SnapShot: Cancer Immunotherapy with Oncolytic Viruses.

Oncolytic viruses (OVs) preferentially infect and kill cancer cells without harming normal cells. OVs can revert cancer-associated immune suppression and initiate clinically meaningful antitumor immune responses. OVs and their resultant immunological events can act at both primary and metastatic sites. Thus, OVs can be exploited for cancer gene therapies and immunotherapies alone or in combination with other interventions, including immune checkpoint blockade.

Oncolytic α-herpesvirus and myeloid-tropic cytomegalovirus cooperatively enhance systemic antitumor responses.

Oncolytic virotherapy aims to activate host antitumor immunity. In responsive tumors, intratumorally injected herpes simplex viruses (HSVs) have been shown to lyse tumor cells, resulting in local inflammation, enhanced tumor antigen presentation, and boosting of antitumor cytotoxic lymphocytes. In contrast to HSV, cytomegalovirus (CMV) is nonlytic and reprograms infected myeloid cells, limiting their antigen-presenting functions and protecting them from recognition by natural killer (NK) cells. Here, we show that when co-injected into mouse tumors with an oncolytic HSV, mouse CMV (mCMV) preferentially targeted tumor-associated myeloid cells, promoted the local release of proinflammatory cytokines, and enhanced systemic antitumor immune responses, leading to superior control of both injected and distant contralateral tumors. Deletion of mCMV genes m06, which degrades major histocompatibility complex class I (MHC class I), or m144, a viral MHC class I homolog that inhibits NK activation, was shown to diminish the antitumor activity of the HSV/mCMV combination. However, an mCMV recombinant lacking the m04 gene, which escorts MHC class I to the cell surface, showed superior HSV adjuvanticity. CMV is a potentially promising agent with which to reshape and enhance antitumor immune responses following oncolytic HSV therapy.

Reshaping the tumor microenvironment of cold soft-tissue sarcomas with oncolytic viral therapy: a phase 2 trial of intratumoral JX-594 combined with avelumab and low-dose cyclophosphamide.

Most soft-tissue sarcomas (STS) exhibit an immunosuppressive tumor microenvironment (TME), leading to resistance against immune checkpoint inhibitors (ICIs) and limited therapeutic response. Preclinical data suggest that oncolytic viral therapy can remodel the TME, facilitating T cell accumulation and enhancing the immunogenicity of these tumors.We conducted the METROMAJX, a phase II clinical trial, to investigate the combination of JX-594, an oncolytic vaccinia virus engineered for selective tumor cell replication, with metronomic cyclophosphamide and the PD-L1 inhibitor avelumab in patients with advanced, 'cold' STS, characterized by an absence of tertiary lymphoid structures. The trial employed a two-stage Simon design. JX-594 was administered intratumorally at a dose of 1.109 pfu every 2 weeks for up to 4 intra-tumoral administrations. Cyclophosphamide was given orally at 50 mg twice daily in a week-on, week-off schedule, and avelumab was administered at 10 mg/kg biweekly. The primary endpoint was the 6-month non-progression rate.Fifteen patients were enrolled, with the most frequent toxicities being grade 1 fatigue and fever. Fourteen patients were assessable for efficacy analysis. At 6 months, only one patient remained progression-free, indicating that the trial did not meet the first stage endpoint of Simon's design. Analysis of sequential tissue biopsies and plasma samples revealed an increase in CD8 density and upregulation of immune-related protein biomarkers, including CXCL10.Intra-tumoral administration of JX-594 in combination with cyclophosphamide and avelumab is safe and capable of modulating the TME in cold STS. However, the limited efficacy observed warrants further research to define the therapeutic potential of oncolytic viruses, particularly in relation to specific histological subtypes of STS.

Long-term activation of anti-tumor immunity in pancreatic cancer by a p53-expressing telomerase-specific oncolytic adenovirus.

