Progress in oncolytic viruses modified with nanomaterials for intravenous application

In oncolytic virus(OV)therapy,a critical component of tumor immunotherapy,viruses selectively infect,replicate within,and eventually destroy tumor cells.Simultaneously,this therapy activates immune responses and mobilizes immune cells,thereby eliminating residual or distant cancer cells.However,because of OVs’high immunogenicity and immune clearance during circulation,their clinical applications are currently limited to intratumoral injections,and their use is severely restricted.In recent years,numerous studies have used nanomaterials to modify OVs to decrease virulence and increase safety for intravenous injection.The most commonly used nanomaterials for modifying OVs are liposomes,polymers,and albumin,because of their biosafety,practicability,and effectiveness.The aim of this review is to summarize progress in the use of these nanomaterials in preclinical experiments to modify OVs and to discuss the challenges encountered from basic research to clinical application.

Therapeutic potential of oncolytic viruses in the era of precision oncology

Oncolytic virus(OV)therapy has been shown to be an effective targeted cancer therapy treatment in recent years,providing an avenue of treatment that poses no damage to surrounding healthy tissues.Not only do OVs cause direct oncolysis,but they also amplify both innate and adaptive immune responses generating long-term anti-tumour immunity.Genetically engineered OVs have become the common promising strategy to enhance anti-tumour immunity,safety,and efficacy as well as targeted delivery.The studies of various OVs have been accomplished through phase I-III clinical trial studies.In addition,the uses of carrier platforms of organic materials such as polymer chains,liposomes,hydrogels,and cell carriers have played a vital role in the potentially targeted delivery of OVs.The mechanism,rational design,recent clinical trials,applications,and the development of targeted delivery platforms of OVs will be discussed in this review.

Emerging systemic delivery strategies of oncolytic viruses:A key step toward cancer immunotherapy

Oncolytic virotherapy(OVT)is a novel type of immunotherapy that induces anti-tumor responses through selective self-replication within cancer cells and oncolytic virus(OV)-mediated immunostimulation.Notably,talimogene laherparepvec(T-Vec)developed by the Amgen company in 2015,is the first FDA-approved OV product to be administered via intratumoral injection and has been the most successful OVT treatment.However,the systemic administration of OVs still faces huge challenges,including in vivo pre-existing neutralizing antibodies and poor targeting delivery efficacy.Recently,state-of-the-art progress has been made in the development of systemic delivery of OVs,which demonstrates a promising step toward broadening the scope of cancer immunotherapy and improving the clinical efficacy of OV delivery.Herein,this review describes the general characteristics of OVs,focusing on the action mechanisms of OVs as well as the advantages and disadvantages of OVT.The emerging multiple systemic administration approaches of OVs are summarized in the past five years.In addition,the combination treatments between OVT and traditional therapies(chemotherapy,thermotherapy,immunotherapy,and radiotherapy,etc.)are highlighted.Last but not least,the future prospects and challenges of OVT are also discussed,with the aim of facilitating medical researchers to extensively apply the OVT in the cancer therapy.

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

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

Preclinical and clinical trials of oncolytic vaccinia virus in cancer immunotherapy:a comprehensive review

Oncolytic virotherapy has emerged as a promising treatment for human cancers owing to an ability to elicit curative effects via systemic administration.Tumor cells often create an unfavorable immunosuppressive microenvironment that degrade viral structures and impede viral replication;however,recent studies have established that viruses altered via genetic modifications can serve as effective oncolytic agents to combat hostile tumor environments.Specifically,oncolytic vaccinia virus(OVV)has gained popularity owing to its safety,potential for systemic delivery,and large gene insertion capacity.This review highlights current research on the use of engineered mutated viruses and gene-armed OVVs to reverse the tumor microenvironment and enhance antitumor activity in vitro and in vivo,and provides an overview of ongoing clinical trials and combination therapies.In addition,we discuss the potential benefits and drawbacks of OVV as a cancer therapy,and explore different perspectives in this field.

