Oncolytic Properties Research Articles

Colonic Epithelial Cells Express an Oncolytic Bispecific IgA/IgG heterodimer

The gastrointestinal epithelium sheds about 10(12) cells per day. Contrary to conventional wisdom a majority of these cells (>90%) are excreted into the fecal stream intact. We first demonstrated the isolation of these cells in a viable state (1991) and showed the feasibility of studying the expression of various bomarkers in health and disease. During the course of our studies mapping the expression of surface markers using flow cytometry we discovered that these cells had the ability to destroy a variety of cancer cells. These colonic cells expressed among other markers (COX‐2 during an inflammatory condition) IgA and IgG along with a subpopulation of cells co‐expressing IgA/IgG. Blocking the IgG component with anti‐IgG antibody discharged the oncolytic property of these cells. We also observed that these cells expressed Lgr5 and Musashi1, the putative markers of gastrointestinal progenitor stem cells. Long term tissue culture experiments revealed the persistence of the heterodimer. In a cohort of 80 random human samples we observed the absence of this hybrid IgA/IgG antibody in two subjects of African American origin. Lineage directed differentiation of these cells generated a progeny that secreted this chimeric antibody. This antibody was shown to arrest the growth of human colon cancer in xenotransplants in nude mice. From these observations It was concluded that this is a novel native antibody that may be absent in certain individuals as a result of a genetic aberration.Support or Funding InformationSBIR grants R43 & R44 DK‐56567 and R‐43 & R‐44 CA‐81799 from the NIDDK and NCI of the National Institutes of Health.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Adaptation of the Newcastle Disease Virus to Cell Cultures for Enhancing Its Oncolytic Properties

This study focuses on the adaptation of natural Newcastle disease virus (NDV) strains isolated from wild birds to human tumor cells. Many candidates for virotherapy are viruses pathogenic for human. During recombination of genetic material, there always exists a risk of getting a virus with an unstable genome. This problem can be solved by using natural apathogenic viruses as oncolytic agents. The Newcastle disease virus is the causative agent of contagious avian diseases. Its natural strains exhibit an antitumor effect and are considered safe for humans. As shown in earlier studies, the oncolytic properties of natural strains can be enhanced during adaptation to cell cultures, without interference in the virus genome. This study demonstrates that serial passaging increases the viral infectious titer in cancer cells. Moreover, the viability of tumor cells decreases post-infection when Newcastle disease virus strains are adapted to these cell cultures. The findings of this study complement the well-known data on the adaptation of the Newcastle disease virus to human cancer cells. Hence, it is possible to obtain a NDV strain with a more pronounced oncolytic potential during adaptation. This should be taken into account when choosing a strategy for designing anticancer drugs based on this virus.

Synthetic Phenolic Antioxidant TS-13 Suppresses the Growth of Lewis Lung Carcinoma and Potentiates Oncolytic Effect of Doxorubicin.

ROS are important intracellular messengers; their ambiguous role in malignant processes was demonstrated in many studies. The effects of a synthetic phenolic antioxidant sodium 3-(3'-tert-butyl-4'-hydroxyphenyl)propyl thiosulfonate sodium (TS-13) on the tumor growth and oncolytic properties of doxorubicin were studied in the experimental model of Lewis lung carcinoma in mice. In mice receiving TS-13 with drinking water (100 mg/kg), suppression of tumor growth by 32.3% was observed on day 21 after inoculation of Lewis lung carcinoma cells. Two-fold intraperitoneal injections of doxorubicin in a cumulative dose of 8 mg/kg were followed by inhibition of tumor growth by 49.5%. Combined treatment with TS-13 and doxorubicin suppressed the tumor growth by 55.4%. In contrast to doxorubicin, TS-13 inhibited NO generation by peritoneal macrophages. The results show the prospect of studying TS-13 in the context of overcoming drug-resistance of tumors.

Oncolitical viruses in the therapy of malignant neoplastic diseases

The main types of oncolytic viruses and the mechanisms of their action on the tumor cells are described in this review. Examples of optimization of the viral genome are given with a view to enhancing the oncolytic properties of the virus. The achievements in the field of development of antitumour agents based on oncolytic viruses and methods of their application in oncology are described.