BACKGROUND: Pancreatic cancer is an aggressive, immunologically "cold" tumor. Oncolytic virotherapy is a promising treatment to overcome this problem. We developed a telomerase-specific oncolytic adenovirus armed with p53 gene (OBP-702). METHODS: We investigated the efficacy of OBP-702 for pancreatic cancer, focusing on its long-term effects via long-lived memory CD8 + T cells including tissue-resident memory T cells (TRMs) and effector memory T cells (TEMs) differentiated from effector memory precursor cells (TEMps). RESULTS: First, in vitro, OBP-702 significantly induced adenosine triphosphate (ATP), which is important for memory T cell establishment. Next, in vivo, OBP-702 local treatment to murine pancreatic PAN02 tumors increased TEMps via ATP induction from tumors and IL-15Rα induction from macrophages, leading to TRM and TEM induction. Activation of these memory T cells by OBP-702 was also maintained in combination with gemcitabine+nab-paclitaxel (GN) in a PAN02 bilateral tumor model, and GN + OBP-702 showed significant anti-tumor effects and increased TRMs in OBP-702-uninjected tumors. Finally, in a neoadjuvant model, in which PAN02 cells were re-inoculated after resection of treated-PAN02 tumors, GN + OBP-702 provided long-term anti-tumor effects even after tumor resection. CONCLUSION: OBP-702 can be a long-term immunostimulant with sustained anti-tumor effects on immunologically cold pancreatic cancer.

Vesicular Stomatitis Virus (VSV) G Glycoprotein Can Be Modified to Create a Her2/Neu-Targeted VSV That Eliminates Large Implanted Mammary Tumors.

Viral oncolytic immunotherapy is a nascent field that is developing tools to direct the immune system to find and eliminate cancer cells. Safety is improved by using cancer-targeted viruses that infect or grow poorly on normal cells. The recent discovery of the low-density lipoprotein (LDL) receptor as the major vesicular stomatitis virus (VSV) binding site allowed for the creation of a Her2/neu-targeted replicating recombinant VSV (rrVSV-G) by eliminating the LDL receptor binding site in the VSV-G glycoprotein (gp) and adding a sequence coding for a single chain antibody (SCA) to the Her2/neu receptor. The virus was adapted by serial passage on Her2/neu-expressing cancer cells resulting in a virus that yielded a 15- to 25-fold higher titer following in vitro infection of Her2/neu+-expressing cell lines than that of Her2/neu-negative cells (~1 × 108/mL versus 4 × 106 to 8 × 106/mL). An essential mutation resulting in a higher titer virus was a threonine-to-arginine change that produced an N-glycosylation site in the SCA. Infection of Her2/neu+ subcutaneous tumors yielded >10-fold more virus on days 1 and 2 than Her2/neu- tumors, and virus production continued for 5 days in Her2/neu+ tumors compared with 3 days that of 3 days in Her2/neu- tumors. rrVSV-G cured 70% of large 5-day peritoneal tumors compared with a 10% cure by a previously targeted rrVSV with a modified Sindbis gp. rrVSV-G also cured 33% of very large 7-day tumors. rrVSV-G is a new targeted oncolytic virus that has potent antitumor capabilities and allows for heterologous combination with other targeted oncolytic viruses. IMPORTANCE A new form of vesicular stomatitis virus (VSV) was created that specifically targets and destroys cancer cells that express the Her2/neu receptor. This receptor is commonly found in human breast cancer and is associated with a poor prognosis. In laboratory tests using mouse models, the virus was highly effective at eliminating implanted tumors and creating a strong immune response against cancer. VSV has many advantages as a cancer treatment, including high levels of safety and efficacy and the ability to be combined with other oncolytic viruses to enhance treatment results or to create an effective cancer vaccine. This new virus can also be easily modified to target other cancer cell surface molecules and to add immune-modifying genes. Overall, this new VSV is a promising candidate for further development as an immune-based cancer therapy.