Novel Functional Motifs of the Cell Entry Glycoprotein D for Oncolytic Herpes Simplex Viruses

Background: Oncolytic herpes simplex virus (oHSV) have been proved effective and safe to treat tumors. Glycoprotein D (gD) has been engineered for targeting cancer cells and de-targeting normal cells successfully, however, the effectiveness and safety of oHSVs still need to be improved. Method: Here we sequenced the DNA encoding gD of our recently isolated new strain HSV-1-LXMW and compared the gD amino acid sequence with the gDs of other 7 HSV-1 and 3 HSV-2 strains. Results: Phylogenetic analysis revealed that HSV-1-LXMW is evolutionarily close to HSV-1-Patton and -KOS strains. The gD amino acid sequence alignment identified 19 conserved and 8 variable regions. We further predicted 10 new motifs in HSV gD for the first time and identified motif differences in HSV-1 and HSV-2. We summarized the gD-engineered oHSVs and found that some of the newly identified gD motifs are actually functional. Conclusion: Our results shed light on HSV gD biology and provided new directions for future gD functional studies and engineering in order to make better oHSVs.

Oncolytic virus therapy in cancer: A current review

In view of the advancement in the understanding about the most diverse types of cancer and consequently a relentless search for a cure and increased survival rates of cancer patients,finding a therapy that is able to combat the mechanism of aggression of this disease is extremely important.Thus,oncolytic viruses(OVs)have demonstrated great benefits in the treatment of cancer because it mediates antitumor effects in several ways.Viruses can be used to infect cancer cells,especially over normal cells,to present tumor-associated antigens,to activate“danger signals”that generate a less immune-tolerant tumor microenvironment,and to serve transduction vehicles for expression of inflammatory and immunomodulatory cytokines.The success of therapies using OVs was initially demonstrated by the use of the genetically modified herpes virus,talimogene laherparepvec,for the treatment of melanoma.At this time,several OVs are being studied as a potential treatment for cancer in clinical trials.However,it is necessary to be aware of the safety and possible adverse effects of this therapy;after all,an effective treatment for cancer should promote regression,attack the tumor,and in the meantime induce minimal systemic repercussions.In this manuscript,we will present a current review of the mechanism of action of OVs,main clinical uses,updates,and future perspectives on this treatment.

Oncolytic Engineering of ICP34.5 and LAT of Herpes Simplex Virus Type 1

Oncolytic virus (OV) is a kind of virus that can preferentially infect and kill tumor cells. The second oncolytic virus drug was oncolytic herpes simplex virus (oHSV) Talimogene Laherparepvec (T-VEC). HSV-1 infectious cell culture protein 34.5 (ICP34.5) and latency-associated transcript (LAT) genes are closely related to virus selective infection and latent infection. Their engineering is essential for constructing efficient and safe oHSV. We summarized the mechanisms of ICP34.5 and LAT in the course of HSV-1 infection and reviewed the engineered oHSVs. We are aimed to provide an insight in developing oHSV in the future.

Immunotherapy in glioblastoma treatment:Current state and future prospects

Glioblastoma remains as the most common and aggressive malignant brain tumor,standing with a poor prognosis and treatment prospective.Despite the aggressive standard care,such as surgical resection and chemoradiation,median survival rates are low.In this regard,immunotherapeutic strategies aim to become more attractive for glioblastoma,considering its recent advances and approaches.In this review,we provide an overview of the current status and progress in immunotherapy for glioblastoma,going through the fundamental knowledge on immune targeting to promising strategies,such as Chimeric antigen receptor T-Cell therapy,immune checkpoint inhibitors,cytokine-based treatment,oncolytic virus and vaccine-based techniques.At last,it is discussed innovative methods to overcome diverse challenges,and future perspectives in this area.

Immunotherapy for advanced or recurrent hepatocellular carcinoma

Hepatocellular carcinoma(HCC)is associated with high morbidity and mortality,and is prone to intra-and extrahepatic metastasis due to the anatomical and functional characteristics of the liver.Due to the complexity and high relapse rate associated with radical surgery or radiofrequency ablation,immune checkpoint inhibitors(ICIs)are increasingly being used to treat HCC.Several immunotherapeutic agents,along with their combinations,have been clinically approved to treat advanced or recurrent HCC.This review discusses the leading ICIs in practice and those currently undergoing randomized phase 1-3 trials as monotherapy or combination therapy.Furthermore,we summarize the rapidly developing alternative strategies such as chimeric antigen receptor-engineered T cell therapy and tumor vaccines.Combination therapy is a promising potential treatment option.These immunotherapies are also summarized in this review,which provides insights into the advantages,limitations,and novel angles for future research in establishing viable and alternative therapies against HCC.

