We recently constructed an oncolytic virus from type 2 herpes simplex virus (HSV-2) that selectively targets and kills tumor cells with an activated Ras signaling pathway. Our recent study (Murphy et al., 2012. Mouse NF1(-) MPNST cell lines and human NF1(-) MPNST stemlike cells (MSLCs) were implanted into the sciatic nerves of immunocompetent and athymic mice, respectively. cited by examiner. While the promise is amazing, Imlygic isn’t the end-all cure that researchers are working toward—on average, the $65,000 treatment extends melanoma patients’ lives by only 4.4 months. Oncolytic virus, a tumor-specific replicating virus, is one of a number of natural or engineered viruses that can selectively replicate in and cleave tumor cells, but not kill normal somatic cells. Selection of vectors carrying the desired fragment is improved since vectors retaining the suicide gene result in cell death.
The method – known as viral immunotherapy – works by launching a “two-pronged attack” on cancer cells. Conclusion: We conclude that the ability of FusOn-H2 to induce tumor-specific cellular immunity expands the oncolytic repertoire of this virus and increases the likelihood that its use in patients would produce significant therapeutic benefits. Most viruses induce apoptosis following infection. Oncolytic HSV G47Δ exhibited robust efficacy in both immunodeficient and immunocompetent MPNST models while maintaining safety. But while tests in cancer cells grown in the lab and animals have been remarkably successful, this promise unfortunately hasn’t yet translated into success in clinical trials with actual cancer patients. Multiple cumulative genetic and/or epigenetic changes are needed to cause cancer. It has also been modified to remove two key genes so that it cannot replicate within healthy cells.
(1) In spite of its neurotropism, HSV-1 possesses a wide range of host cells, which is superior to adenovirus. (2) HSV-1 is able to infect dividing cells as well as nondividing cells. Stage Ta tumors are generally low grade, with only about 7% diagnosed as high grade . Solove Research Institute strives to create a cancer-free world by integrating scientific research with excellence in education and patient-centered care, a strategy that leads to better methods of prevention, detection and treatment. (4) Its genome will not integrate into the cellular genome, resulting in little insertional mutagenesis, which is the major concern in retrovirus and adeno-associated virus vectors. (5) The entire replication cycle is usually about 20 h in permissive cells, and that of adenovirus is 48-72 h. While the latest figures are yet to be revealed, this is a troublesome situation that can find relief with oncolytic viral therapy.
Gene technology means that scientists can now manipulate viruses to behave in certain ways – in this case, to only infect and attack cancer cells, bursting them from the inside. What brain tumor profiling offers is not only a sophisticated prediction of outcome, but also a selection of appropriate therapy for a patient with that tumor. Louis, Missouri, finds the results interesting, and suggested that a better understanding of viral biology will help move this potentially therapeutic field forward. Immun., 158, 299 (1973). Finally, we explored whether the disruption of the type-I IFN clearance mechanism in cancer cells was exploited by JX-594. The first half of this Review will discuss the principles of retargeting viruses to cancer cells, which are primarily illustrated using an RNA virus, MV, and a DNA virus, Ad. After many years of research on chemotherapy and radiotherapy scientists did not find the perfect drug.
Replication-defective vectors, in which either one of a few essential viral genes are deleted and then transgene expression cassettes are inserted in a viral genome, can effectively express transgene products, but are unable to replicate in cells unless host cells can supply the deleted viral functions. The HSV-1 mutant is used as a transgene in nerve cells. The HSV-1 thymidine kinase (TK) gene, a suicide gene encoded by UL23, is unique and most frequently used. TK protein can transform innocuous prodrugs such as GCV into cytotoxic drugs, resulting in termination of DNA synthesis in active cells, especially in tumor cells. Furthermore, bystander effects generated by TK/GCV systems are also toxic to tumor cells, but not towards neurons and quiescent glia. Aghi et al., Effect of chemotherapy-induced DNA repair on oncolytic herpes simplex viral replication. In addition, multiple therapeutic genes, for example, co-expressing TK and TNF-α, TK, connexin-43 and TNF-α, TK and IL-12 , have simultaneously been delivered in replication-defective HSV-1 vectors in extensive studies.