Exploration of the Delivery of Oncolytic Newcastle Disease Virus by Gelatin Methacryloyl Microneedles.

Oncolytic Newcastle disease virus is a new type of cancer immunotherapy drug. This paper proposes a scheme for delivering oncolytic viruses using hydrogel microneedles. Gelatin methacryloyl (GelMA) was synthesized by chemical grafting, and GelMA microneedles encapsulating oncolytic Newcastle disease virus (NDV) were prepared by micro-molding and photocrosslinking. The release and expression of NDV were tested by immunofluorescence and hemagglutination experiments. The experiments proved that GelMA was successfully synthesized and had hydrogel characteristics. NDV was evenly dispersed in the allantoic fluid without agglomeration, showing a characteristic virus morphology. NDV particle size was 257.4 ± 1.4 nm, zeta potential was -13.8 ± 0.5 mV, virus titer TCID50 was 107.5/mL, and PFU was 2 × 107/mL, which had a selective killing effect on human liver cancer cells in a dose and time-dependent manner. The NDV@GelMA microneedles were arranged in an orderly cone array, with uniform height and complete needle shape. The distribution of virus-like particles was observed on the surface. GelMA microneedles could successfully penetrate 5% agarose gel and nude mouse skin. Optimal preparation conditions were freeze-drying. We successfully prepared GelMA hydrogel microneedles containing NDV, which could effectively encapsulate NDV but did not detect the release of NDV.

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

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

Evaluation of a Novel Oncolytic Adenovirus Silencing SYVN1.

Oncolytic adenoviruses are promising new anticancer agents. To realize their full anticancer potential, they are being engineered to express therapeutic payloads. Tumor suppressor p53 function contributes to oncolytic adenovirus activity. Many cancer cells carry an intact TP53 gene but express p53 inhibitors that compromise p53 function. Therefore, we hypothesized that oncolytic adenoviruses could be made more effective by suppressing p53 inhibitors in selected cancer cells. To investigate this concept, we attenuated the expression of the established p53 inhibitor synoviolin (SYVN1) in A549 lung cancer cells by RNA interference. Silencing SYVN1 inhibited p53 degradation, thereby increasing p53 activity, and promoted adenovirus-induced A549 cell death. Based on these observations, we constructed a new oncolytic adenovirus that expresses a short hairpin RNA against SYVN1. This virus killed A549 cells more effectively in vitro and inhibited A549 xenograft tumor growth in vivo. Surprisingly, increased susceptibility to adenovirus-mediated cell killing by SYVN1 silencing was also observed in A549 TP53 knockout cells. Hence, while the mechanism of SYVN1-mediated inhibition of adenovirus replication is not fully understood, our results clearly show that RNA interference technology can be exploited to design more potent oncolytic adenoviruses.

An Ion-Enhanced Oncolytic Virus-Like Nanoparticle for Tumor Immunotherapy.

T lymphocytes (T cells) are essential for tumor immunotherapy. However, the insufficient number of activated T cells greatly limits the efficacy of tumor immunotherapy. Herein, we proposed an oncolytic virus-mimicking strategy to enhance T cell recruitment and activation for tumor treatment. We constructed an oncolytic virus-like nanoplatform (PolyIC@ZIF-8) that was degraded in the acidic tumor environment to release PolyIC and Zn2+ . The released PolyIC exhibited an oncolytic virus-like function that induced tumor cell apoptosis and promoted T cell recruitment and activation through a tumor antigen-dependent manner. More importantly, the released Zn2+ not only enhanced T cell recruitment by inducing CXCL9/10/11 expression but also promoted T cell activation to increase interferon-γ (INF-γ) expression by inducing the phosphorylation of ZAP-70 via a tumor antigen-independent manner. This Zn2+ -enhanced oncolytic virus-mimicking strategy provides a new approach for tumor immunotherapy.

Oncolytic Adenovirus Armed with BiTE, Cytokine, and Checkpoint Inhibitor Enables CAR T Cells to Control the Growth of Heterogeneous Tumors.