Molecular therapy and prevention of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in some areas of the world with an extremely poor prognosis. The major etiologic risk factors for HCC development include hepatitis B virus (HBV) and hepatitis C virus (HCV) infection, toxins (alcohol, aflatoxin BI) and various inherited metabolic liver diseases, such as hemochromatosis and alpha-1-antitrypsin deficiency. Central to the molecular pathogenesis of HCC are mutations of various genes and genetic/chromosomal instability that result from chronic liver disease and the associated enhanced liver cell regeneration and mitotic activity. Alterations in the structure or expression of several tumor suppressor genes and oncogenes have been described. In addition, mechanisms leading to genetic instability due to mismatch repair deficiency or chromosomal instability and aneuploidy due to defective chromosomal segregation appear to be involved. The prognosis of HCC patients is generally very poor. Most studies have shown a five-year survival rate of less than 5% in symptomatic patients. HCC has been found to be quite resistant to radio- or chemotherapy. Investigations of the natural history and clinical course of HCC revealed a long-term survival of patients only with small asymptomatic HCC that could be treated surgically or nonsurgically. For patients with advanced symptomatic HCC, novel therapeutic strategies such as gene therapy are urgently needed. Apart from exploring and refining new HCC treatment strategies, the implementation of the existing measures or the development of novel measures to prevent HCC is most important. Primary HCC prevention could have a major impact on the incidence of HCC. Further, secondary prevention of a local recurrence or of new HCC lesions in patients after successful surgical or nonsurgical HCC treatment is of paramount importance and is expected to significantly improve disease-free and overall survival rates of patients. Based on rapid scientific advances, molecular diagnosis, gene therapy and molecular prevention are becoming increasingly part of our patient management and will eventually complement or in part replace the existing diagnostic, therapeutic and preventive strategies. Overall, this should result in a reduced HCC incidence and an improved clinical outcome for patients with HCC, one of the most devastating malignancies worldwide.

The antitumor effects of Newcastle disease virus on glioma

Glioma is the most common primary malignant brain tumor with a poor survival rate.In recent years,no significant progress has been made in the treatment of gliomas in contrast to the development of improved diagnosis via molecular typing.Newcastle disease virus(NDV),a negative-stranded RNA virus that exhibits oncolytic activity,has been investigated for its capacity to elicit antitumor activity in many types of cancers,including glioma.Therefore,application of oncolytic viruses,such as NDV,as a new treatment strategy to specifically target aberrant signaling in glioblastomas has brought new hope.For many years,NDV has been investigated for its in vivo and in vitro efficacy in the treatment of various tumor cells.Based on its safety in humans,specificity for tumor cells,and immunostimulatory properties,NDV represents a promising antitumor agent.In this review,we summarize the background of NDV and the antitumor mechanisms of NDV-mediated oncolysis,discuss the potential value and role of NDV in gliomas,and describe new advances and perspectives for future research.

Polymer-based synthetic oncolytic virus-like nanoparticles for cancer immunotherapy

Oncolytic viruses have emerged as new powerful therapeutic agents for cancer therapy by specifically lysing cancer cells while activating innate immune responses at the same time.However,due to the thorny issues of safety concerns and host immune reaction,the clinical application of oncolytic viruses is still limited.Herein,we report a rationally designed oncolytic virus-like nanoparticles(OV-NPs)composed of stimulator of interferon genes(STING)-stimulating polymer loaded with therapeutic genes for cancer immunotherapy.After injection into tumor,the OV-NPs carrying OX40L plasmid could reprogram tumor cells to express OX40L immune checkpoint molecules and activate the STING pathway for cooperatively enhancing antitumor immunity,with a tumor suppression rate of 92.3%in B16F10 tumor model and 78.7%in MC38 tumor model without causing any toxicity.The OV-NPs could be further applied in carrying other plasmids(IL-12)and utilization in gene combination therapy.This study should inspire designing synthetic OV-NPs as alternative strategies for extending oncolytic virus application in cancer immunotherapy.