As a result, tumor growth was significantly inhibited. Retrieved 15 November 2014. In several animal tumor models, HSV-1 mutants with TK gene deletion were created and tested for oncolytic virotherapy, which could induce tumor regression following intra-neoplastic administration. All experimental procedures involving animals were approved by the Baylor College of Medicine Animal Care and Use Committee. It was demonstrated that hrR3 had produced significant antitumor effects and survival benefits in animal models such for brain, colon, pancreas and liver cancers. The nerves were postfixed with osmium tetroxide, en bloc stained with 2.0% uranyl acetate, dehydrated in a graded ethanol series, embedded in pure epoxy resin, and polymerized overnight at 60°C in a Leica Lynx automatic tissue processor. We need to see results from many more patients to know whether the virus is safe and effective at treating cancer and that Stacy’s incredible outcome wasn’t just a fluke.
Significantly, prior pilot studies suggested that the treatment of the prostate cancer cells with the suicide genes introduced by the oncolytic virus increased cancer cell sensitivity to radiation and chemotherapy. coli lacZ gene in UL39 gene which encodes ICP6, had some favorable properties for cancer treatment. Competent replication in tumor cells, attenuated neurovirulence, GCV hypersensitivity, temperature sensitivity and the product of lacZ gene were easily detectable. G47Δ, a derivative of G207 with an additional ICP47 gene deletion, could more efficaciously inhibit tumor growth in vivo than its parent G207, while safety was unaffected. The first is to delete gene functions that are critical for efficient viral replication in normal cells but are expendable in tumor cells [38, 39]. Compared with R3616[22,23] (double ICP34.5-deletion mutant), R7020 was more efficacious in inhibiting the growth of tumors, and more sensitive to ACV and GCV. Myb34.5 had the deletion of both endogenous copies of the ICP34.5 gene and re-insertion of this gene into the ICP6 locus, with the new ICP34.5 gene under the control of the B-myb promoter.
In contrast to hrR3, Myb34.5 was active in tumor cells, but was more attenuated in normal cells. Although the usefulness of HSV-1 vectors for treating tumors have been confirmed, there are some limitations in their application. (1) It is more difficult to produce multiple gene deleted HSV-1 vectors than the wild-type virus, resulting in a lower yield. The trial is currently closed to enrollment, but we have acquired some promising information from the results of the first 20 patients. (2) It is particularly difficult to keep long-term stability (over 6-mo period) of HSV-1 derived vectors, either in aqueous solution or in lyophilized form. (3) The virus may rapidly spread in individuals with immunodeficiency. The efficacy may be reduced by immune response induced by antiviral or antitransgene products.
Reprogramming oncolytic viruses requires at least two steps: first, retargeting by adding new ligands to mediate binding to receptors that are expressed on cancer cells, and second, detargeting by blocking promiscuous binding to non-cancer cells. At that time people knew that diseases could be transmitted so the tumor regression had something to do with the previous patients. HSV-1 mutants can selectively infect tumor cells, but not suppress the growth of normal cells. There may be a synergistic antitumor effect, when they are labeled with radionuclide. With the help of the viral vectors, radionuclide will be carried into tumor tissues and bring about radiation damage to tumor cells. It is rarely reported whether HSV-1 can be labeled with radionuclide, whether viral bioactivity may be influenced by the virus labeled or radionuclide which will enter into tumor cells together with virus. We analyzed these issues in this overview.
Hoffmann et al., Comparison of herpes simplex virus- and conditionally replicative adenovirus-based vectors for glioblastoma treatment. Located in the core of the virus, dsDNA is surrounded by a protein shell called a capsid which consists of 162 capsomeres arranged in a T = 16 icosahedral symmetry. The channels which are controlled by tegument proteins are contained in the capsid, controlling the transport of dsDNA through the channel. Surrounding the capsid, an amorphous tegument contains at least eight types of proteins that play an important role during HSV-1 infection. An outer envelope is composed of lipid bilayer with about 13 different viral glycoproteins. After 24 h, the supernatants were harvested and analyzed for mouse IFN-γ, tumor necrosis factor-α, and interleukin-2 with the BD Mouse Th1/Th2 Cytokine Cytometric Bead Array Kit according to the manufacturer’s instructions (BD Bioscience). However, HSV-1 mutants are generally constructed by modifying the dsDNA without altering their tegument-capsid.
Mice were sacrificed due to tumor size or ulceration. Furthermore, the proteins such as monoclonal antibody, polypeptide and ligand, can all be labeled successfully[30,31]. As for radionuclide, there are 125I, 131I, 32P, 35S, 99mTc, 188Re, 186Re, 90Y and so on. In a word, the proteins contained in HSV-1 structural elements are considerably suitable for radiolabelling. During initial infection, HSV-1 attaches first to the host cell surface receptor, and fuses with the membrane of host cells, and the de-enveloped tegument-capsid is efficiently and rapidly transported to the nuclear pore complexes, where the viral dsDNA is released. The capsid with associated tegument structures can also be carried to the nuclear pore through the microtubules. RR plays a key role in making the deoxyribonucleotides (dNTPs) that are needed for DNA synthesis .
