Advances in the therapeutic study of oncolytic virus in colorectal cancer

Colorectal cancer(CRC)represents a considerable global health challenge,ranking third in incidence and second in mortality worldwide.However,existing therapies for diseases with advanced stages often fail,thereby necessitating the search for more comprehensive treatments.Oncolytic virus,a novel anticancer approach,exhibits promising capabilities in selectively targeting and destroying tumor cells while augmenting their efficacy through genetic engineering modifications.Anticipated as a new therapeutic paradigm for CRC,this study aimed to assess the performance of oncolytic virus in clinical trials and explore their potential synergies with other therapeutic modalities,offering insights into the future direction of CRC treatment.

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.

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.

Clinical development of reovirus for cancer therapy:An oncolytic virus with immune-mediated antitumor activity

Reovirus is a double-stranded RNA virus with demonstrated oncolysis or preferential replication in cancer cells. The oncolytic properties of reovirus appear to be dependent, in part, on activated Ras signaling. In addition, Ras-transformation promotes reovirus oncolysis by affecting several steps of the viral life cycle. Reovirusmediated immune responses can present barriers to tumor targeting, serve protective functions against reovirus systemic toxicity, and contribute to therapeutic efficacy through antitumor immune-mediated effects via innate and adaptive responses. Preclinical studies have demonstrated the broad anticancer activity of wild-type, unmodified type 3 Dearing strain reovirus（Reolysin） across a spectrum of malignancies. The development of reovirus as an anticancer agent and available clinical data reported from 22 clinical trials will be reviewed.

Anti-tumor effect of oncolytic herpes simplex virus G47delta on human nasopharyngeal carcinoma

Oncolytic herpes simplex virus (HSV) can replicate in and kill cancer cells without harming normal tissue. G47Δ is a third-generation HSV vector. In this study, the therapeutic effects of G47Δ on human nasopharyngeal carcinoma (NPC) were determined in vitro and in vivo. The human NPC cell lines CNE-2 and SUNE-1, primary normal nasopharyngeal epithelial cells (NPECs), and immortalized nasopharyngeal cells NP-69 and NPEC2/Bmi1 were infected with G47Δ at different multiplicities of infection (MOIs). The survival of infected cells was observed daily. Two subcutaneous models of NPC were established with CNE-2 and SUNE-1 in Balb/c nude mice. G47Δ or virus buffer as control was injected into the subcutaneous tumors. Tumor size was measured twice a week, and animals were euthanized when the diameter of their tumors exceeded 18 mm or when the animals appeared moribund. For the NPC cell lines CNE-2 and SUNE-1, more than 85% and 95% of cells were killed on day 5 after G47Δ infection at MOI = 0.01 and MOI = 0.1, respectively. Similar results were observed for an immortalized cell line NPEC2/Bmi-1. A moderate effect of G47Δ was also found on another immortalized cell line NP-69, of which only 27.7% and 75.9% of cells were killed at MOI = 0.01 and MOI = 0.1, respectively. On the contrary, there was almost no effect observed on NPECs. The in vivo experiments showed that tumors in mice in the G47Δ-treated group regressed completely, and the mice exhibited much longer survival time than those in the control groups. Our results suggest that the potential therapeutic effects of G47Δ would be applicable for treatment of NPC patients in the future.

Mathematical Modeling and Analysis of Tumor Therapy with Oncolytic Virus

In this paper, we have proposed and analyzed a nonlinear mathematical model for the study of interaction between tumor cells and oncolytic viruses. The model is analyzed using stability theory of differential equa- tions. Positive equilibrium points of the system are investigated and their stability analysis is carried out. Moreover, the numerical simulation of the proposed model is also performed by using fourth order Runge- Kutta method which supports the theoretical findings. It is found that both infected and uninfected tumor cells and hence tumor load can be eliminated with time, and complete recovery is possible because of virus therapy, if certain conditions are satisfied. It is further found that the system appears to exhibit periodic limit cycles and chaotic attractors for some ranges of the system parameters.

