RESUMEN
The αGal HyperAcute(®) Technology exploits a robust zoonotic blockade to enhance potency of antiviral vaccines. Naturally acquired immunity against the common αGal epitope [galactose-alpha(1,3)-galactose-beta(1,4)N-acetylglucosamine-R (Gal-α(1,3)-Gal-ß(1,4)-GlcNAc-R)] is facilitated by the loss of a key enzyme in the epitope's biosynthetic pathway. As human cells are devoid of this epitope, chronic stimulus from gut flora leads to high levels of circulating anti-αGal antibodies and the development of a robust immune pathway. As the αGal epitope is immediately recognized as foreign, the naturally acquired αGal immune pathway in humans serves as a strong barrier to zoonotic infection. The αGal HyperAcute(®) Technology takes advantage of this natural process to facilitate the rapid presentation of modified antigens to antigen-presenting cells, leading to a strong immune response. The evolutionary immunity to αGal ensures that the presence of αGal epitopes on antigens will lead to a robust immune response involving cross-activation of T(H)1 immunity, characterized by cytokine secretion and increased phagocytic activity, and T(H)2 immunity characterized by high antibody titres. αGal epitopes can be applied to antiviral vaccines by biological, enzymatic or chemical means. Several detection methods that directly and indirectly verify αGal addition are discussed. Enhanced immunogenicity (humoral and cellular) of αGal-modified vaccines is shown for several antiviral vaccine candidates. αGal modification of antiviral vaccine components leads to enhanced immunogenicity. The existing body of literature describing the utility of αGal epitopes as a safe and robust immunostimulatory and -modulatory agent in humans supports the basis for applying the αGal HyperAcute(®) Technology to the improvement of antiviral vaccines, both new and currently approved.
Asunto(s)
Galactosiltransferasas/inmunología , Galactosiltransferasas/metabolismo , Vacunas Virales/inmunología , Adyuvantes Inmunológicos , Animales , Células Presentadoras de Antígenos/inmunología , Células Presentadoras de Antígenos/metabolismo , Células Cultivadas , Epítopos/metabolismo , Humanos , Vacunación , ZoonosisRESUMEN
Ataxia-telangiectasia (AT) is a human autosomal recessive disease with a pleiotropic phenotype characterized by cerebellar degeneration, immunodeficiency, premature aging, cancer predisposition, and radiation sensitivity. The gene mutated in AT, ATM (for AT-mutated), had been cloned and found to have ionizing radiation and oxidative stress-inducible kinase activity. No treatment can stop the progression of the disease. In this study, the complete open-reading frame of ATM cDNA was cloned into a Herpes simplex virus type-1 (HSV-1) amplicon vector (pTO-ATM), and the transduction of cultured AT cells was demonstrated by immunohistochemistry and Western blot analysis. Functional gene expression was evaluated by cell colony-forming assays following exposure to oxidative stress. The survival of AT cells with ATM gene transduction was about 100% higher compared to nontransduced cells after t-butyl hydroperoxide treatments. Next, the normal ATM gene expression in different regions of the rat brain was studied. Immunohistochemistry staining demonstrated weak endogenous ATM protein expression in neurons of the caudate-putamen, with significantly higher levels of expression detected in neurons in other brain regions. Exogenous ATM gene expression from pTO-ATM after viral transduction in the caudate-putamen of the adult rat was examined. At 3 days after injection of the pTO-ATM viral vector, abundant positive ATM staining of the neurons was found at the injection sites, in comparison to the controls. These data demonstrate that the relatively large ATM cDNA can be transduced and expressed in vitro and in vivo from an HSV amplicon viral vector. These data provide initial evidence that the replacement of the ATM gene into the cells of AT patients might be possible some day.
