Human colorectal carcinoma (CRC) cell lines as well as human normal colon cell lines were subjected to various starvation regimes and infected with MeV-GFP. The applied fasting regimes were either short-term (24 h pre-infection) or long-term (24 h pre- plus 96 h post-infection). Cell-killing features of (i) virotherapy, (ii) starvation, as well as (iii) the combination of both were analyzed by cell viability assays and virus growth curves. Remarkably, while long-term low-serum, standard glucose starvation potentiated the efficacy of MeV-mediated cell killing in CRC cells, it was found to be decreased in normal colon cells. Interestingly, viral replication of MeV-GFP in CRC cells was decreased in long-term-starved cells and increased after short-term low-glucose, low-serum starvation. In conclusion, starvation-based virotherapy has the potential to differentially enhance MeV-mediated oncolysis in the context of CRC cancer patients while protecting normal colon cells from unwanted off-target effects.

Mammalian reovirus is a double-stranded RNA virus that selectively infects and lyses transformed cells, making it an attractive oncolytic agent. Despite clinical evidence for anti-tumor activity, its efficacy as a stand-alone therapy remains to be improved. The success of future trials can be greatly influenced by the identification and the regulation of the cellular pathways that are important for reovirus replication and oncolysis. Here, we demonstrate that reovirus induces autophagy in several cell lines, evident from the formation of Atg5-Atg12 complexes, microtubule-associated protein 1 light chain 3 (LC3) lipidation, p62 degradation, the appearance of acidic vesicular organelles, and LC3 puncta. Furthermore, in electron microscopic images of reovirus-infected cells, autophagosomes were observed without evident association with viral factories. Using UV-inactivated reovirus, we demonstrate that a productive reovirus infection facilitates the induction of autophagy. Importantly, knock-out cell lines for specific autophagy-related genes revealed that the expression of Atg3 and Atg5 but not Atg13 facilitates reovirus replication. These findings highlight a central and Atg13-independent role for the autophagy machinery in facilitating reovirus infection and contribute to a better understanding of reovirus-host interactions. [ABSTRACT FROM AUTHOR]

Adenovirus-based vectors comprise the most frequently used vector type in clinical studies to date. Both intense lab research and insights from the clinical trials reveal the importance of a comprehensive understanding of vector-host interactions. Especially for systemic intravenous adenovirus vector delivery, it is paramount to develop safe and efficacious vectors. Very early vector-host interactions that take place in blood long before the first cell is being transduced are phenomena triggered by the surface, shape, and size of the adenovirus vector particles. Not surprisingly, a multitude of different technologies ranging from genetics to chemistry has been developed to alter the adenovirus vector surface. In this review, we discuss the most important technologies and evaluate them for their suitability to overcome hurdles imposed by early vector-host interactions. [ABSTRACT FROM AUTHOR]

Reovirus is under development as a therapeutic for numerous types of cancer. In contrast to other oncolytic viruses, the safety and efficacy of reovirus have not been improved through genetic manipulation. Here, we tested the oncolytic capacity of recombinant strains (rs) of prototype reovirus laboratory strains T1L and T3D (rsT1L and rsT3D, respectively) in a panel of non-small cell lung cancer (NSCLC) cell lines. We found that rsT1L was markedly more cytolytic than rsT3D in the large cell carcinoma cell lines tested, whereas killing of adenocarcinoma cell lines was comparable between rsT1L and rsT3D. Importantly, non-recombinant T1L and T3D phenocopied the kinetics and magnitude of cell death induced by recombinant strains. We identified gene segments L2, L3, and M1 as viral determinants of strain-specific differences cell killing of the large cell carcinoma cell lines. Together, these results indicate that recombinant reoviruses recapitulate the cell killing properties of non-recombinant, tissue culture-passaged strains. These studies provide a baseline for the use of reverse genetics with the specific objective of engineering more effective reovirus oncolytics. This work raises the possibility that type 1 reoviruses may have the capacity to serve as more effective oncolytics than type 3 reoviruses in some tumor types. [ABSTRACT FROM AUTHOR]

Newcastle disease virus (NDV) have shown oncolytic therapeutic efficacy in preclinical studies and are currently proved for clinical trials. We have previously reported, for the first time, NDV Anhinga strain has an efficient cancer therapeutic efficacy in hepatoma. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) functions as a cytokine to selectively kill various cancer cells without toxicity to most normal cells. Numerous studies have demonstrated the potential use of recombinant soluble TRAIL as a cancer therapeutic agent. In this study, we have showed administration of a recombinant NDV Anhinga strain expressing soluble TRAIL (NDV/Anh-TRAIL) results in an efficient suppression of hepatocellular carcinoma without significant toxicity. The results show that recombinant NDV Anhinga strain expressing soluble TRAIL is a promising candidate for hepatoma therapy. [ABSTRACT FROM AUTHOR]