CXCL12 Retargeting of an Oncolytic Adenovirus Vector to the Chemokine CXCR4 and CXCR7 Receptors in Breast Cancer

Breast cancer is the most frequently diagnosed cancer in women under 60, and the second most diagnosed cancer in women over 60. While significant progress has been made in developing targeted therapies for breast cancer, advanced breast cancer continues to have high mortality, with poor 5-year survival rates. Thus, current therapies are insufficient in treating advanced stages of breast cancer;new treatments are sorely needed to address the complexity of advanced-stage breast cancer. Oncolytic virotherapy has been explored as a therapeutic approach capable of systemic administration, targeting cancer cells, and sparing normal tissue. In particular, oncolytic adenoviruses have been exploited as viral vectors due to their ease of manipulation, production, and demonstrated clinical safety profile. In this study, we engineered an oncolytic adenovirus to target the chemokine receptors CXCR4 and CXCR7. The overexpression of CXCR4 and CXCR7 is implicated in the initiation, survival, progress, and metastasis of breast cancer. Both receptors bind to the ligand, CXCL12 (SDF-1), which has been identified to play a crucial role in the metastasis of breast cancer cells. This study incorporated a T4 fibritin protein fused to CXCL12 into the tail domain of an adenovirus fiber to retarget the vector to the CXCR4 and CXCR7 chemokine receptors. We showed that the modified virus targets and infects CXCR4- and CXCR7-overexpressing breast cancer cells more efficiently than a wild-type control vector. In addition, the substitution of the wild-type fiber and knob with the modified chimeric fiber did not interfere with oncolytic capability. Overall, the results of this study demonstrate the feasibility of retargeting adenovirus vectors to chemokine receptor-positive tumors.

Construction of a replication-competent hepatitis B virus vector carrying secreted luciferase transgene and establishment of new hepatitis B virus replication and expression cell lines

BACKGROUND Previously,we have successfully constructed replication-competent hepatitis B virus(HBV)vectors by uncoupling the P open reading frame(ORF)from the preC/C ORF to carefully design the transgene insertion site to overcome the compact organization of the HBV genome and maintain HBV replication competence.Consequently,the replication-competent HBV vectors carrying foreign genes,including pCH-BsdR,carrying blasticidin resistance gene(399 bp),and pCH-hrGFP,carrying humanized renilla green fluorescent protein gene(720 bp),were successfully obtained.However,the replication efficiency of the former is higher but it is tedious to use,while that of the latter is poor and cannot be quantified.Hence,we need to search for a new reporter gene that is convenient and quantifiable for further research.AIM To establish a helpful tool for intracellular HBV replication and anti-viral drugs screening studies.METHODS We utilized the replication-competent HBV viral vectors constructed by our laboratory,combined with the secreted luciferase reporter gene,to construct replication-competent HBV vectors expressing the reporter gene secretory Nanoluc Luciferase(SecNluc).HepG2.TA2-7 cells were transfected with this vector to obtain cell lines with stably secreted HBV particles carrying secNluc reporter gene.RESULTS The replication-competent HBV vector carrying the SecNluc reporter gene pCHsNLuc could produce all major viral RNAs and a full set of envelope proteins and achieve high-level secreted luciferase expression.HBV replication intermediates could be produced from this vector.Via transfection with pTRE-sNLuc and selection by hygromycin,we obtained isolated cell clones,named HBV-NLuc-35 cells,which could secrete secNLuc recombinant viruses,and were sensitive to existing anti-HBV drugs.Using differentiated HepaRG cells,it was verified that recombinant HBV possessed infectivity.CONCLUSION Our research demonstrated that a replication-competent HBV vector carrying a secreted luciferase transgene possesses replication and expression ability,and the established HBV replication and expression cell lines could stably secrete viral particles carrying secNluc reporter gene.More importantly,the cell line and the secreted recombinant viral particles could be used to trace HBV replication or infection.