Targeted therapy of human glioblastoma combining the oncolytic properties of parvovirus H-1 and attenuated strains of the vaccinia virus

Targeted therapy of human glioblastoma combining the oncolytic properties of parvovirus H-1 and attenuated strains of the vaccinia virus

Poxviruses as Gene Therapy Vectors: Generating Poxviral Vectors Expressing Therapeutic Transgenes.

Treatments with poxvirus vectors can have long-lasting immunological impact in the host, and thus they have been extensively studied to treat diseases and for vaccine development. More importantly, the oncolytic properties of poxviruses have led to their development as cancer therapeutics. Two poxviruses, vaccinia virus (VACV) and myxoma virus (MYXV), have been extensively studied as virotherapeutics with promising results. Vaccinia virus vectors have advanced to the clinic and have been tested as oncolytic therapeutics for several cancer types with successes in phase I/II clinical trials. In addition to oncolytic applications, MYXV has been explored for additional applications including immunotherapeutics, purging of cancer progenitor cells, and treatments for graft-versus-host diseases. These novel therapeutic applications have encouraged its advancement into clinical trials. To meet the demands of different treatment needs, VACV and MYXV can be genetically engineered to express therapeutic transgenes. The engineering process used in poxvirus vectors can be very different from that of other DNA virus vectors (e.g., the herpesviruses). This chapter is intended to serve as a guide to those wishing to engineer poxvirus vectors for therapeutic transgene expression and to produce viral preparations for preclinical studies.

Arming an Oncolytic Herpes Simplex Virus Type 1 with a Single-chain Fragment Variable Antibody against PD-1 for Experimental Glioblastoma Therapy.

Glioblastoma (GBM) is resistant to standard of care. Immune checkpoints inhibitors (such as anti-PD-1 mAbs) efficiently restore antitumor T-cell activity. We engineered a new oncolytic herpes simplex virus (oHSV) expressing a single-chain antibody against PD-1 (scFvPD-1) to evaluate its efficacy in mouse models of GBM. NG34scFvPD-1 expresses the human GADD34 gene transcriptionally controlled by the Nestin promoter to allow replication in GBM cells and a scFvPD-1 cDNA transcriptionally controlled by the CMV promoter. ELISA assays were performed to detect binding of scFvPD-1 to mouse and human PD-1. In vitro cytotoxicity and replication assays were performed to measure NG34scFvPD-1 oncolysis, and scFvPD-1 expression and secretion were determined. In vivo survival studies using orthotopic mouse GBM models were performed to evaluate the therapeutic potency of NG34scFvPD-1. NG34scFvPD-1-infected GBM cells express and secrete scFvPD-1 that binds mouse PD-1. The introduction of the scFvPD-1 sequence in the viral backbone does not alter the oncolytic properties of NG34scFvPD-1. In situ NG34scFvPD-1 treatment improved the survival with a tail of durable survivorship in 2 syngeneic immunocompetent mouse models of GBM. Mice that survived the first GBM challenge rejected the second challenge of GBM when implanted in the contralateral hemisphere. However, this was not true when athymic mice were employed as the recipients of the second challenge, consistent with the need for an intact immune system to obtain a memory response. NG34scFvPD-1 treatment induces a durable antitumor response in 2 preclinical mouse models of GBM with evidence for antitumor memory.

Oncolytic properties of non-vaccinia poxviruses.