No single cancer immunotherapy will likely defeat all evasion mechanisms of solid tumors, including plasticity of tumor antigen expression and active immune suppression by the tumor environment. In this study, we increase the breadth, potency, and duration of anti-tumor activity of chimeric antigen receptor (CAR) T cells using an oncolytic virus (OV) that produces cytokine, checkpoint blockade, and a bispecific tumor-targeted T cell engager (BiTE) molecule. First, we constructed a BiTE molecule specific for CD44 variant 6 (CD44v6), since CD44v6 is widely expressed on tumor but not normal tissue, and a CD44v6 antibody has been safely administered to cancer patients. We then incorporated this BiTE sequence into an oncolytic-helper binary adenovirus (CAdDuo) encoding an immunostimulatory cytokine (interleukin [IL]-12) and an immune checkpoint blocker (PD-L1Ab) to form CAdTrio. CD44v6 BiTE from CAdTrio enabled HER2-specific CAR T cells to kill multiple CD44v6+ cancer cell lines and to produce more rapid and sustained disease control of orthotopic HER2+ and HER2-/- CD44v6+ tumors than any component alone. Thus, the combination of CAdTrio with HER2.CAR T cells ensures dual targeting of two tumor antigens by engagement of distinct classes of receptor (CAR and native T cell receptor [TCR]), and significantly improves tumor control and survival.

Bluetongue Viruses Act as Novel Oncolytic Viruses to Effectively Inhibit Human Renal Cancer Cell Growth In Vitro and In Vivo.

BACKGROUND The bluetongue virus (BTV) is the prototype virus in the genus Orbivirus within the family Reoviridae. Recent studies indicate that BTVs are capable of infecting and selectively lysing human hepatic carcinoma cells (Hep-3B) and prostate carcinoma cells (pc-3). This study was designed to evaluate the oncolytic potential of BTV in experimental models of human renal cancer in vitro and in vivo. MATERIAL AND METHODS Five human renal cancer cell lines, ACHN, CAKI-1, OS-RC-2, 786-O, and A498, were used in this study to analyze BTV replication. These cells were lysed by oncolysis compared to normal control. Xenograft models were used to assess the efficacy and toxicity of BTVs in vivo. Data were analyzed by one-way ANOVA or two-sided unpaired t tests. RESULTS The results showed HPTEC cells to be relatively resistant to cytotoxic effects of BTVs and exhibited normal growth rate even at high dose of BTVs. Nonetheless, the renal cancer cells showed a remarkably higher sensitivity to BTVs. Moreover, the ultramicroscopic subcellular changes were also detected in the renal cells. The viral particles were observed in all the RCC cell lines, but not in HPTEC cells. Intratumoral injections of BTVs significantly decreased the tumor volume as compared to animals that received no virus treatment. Infection with BTVs significantly increased the percentage of apoptotic renal cancer cells but not the HPTEC cells. Moreover, BTV triggered apoptosis in renal cancer cells via a mitochondria-mediated pathway. CONCLUSIONS This study for the first time demonstrated the oncolytic potential of BTV in experimental models of human renal cancer. BTV exhibits the potential to inhibit human renal cancer cell growth in vitro and in vivo.

Targeting aerobic glycolysis by dichloroacetate improves Newcastle disease virus-mediated viro-immunotherapy in hepatocellular carcinoma.