At the early phase of virus infection, the viral envelope glycoproteins, gC and gB, bind to cell surface heparin sulfate. Then, viral glycoprotein gD binds to certain cell surface receptor (e.g., nectin-1a, nectin-1b, 2a, 2d, HveA), contributing to virion-cell fusion. Besides, three other viral envelope glycoproteins, gB, gH and gL, have been shown to be helpful for the HSV-1 penetration into host cells. As a result, the viral proteins are delivered into different metastructures. So, it is feasible that HSV-1 vector mutants could carry radionuclide-labeled proteins into tumor cells. These new blood vessels feed the tumor, bring it more nutrients, allow it to grow and divide, and cause more problems. A study on the combination of gene therapy with radiotherapy for tumors revealed that the gene products in mice lung cancer cells had increased dose-dependently, when irradiated by gamma-ray at doses of 2-40 Gy followed by AdCMVlu transfection.
The efficacy could be up to 24 times higher, and tumor growth was inhibited. Kanazawa demonstrated that the number of replicative dsDNA of the laryngeal cancer cell line (HEp-2) and Henrietta Lacks (HeLa) strain of cancer cells had a significant enhancement in the combination of virus system and radiotherapy. Enveloped viruses provide an optimal platform for applying scFvs, as both the ligands and viral envelope glycoproteins are naturally secreted through the same pathway. As a result a viral half-life is about 2 minutes in mice  and goes up to 12 minutes in humans . These experiments in vitro suggested that the combination of AAVtk/GCV system with radiotherapy was significantly effective in the treatment of cancers. Weichselbaum RR found radiation could induce the transcription of CarG elements in the Egr-1 promoter sequences which lies the upstream of TNF-α cDNA. At the same time, TNF-α obtained a high expression.
Generally, radiotherapy would stimulate the virus replication, resulting in a higher HSV-1 antitumor activity. Other studies had also indicated that ionizing radiation could enhance anti-cancer activity of hrR3 without altering its replication. Similarly, a synergistic antitumor response, with more tumor regression and better survival rate, was induced by the combination of ionizing radiation and R3616 deleted ICP34.5. So, radionuclide labeled to HSV-1 mutants does not damage the viral biological function, but can enhance the antitumor effect. It is extremely important that compounds labeled with radionuclide should possess a good stability in vivo. The labeled compounds should stay in the tumor cell cytoplasm while the HSV-1 mutant dsDNA enters the nucleus. HSV-1 recombinant-labeled radionuclide should, therefore, have a favourable stability before penetration into the tumor cell nucleus.
2 ). Diethylenetriaminepentaacetic acid (DTPA) is known as one of the difunctional chelators. Merged phase contrast–fluorescent images (infected cells are red). Thus, radionuclide (188Re, 90Y) is indirectly linked up with protein molecule, and the compounds labeled with radionuclide is stable in vivo. Moreover, the biochemical activity of radiolabeled complex will not be influenced. As a chelating agent, DTPA has a potential and broad applicability[30,31]. As far as radiolabeling and the structure of HSV-1 are concerned, the feasibility of labeling radionuclide to HSV-1 mutants is demonstrated by a plenty of animal experiments and clinical trials.
Furthermore, once the radionuclide is introduce, nuclear medicine approaches may be employed in the clinic to monitor and assess the therapeutic efficacy in vitro in a non-invasive manner. have reported results with OncoVEXGALV/CD as an intravesical therapy for bladder cancer. coli Z gene and TNFα gene in UL39 gene. Then HSV-1 GRT can be labelled with 131I or 188Re directly or indirectly. We will study the expression of HSV-1 GRT or radioactive compounds (131I-HSV-1 GRT, 188Re-HSV-1 GRT and 188Re-DTPA-HSV-1 GRT) in tumor cells and mechanism of inhibiting or killing tumor cells. In other words, our aim is to develop an ideal drug which can combine viral oncolysis with radionuclids therapy. With the help of the HSV-1 GRT, radionuclids (131I or 188Re) can be carried into tumor tissues and bring about radiation damage to tumor cells.
Some of these markers are specific to cancer stem cells, and CD 133 is one of them. The combination of viral oncolysis with radionuclide therapy will achieve a synergistic anticancer effect, with more inhibition of tumor growth, less toxicity and fewer side effects than either HSV-1 mutants or radionuclide therapy. It is reasonably concluded that HSV-1 mutants labeled with radionuclide will be a potential focus for tumor treatment.