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Hogan DJ, Zhu JJ, Diago OR, Gammon D, Haghighi A, Lu G, Das A, Gruber HE, Jolly DJ, Ostertag D. Molecular Analyses Support the Safety and Activity of Retroviral Replicating Vector Toca 511 in Patients. Clin Cancer Res 2018; 24:4680-4693. [DOI: 10.1158/1078-0432.ccr-18-0619] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 05/03/2018] [Accepted: 06/13/2018] [Indexed: 11/16/2022]
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2
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Hohn O, Krause H, Barbarotto P, Niederstadt L, Beimforde N, Denner J, Miller K, Kurth R, Bannert N. Lack of evidence for xenotropic murine leukemia virus-related virus(XMRV) in German prostate cancer patients. Retrovirology 2009; 6:92. [PMID: 19835577 PMCID: PMC2770519 DOI: 10.1186/1742-4690-6-92] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 10/16/2009] [Indexed: 11/21/2022] Open
Abstract
Background A novel gammaretrovirus named xenotropic murine leukemia virus-related virus (XMRV) has been recently identified and found to have a prevalence of 40% in prostate tumor samples from American patients carrying a homozygous R462Q mutation in the RNaseL gene. This mutation impairs the function of the innate antiviral type I interferon pathway and is a known susceptibility factor for prostate cancer. Here, we attempt to measure the prevalence of XMRV in prostate cancer cases in Germany and determine whether an analogous association with the R462Q polymorphism exists. Results 589 prostate tumor samples were genotyped by real-time PCR with regard to the RNaseL mutation. DNA and RNA samples from these patients were screened for the presence of XMRV-specific gag sequences using a highly sensitive nested PCR and RT-PCR approach. Furthermore, 146 sera samples from prostate tumor patients were tested for XMRV Gag and Env antibodies using a newly developed ELISA assay. In agreement with earlier data, 12.9% (76 samples) were shown to be of the QQ genotype. However, XMRV specific sequences were detected at neither the DNA nor the RNA level. Consistent with this result, none of the sera analyzed from prostate cancer patients contained XMRV-specific antibodies. Conclusion Our results indicate a much lower prevalence (or even complete absence) of XMRV in prostate tumor patients in Germany. One possible reason for this could be a geographically restricted incidence of XMRV infections.
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Affiliation(s)
- Oliver Hohn
- Robert Koch-Institute, Centre for Biological Safety 4, Nordufer 20, 13353 Berlin, Germany.
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3
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4
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Abstract
Retroviral vectors based on murine leukemia viruses (MuLV) have been used in clinical investigations for over a decade. Alternative retroviruses, most notably vectors based on HIV-1 and other lentiviruses, are now entering into clinical trials. Although vectors are designed to be replication defective, recombination events during vector production could lead to the generation of replication competent retroviruses (RCR) or replication competent lentiviruses (RCL). Careful screening of vector prior to human use must insure that patients are not inadvertently exposed to RCR or RCL. We describe methods capable of detecting low levels of virus contamination and discuss the current regulatory guidelines for screening gene therapy products intended for human use.
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Affiliation(s)
- Lakshmi Sastry
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
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5
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Rodrigues T, Carrondo MJT, Alves PM, Cruz PE. Purification of retroviral vectors for clinical application: Biological implications and technological challenges. J Biotechnol 2007; 127:520-41. [PMID: 16950534 DOI: 10.1016/j.jbiotec.2006.07.028] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Revised: 07/12/2006] [Accepted: 07/25/2006] [Indexed: 11/16/2022]
Abstract
For centuries mankind led a difficult battle against viruses, the smallest infectious agents at the surface of the earth. Nowadays it is possible to use viruses for our benefit, both at a prophylactic level in the production of vaccines and at a therapeutic level in the promising field of gene therapy. Retroviruses were discovered at the end of the 19th century and constitute one of the most effective entities for gene transfer and insertion into the genome of mammalian cells. This attractive feature has intensified research in retroviral vectors development and production over the past years, mainly due to the expectations raised by the concept of gene therapy. The demand for high quality retroviral vectors that meet standard requisites from the regulatory agencies (FDA and EMEA) is therefore increasing, as the technology has moved into clinical trials. The development of safer producer cell lines that can be used in large-scale production will result in the production of large quantities of retroviral stocks. Cost-efficient and scalable purification processes are essential for production of injectable-grade preparations to achieve final implementation of these vectors as therapeutics. Several preparative purification steps already established for proteins can certainly be applied to retroviral vectors, in particular membrane filtration and chromatographic methods. Nevertheless, the special properties of these complex products require technological improvement of the existing purification steps and/or development of particular purification steps to increase productivity and throughput, while maintaining biological activity of the final product. This review focuses on downstream process development in relation to the retroviral vectors characteristics and quality assessment of retroviral stocks for intended use in gene therapy.