Oncoselectivity in Oncolytic Viruses against Colorectal Cancer

In humans colorectal cancer (CRC) is a significant cause of morbidity and mortality. New treatment options are urgently needed to supplement existing therapies. Replication-competent oncolytic viruses (RCOVs) for the treatment of cancerous tumors?in vivo?is a relatively new therapeutic modality with great but largely unrealized potential against CRC. In the context of oncolytic virus safety, oncoselectivity is an important criterion. It is at the conceptual intersection of viral replication strategy and tumor cell biology that RCOVs acquire their oncoselectivity, and thus their safety. Every aspect of tumor molecular biology which distinguishes it from normal, non-neoplastic cells is a potential target for exploitation. In the first section of this review we will provide an explanation of some of the successful and widely used strategies for improving oncoselectivity in wild-type viruses to make them more suitable as RCOVs. In the second section we will describe some of the characteristics of CRC biology which can be exploited to provide oncoselectivity against CRC. Throughout the review examples of successfully-engineered RCOVs which embody the approach or strategy under discussion are noted. By showing what has been done, we hope to highlight what is possible and what remains to be done to generate oncoselective RCOVs for use against CRC in humans.

Oncolytic Herpes Simplex Virus ICP47 Deletion Reverses Tumor Immune Evasion

Herpes simplex virus (HSV) is an enveloped, double-stranded DNA virus that has been used with modification as oncolytic viruses (OVs) against a number of tumor types. OVs represent a new class of therapeutic agents that promote anti-tumour responses through a dual mechanism of action that is dependent on selective tumor cell killing and the induction of systemic anti-tumour immunity. Among OVs, HSVs preferentially replicate in and lyse cancer cells, leading to in situ autovaccination, adaptive anti-virus and anti-tumor immunity. Suppression of antitumor immunity after OV therapy has been observed and the molecular and cellular mechanisms of action are recently reported. ICP47, a small protein produced by the herpes simplex virus, is considered as an important factor in the evasion of cellular immune responses in HSV-infected cells. Therefore, reviewing the research status of ICP47 is certainly helpful to improve the anti-tumor effect of oncolytic HSVs (oHSVs). Here, this review will focus on the following contents: 1) Anti-tumor mechanism of OVs;2) Functions of early HSV genes;3) The mechanism of immune escape of ICP47;4) Recombinant HSV against cancer;5) The functional verification of ICP47 deletion. This review highlights the current understanding of recombinant HSVs against cancers.

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.

Potential of vesicular stomatitis virus as an oncolytic therapy for recurrent and drug-resistant ovarian cancer

In the last decade, we have gained significant understanding of the mechanism by which vesicular stomatitis virus (VSV) specifically kills cancer cells. Dysregulation of translation and defective innate immunity are both thought to contribute to VSV oncolysis. Safety and efficacy are important objectives to consider in evaluating VSV as a therapy for malignant disease. Ongoing efforts may enable VSV virotherapy to be considered in the near future to treat drug-resistant ovarian cancer when other options have been exhausted. In this article, we review the development of VSV as a potential therapeutic approach for recurrent or drug-resistant ovarian cancer.

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.

Pharmacokinetic enhancement of oncolytic virus M1 by inhibiting JAK-STAT pathway

Oncolytic viruses(OVs),a group of replication-competent viruses that can selectively infect and kill cancer cells while leaving healthy cells intact,are emerging as promising living anticancer agents.Unlike traditional drugs composed of non-replicating compounds or biomolecules,the replicative nature of viruses confer unique pharmacokinetic properties that require further studies.Despite some pharmacokinetics studies of OVs,mechanistic insights into the connection between OV pharmacokinetics and antitumor efficacy remain vague.Here,we characterized the pharmacokinetic profile of oncolytic virus M1(OVM)in immunocompetent mouse tumor models and identified the JAK-STAT pathway as a key modulator of OVM pharmacokinetics.By suppressing the JAK-STAT pathway,early OVM pharmacokinetics are ameliorated,leading to enhanced tumor-specific viral accumulation,increased AUC and Cmax,and improved antitumor efficacy.Rather than compromising antitumor immunity after JAK-STAT inhibition,the improved pharmacokinetics of OVM promotes T cell recruitment and activation in the tumor microenvironment,providing an optimal opportunity for the therapeutic outcome of immune checkpoint blockade,such as anti-PD-L1.Taken together,this study advances our understanding of the pharmacokinetic-pharmacodynamic relationship in OV therapy.