Vaccinia virus, a member of the Poxviridae family, has been extensively used as an oncolytic agent and has entered late stage clinical development. In this study, we evaluated the potential oncolytic properties of other members of the Poxviridae family. Numerous tumor cell lines were infected with ten non-vaccinia poxviruses to identify which virus displayed the most potential as an oncolytic agent. Cell viability indicated that tumor cell lines were differentially susceptible to each virus. Raccoonpox virus was the most potent of the tested poxviruses and was highly effective in controlling cell growth in all tumor cell lines. To investigate further the oncolytic capacity of the Raccoonpox virus, we have generated a thymidine kinase (TK)-deleted recombinant Raccoonpox virus expressing the suicide gene FCU1. This TK-deleted Raccoonpox virus was notably attenuated in normal primary cells but replicated efficiently in numerous tumor cell lines. In human colon cancer xenograft model, a single intratumoral inoculation of the recombinant Raccoonpox virus, in combination with 5-fluorocytosine administration, produced relevant tumor growth control. The results demonstrated significant antitumoral activity of this new modified Raccoonpox virus armed with FCU1 and this virus could be considered to be included into the growing armamentarium of oncolytic virotherapy for cancer.

Vaccinia Virus Shuffling: deVV5, a Novel Chimeric Poxvirus with Improved Oncolytic Potency.

Oncolytic virus (OV) therapy has emerged as a promising approach for cancer treatment with the potential to be less toxic and more efficient than classic cancer therapies. Various types of OVs in clinical development, including Vaccinia virus (VACV)-derived OVs, have shown good safety profiles, but limited therapeutic efficacy as monotherapy in some cancer models. Many different methods have been employed to improve the oncolytic potency of OVs. In this study, we used a directed evolution process, pooling different strains of VACV, including Copenhagen, Western Reserve and Wyeth strains and the attenuated modified vaccinia virus Ankara (MVA), to generate a new recombinant poxvirus with increased oncolytic properties. Through selective pressure, a chimeric VACV, deVV5, with increased cancer cell killing capacity and tumor selectivity in vitro was derived. The chimeric viral genome contains sequences of all parental strains. To further improve the tumor selectivity and anti-tumor activity of deVV5, we generated a thymidine kinase (TK)-deleted chimeric virus armed with the suicide gene FCU1. This TK-deleted virus, deVV5-fcu1 replicated efficiently in human tumor cells, and was notably attenuated in normal primary cells. These studies demonstrate the potential of directed evolution as an efficient way to generate recombinant poxviruses with increased oncolytic potency, and with high therapeutic index to improve cancer therapy.

Preclinical Development of Oncolytic Immunovirotherapy for Treatment of HPVPOS Cancers

Immunotherapy for HPVPOS malignancies is attractive because well-defined, viral, non-self tumor antigens exist as targets. Several approaches to vaccinate therapeutically against HPV E6 and E7 antigens have been adopted, including viral platforms such as VSV. A major advantage of VSV expressing these antigens is that VSV also acts as an oncolytic virus, leading to direct tumor cell killing and induction of effective anti-E6 and anti-E7 T cell responses. We have also shown that addition of immune adjuvant genes, such as IFNβ, further enhances safety and/or efficacy of VSV-based oncolytic immunovirotherapies. However, multiple designs of the viral vector are possible—with respect to levels of immunogen expression and method of virus attenuation—and optimal designs have not previously been tested head-to-head. Here, we tested three different VSV engineered to express a non-oncogenic HPV16 E7/6 fusion protein for their immunotherapeutic and oncolytic properties. We assessed their profiles of efficacy and toxicity against HPVPOS and HPVNEG murine tumor models and determined the optimal route of administration. Our data show that VSV is an excellent platform for the oncolytic immunovirotherapy of tumors expressing HPV target antigens, combining a balance of efficacy and safety suitable for evaluation in a first-in-human clinical trial.

Abstract 4934: Immunostimulatory and oncolytic properties of rotavirus can overcome resistance to immune checkpoint blockade therapy