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Affiliation(s)
- Teresa Rodrigues
- IBET/ITQB, Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2781-901 Oeiras, Portugal
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6
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Cornetta K, Matheson L, Ballas C. Retroviral vector production in the National Gene Vector Laboratory at Indiana University. Gene Ther 2006; 12 Suppl 1:S28-35. [PMID: 16231053 DOI: 10.1038/sj.gt.3302613] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The National Gene Vector Laboratory (NGVL) is a US National Institutes of Health initiative charged with providing clinical grade vectors for gene therapy trials. The program was started in 1995 and Indiana University has served as the production site for retroviral vectors and is also accepting applications for production of lentiviral vectors. The facility is designed to produce vectors for Phase I and Phase II clinical trials with the specific mandate to facilitate investigator-initiated research for academic institutions. To date, the facility has generated over 30 Master Cell Banks for gene therapy investigators throughout the United States. This required the facility to develop a system that can adapt to the varied needs of investigators, most of whom request different vector backbones, packaging cell lines, final product volumes, and media. In this review, we will illustrate some of the experiences of the Indiana University NGVL during the generation of retroviral vectors using murine-based packaging cell lines.
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Affiliation(s)
- K Cornetta
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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7
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Abstract
Mouse mammary tumor virus (MMTV) has long been speculated to be involved in human breast cancer and more recently in human primary biliary cirrhosis. Despite complete proviral sequences markedly homologous to MMTV being identified in human breast cancer tissue, no convincing evidence has been presented to date that MMTV can infect human cells. Using both wild-type and a genetically marked virus (MMTV-EGFP), we show here the successful infection of a number of different human cells by MMTV. Furthermore, infection of human cells is shown to be almost as efficient as the infection of murine mammary epithelial cells. Sequencing of PCR products from integrated proviruses reveals that reverse transcription and integration of the viral genome has occurred as expected. Furthermore, sequencing of two independent MMTV proviral integration sites reveal them to be present only in the human and not in the mouse genome. Infection requires an intact MMTV envelope protein and is blocked either by heat inactivation of the virus or by specific neutralizing anti-MMTV serum, ruling out a nonspecific mechanism of viral transfer. Thus, MMTV can infect human cells and this finding provides a possible explanation for the detection by others of MMTV sequences in human breast cancer patients.
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Affiliation(s)
- Stanislav Indik
- Research Institute for Virology and Biomedicine, University of Veterinary Medicine, Vienna, Austria
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8
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Sastry L, Xu Y, Duffy L, Koop S, Jasti A, Roehl H, Jolly D, Cornetta K. Product-Enhanced Reverse Transcriptase Assay for Replication-Competent Retrovirus and Lentivirus Detection. Hum Gene Ther 2005; 16:1227-36. [PMID: 16218784 DOI: 10.1089/hum.2005.16.1227] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The product-enhanced reverse transcriptase (PERT) assay has been used to detect reverse transcriptase (RT) activity associated with retroviruses. Although the PERT assay has been proposed as a method for detection of replication-competent retrovirus (RCR) and lentivirus (RCL), it has not been rigorously compared with existing methods for RCR and RCL detection. We have assessed the PERT assay for detection of RCL and RCR that may contaminate lentiviral and retroviral vectors and compared it with published methods for RCL (p24gag ELISA/gag PCR) and RCR (S+/L-) detection. Our results suggest that the PERT assay is as sensitive as p24gag ELISA and gag PCR for detection of replication-competent HIV-1 in an RCL detection assay. Comparison of detection of replication-competent retroviruses, GALV and RD114, by extended S+/L- and PERT assays indicates that both assays can detect 1 IU of each virus. Our findings suggest that the PERT assay can be used for RCL and RCR testing of a variety of retroviral vectors regardless of the structure, sequence, and envelope of the vectors.