BACKGROUND: Oncolytic viro-immunotherapy holds promise for cancer treatment. While immune activation can be robustly triggered by oncolytic viruses, negative feedback is often upregulated in the tumour microenvironment (TME). Lactate accumulation, signal transducer and activator of transcription 3 (STAT3) activation, indoleamine 2,3-dioxygenase 1 (IDO1) expression, and myeloid-derived suppressor cell (MDSC) infiltration coordinate to shape the immunosuppressive TME. METHODS: Representative hepatocellular carcinoma (HCC) cell lines and HCC-bearing mice were treated with oncolytic Newcastle disease virus (NDV), alone or in combination with dichloroacetate (DCA, a pyruvate dehydrogenase kinase (PDK) inhibitor). RESULTS: We found that infection with oncolytic NDV led to significant induction of the aforementioned suppressive factors. Interestingly, DCA significantly reduced lactate release, STAT3 activation, IDO1 upregulation, and MDSC infiltration in NDV-treated HCC. Consequently, DCA significantly enhanced the antitumour immune responses, leading to improved antitumour efficacy and prolonged survival in mouse models of ascitic and subcutaneous HCC. Furthermore, DCA increased NDV replication in a PDK-1-dependent manner in HCC. CONCLUSIONS: Targeting aerobic glycolysis by DCA improves NDV-mediated viro-immunotherapy in HCC by mitigating immune negative feedback and promoting viral replication. These findings provide a rationale for targeting reprogrammed metabolism together with oncolytic virus-mediated viro-immunotherapy for HCC treatment.

Xenoantigen-Dependent Complement-Mediated Neutralization of Lymphocytic Choriomeningitis Virus Glycoprotein-Pseudotyped Vesicular Stomatitis Virus in Human Serum.

Neutralization by antibodies and complement limits the effective dose and thus the therapeutic efficacy of oncolytic viruses after systemic application. We and others previously showed that pseudotyping of oncolytic rhabdoviruses such as maraba virus and vesicular stomatitis virus (VSV) with the lymphocytic choriomeningitis virus glycoprotein (LCMV-GP) results in only a weak induction of neutralizing antibodies. Moreover, LCMV-GP-pseudotyped VSV (VSV-GP) was significantly more stable in normal human serum (NHS) than VSV. Here, we demonstrate that depending on the cell line used for virus production, VSV-GP showed different complement sensitivities in nonimmune NHS. The NHS-mediated titer reduction of VSV-GP was dependent on activation of the classical complement pathway, mainly by natural IgM antibodies against xenoantigens such as galactose-α-(1,3)-galactose (α-Gal) or N-glycolylneuraminic acid (Neu5Gc) expressed on nonhuman production cell lines. VSV-GP produced on human cell lines was stable in NHS. However, VSV-GP generated in transduced human cells expressing α-Gal became sensitive to NHS. Furthermore, GP-specific antibodies induced complement-mediated neutralization of VSV-GP independently of the producer cell line, suggesting that complement regulatory proteins potentially acquired by the virus during the budding process are not sufficient to rescue the virus from antibody-dependent complement-mediated lysis. Thus, our study points to the importance of a careful selection of cell lines for viral vector production for clinical use.IMPORTANCE Systemic application aims to deliver oncolytic viruses to tumors as well as to metastatic lesions. However, we found that xenoantigens incorporated onto the viral surface from nonhuman production cell lines are recognized by natural antibodies in human serum and that the virus is thereby inactivated by complement lysis. Hence, to maximize the effective dose, careful selection of cell lines for virus production is crucial.

In Vivo Live Imaging of Oncolytic Mammalian Orthoreovirus Expressing NanoLuc Luciferase in Tumor Xenograft Mice.