Asunto(s)
Ataxia Telangiectasia/terapia , Encéfalo/metabolismo , Terapia Genética/métodos , Vectores Genéticos/administración & dosificación , Simplexvirus/genética , Animales , Ataxia Telangiectasia/genética , Western Blotting/métodos , Línea Celular , Expresión Génica , Vectores Genéticos/genética , Inmunohistoquímica/métodos , Masculino , Ratas , Ratas Sprague-Dawley , Transducción Genética/métodosRESUMEN
Transduction of stem cells with a marking gene holds promise to determine if tissue repair or regeneration is derived from the adult hematopoietic stem cell and if relapse of an autoimmune disease should occur whether relapse arises from the stem cell compartment or from lymphocytes surviving the conditioning regimen. New safety concerns about gene-modified stem cell would entail new safety testing such as documentation of the insertional site prior to release.
Asunto(s)
Genes Reporteros/genética , Células Madre Hematopoyéticas/metabolismo , Kanamicina Quinasa/genética , Transducción Genética/métodos , Antígenos CD/análisis , Antígenos CD34/análisis , Técnicas de Cultivo de Célula , Diferenciación Celular , Vectores Genéticos , Humanos , Retroviridae/genética , Factores de TiempoRESUMEN
Adoptive cellular therapy is developing as a supplement or alternative to chemotherapy and/or radiation for malignant disease. Our focus is two ongoing clinical studies with transgeneic (genetically altered) cellular therapy; one uses allogeneic (from another person) lymphocytes to treat leukemia, and the second uses xenogeneic (from another species) fibroblast cells genetically altered to contain a toxin-producing suicide gene to treat ovarian cancer. Allogeneic donor lymphocyte infusions (DLI) are known to induce remission of hematologic malignancies. However, the toxicity associated with DLI is related to graft-versus-host-disease, which is due to donor lymphocytes attacking normal tissue in the recipient. Therefore, we have taken the approach of infusing DLI that have been modified to contain a latent suicide gene to treat leukemia. To treat ovarian cancer, we used xenogeneic nonimmune fibroblast-derived cells to deliver a tumor-directed cytotoxic gene to carcinoma cells. These cells release HStk transgene retroviruses that in turn transduce replicating tumor cells but not quiescent epithelium, rendering the tumor selectively susceptible to ganciclovir-mediated killing. These initial trials summarize the early stage of allogeneic/xenogeneic adoptive cellular therapy for cancer, and although the data are limited, it is encouraging to see some patients with evidence of antitumor responses. Advances in our understanding of the basic science of these treatments, together with improvements in the technology of vector design, will be required to streamline these methodologies into broader application.
Asunto(s)
Apoptosis/fisiología , Trasplante de Células , Neoplasias/cirugía , Trasplante Heterólogo/métodos , Trasplante Homólogo/métodos , Animales , Femenino , Humanos , Leucemia/cirugía , Neoplasias Ováricas/cirugíaRESUMEN
Adenovirus-p53-mediated apoptosis has been extensively evaluated in animal xenografts derived from human epithelial tumors and recently began testing in phase I clinical trials, but has not been evaluated for lymphoid malignancies. Cell lines derived from anaplastic large cell lymphoma (ALCL) carrying the t(2;5) translocation are efficiently transduced by adenoviral vector expressing p53 and undergo apoptosis. To test the in vivo efficiency of adenovirus-mediated-p53 expression and apoptosis induction, SUDHL-1 cells (derived from human ALCL) were injected subcutaneously into athymic nude mice. Cells from the xenograft had typical morphology of human ALCL by standard hematoxylin-eosin staining, CD5+, CD45+ and CD30+ immunophenotype, the t(2;5) translocation by PCR. Six tumors from an initial set of mice were evaluated for apoptosis by TUNEL and for necrosis by hematoxylin-eosin staining 48-72 h after injection with 1 x 108 p.f.u. of AdWTp53 (adenoviral vector expressing p53), of AdNull (adenoviral vector backbone) and PBS (mock), respectively. TUNEL staining was positive only in tumors injected with AdWTp53 and was mainly localized around the needle track. Differences of the means of the counts of the necrotic cells were statistically significant at P = 0.02 between AdWTp53 and mock and only borderline between AdWTp53 and AdNull. Twenty-three tumors from a separate set of mice were subsequently injected with AdWTp53, AdNull and PBS and evaluated for in vivo tumor response. Three total injections of viral vectors (1 x 108 p.f.u.) and PBS were given every 48-72 h. Only tumors injected with AdWTp53 showed tumor growth inhibition with a mean final tumor volume that was statistically significantly smaller than AdNull (P = 0.007) and mock (P = 0.002). Based on these results we foresee a potential application of adenovirus-mediated p53 apoptosis as gene therapy of lymphomas.