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Affiliation(s)
- Lakshmi Sastry
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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9
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Sastry L, Xu Y, Duffy L, Koop S, Jasti A, Roehl H, Jolly D, Cornetta K. Product-Enhanced Reverse Transcriptase Assay for Replication-Competent Retrovirus and Lentivirus Detection. Hum Gene Ther 2005. [DOI: 10.1089/hum.2005.16.ft-122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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10
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Kim S, Park EJ, Yu SS, Kim S. Development of enzyme-linked immunosorbent assay for detecting antibodies to replication-competent murine leukemia virus. J Virol Methods 2004; 118:1-7. [PMID: 15158062 DOI: 10.1016/j.jviromet.2004.01.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2003] [Revised: 12/20/2003] [Accepted: 01/15/2004] [Indexed: 10/26/2022]
Abstract
A method for detecting the antibodies to replication-competent retrovirus (RCR) was developed. Specific fragments of murine leukemia virus (MLV) Gag or Env protein were cloned and expressed in Escherichia coli, and used subsequently to develop the ELISA system. It was found that CA of Gag and SU of Env, but not the transmembrane portion of Env, could be used in ELISA. ELISA conditions such as coating buffer and blocking solution were optimized using sera obtained from mice immunized with amphotropic MLV particles. In an optimized ELISA system, serum samples from normal healthy individuals provided very low absorbance values. ELISA was performed using serum samples from patients who had received skin fibroblasts engineered with MLV-based retroviral vector. Experimental samples presented absorbance values comparable to those found with control serum samples from normal, healthy individuals, showing no evidence of RCR infection.
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MESH Headings
- Animals
- Antibodies, Viral/analysis
- Antibodies, Viral/blood
- Antigens, Viral/genetics
- Base Sequence
- DNA, Viral/genetics
- Enzyme-Linked Immunosorbent Assay/methods
- Enzyme-Linked Immunosorbent Assay/statistics & numerical data
- Gene Products, env/genetics
- Gene Products, env/immunology
- Gene Products, gag/genetics
- Gene Products, gag/immunology
- Genetic Therapy/adverse effects
- Genetic Vectors
- Humans
- Leukemia Virus, Murine/genetics
- Leukemia Virus, Murine/immunology
- Leukemia Virus, Murine/physiology
- Mice
- Mice, Inbred BALB C
- Recombinant Proteins/genetics
- Recombinant Proteins/immunology
- Safety
- Sensitivity and Specificity
- Virology/methods
- Virology/statistics & numerical data
- Virus Replication
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Affiliation(s)
- Sujeong Kim
- ViroMed Co., Ltd., 1510-8 Bongcheon-Dong, Gwanak-Gu, Seoul 151-818, South Korea.
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11
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Ebeling SB, Simonetti ER, Borst HPE, Blok A, Schelen AM, Braakman E, Ederveen J, Hagenbeek A. Human primary T lymphocytes have a low capacity to amplify MLV-based amphotropic RCR and the virions produced are largely noninfectious. Gene Ther 2003; 10:1800-6. [PMID: 12960969 DOI: 10.1038/sj.gt.3302080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The presence of replication-competent retrovirus (RCR) in retroviral-based gene therapy products poses a potential safety risk for patients. Therefore, RCR testing of clinical gene therapy products and monitoring of patients enrolled in gene therapy trials is required to assure viral safety. The requirement to test ex vivo-transduced cells originates from the presumed amplification of adventitious RCR during the transduction procedure. However, data on the capacity of different cell types to do so are lacking. In this study, we sought to analyze the amplification potential of primary human T lymphocytes after infection with amphotropic MLV-based RCR. The total number of viral particles produced after 1 or 2 weeks was measured by a quantitative 4070A env-specific RT-PCR assay. The fraction of infectious replication-competent viral particles was analyzed in the PG-4 S+L- assay. From this study, we conclude that the total number of viral particles RCR produced by T lymphocytes is 2-4 logs lower than the number produced by NIH-3T3 cells. Surprisingly, less than 1% of the viral particles produced by primary T lymphocytes appeared to be infectious, while nearly all virions produced by NIH-3T3 were. We conclude that primary human T lymphocytes are low producers of MLV-based amphotropic RCR.