Abstract Immune checkpoint targeted therapies against PD-1, PD-L1 and CTLA-4 are currently revolutionizing cancer care. However, only a minority of patients generate objective tumor responses with these treatments. Therefore, new therapeutic interventions are needed to increase the immunogenicity of tumors in order to overcome the resistance to immune checkpoint blockade therapy. Pattern recognition receptors (PRR) such as toll-like receptor agonists have been shown to overcome resistance to immune checkpoint targeted therapy in pre-clinical models. Besides their intrinsic ability to stimulate PRR, the oncolytic properties of common viruses can be exploited also for the priming of anti-tumor immune responses. Several oncolytic viruses are currently in clinical development for cancer immunotherapy. However the routine implementation of these therapies is limited by the ongoing regulations on GMOs. With the aim to analyze if anti-infectious vaccines can be used as a source or PRR agonists and/or oncolytic viruses, we infected different tumors cell lines with commercially available anti-infectious vaccines. We first confirmed that commercially available vaccines do have PRR agonist properties. More interestingly, we discovered that rotavirus vaccines also have oncolytic properties. These attenuated viruses can directly kill cancer cells with features of immunogenic cell death such as upregulation of calreticulin on dying cancer cells but doesn't have cytotoxicity on healthy primary fibroblasts. Moreover, they have pro-inflammatory properties and can activate the NF-KB pathway in a toll-like receptor and IRF3 independent manner. These in vitro biological properties translate into in vivo anti-tumor activity. Intra-tumoral (IT) rotavirus therapy has anti-tumor effects which are mainly immune mediated as demonstrated by their weaken activity in NSG mice. Interestingly, in immunocompetent syngeneic murine tumor models of neuroblastoma and lymphoma, IT rotavirus therapy can overcome resistance to immune checkpoint targeted therapy and in particular synergies with anti-CTLA4. This therapeutic effect relied on specific modifications of tumor immune infiltrates and immune activation pathways. IT rotavirus vaccines was associated to an increase of myeloid infiltrating cells expressing up-regulated level of CD86 in the tumor microenvironment, and upregulation of activation markers such as OX40/CD137 on T cells. Rotavirus vaccines are clinical grade products, including for children. Therefore, in situ immunization strategies with IT attenuated rotavirus can be implemented quickly in the clinic including in pediatric cancers. IT priming of the anti-tumor immunity with oncolytic and immunostimulatory rotavirus vaccines could be a feasible strategy to overcome resistance to anti-PD-1/anti-CTLA-4 therapy in patients with cancer.* co-last authors. Citation Format: Tala Shekarian, Stéphane Depil, Anne-Catherine Jallas, Christophe Bergeron, Christophe Caux, Aurélien Marabelle, Sandrine Valsesia-Wittmann. Immunostimulatory and oncolytic properties of rotavirus can overcome resistance to immune checkpoint blockade therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4934.

Zika Virus Selectively Kills Aggressive Human Embryonal CNS Tumor Cells In Vitro and In Vivo.

Zika virus (ZIKV) is largely known for causing brain abnormalities due to its ability to infect neural progenitor stem cells during early development. Here, we show that ZIKV is also capable of infecting and destroying stem-like cancer cells from aggressive human embryonal tumors of the central nervous system (CNS). When evaluating the oncolytic properties of Brazilian Zika virus strain (ZIKVBR) against human breast, prostate, colorectal, and embryonal CNS tumor cell lines, we verified a selective infection of CNS tumor cells followed by massive tumor cell death. ZIKVBR was more efficient in destroying embryonal CNS tumorspheres than normal stem cell neurospheres. A single intracerebroventricular injection of ZIKVBR in BALB/c nude mice bearing orthotopic human embryonal CNS tumor xenografts resulted in a significantly longer survival, decreased tumor burden, fewer metastasis, and complete remission in some animals. Tumor cells closely resembling neural stem cells at the molecular level with activated Wnt signaling were more susceptible to the oncolytic effects of ZIKVBR Furthermore, modulation of Wnt signaling pathway significantly affected ZIKVBR-induced tumor cell death and viral shedding. Altogether, these preclinical findings indicate that ZIKVBR could be an efficient agent to treat aggressive forms of embryonal CNS tumors and could provide mechanistic insights regarding its oncolytic effects.Significance: Brazilian Zika virus strain kills aggressive metastatic forms of human CNS tumors and could be a potential oncolytic agent for cancer therapy. Cancer Res; 78(12); 3363-74. ©2018 AACR.