Asunto(s)
Adenoviridae/genética , Apoptosis/genética , Genes p53 , Terapia Genética/métodos , Vectores Genéticos/administración & dosificación , Linfoma de Células B Grandes Difuso/terapia , Animales , Humanos , Linfoma de Células B Grandes Difuso/patología , Ratones , Ratones Desnudos , Necrosis , Trasplante de Neoplasias , Transfección/métodosAsunto(s)
Galactosiltransferasas/genética , Técnicas de Transferencia de Gen , Vectores Genéticos , Neoplasias Ováricas/terapia , Simplexvirus , Animales , Ensayos Clínicos Fase I como Asunto , Clonación Molecular , Femenino , Vectores Genéticos/genética , Humanos , Neoplasias Ováricas/inmunología , Recurrencia , Simplexvirus/genéticaRESUMEN
Most retroviral packaging cell lines were established by a helper virus plasmid cotransfected with a separate plasmid encoding a selection marker. Since this selection marker coexisted in trans with the helper virus sequence, helper virus gene expression could be inactivated by host DNA methylation despite selection for the cotransfected selection marker. We have reported that DNA methylation could occur in the long terminal repeat (LTR) region of helper virus in vector producer cells (VPC) in up to 2% of the population per day (W. B. Young, G. L. Lindberg, and C. J. Link, Jr., J. Virol. 74:3177-3187, 2000). To overcome host cell DNA methylation that suppresses viral gene expression, we constructed a chimeric retroviral helper virus, pAM3-IRES-Zeo, that contains Moloney murine leukemia virus as a helper virus and a picornavirus internal ribosome entry site (IRES) sequence followed by a Zeocin selection marker at the 3' end of the env sequence. This pAM3-IRES-Zeo permitted selection for intact and functional helper virus in transfected cells without subcloning. By selection with Zeocin, a mixed population of pAM3-IRES-Zeo-transfected NIH3T3 cells (AMIZ cells) was maintained with little or no DNA methylation of the helper virus 5' LTR. The high level of pAM3-IRES-Zeo gene expression resulted in no detectable vector superinfection and in high vector titers (2 x 10(6) to 1.5 x 10(7) CFU/ml) after introduction of a retroviral vector. When Zeocin selection was withdrawn from AMIZ cells, methylation of the 5' LTR increased from 17 to 36% of the population during 67 days of continuous culture and the cells became susceptible to superinfection. During this period, gene expression of pAM3-IRES-Zeo decreased and vector titer production was reduced to 2 x 10(4) CFU/ml. These data demonstrate an important role of DNA methylation in the genetic instability of VPC. The chimeric helper virus allows the establishment of a mixed population of packaging cells capable of high-level and sustained vector production without cloning procedures.