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Affiliation(s)
- S B Ebeling
- Jordan Laboratory for Hemato-Oncology, Department of Hematology, University Medical Center Utrecht, Utrecht, The Netherlands
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12
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Reeves L, Duffy L, Koop S, Fyffe J, Cornetta K. Detection of ecotropic replication-competent retroviruses: comparison of s(+)/l(-) and marker rescue assays. Hum Gene Ther 2002; 13:1783-90. [PMID: 12396630 DOI: 10.1089/104303402760293619] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Guidelines for testing gene therapy products for ecotropic replication-competent retrovirus (Eco-RCR) have not been delineated as they have for amphotropic viruses. To evaluate biologic assays that can detect these viruses, we compared an S(+)/L(-) assay and a marker rescue assay designed specifically for Eco-RCR detection. Moloney murine leukemia virus (Mo-MuLV) obtained from the American Type Culture Collection was used as the positive control. For marker rescue, NIH 3T3 cells were transduced with a retroviral vector expressing the neomycin phosphotransferase gene (3T3/Neo). Inoculation and passage of test material in 3T3/Neo cells for 3 weeks (amplification) and subsequent testing in the S(+)/L(-) assay or the marker rescue assay increased the level of sensitivity for virus detection greater than 10-fold compared with direct inoculation of D56 S(+)/L(-) cells. When serial dilutions of Mo-MuLV stock were evaluated, six of six cultures had detectable virus by the S(+)/L(-) and marker rescue assays at dilutions of 10(-5) and 10(-6). At the 10(-7) dilution, five of six assays had detectable virus in both assays. The ability to detect virus-infected cells was also evaluated in a modification that substituted cells for supernatant. Fifteen 3T3/Neo cultures inoculated with 10(6) 293 cells containing 100 or 10 Mo-MuLV/3T3 cells were all positive by marker rescue. For dilution with 1 virus-infected cell per 10(6) 293 cells, 10 of 15 cultures were positive. At the 0.1-cell dilution only 2 of 15 cultures were positive. If we hope to detect one infected cell in a test article, the probability of detecting virus if the assay is performed in triplicate is 96.3%. In summary, after 3 weeks of amplification the S(+)/L(-) and marker rescue assays can detect virus with similar sensitivities. We prefer the marker rescue assay because of the more reliable growth features of NIH 3T3 cells compared with the D56 cell line. For laboratories analyzing clinical materials, this report may prove useful in establishing detection assays for Eco-RCR.
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Affiliation(s)
- Lilith Reeves
- Division of Hematology/Oncology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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13
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Singh S, Cunningham C, Buchanan A, Jolly DJ, Nemunaitis J. Toxicity assessment of intratumoral injection of the herpes simplex type I thymidine kinase gene delivered by retrovirus in patients with refractory cancer. Mol Ther 2001; 4:157-60. [PMID: 11482988 DOI: 10.1006/mthe.2001.0430] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Introduction of the herpes simplex type I thymidine kinase (HSV-TK) gene into tumor tissue, followed by ganciclovir, initiates a phosphorylation cascade that induces formation of a toxic ganciclovir triphosphate. Animal trials suggest that this ganciclovir triphosphate has antitumor activity. Here we report application of the HSV-TK transfection approach using a retroviral construct. Sixteen patients (median age 61.5 years) with refractory carcinoma (13 melanoma, 1 breast cancer, 1 nonsmall-cell lung cancer, and 1 osteogenic sarcoma) received intratumoral injection of HSV-TK retroviral vector at escalating doses (0.2x10(7) cfu per injection x 5 daily doses) and we evaluated them for toxicity and activity. We observed grade III pain associated with cellulitis in one patient following injection. Analysis of blood samples drawn between 3 and 28 weeks from 14 patients for replication-competent retrovirus by PCR analysis of the amphotrophic envelope revealed no replication-competent retrovirus. We injected 21 lesions. We identified no tumor responses of the injected lesions. Of 13 patients with advanced melanoma, 6 survived over one year. Thus, injection of retroviral delivered HSV-TK in patients with refractory cancer was well-tolerated.