Histiocytic sarcoma represents a rare malignant tumour with a short survival time, indicating the need of novel treatment strategies including oncolytic virotherapy. The underlying molecular mechanisms of viral oncolysis are largely unknown. As cancer in companion animals shares striking similarities with human counterparts, we chose a permanent canine histiocytic sarcoma cell line (DH82 cells) to identify global transcriptome changes following infection with canine distemper virus (CDV), a paramyxovirus closely related to human measles virus. Microarray analysis identified 3054 differentially expressed probe sets (DEPs), encoding for 892 up- and 869 down-regulated unique canine genes, respectively, in DH82 cells persistently infected with the vaccine strain Onderstepoort of CDV (DH82-Ond-pi), compared to non-infected DH82 cells. Up-regulated genes were predominantly related to immune processes, as demonstrated by functional enrichment analysis. Moreover, there was substantial enrichment of genes characteristic for classically activated M1 and alternatively activated M2 macrophages in DH82-Ond-pi; however, significant polarization into either of both categories was lacking. 'Angiogenesis' was the dominant enriched functional term for the down-regulated genes, highlighting decreased blood vessel generation as a potential mechanism of paramyxovirus-induced oncolysis in DH82 cells. The anti-angiogenic effect of infection was verified by immunohistochemistry, which revealed a lower blood vessel density in an in vivo mouse model, xenotransplanted with DH82-Ond-pi, compared to mice transplanted with non-infected DH82 cells. Reduction in angiogenesis appears to be an important oncolytic mechanism of CDV in DH82 cells, suggesting that similar mechanisms might account for human histiocytic sarcoma and maybe other tumours in conjunction with measles virus. [ABSTRACT FROM AUTHOR]

Background/Aims: The association between postoperative infection and prolonged survival in high-grade glioma is still a matter of debate. Previously we demonstrated that the intracerebral (i.c.) injection of heat-inactivated staphylococcal epitopes (HISE) resulted in a well-defined infux of immunocompetent cells across the blood-brain barrier. The present study investigated the potential antitumoral effect of HISE-immunostimulation in an experimental glioma model. Methods: Wistar rats were intracerebrally implanted with 9L gliosarcoma cells (n=6), 9L cells mixed with HISE (n=12), or phosphate buffered saline (n=4). Tumor growth was measured by serial magnetic resonance imaging (MRI). After death due to the tumor burden, the brains were histopathologically assessed for inflammation and oncolysis. A toxicity assay was performed to quantify potential impairment of HISE on tumor cell growth in vitro. Results: Animals treated by HISE showed a significant increase in average survival and even complete regression of an already established mass in one case. Naïve 9L gliosarcomas failed to recruit significant numbers of systemic immune cells. In contrast, concomitant intracerebral HISE inoculation lead to a oncolysis and a distinct peri- and intratumoral infiltration of macrophages, CD8 and CD4 co-expressing T-lymphocytes in two thirds of the tumor-bearing animals. The toxicity screening showed HISE-mediated oncolysis to be ineffective ex vivo. Conclusion: This study describes a novel approach for combatting malignant glioma using inactivated staphylococci as potent immunomodulators. Our results provide an outline for investigating the strategic potential of bacteria as emerging future therapeutics.

Oncolytic viruses show intriguing potential as cancer therapeutic agents. These viruses are capable of selectively targeting and killing cancerous cells while leaving healthy cells largely unaffected. The use of oncolytic viruses for cancer treatments in selected circumstances has recently been approved by the Food and Drug Administration (FDA) of the US and work is progressing on engineering viral vectors for enhanced selectivity, efficacy and safety. However, a better fundamental understanding of tumour and viral biology is essential for the continued advancement of the oncolytic field. This knowledge will not only help to engineer more potent and effective viruses but may also contribute to the identification of biomarkers that can determine which patients will benefit most from this treatment. A mechanistic understanding of the overlapping activity of viral and standard chemotherapeutics will enable the development of better combinational approaches to improve patient outcomes. In this review, we will examine each of the factors that contribute to productive viral infections in cancerous cells versus healthy cells. Special attention will be paid to reovirus as it is a well-studied virus and the only wild-type virus to have received orphan drug designation by the FDA. Although considerable insight into reoviral biology exists, there remain numerous deficiencies in our understanding of the factors regulating its successful oncolytic infection. Here we will discuss what is known to regulate infection as well as speculate about potential new mechanisms that may enhance successful replication. A joint appreciation of both tumour and viral biology will drive innovation for the next generation of reoviral mediated oncolytic therapy.