Asunto(s)
Metilación de ADN , Vectores Genéticos , Virus Helper , Picornaviridae/genética , Retroviridae , Células 3T3 , Animales , Bleomicina , Expresión Génica , Ratones , Virus de la Leucemia Murina de Moloney , TransfecciónRESUMEN
Adoptive cellular therapy is developing as a supplement or alternative to chemotherapy and/or radiation for malignant disease. Our focus is two ongoing clinical studies with transgeneic (genetically altered) cellular therapy; one uses allogeneic (from another person) lymphocytes to treat leukemia, and the second uses xenogeneic (from another species) fibroblast cells genetically altered to contain a toxin-producing suicide gene to treat ovarian cancer. Allogeneic donor lymphocyte infusions (DLI) are known to induce remission of hematologic malignancies. However, the toxicity associated with DLI is related to graft-versus-host-disease, which is due to donor lymphocytes attacking normal tissue in the recipient. Therefore, we have taken the approach of infusing DLI that have been modified to contain a latent suicide gene to treat leukemia. To treat ovarian cancer, we used xenogeneic nonimmune fibroblast-derived cells to deliver a tumor-directed cytotoxic gene to carcinoma cells. These cells release HStk transgene retroviruses that in turn transduce replicating tumor cells but not quiescent epithelium, rendering the tumor selectively susceptible to ganciclovir-mediated killing. These initial trials summarize the early stage of allogeneic/xenogeneic adoptive cellular therapy for cancer, and although the data are limited, it is encouraging to see some patients with evidence of antitumor responses. Advances in our understanding of the basic science of these treatments, together with improvements in the technology of vector design, will be required to stream-line these methodologies into broader application.
Asunto(s)
Apoptosis , Terapia Genética/métodos , Inmunoterapia Adoptiva , Leucemia/terapia , Neoplasias Ováricas/terapia , Femenino , Fibroblastos , Humanos , Leucemia/genética , Transfusión de Linfocitos , Neoplasias Ováricas/genética , Trasplante Heterólogo , Trasplante HomólogoRESUMEN
Retroviral vector producer cells (VPC) have been considered genetically stable. A clonal cell population exhibiting a uniform vector integration pattern is used for sustained vector production. Here, we observed that the vector copy number is increased and varied in a population of established LTKOSN.2 VPC. Among five subclones of LTKOSN.2 VPC, the vector copy number ranged from 1 to approximately 29 copies per cell. A vector superinfection experiment and Northern blot analysis demonstrated that suppression of helper virus gene expression decreased Env-receptor interference and allowed increased superinfection. The titer production was tightly associated with helper virus gene expression and varied between 0 and 2.2 x 10(5) CFU/ml in these subclones. In one analyzed subclone, the number of integrated vectors increased from one copy per cell to nine copies per cell during a 31-day period. Vector titer was reduced from 1.5 x 10(5) CFU to an undetectable level. To understand the mechanism involved, helper virus and vectors were examined for DNA methylation status by methylation-sensitive restriction enzyme digestion. We demonstrated that DNA methylation of helper virus 5' long terminal repeat occurred in approximately 2% of the VPC population per day and correlated closely with inactivation of helper virus gene expression. In contrast, retroviral vectors did not exhibit significant methylation and maintained consistent transcription activity. Treatment with 5-azacytidine, a methylation inhibitor, partially reversed the helper virus DNA methylation and restored a portion of vector production. The preference for methylation of helper virus sequences over vector sequences may have important implications for host-virus interaction. Designing a helper virus to overcome cellular DNA methylation may therefore improve vector production. The maintenance of increased viral envelope-receptor interference might also prevent replication-competent retrovirus formation.