Cancer immunotherapy with envelopedself-amplifying mRNA CARG-2020 thatmodulates IL-12,IL-17 and PD-L1 pathways toprevent tumor recurrence

Targeting multiple immune mechanisms may overcome therapy resistance and further improve cancer immunotherapy for humans.Here,we describe the application of virus-like vesicles(VLV)for delivery of three immunomodulators alone and in combination,as a promising approach for cancer immunotherapy.VLV vectors were designed to deliver single chain interleukin(IL)-12,shorthairpin RNA(shRNA)targeting programmed death ligand 1(PD-L1),and a dominant-negative form of IL-17 receptor A(dn-IL17RA)as a single payload or as a combination payload.Intralesional delivery of the VLV vector expressing IL-12 alone,as well as the trivalent vector(designated CARG-2020)eradicated large established tumors.However,only CARG-2020 prevented tumor recurrence and provided long-term survival benefit to the tumor-bearing mice,indicating a benefit of the combined immunomodulation.The abscopal effects of CARG-2020 on the non-injected contralateral tumors,as well as protection from the tumor cell re-challenge,suggest immune-mediated mechanism of protection and establishment of immunological memory.Mechanistically,CARG-2020 potently activates Th1 immune mechanisms and inhibits expression of genes related to T cell exhaustion and cancer-promoting inflammation.The ability of CARG-2020 to prevent tumor recurrence and to provide survival benefit makes it a promising candidate for its development for human cancer immunotherapy.

Oncolytic herpes simplex virus vectors for the treatment of human breast cancer

Background Oncolytic herpes simplex virus (HSV) vectors can be used for cancer therapy as direct cytotoxic agents, inducers of anti-tumor immune responses, and as expressers of anti-cancer genes. In this study, the efficacy of HSV vectors, G47Delta and NV1023 were examined for the treatment of the human breast cancer. Methods Human breast cancer MDA-MB-435 cells were cultured or implanted subcutaneously in BALB/c nude mice. The cells or tumors were inoculated with G47Delta or NV1023, and cell killing or inhibition of tumor growth determined. Both viruses contained the LacZ gene and expression in infected cells was detected with X-gal histochemistry. Results G47Delta and NV1023 were highly cytotoxic to MDA-MB-435 cells in vitro at very low multiplicities of infection. X-gal staining of infected tumor cells in vitro and in vivo illustrated the replication and spread of both viruses. G47Delta and NV1023 inoculation inhibited tumor growth and prolonged mouse survival. Both vectors behaved similarly. Conclusions Oncolytic HSV vectors, G47Delta and NV1023, were extremely effective at killing human breast cancer cells in vitro and in tumor xenografts in vivo. This novel form of cancer therapy warrants further investigation and consideration of clinical application.

Development of oncolytic virotherapy:from genetic modification to combination therapy

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

Combining oncolytic virus and radiation therapy for cancer management

Cancer has caused a tremendous burden in developing countries.Oncolytic virus(OV)therapy is an emerging modality with the potential to be a single or combination agent with radiation therapy(RT).Following entry of OV to the cell,OV will replicate and assemble before exiting from tumor cells.Construction of OV can be done by modifying the capsid,genome,and chemical material of viruses.Irradiation will induce double-strand breaks,and further integration of OV with DNA damage response pathway will interact with the MRE11-Rad50-Nbs1 complex to regulate the mobilization of E4 open reading frame 6,protein phosphatase 2A,poly(ADP-ribose)polymerase,apoptosis-inducing factor,and topoisomerase-IIβ-binding protein 1.Degradation of DNA-dependent protein kinase catalytic subunits via human simplex virus-1-infected cell polypeptide 0 will inhibit DNA repair.OV and RT have a synergistic interaction to cause viral oncolysis and upregulation of immune response.In the clinical setting,most studies have demonstrated that OV is a safe treatment with less toxicity.Moreover,OV+RT resulted in longer median survival(62.4 vs.37.7 weeks)in malignant glioma.