An experimental study on antitumoral effects of KI-21-3, a synthetic fragment of antimicrobial peptide LL-37, on oral squamous cell carcinoma

PurposeThe aim of this study was to investigate the oncolytic properties of KI-21-3, a shortened fragment of LL-37, against oral squamous cell carcinoma (OSCC) in an animal model. Materials and MethodsTwelve athymic nude mice were divided into a therapy and a control group of six animals each. In both groups, SCC-4 cells were administered extraorally into the floor of the mouth in order to create an OSCC model. In the study group, KI-21-3 was applied intravenously during the 8th and 9th weeks. The subjects in the control group were injected with phosphate buffered saline solution in the same manner. During an examination period of 12 weeks, weight control was performed twice a week. Tumor growth was further controlled volumetrically via ultrasonography once a week with regular intervals. Following sacrifice, ablated tumoral tissues were immunohistochemically evaluated in order to determine the proliferation and apoptotic properties. ResultsThe mean tumor weight in the AMP group was 0.0236 ± 0.023 g, which was 30% lower than the control group with the mean value of 0.01651 ± 0.012 g. In the control group, the approximate number of the proliferating cells per visualized field was fourfold higher compared to the therapy group. Moreover, in the control group, the number of apoptotic cells per visualized field was significantly lower compared to the therapy group. ConclusionKI-21-3 showed considerable oncolytic properties on SCC-4 carcinoma cells via antiproliferative and caspase-3 apoptotic pathway. Further investigations are necessary to clarify the dose-dependent effects of this agent.

Improving CART-Cell Therapy of Solid Tumors with Oncolytic Virus-Driven Production of a Bispecific T-cell Engager.

T cells expressing chimeric antigen receptors (CART) have shown significant promise in clinical trials to treat hematologic malignancies, but their efficacy in solid tumors has been limited. Oncolytic viruses have the potential to act in synergy with immunotherapies due to their immunogenic oncolytic properties and the opportunity of incorporating therapeutic transgenes in their genomes. Here, we hypothesized that an oncolytic adenovirus armed with an EGFR-targeting, bispecific T-cell engager (OAd-BiTE) would improve the outcome of CART-cell therapy in solid tumors. We report that CART cells targeting the folate receptor alpha (FR-α) successfully infiltrated preestablished xenograft tumors but failed to induce complete responses, presumably due to the presence of antigen-negative cancer cells. We demonstrated that OAd-BiTE-mediated oncolysis significantly improved CART-cell activation and proliferation, while increasing cytokine production and cytotoxicity, and showed an in vitro favorable safety profile compared with EGFR-targeting CARTs. BiTEs secreted from infected cells redirected CART cells toward EGFR in the absence of FR-α, thereby addressing tumor heterogeneity. BiTE secretion also redirected CAR-negative, nonspecific T cells found in CART-cell preparations toward tumor cells. The combinatorial approach improved antitumor efficacy and prolonged survival in mouse models of cancer when compared with the monotherapies, and this was the result of an increased BiTE-mediated T-cell activation in tumors. Overall, these results demonstrated that the combination of a BiTE-expressing oncolytic virus with adoptive CART-cell therapy overcomes key limitations of CART cells and BiTEs as monotherapies in solid tumors and encourage its further evaluation in human trials. Cancer Immunol Res; 6(5); 605-16. ©2018 AACR.

Development of improved therapeutic mesothelin-based vaccines for pancreatic cancer.

Pancreatic cancer is the 5th leading cause of cancer deaths, and there are no effective treatments. We developed a poxvirus platform vaccine with improved immunogenicity and inserted the mesothelin gene to create an anti-mesothelin cancer vaccine. Mesothelin expression is mostly restricted to tumors in adult mammals and thus may be a good target for cancer treatment. We show here that the modified vaccinia virus Ankara (MVA) virus expressing mesothelin and the enhanced MVA virus missing the immunosuppressive A35 gene and expressing mesothelin were both safe in mice and were able to induce IFN-gamma secreting T cells in response to mesothelin expressing tumor cells. In addition, the MVA virus has oncolytic properties in vitro as it can replicate in and kill Panc02 pancreatic adenocarcinoma cell line tumor cells, even though it is unable to replicate in most mammalian cells. Deletion of the A35 gene in MVA improved T cell responses as expected. However, we were unable to demonstrate inhibition of Panc02 tumor growth in immunocompetent mice with pre-vaccination of mice, boosts, or even intratumoral injections of the recombinant viruses. Vaccine efficacy may be limited by shedding of mesothelin from tumor cells thus creating a protective screen from the immune system.