Asunto(s)
Vectores Genéticos/genética , Virus Helper/genética , Línea Celular , Metilación de ADN , ADN Viral/genética , Virus Helper/metabolismo , Provirus/genética , Eliminación de Secuencia , Transcripción Genética , Integración Viral/genéticaAsunto(s)
Vectores Genéticos , Proteínas Luminiscentes/genética , Melanoma Experimental/genética , Animales , Biotecnología , Expresión Génica , Proteínas Fluorescentes Verdes , Herpesvirus Humano 1/genética , Herpesvirus Humano 4/genética , Humanos , Ratones , Ratones Desnudos , Microscopía Fluorescente , Trasplante de Neoplasias , Transducción Genética , Trasplante HeterólogoRESUMEN
Adenoviral vector-mediated p53 expression induced apoptosis is a well established gene therapy approach that has been evaluated extensively in epithelial tumors but only recently in lymphoid malignancies mainly due to the known resistance of the lymphoid lineage to adenovirus infection. Recently, it was shown that this resistance is not absolute and that cell lines derived from anaplastic large cell lymphoma (ALCL) and some other lymphoid malignancies are efficiently transduced by adenoviral vectors. Normal circulating T lymphocytes do not express coxsackie-adenovirus receptor (CAR) and alpha(nu)beta integrins and are relatively resistant to infection by adenovirus. These molecules serve as receptors for adenovirus entry into the cells. ALCL-derived SUDHL-1 cells were evaluated for transduction efficiency and expression of p53 after infection with an adenoviral vector containing wild-type p53 (AdWTp53). Cells derived from ALCL and circulating mononucleated cells (MNCs) were also evaluated for expression of CAR and alpha(nu)beta integrins. AdWTp53-mediated expression of p53 resulted in p21/WAF1 induction, G1 arrest, and apoptosis in SUDHL-1 cells. The expression of CAR and alpha(nu)beta5 integrin was high in SUDHL-1 cells and comparable to levels observed with epithelial tumor cells, but it was absent in MNCs. The susceptibility to adenoviral vector transduction of the tumor-derived cells implies an important biological difference between them and circulating MNCs, possibly underlying the malignant transformation that ALCL cells undergo. Further studies will be required to evaluate this initial observation in more cell lines and tissue derived from ALCL.
Asunto(s)
Adenoviridae , Genes p53 , Integrinas/fisiología , Linfoma de Células B Grandes Difuso/patología , Receptores Virales/fisiología , Receptores de Vitronectina , Adenoviridae/fisiología , Ciclo Celular , Supervivencia Celular , Proteína de la Membrana Similar al Receptor de Coxsackie y Adenovirus , Inhibidor p21 de las Quinasas Dependientes de la Ciclina , Ciclinas/genética , Ciclinas/fisiología , Citometría de Flujo , Vectores Genéticos , Humanos , Etiquetado Corte-Fin in Situ , Integrinas/genética , Linfoma de Células B Grandes Difuso/inmunología , Receptores Virales/genética , Transfección , Células Tumorales Cultivadas , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
Retroviral vector producer cells (VPC) can effectively transfer genes in vivo. To develop a safe method to target gene delivery into intraperitoneal tumors, we have examined the toxicity of intraperitoneal (i.p.) infusion of retroviral VPC in a xenogeneic canine model. Mongrel dogs were injected intraperitoneally (i.p.) with 2 x 10(9) murine LTKOSN.2 VPC. The animals did not demonstrate acute toxicity and tolerated the i.p. infusion of the cells without difficulty. Starting 7 days after i.p. injection, the dogs received intravenous injections of ganciclovir (GCV) twice daily (5 mg/kg) for 7 days. The treatment dogs underwent peritoneal washings on days 3, 7 and 14 after their initial infusion of cells to study the persistence of the VPC. GCV treatment did not cause significant toxicities. Dogs underwent serial blood tests to evaluate bone marrow, renal, liver and immunological function. Complete blood counts, electrolytes and renal function remained normal throughout the study. Although, transient mild elevations occurred of serum alkaline phosphate, the remaining hepatic enzymes remained normal. Histologic examination of tissues from animals sacrificed after the i.p. administration of the VPC revealed no tissue destruction of the normal peritoneal lining. The dogs mounted an antibody response to the murine VPC that was first observed 7 days post injection. PCR analysis of selected tissues after GCV administration did not reveal persistent vector sequences. These results demonstrated that the injection of xenogeneic VPC is not accompanied by significant adverse effects over a 1 month period following administration into the canine peritoneal cavity. These data support the potential clinical application of the VPC in Phase I clinical trials in humans.