Wild-type mammalian reoviruses (MRVs) have been evaluated as oncolytic agents against various cancers; however, genetic modification methods for improving MRV agents have not been exploited fully. In the present study, using MRV strain T1L, we generated a reporter MRV that expresses a NanoLuc luciferase (NLuc) gene and used it for noninvasive imaging of MRV infection in tumor xenograft mice. NLuc and a P2A self-cleaving peptide gene cassette were placed upstream of the L1 gene open reading frame to enable bicistronic expression of NLuc and the L1 gene product. BALB/c nude mice intranasally infected with MRV expressing NLuc (rsT1L-NLuc) displayed bioluminescent signals in the chest area at 4 days postinfection (dpi), which is consistent with natural MRV infection in the lung. Furthermore, to monitor tumor-selective infection by MRV, nude mice bearing human cancer xenografts were infected intravenously with rsT1L-NLuc. Bioluminescent signals were detected in tumors as early as 3 dpi and persisted for 2 months. The results demonstrate the utility of an autonomous replicating reporter MRV for noninvasive live imaging of replicating oncolytic MRV agents.IMPORTANCE Engineering of recombinant MRV for improved oncolytic activity has not yet been achieved due to difficulty in generating autonomous replicating MRV harboring transgenes. Here, we constructed a reporter MRV that can be used to monitor cancer-selective infection by oncolytic MRV in a mouse model. Among the numerous oncolytic viruses, MRV has an advantage in that the wild-type virus shows marked oncolytic activity in patients without any notable adverse effects. The reporter MRV developed herein will open avenues to the development of recombinant MRV vectors armed with anticancer transgenes.

Potentiating Oncolytic Virus-Induced Immune-Mediated Tumor Cell Killing Using Histone Deacetylase Inhibition.

A clinical oncolytic herpes simplex virus (HSV) encoding granulocyte-macrophage colony-stimulating factor (GM-CSF), talimogene laherparepvec, causes regression of injected and non-injected melanoma lesions in patients and is now licensed for clinical use in advanced melanoma. To date, limited data are available regarding the mechanisms of human anti-tumor immune priming, an improved understanding of which could inform the development of future combination strategies with improved efficacy. This study addressed direct oncolysis and innate and adaptive human immune-mediated effects of a closely related HSV encoding GM-CSF (HSVGM-CSF) alone and in combination with histone deacetylase inhibition. We found that HSVGM-CSF supported activation of anti-melanoma immunity via monocyte-mediated type I interferon production, which activates NK cells, and viral maturation of immature dendritic cells (iDCs) into potent antigen-presenting cells for cytotoxic T lymphocyte (CTL) priming. Addition of the histone deacetylase inhibitor valproic acid (VPA) to HSVGM-CSF treatment of tumor cells increased viral replication, viral GM-CSF production, and oncolysis and augmented the development of anti-tumor immunity. Mechanistically, VPA increased expression of activating ligands for NK cell recognition and induced expression of tumor-associated antigens, supporting innate NK cell killing and CTL priming. These data support the clinical combination of talimogene laherparepvec with histone deacetylase inhibition to enhance oncolysis and anti-tumor immunity.

Arming Oncolytic Adenoviruses: Effect of Insertion Site and Splice Acceptor on Transgene Expression and Viral Fitness.

Oncolytic adenoviruses (OAds) present limited efficacy in clinics. The insertion of therapeutic transgenes into OAds genomes, known as "arming OAds", has been the main strategy to improve their therapeutic potential. Different approaches were published in the decade of the 2000s, but with few comparisons. Most armed OAds have complete or partial E3 deletions, leading to a shorter half-life in vivo. We generated E3+ OAds using two insertion sites, After-fiber and After-E4, and two different splice acceptors linked to the major late promoter, either the Ad5 protein IIIa acceptor (IIIaSA) or the Ad40 long fiber acceptor (40SA). The highest transgene levels were obtained with the After-fiber location and 40SA. However, the set of codons of the transgene affected viral fitness, highlighting the relevance of transgene codon usage when arming OAds using the major late promoter.

Herpes Simplex Virus Oncolytic Immunovirotherapy: The Blossoming Branch of Multimodal Therapy.

Oncolytic viruses are smart therapeutics against cancer due to their potential to replicate and produce the needed therapeutic dose in the tumor, and to their ability to self-exhaust upon tumor clearance. Oncolytic virotherapy strategies based on the herpes simplex virus are reaching their thirties, and a wide variety of approaches has been envisioned and tested in many different models, and on a range of tumor targets. This huge effort has culminated in the primacy of an oncolytic HSV (oHSV) being the first oncolytic virus to be approved by the FDA and EMA for clinical use, for the treatment of advanced melanoma. The path has just been opened; many more cancer types with poor prognosis await effective and innovative therapies, and oHSVs could provide a promising solution, especially as combination therapies and immunovirotherapies. In this review, we analyze the most recent advances in this field, and try to envision the future ahead of oHSVs.