Immune landscape and response to oncolytic virus-based immunotherapy

Oncolytic virus(OV)-based immunotherapy has emerged as a promising strategy for cancer treatment,offering a unique potential to selectively target malignant cells while sparing normal tissues.However,the immunosuppressive nature of tumor microenvironment(TME)poses a substantial hurdle to the development of OVs as effective immunotherapeutic agents,as it restricts the activation and recruitment of immune cells.This review elucidates the potential of OV-based immunotherapy in modulating the immune landscape within the TME to overcome immune resistance and enhance antitumor immune responses.We examine the role of OVs in targeting specific immune cell populations,including dendritic cells,T cells,natural killer cells,and macrophages,and their ability to alter the TME by inhibiting angiogenesis and reducing tumor fibrosis.Additionally,we explore strategies to optimize OV-based drug delivery and improve the efficiency of OV-mediated immunotherapy.In conclusion,this review offers a concise and comprehensive synopsis of the current status and future prospects of OV-based immunotherapy,underscoring its remarkable potential as an effective immunotherapeutic agent for cancer treatment.

A novel vesicular stomatitis virus armed with IL-2 mimic for oncolytic therapy

Oncolytic virus(OV)is increasingly being recognized as a novel vector in cancer immunotherapy.Increasing evidence suggests that OV has the ability to change the immune status of tumor microenvironment,so called transformation of‘cold’tumors into‘hot’tumors.The improved anti-tumor immunity can be induced by OV and further enhanced through the combination of various immunomodulators.The Neo-2/15 is a newly de novo synthesized cytokine that functions as both IL-2 and IL-15.However,it specifically lacks the binding site of IL-2 receptorαsubunit(CD25),therefore unable to induce the Treg proliferation.In present study,a recombinant vesicular stomatitis virus expressing the Neo-2/15(VSVM51R-Neo-2/15)was generated.Intratumoral delivery of VSVM51R-Neo-2/15 efficiently inhibited tumor growth in mice without causing the IL-2-related toxicity previously observed in clinic.Moreover,treatment with VSVM51R-Neo-2/15 increased the number of activated CD8t T cells but not Treg cells in tumors.More tumor-bearing mice were survival with VSVM51R-Neo-2/15 treatment,and the surviving mice displayed enhanced protection against tumor cell rechallenge due to the induced anti-tumor immunity.In addition,combination therapy of OV and anti-PD-L1 immune checkpoint inhibitors further enhanced the anti-tumor immune response.These findings suggest that our novel VSVM51R-Neo-2/15 can effectively inhibit the tumor growth and enhance the sensitivity to immune checkpoint inhibitors,providing promising attempts for further clinical trials.

Oncolytic Virus Senecavirus A Inhibits Hepatocellular Carcinoma Proliferation and Growth by Inducing Cell Cycle Arrest and Apoptosis

Background and Aims:Hepatocellular carcinoma(HCC)isa highly aggressive tumor with limited treatment options andhigh mortality.Senecavirus A(SVA)has shown potential inselectively targeting tumors while sparing healthy tissues.This study aimed to investigate the effects of SVA on HCCcells in vitro and in vivo and to elucidate its mechanisms ofaction.Methods:The cell counting kit-8 assay and colonyformation assay were conducted to examine cell proliferation.Flow cytometry and nuclear staining were employed toanalyze cell cycle distribution and apoptosis occurrence.Asubcutaneous tumor xenograft HCC mouse model was createdin vivo using HepG2 cells,and Ki67 expression in thetumor tissues was assessed.The terminal deoxynucleotidyltransferase dUTP nick end labeling assay and hematoxylinand eosin staining were employed to evaluate HCC apoptosisand the toxicity of SVA on mouse organs.Results:In vitro,SVA effectively suppressed the growth of tumor cells by inducingapoptosis and cell cycle arrest.However,it did nothave a notable effect on normal hepatocytes(MIHA cells).In an in vivo setting,SVA effectively suppressed the growthof HCC in a mouse model.SVA treatment resulted in a significantdecrease in Ki67 expression and an increase in apoptosisof tumor cells.No notable histopathological alterationswere observed in the organs of mice during SVA administration.Conclusions:SVA inhibits the growth of HCC cells byinducing cell cycle arrest and apoptosis.It does not causeany noticeable toxicity to vital organs.