Visualization of the Oncolytic Alphavirus M1 Life Cycle in Cancer Cells

Oncolytic alphavirus M1 has been shown to selectively target and kill cancer cells,but cytopathic morphologies induced by M1 virus and the life cycle of the M1 strain in cancer cells remain unclear.Here,we study the key stages of M1 virus infection and replication in the M1 virus-sensitive HepG2 liver cancer cell line by transmission electron microscopy,specifically examining viral entry,assembly,maturation and release.We found that M1 virus induces vacuolization of cancer cells during infection and ultimately nuclear marginalization,a typical indicator of apoptosis.Specifically,our results suggest that the endoplasmic reticulum participates in the assembly of nucleocapsids.In the early and late stage of infection,three kinds of special cytopathic vacuoles are formed and appear to be involved in the replication,maturation and release of the virus.Taken together,our data displayed the process of M1 virus infection of tumor cells and provide the structural basis for the study of M1 virus-host interactions.

A recombinant Newcastle disease virus expressing MMP8 promotes oncolytic efficacy

Oncolytic virus is an emerging anti-cancer strategy. However, extracellular matrix(ECM), as a physical barrier, limits virus spread within the tumor. To overcome the obstacle, we constructed a recombinant Newcastle disease virus(NDV) expressing matrix metalloproteinase(MMP8)(NDV-MMP8) using with reverse genetic technology. In vitro, NDV-MMP8 was identified and verified by WB and ELISA. Cell viability was detected by CCK-8 assay. In vivo, we established two liver cancer xenograft models. NDV-MMP8 was injected into the tumor to observe the tumor volume and survival of mice. The changes in extracellular matrix were observed by Masson’s trichrome staining. Virus expression in tumor tissues was detected by immunofluorescence assay. The virus titer in tumor tissues was detected by TCID50. Histopathological changes were detected by hematoxylin and eosin(HE) and terminal deoxynucleotidyl transferase d UTP nick end labeling(TUNEL) staining. Intratumoral administration of NDV-MMP8 can effectively degrade ECM, promote the spread of the virus within the tumor, and reduce tumor growth rate. Therefore, the method of increasing intratumoral virus accumulation by degradation of the ECM to enhance the oncolytic effect has great potential for clinical application.

Combined effects of oncolytic vaccinia virus and dendritic cells on the progression of melanoma B16-F10 in mice

Aim:We aimed to test the hypothesis that loading of dendritic cells(DCs)with both viral and tumor-specific antigens would enhance the efficacy antitumor DC-based therapy applied simultaneously with oncolytic virus.Methods:Vaccinia virus LIVP/GFP and melanoma B16-F10 were used in this study.DCs were pulsed with various combinations of viral and tumor-associated antigens.The maturation status of DCs was verified by expression of the markers CD80,CD86,and CCR7 and assessment of IL-6,TNF-α,and IL-12 secretion.The most efficient combination of antigens for DC loading was selected based on the analysis of the cytotoxic activity of T lymphocytes.Combination therapy using vaccinia virus LIVP/GFP and DCs pulsed with viral and tumor-specific antigens was administered to the B16-F10 melanoma/mouse C57Bl tumor model.Results:We found that loading of DCs with viral antigens,or with a combination of viral and tumor antigens,resulted in similar levels of expression of DC maturation markers.The maximal in vitro cytotoxicity against virus-infected and non-infected B16 melanoma cells exhibited T lymphocytes activated by DCs loaded with the heat inactivated lysate of vaccinia virus LIVP/GFP infected tumor cell.The results show that the combination of vaccinia virus LIVP/GFP and DCs loaded with both tumor and viral antigens inhibit tumor growth of B16-F10 murine melanoma by more than two-fold.Conclusions:Combination therapy with oncolytic vaccinia virus LIVP/GFP and tumor/virus antigen-loaded DCs limited the growth of established melanoma B16-F10,but no synergistic antitumor effects were observed.We propose that optimization of the therapy regimen could enhance the efficiency of combination therapy.