Current oncolytic virotherapy strategies are based in the accumulated understanding of the common molecular mechanisms displayed during cell transformation and viral infection, like cell cycle and apoptosis deregulations. Oncolytic virotherapy aims to achieve a strong cytolytic effect, highly restricted to transformed cells. Here, we describe the oncolytic virotherapy defined as the use of viruses like antitumor agents (wild and gene-modified oncolytic viruses) and the developed strategies to increase antitumor efficacy and safety. In addition, we discuss the advances and challenges concerning the use virotherapy in animal models and clinical trials. Some clinical trials of virotherapy have demonstrated promising results, particularly when combined with standard antineoplastic therapies. These preliminary accomplishments are opening the field for more research in several aspects, like vector modifications, pharmacodynamics, biosafety, new clinical applications, etc.

The strong dependency of almost all malignant tumors on methionine potentially offers a pathway for cancer treatment. We engineer an attenuated strain of Salmonella typhimurium to overexpress an L-methioninase with the aim of specifically depriving tumor tissues of methionine. The engineered microbes target solid tumors and induce a sharp regression in several very divergent animal models of human carcinomas, cause a significant decrease in tumor cell invasion, and essentially eliminate the growth and metastasis of these tumors. RNA sequencing analyses reveal that the engineered Salmonella reduce the expression of a series of genes promoting cell growth, cell migration, and invasion. These findings point to a potential treatment modality for many metastatic solid tumors, which warrants further tests in clinical trials., Competing Interests: Declaration of interests Author Dr. Allan Zhao is a shareholder of Guangzhou Sinogen Pharmaceutical, Ltd. This work has multiple patents related to the data presented in this paper: US9439934B1, US9816083B2, US11318172B2., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Together with an anti-tumor immune response, oncolysis using a recombinant viral vector promises to eliminate cancer cells by both gene transfer and host-mediated functions. In this study we explore oncolysis induced by nonreplicating adenoviral vectors used for p14 ARF and interferon-β (hIFNβ) gene transfer in human melanoma cell lines, revealing an unexpected role for p14 ARF in promoting cellular responses predictive of immune stimulation. Oncolysis was confirmed when UACC-62 (p53 wild-type) cells succumbed upon p14 ARF gene transfer in vitro , whereas SK-Mel-29 (p53-mutant) benefitted from its combination with hIFNβ. In the case of UACC-62, in situ gene therapy in nude mice yielded reduced tumor progression in response to the p14 ARF and hIFNβ combination. Potential for immune stimulation was revealed where p14 ARF gene transfer in vitro was sufficient to induce emission of immunogenic cell death factors in UACC-62 and upregulate pro-immune genes, including IRF1, IRF7, IRF9, ISG15, TAP-1, and B2M. In SK-Mel-29, p14 ARF gene transfer induced a subset of these factors. hIFNβ was, as expected, sufficient to induce these immune-stimulating genes in both cell lines. This work is a significant advancement for our melanoma gene therapy strategy because we revealed not only the induction of oncolysis, but also the potential contribution of p14 ARF to immune stimulation.

Oncolytic adenoviruses (Ads) have been shown to be safe and have great potential for the treatment of solid tumors. However, the therapeutic efficacy of Ads is antagonized by limited spread within solid tumors. To develop Ads with enhanced spread, viral particles of an E1-wildtype Ad5 dl309 was repeatedly treated with UV type C irradiation and selected for the efficient replication and release from cancer cells. After 72 cycles of treatment and cancer selection, AdUV was isolated. This vector has displayed many favorable characteristics for oncolytic therapy. AdUV was shown to lyse cancer cells more effectively than both E1-deleted and E1-wildtype Ads. This enhanced cancer cell lysis appeared to be related to increased AdUV replication in and release from infected cancer cells. AdUV-treated A549 cells displayed greater expression of the autophagy marker LC3-II during oncolysis and formed larger viral plaques upon cancer cell monolayers, indicating increased virus spread among cancer cells. This study indicates the potential of this approach of irradiation of entire viral particles for the development of oncolytic viruses with designated therapeutic properties. [ABSTRACT FROM AUTHOR]