Asunto(s)
Terapia Genética/métodos , Vectores Genéticos , Herpesvirus Humano 1/genética , Cavidad Peritoneal/citología , Fosfatasa Alcalina/sangre , Animales , Bovinos , Supervivencia Celular/efectos de los fármacos , Perros , Ganciclovir/farmacología , Pruebas Hematológicas , Herpesvirus Humano 1/enzimología , Humanos , Pruebas de Función Renal , Pruebas de Función Hepática , Ratones , Modelos Animales , Lavado Peritoneal , Reacción en Cadena de la Polimerasa , Timidina Quinasa/genética , Transfección , Células Tumorales Cultivadas/inmunología , Células Tumorales Cultivadas/trasplanteRESUMEN
To develop a safe method to target gene delivery into intrahepatic tumors, we examined the toxicity of intrahepatic (IH) injection of retroviral vector producer cells (VPC) into the canine liver. VPC have been demonstrated to effectively transfer genes in vivo. To evaluate for adverse effects form xenogeneic cell transplantation, mongrel dogs were injected IH with 1 x 10(9) murine LTKOSN.2 VPC divided into three aliquots. The animals were then monitored for acute toxicity induced by the VPC. The intraoperative IH injections of the cells were tolerated without difficulty. Starting 7 days after IH injection, the dogs then received intravenous ganciclovir (GCV) twice daily (5 mg/kg) for 7 days. GCV treatment did not cause significant toxicities. Dogs underwent serial blood tests to evaluate bone marrow, renal, liver and immunological function. Complete blood counts, electrolytes, liver function and renal function tests remained normal except for mild elevations of alkaline phosphatase. Histologic examination of liver tissues from the IH injection site revealed no apparent normal tissue destruction induced by the VPC. Two of the four treated dogs underwent liver biopsy on day 3. These biopsy specimens were cultured and persistent, viable VPC were recovered. The dogs mounted an antibody response to the murine VPC that was first demonstrated 5 days post injection. PCR analysis demonstrated low level gene transfer into dog liver tissue. Overall, our results demonstrate that IH xenogeneic VPC injections are not accompanied by significant adverse effects over a 1 month period following administration into the canine liver. These data support the safety aspects of using murine VPC in Phase I clinical trials.
Asunto(s)
Terapia Genética/métodos , Vectores Genéticos , Herpesvirus Humano 1/genética , Hígado/patología , Fosfatasa Alcalina/sangre , Animales , Bovinos , Supervivencia Celular/efectos de los fármacos , Perros , Ganciclovir/farmacología , Pruebas Hematológicas , Herpesvirus Humano 1/enzimología , Humanos , Riñón/fisiología , Pruebas de Función Renal , Hígado/fisiología , Pruebas de Función Hepática , Ratones , Modelos Animales , Reacción en Cadena de la Polimerasa , Timidina Quinasa/genética , Transfección , Células Tumorales Cultivadas/inmunología , Células Tumorales Cultivadas/trasplanteRESUMEN
Patients with recurrent leukemia after an allogeneic hematopoietic stem cell transplant may be treated with donor lymphocyte infusions (DLI). The transfusion of lymphocytes from the original hematopoietic stem cell donor induces remission in approximately one third of relapsed AML cases and 80% of relapsed CML. DLI may be complicated by delayed and sometimes lethal graft-versus-host disease (GVHD). In an attempt to avoid this complication, several centers have initiated DLI trials in which the infused lymphocytes carry a suicide gene, herpes simplex thymidine kinase (HStk), which confers sensitivity to ganciclovir (GCV). In the event of severe GVHD, administration of GCV should terminate or ameliorate GVHD.