Oncolytic influenza virus infection restores immunocompetence of lung tumor-associated alveolar macrophages

ABSTRACTNon-small-cell lung cancer (NSCLC) is the most frequent type of lung cancer and demonstrates high resistance to radiation and chemotherapy. These tumors evade immune system detection by promoting an immunosuppressive tumor microenvironment. Genetic analysis has revealed oncogenic activation of the Ras/Raf/MEK/ERK signaling pathway to be a hallmark of NSCLCs, which promotes influenza A virus (IAV) infection and replication in these cells. Thus, we aimed to unravel the oncolytic properties of IAV infection against NSCLCs in an immunocompetent model in vivo. Using Raf-BxB transgenic mice that spontaneously develop NSCLCs, we demonstrated that infection with low-pathogenic IAV leads to rapid and efficient oncolysis, eliminating 70% of the initial tumor mass. Interestingly, IAV infection of Raf-BxB mice caused a functional reversion of immunosuppressed tumor-associated lung macrophages into a M1-like pro-inflammatory active phenotype that additionally supported virus-induced oncolysis of cancer cells. Altogether, our data demonstrate for the first time in an immunocompetent in vivo model that oncolytic IAV infection is capable of restoring and redirecting immune cell functions within the tumor microenvironment of NSCLCs.

Antigen-specific oncolytic MV-based tumor vaccines through presentation of selected tumor-associated antigens on infected cells or virus-like particles

Recombinant vaccine strain-derived measles virus (MV) is clinically tested both as vaccine platform to protect against other pathogens and as oncolytic virus for tumor treatment. To investigate the potential synergism in anti-tumoral efficacy of oncolytic and vaccine properties, we chose Ovalbumin and an ideal tumor antigen, claudin-6, for pre-clinical proof of concept. To enhance immunogenicity, both antigens were presented by retroviral virus-like particle produced in situ during MV-infection. All recombinant MV revealed normal growths, genetic stability, and proper expression and presentation of both antigens. Potent antigen-specific humoral and cellular immunity were found in immunized MV-susceptible IFNAR−/−-CD46Ge mice. These immune responses significantly inhibited metastasis formation or increased therapeutic efficacy compared to control MV in respective novel in vivo tumor models using syngeneic B16-hCD46/mCLDN6 murine melanoma cells. These data indicate the potential of MV to trigger selected tumor antigen-specific immune responses on top of direct tumor lysis for enhanced efficacy.

Newcastle disease virus mediates pancreatic tumor rejection via NK cell activation and prevents cancer relapse by prompting adaptive immunity.

Pancreatic cancer is the 8th most common cause of cancer-related deaths worldwide and the tumor with the poorest prognosis of all solid malignancies. In 1957, it was discovered that Newcastle disease virus (NDV) has oncolytic properties on tumor cells. To study the oncolytic properties of NDV in pancreatic cancer a single dose was administered intravenously in a syngeneic orthotopic tumor model using two different murine pancreatic adenocarcinoma cell lines (DT6606PDA, Panc02). Tumor growth was monitored and immune response was analyzed. A single treatment with NDV inhibited DT6606PDA tumor growth in mice and prevented recurrence for a period of three months. Tumor infiltration and systemic activation of NK cells, cytotoxic and helper T-cells was enhanced. NDV-induced melting of Panc02 tumors until d7 pi, but they recurred displaying unrestricted tumor growth, low immunogenicity and inhibition of tumor-specific immune response. Arrest of DT6606PDA tumor growth and rejection was mediated by activation of NK cells and a specific antitumor immune response via T-cells. Panc02 tumors rapidly decreased until d7 pi, but henceforth tumors characterized by the ability to perform immune-regulatory functions reappeared. Our results demonstrated that NDV-activated immune cells are able to reject tumors provided that an adaptive antitumor immune response can be initiated. However, activated NK cells that are abundant in Panc02 tumors lead to outgrowth of nonimmunogenic tumor cells with inhibitory properties. Our study emphasizes the importance of an adaptive immune response, which is initiated by NDV to mediate long-term tumor surveillance in addition to direct oncolysis.