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Affiliation(s)
- S Singh
- US Oncology, Dallas, Texas 75246, USA
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14
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McCormack JE, Edwards W, Sensintaffer J, Lillegren L, Kozloski M, Brumm D, Karavodin L, Jolly DJ, Greengard J. Factors affecting long-term expression of a secreted transgene product after intravenous administration of a retroviral vector. Mol Ther 2001; 3:516-25. [PMID: 11319912 DOI: 10.1006/mthe.2000.0259] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have studied parameters affecting in vivo expression of human growth hormone (hGH) in mice after intravenous administration of a retroviral vector encoding the protein as a model system for clotting factor VIII gene therapy. Such treatment results in a brief burst of high-level expression followed by lower level sustained expression of the hGH in the circulation. The major targets for transduction in the mouse are liver and spleen. Such direct transduction (i.e., without surgical or chemical induction of cell division) requires vector at high titer (>/=10(8) cfu/ml) and is dose dependent. Transduction efficiency decreases with increasing age of the recipient. Nevertheless, long-term expression in adults is observed after administration of vector as a split dose on 2 consecutive days. We also show that anti-vector immune responses may enhance long-term expression and that both anti-vector and anti-transgene immunity can be modulated. This work provides a framework for the rational development of means to enhance the efficiency of retroviral vectors for use in clinical gene replacement therapy.
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Affiliation(s)
- J E McCormack
- Chiron Corporation Center for Gene Therapy, 11055 Roselle Street, San Diego, California 92121, USA
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15
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Chen J, Reeves L, Sanburn N, Croop J, Williams DA, Cornetta K. Packaging cell line DNA contamination of vector supernatants: implication for laboratory and clinical research. Virology 2001; 282:186-97. [PMID: 11259201 DOI: 10.1006/viro.2001.0826] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Investigators conducting retroviral gene therapy trials are required to monitor for the presence of replication-competent retrovirus (RCR). The required testing utilizes a combination of biologic assays and molecular tests using PCR. In the course of a human clinical gene therapy trial, we detected 4070A viral envelope sequences in CD34(+) peripheral blood stem cells 2 days after transduction using a PCR-based assay, suggesting the presence of RCR. The supernatant and producer cells used for vector generation had been negative in extensive screening using the extended S(+)/L(-) assay. The presence of a replication-competent virus was subsequently excluded by a combination of biologic and PCR analyses. The source of the 4070A viral envelope sequences was determined to be packaging cell line DNA in the vector supernatant. The analysis of a variety of vector supernatants by quantitative real-time PCR revealed 4070A envelope DNA sequences from the packaging cell line in concentrations equivalent to approximately 50-500 focus-forming units per milliliter of wild-type 4070A virus. When PCR was performed after reverse transcriptase treatment of supernatant (i.e., assessing both RNA and DNA content), 4070A envelope sequence concentrations ranged from 10(2) to 3.5 x 10(3) focus-forming units per milliliter of wild-type 4070A virus. Our data indicate that PCR should not be used to analyze transduced cells for RCR within the first 2 weeks of vector exposure. Furthermore, investigators using PCR to analyze transduction efficiency shortly after vector exposure may experience false-positive findings.