Implementation of the Guidelines for Oncolytic Viruses in China

Objective To study related guidelines such as“Guidelines for Clinical Trial Design of Oncolytic Viruses”“Technical Guidelines for Non-clinical Research and Evaluation of Gene Therapy Products”and“Technical Guidelines for Pharmacological Research and Evaluation of Oncolytic Viruses(OVs)Products”issued by the Center for Drug Evaluation(CDE)on OV and offer some suggestions for further improvement of the policies and regulations.Methods Literature comparison and questionnaire survey were used in this paper to investigate the difficulties encountered in the practical work of domestic companies that have conducted clinical trials,thus drawing some lessons to help the subsequent implementation of the guidelines.Results and Conclusion According to the characteristics of specific varieties and the published laws,regulations and guidelines,companies can adopt more suitable and scientific strategies to accelerate the development of anti-cancer drugs.In the future,as more clinical studies and product development for various cancers expand,regulatory requirements are expected to become more specialized and complex.Learning from the regulatory experience of developed countries and regions,we can improve the regulatory system by adapting it to national conditions and development status of China.Additionally,some ideas and useful inspirations can be provided after reviewing the content of the relevant guidelines and the obstacles in the practice of corporate R&D process can be addressed.These efforts will facilitate the speed of R&D and allow enterprises to work more smoothly and efficiently.

Application of Newcastle disease virus in the treatment of colorectal cancer

Colorectal cancer (CRC) is one of the main reasons of tumor-related deaths worldwide.At present,the main treatment is surgery,but the results are unsatisfactory,and the prognosis is poor.The majority of patients die due to liver or lung metastasis or recurrence.In recent years,great progress has been made in the field of tumor gene therapy,providing a new treatment for combating CRC.As oncolytic viruses selectively replicate almost exclusively in the cytoplasm of tumor cells and do not require integration into the host genome,they are safer,more effective and more attractive as oncolytic agents.Newcastle disease virus (NDV) is a natural RNA oncolytic virus.After NDV selectively infects tumor cells,the immune response induced by NDV’s envelope protein and intracellular factors can effectively kill the tumor without affecting normal cells.Reverse genetic techniques make NDV a vector for gene therapy.Arming the virus by inserting various exogenous genes or using NDV in combination with immunotherapy can also improve the anti-CRC capacity of NDV,and good results have been achieved in animal models and clinical treatment trials.This article reviews the molecular biological characteristics and oncolytic mechanism of NDV and discusses in vitro and in vivo experiments on NDV anti-CRC capacity and clinical treatment.In conclusion,NDV is an excellent candidate for cancer treatment,but more preclinical studies and clinical trials are needed to ensure its safety and efficacy.

Feasibility of herpes simplex virus type 1 mutants labeled with radionuclides for tumor treatment

For over one hundred years, viruses have been recognized as capable of killing tumor cells. At present, people are still researching and constructing more suitable oncolytic viruses for treating different malignant tumors. Although extensive studies have demonstrated that herpes simplex virus type 1 (HSV-1) is the most potential oncolytic virus, therapies based on herpes simplex virus type 1 vectors still arouse bio-safety and risk management issues. Researchers have therefore introduced the new idea of treating cancer with HSV-1 mutants labeled with radionuclides, combining radionuclide and oncolytic virus therapies. This overview briefly summarizes the status and mechanisms by which oncolytic viruses kill tumor cells, discusses the application of HSV-1 and HSV-1 derived vectors for tumor therapy, and demonstrates the feasibility and prospect of HSV-1 mutants labeled with radionuclides for treating tumors.