Adenovirus Receptor Expression in Cancer and Its Multifaceted Role in Oncolytic Adenovirus Therapy.

Oncolytic adenovirus therapy is believed to be a promising way to treat cancer patients. To be able to target tumor cells with an oncolytic adenovirus, expression of the adenovirus receptor on the tumor cell is essential. Different adenovirus types bind to different receptors on the cell, of which the expression can vary between tumor types. Pre-existing neutralizing immunity to human adenovirus species C type 5 (HAdV-C5) has hampered its therapeutic efficacy in clinical trials, hence several adenoviral vectors from different species are currently being developed as a means to evade pre-existing immunity. Therefore, knowledge on the expression of appropriate adenovirus receptors on tumor cells is important. This could aid in determining which tumor types would benefit most from treatment with a certain oncolytic adenovirus type. This review provides an overview of the known receptors for human adenoviruses and how their expression on tumor cells might be differentially regulated compared to healthy tissue, before and after standardized anticancer treatments. Mechanisms behind the up- or downregulation of adenovirus receptor expression are discussed, which could be used to find new targets for combination therapy to enhance the efficacy of oncolytic adenovirus therapy. Additionally, the utility of the adenovirus receptors in oncolytic virotherapy is examined, including their role in viral spread, which might even surpass their function as primary entry receptors. Finally, future directions are offered regarding the selection of adenovirus types to be used in oncolytic adenovirus therapy in the fight against cancer.

EGFR-Binding Peptides: From Computational Design towards Tumor-Targeting of Adeno-Associated Virus Capsids.

The epidermal growth factor receptor (EGFR) plays a central role in the progression of many solid tumors. We used this validated target to analyze the de novo design of EGFR-binding peptides and their application for the delivery of complex payloads via rational design of a viral vector. Peptides were computationally designed to interact with the EGFR dimerization interface. Two new peptides and a reference (EDA peptide) were chemically synthesized, and their binding ability characterized. Presentation of these peptides in each of the 60 capsid proteins of recombinant adeno-associated viruses (rAAV) via a genetic based loop insertion enabled targeting of EGFR overexpressing tumor cell lines. Furthermore, tissue distribution and tumor xenograft specificity were analyzed with systemic injection in chicken egg chorioallantoic membrane (CAM) assays. Complex correlations between the targeting of the synthetic peptides and the viral vectors to cells and in ovo were observed. Overall, these data demonstrate the potential of computational design in combination with rational capsid modification for viral vector targeting opening new avenues for viral vector delivery and specifically suicide gene therapy.

The practical self-targeted oncolytic adenoviral nanosphere based on immuno-obstruction method via polyprotein surface precipitation technique enhances transfection efficiency for virotherapy.

Recent developments in tumour treatment had focused on virotherapies that were currently revolutionising new innovated treatment pathways. This study focused on the fabrication of oncolytic adenoviral vector (Ad) nanosphere that self-targeted at lung tumour cells (A549), utilising the immune response for upper respiratory tract infection, caused by the Ad infection. This system was dependent upon T-cell immune response, surface charge and blood metabolism. Oncolytic Ad attacked lung A549 tumour cells by incorporated its own DNA to replace A549's, the triggered immune response generated T-cells also further attack A549. Direct Ad injection was demonstrated to be lethal and prohibited in vivo. In this research a multifunctional principal using polyprotein surface precipitation technique (PSP) whist maintaining biological controls for self-assembly polyprotein Ad nanosphere both biocompatible and reproducible, was demonstrated as a result of the enhanced transfection efficiency and a successful multifunctional drug delivery system for virotherapy.