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Affiliation(s)
- J Chen
- Department of Medicine, Division of Hematology/Oncology, Indiana University School of Medicine, Indianapolis 46202, USA
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16
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Supplemental guidance on testing for replication-competent retrovirus in retroviral vector-based gene therapy products and during follow-up of patients in clinical trials using retroviral vectors. Hum Gene Ther 2001; 12:315-20. [PMID: 11177567 DOI: 10.1089/10430340150218440] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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17
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Chen J, Reeves L, Cornetta K. Safety testing for replication-competent retrovirus associated with gibbon ape leukemia virus-pseudotyped retroviral vectors. Hum Gene Ther 2001; 12:61-70. [PMID: 11177543 DOI: 10.1089/104303401450979] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The potential pathogenicity of replication-competent retroviruses (RCR) requires vigilant testing to exclude inadvertent contamination of clinical gene therapy vector products with RCR. Pseudotyped vectors using the gibbon ape leukemia virus (GALV) envelope have entered into clinical trials but specific recommendations regarding methods for screening of vector product and analysis of clinical samples have not been set forth. Unfortunately, current screening assays used for detecting amphotropic RCR are not suitable for GALV-pseudotyped RCR. We modified the extended S+/L- assay for RCR detection by using human 293 cells for virus amplification. Of five cell lines tested, 293 cells were selected because they combined a high transduction efficiency and an ability to generate RCR at high titer. After optimizing the amplification assay, a dilution of GALV virus could consistently be detected at a dilution of 10(-6). In coculture experiments, one GALV-infected cell could be consistently detected in 10(6) uninfected cells. A PCR-based assay was developed that was capable of detecting 100 copies of a GALV envelope containing plasmid diluted in 1 microg of DNA obtained from uninfected cells. PCR was also able to detect one GALV-infected cell in 10(6) uninfected cells. These assays will be suitable for testing of vector preparations and for monitoring of clinical samples from patients treated in clinical gene therapy protocols. The assays developed are similar in methodology and sensitivity to those currently used for certification of amphotropic retroviral vectors.
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Affiliation(s)
- J Chen
- Division of Hematology/Oncology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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18
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Romano G, Michell P, Pacilio C, Giordano A. Latest developments in gene transfer technology: achievements, perspectives, and controversies over therapeutic applications. Stem Cells 2000; 18:19-39. [PMID: 10661569 DOI: 10.1634/stemcells.18-1-19] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Over the last decade, more than 300 phase I and phase II gene-based clinical trials have been conducted worldwide for the treatment of cancer and monogenic disorders. Lately, these trials have been extended to the treatment of AIDS and, to a lesser extent, cardiovascular diseases. There are 27 currently active gene therapy protocols for the treatment of HIV-1 infection in the USA. Preclinical studies are currently in progress to evaluate the possibility of increasing the number of gene therapy clinical trials for cardiopathies, and of beginning new gene therapy programs for neurologic illnesses, autoimmuno diseases, allergies, regeneration of tissues, and to implement procedures of allogeneic tissues or cell transplantation. In addition, gene transfer technology has allowed for the development of innovative vaccine design, known as genetic immunization. This technique has already been applied in the AIDS vaccine programs in the USA. These programs aim to confer protective immunity against HIV-1 transmission to individuals who are at risk of infection. Research programs have also been considered to develop therapeutic vaccines for patients with AIDS and generate either preventive or therapeutic vaccines against malaria, tuberculosis, hepatitis A, B and C viruses, influenza virus, La Crosse virus, and Ebola virus. The potential therapeutic applications of gene transfer technology are enormous. However, the effectiveness of gene therapy programs is still questioned. Furthermore, there is growing concern over the matter of safety of gene delivery and controversy has arisen over the proposal to begin in utero gene therapy clinical trials for the treatment of inherited genetic disorders. From this standpoint, despite the latest significant achievements reported in vector design, it is not possible to predict to what extent gene therapeutic interventions will be effective in patients, and in what time frame.