Bioselection of coxsackievirus B6 strain variants with altered tropism to human cancer cell lines.

Cancer cells develop increased sensitivity to members of many virus families and, in particular, can be efficiently infected and lysed by many low-pathogenic human enteroviruses. However, because of their great genetic heterogeneity, cancer cells display different levels of sensitivity to particular enterovirus strains, which may substantially limit the chances of a positive clinical response. We show that a non-pathogenic strain of coxsackievirus B6 (LEV15) can efficiently replicate to high titers in the malignant human cell lines C33A, DU145, AsPC-1 and SK-Mel28, although it displays much lower replication efficiency in A431 and A549 cells and very limited replication ability in RD and MCF7 cells, as well as in the normal lung fibroblast cell line MRC-5 and the immortalized mammary epithelial cell line MCF10A. By serial passaging in RD, MCF7 and A431 cells, we obtained LEV15 strain variants that had acquired high replication capacity in the appropriate carcinoma cell lines without losing their high replication capability in the original set of cancer cell lines and had limited replication capability in untransformed cells. The strains demonstrated improved oncolytic properties in nude-mouse xenografts. We identified nucleotide changes responsible for the phenotypes and suggest a bioselection approach for a generation of oncolytic virus strains with a wider spectrum of affected tumors.

Oncolytic property of HSV-1 recombinant viruses carrying the human IL-12

Objective: Constructed the recombinant HSV-1 deleted ICP47 and inserted human IL-12, and investigate the virus' replication ability and oncolytic property in vitro and vivo. Methods: The recombinant HSV-1 deleting ICP47 (MH1005) and then inserting human IL-12 (MH1006) were obtained with bacterial artificial chromosome technology.The replication ability and the efficiency of inhibiting tumor were detected in several nerve tumor cell lines infected with HSV-wt, MH1005 and MH1006 respectively.The murine tumor model was established by subcutaneous inoculation Neuro-2a cells on both sides of mice back respectively.A dosage of 2×10(6) PFU of HSV-wt, MH1001(recombinant HSV-1 deleted IR), MH1005, MH1006 and Mock were injected 3 times intratumorally on one side of mice back in every 3 days, the tumor volume and survival rate of the mice were measured. Results: The replication abilities of MH1005, MH1006 and HSV-wt in 293FT cells were insignificant (P>0.05); the replication abilities of recombinant HSV-1 in G422 and Neuro-2a were higher than that in SK-N-SH; and the nerve tumor cells could be inhibited significantly by recombinant HSV-1.After 15 days of treatment, on the mouse backside with injection treatment, the tumor volumes of group HSV-wt (6 267±484), MH1001 (5 730±1 071), MH1005 (4 537±538)and MH1006 (4 150±476)mm(3) were smaller than that of group Mock (6 957±722) mm(3) significantly (all P<0.01); on the mouse backside without injection treatment, the tumor volumes of group MH1005 (5 952±607) and MH1006 (5 473±661) mm(3) were smaller than those of HSV-wt (6 785±1 063), MH1001 (6 774±808) and Mock (6 957±190) mm(3) significantly (all P<0.05); after 35 days of treatment, the mice survival rates of group MH1005 (100%) and MH1006 (100%) were higher than those of MH1001 (67%), HSV-wt (50%) and Mock (33%) significantly (all P<0.05). Conclusion: MH1005 and MH1006 can infect nerve tumor cells and replicate at high level, the viruses not only kill tumor cells directly but also induce immunological rejection to tumor, and prolong the survival of mice bearing tumor.