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Affiliation(s)
- G Romano
- Kimmel Cancer Institute, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
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19
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Powell SK, Artlip M, Kaloss M, Brazinski S, Lyons R, McGarrity GJ, Otto E. Efficacy of antiretroviral agents against murine replication-competent retrovirus infection in human cells. J Virol 1999; 73:8813-6. [PMID: 10482636 PMCID: PMC112903 DOI: 10.1128/jvi.73.10.8813-8816.1999] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Retroviral vectors for gene therapy are designed to minimize the occurrence of replication-competent retrovirus (RCR); nonetheless, it is possible that a vector-derived RCR could establish an infection in a patient. Since the efficacy of antiretroviral agents can be impacted by interactions between virus, host cell, and drug, five commonly used antiretroviral drugs were evaluated for their abilities to inhibit the replication of a murine leukemia virus (MLV)-derived RCR in human cells. The results obtained indicate that the combination of nucleoside analogs zidovudine and dideoxyinosine with the protease inhibitor indinavir effectively inhibits MLV-derived RCR replication in three human cell lines. In addition, MLV-derived RCR was found to be inherently resistant to the nucleoside analogs lamivudine and stavudine, suggesting that mutations conferring resistance to nucleoside analogs in human immunodeficiency virus type 1 have the same effect even in an alternative viral backbone.
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Affiliation(s)
- S K Powell
- Genetic Therapy, Inc., a Novartis Company, Gaithersburg, Maryland 20878, USA.
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20
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Powell SK, Kaloss M, Burimski I, Weaver L, Long Z, Lyons R, McGarrity GJ, Otto E. In vitro analysis of transformation potential associated with retroviral vector insertions. Hum Gene Ther 1999; 10:2123-32. [PMID: 10498244 DOI: 10.1089/10430349950017112] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
While replication-defective retroviral vectors provide excellent vehicles for the long-term expression of therapeutic genes, they also harbor the potential to induce undesired genetic changes by random insertions into the host genome. The rate of insertional mutagenesis for retroviral vectors has been determined in several different assay systems; however, the rate at which such events induce cellular transformation has not been directly determined. Such measurements are critical to determining the actual risk of carcinogenesis resulting from retroviral gene therapy. In this study, the ability of a replication-defective retroviral vector, GlnBgSvNa, to induce cellular transformation in the BALB/c-3T3 in vitro transformation assay was assessed. The transformation frequency observed in vector-transduced BALB/c-3T3 cells, which contained one to six copies of integrated provirus, was not significantly different from that of untreated control cells. The finding that GlnBgSvNa was nontransforming in this assay indicates that the rate of transformation induced by retroviral insertions is less than the spontaneous rate of cellular transformation by BALB/c-3T3 cells, or less than 1.1 x 10(-5). These results are the first to define an upper limit for the rate of transformation induced by retroviral vectors.
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Affiliation(s)
- S K Powell
- Genetic Therapy, Inc., a Novartis Company, Gaithersburg, MD 20878, USA
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21
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Tam YK, Maki G, Miyagawa B, Hennemann B, Tonn T, Klingemann HG. Characterization of genetically altered, interleukin 2-independent natural killer cell lines suitable for adoptive cellular immunotherapy. Hum Gene Ther 1999; 10:1359-73. [PMID: 10365666 DOI: 10.1089/10430349950018030] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
NK-92 is a highly cytotoxic natural killer (NK) tumor cell line that possesses properties that make it an excellent candidate for adoptive cellular immunotherapy. However, the cytotoxicity of NK cells is dependent on cytokines such as interleukin 2 (IL-2). Although NK-92 cells maintain cytotoxicity for a time after withdrawal of IL-2, clinical use will probably require prolonged treatment with fully activated cells to eliminate disease effectively. The ability to support cytotoxic cells with exogenously administered IL-2 is limited by associated toxicity. Therefore, we describe the transfection of the IL-2-dependent NK-92 cell line with human IL-2 (hIL-2) cDNA by particle-mediated gene transfer to create two IL-2-independent variants, NK-92MI and NK-92 CI, and describe their characterization and comparison with parental cells. Both variants were shown to contain, express, and synthesize the hIL-2 cDNA. IL-2 synthesis was higher in NK-92MI cells compared with NK-92CI cells, with no expression in parental cells. Functionally, the cytotoxicity of all three cell lines was similar and coincubation with IL-2-independent variants did not affect hematopoietic progenitor cells. NK-92MI and NK-92CI cells were more radiosensitive than NK-92 cells, with proliferation inhibited at lower radiation doses and increased morality and decreased cytotoxicity compared with parental cells. Data presented here show that we have created by particle-mediated gene transfer two IL-2-independent variants of NK-92 that are identical to parental cells in virtually all respects, including high cytotoxic activity. The nonviral transfection of these cells makes them suitable for clinical applications. These IL-2-independent cells should allow prolonged treatment with fully active natural killer cells without the need for exogenous IL-2 support.
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Affiliation(s)
- Y K Tam
- Division of Hematology, Terry Fox Laboratory, BC Cancer Agency, Vancouver, Canada.
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22
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Long Z, Lu P, Grooms T, Mychkovsky I, Westley T, Fitzgerald T, Sharma-Chibber S, Shand N, McGarrity G, Otto E. Molecular evaluation of biopsy and autopsy specimens from patients receiving in vivo retroviral gene therapy. Hum Gene Ther 1999; 10:733-40. [PMID: 10210141 DOI: 10.1089/10430349950018490] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We used the polymerase chain reaction (PCR) to assay for the presence of retroviral vector and replication-competent retrovirus (RCR) in autopsy and biopsy specimens from patients who received inoculations of retroviral vector producer cells (VPCs) into brain tumors or apparently normal tissues surrounding resected tumors. The PCR assays were capable of detecting 1 or more proviral copies of vector or RCR in 500,000 cells. Of 113 patients treated in clinical trials between 1994 and 1997, autopsy specimens were available from 32 patients. Brain tumor biopsies were also available from 24 patients. A total of 346 specimens was analyzed. Vector DNA was detected in 55% of tumor samples and 22% of brain samples obtained from resection margins. In contrast, most of the nonbrain tissues were negative for vector DNA; only low levels (<0.03%) of vector sequence were detected in 6 of 240 (2.5%) nonbrain tissues. Vector DNA was not detected in gonadal tissues from 12 men and 10 women. More importantly, RCR was not detected in any of the 134 biopsy and autopsy tissues tested, including all brain tumor, brain, and gonadal specimens. These results comprise the largest data set on molecular analysis of autopsy specimens from patients receiving retroviral gene therapy and indicate that distribution of retroviral vectors following injection of high doses of VPCs is limited to the site of inoculation.
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Affiliation(s)
- Z Long
- Genetic Therapy, Inc., Gaithersburg, MD 20878, USA.
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23
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McCormack JE, Martineau D, DePolo N, Maifert S, Akbarian L, Townsend K, Lee W, Irwin M, Sajjadi N, Jolly DJ, Warner J. Anti-vector immunoglobulin induced by retroviral vectors. Hum Gene Ther 1997; 8:1263-73. [PMID: 9215743 DOI: 10.1089/hum.1997.8.10-1263] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Replication-incompetent retroviruses have been employed as gene therapy vectors in experimental settings for more than a decade. More recently, these vectors have been tested in the clinic as immunotherapeutic agents and anticancer agents. One potential problem with the use of such vectors is the possible development of immune responses directed against the vector particles themselves. Here, we examine immunoglobulin (Ig) responses specific for retroviral vectors derived from murine leukemia virus (MLV). Anti-MLV Ig is seen following intramuscular (i.m.) administration of retroviral vectors in mice, and in nonhuman primates; as expected, these responses are dependent upon the vector dose delivered. Furthermore, serum from vector-treated animals is capable of partially neutralizing vector-mediated transduction of target cells in an in vitro assay. Nevertheless, even in the presence of significant levels of anti-vector Ig in vivo, i.m. administration of retroviral vector is still capable of driving both Ig and cytotoxic T lymphocyte (CTL) responses specific for vector-encoded gene products. This work suggests that although retroviral vectors may readily induce immune responses directed against the vector particles themselves, such responses will not significantly affect the efficiency of these vectors in an immunotherapeutic protocol.
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Affiliation(s)
- J E McCormack
- Chiron Technologies, Center for Gene Therapy, San Diego, CA 92121, USA
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