Asunto(s)
Ganciclovir/uso terapéutico , Leucemia Mieloide Aguda/terapia , Transfusión de Linfocitos , Simplexvirus/enzimología , Simplexvirus/genética , Timidina Quinasa/genética , Enfermedad Injerto contra Huésped/prevención & control , Trasplante de Células Madre Hematopoyéticas , Humanos , Timidina Quinasa/metabolismo , TransfecciónRESUMEN
Genetic diseases are often caused by nonsense mutations. The resulting defect in protein translation can be restored by expressing suppressor tRNA in the mutant cells. Our goal was to demonstrate both protein restoration and phenotypic correction using these small transgenes. Functional activity of an arginine opal suppressor tRNA in cells expressing a nonsense mutated GFP gene was demonstrated by restored fluorescence. This suppressor tRNA was expressed in xeroderma pigmentosum group A cells, containing a homozygous nonsense mutation at Arg-207 in the XPA complementing gene. The transfected XPA cell population showed a twofold increase in cell survival after UV irradiation as determined by colony-forming assays compared with cell populations without the suppressor tRNA gene. The UV doses required for 37% survival of XP cells and XP cells expressing the suppressor tRNA were 0.6 and 1.2 J/m2. A similar twofold increase in the reactivation of UV-irradiated plasmid DNA was observed in XP cells expressing the suppressor tRNA. However, there was no detectable increase in XPA protein levels. Several potential limitations of this approach exist, including the availability of mutant RNA transcripts, the efficiency of suppression by the suppressor tRNA, and the abundance and availability and continued expression of the suppressor tRNA. The unique feature of this study is the relatively small size (88 bp) of the suppressor tRNA. Small-sized suppressor tRNAs can be synthetically constructed and subcloned into different viral vectors for delivery into the target cells. This approach may be useful for other genetic diseases caused by nonsense mutations.
Asunto(s)
Proteínas de Unión al ADN/genética , Técnicas de Transferencia de Gen , ARN de Transferencia de Arginina/biosíntesis , Xerodermia Pigmentosa/patología , Línea Celular , Supervivencia Celular/efectos de la radiación , Herpesvirus Humano 1/genética , Humanos , Mutación Puntual , ARN de Transferencia de Arginina/genética , Supresión Genética , Transfección , Rayos Ultravioleta , Xerodermia Pigmentosa/genética , Xerodermia Pigmentosa/metabolismo , Proteína de la Xerodermia Pigmentosa del Grupo ARESUMEN
A variety of approaches to antitumor therapy are currently being explored that use both antigen-encoding DNA and noncoding nucleotides as a component of gene vaccination. Among the specific strategies reviewed are a construct that fuses a single-chain variable fragment (scFv) that incorporates both the variable-region genes necessary to encode the idiotypic determinants with fragment C (FrC) of tetanus toxin; a novel vector system using herpes simplex virus 1 (HSV-1) for in vivo gene delivery; the possibility of eliciting hyperacute xenograft response to treat human cancer; and the use of gene gun-mediated granulocyte-macrophage colony-stimulating factor (GM-CSF) cDNA-based tumor cell vaccines. The protection provided by DNA vaccination against viral diseases such as influenza suggested a role for such vaccines against cancer. However, unlike vaccines against infectious diseases, cancer vaccines are therapeutic, rather than prophylactic. With multiple myeloma, for example, it is possible that the optimal timing of administration of such a vaccine is during a remission that has been induced by traditional therapies, to eliminate residual disease. DNA cancer vaccines are designed to activate immune responses to tumor antigens to which the immune system has already been exposed. To do so, the vaccines must first overcome immune tolerance that may have already developed to the tumor. There is increasing evidence that tumor antigens, unlike viral or bacterial antigens, do not consistently activate an immune response. One major factor in determining whether a reaction occurs appears to be whether antigen presentation is accompanied by danger signals. With viral or bacterial infection, the accompanying tissue destruction and inflammation produce costimulatory signals that promote T-cell activation. However, inflammatory and tissue-destructive processes are absent during initial tumor transformation. The typical outcome may be immunologic tolerance.
Asunto(s)
Mieloma Múltiple/inmunología , Mieloma Múltiple/terapia , Vacunas de ADN/inmunología , Terapia Genética , Humanos , Mieloma Múltiple/genéticaRESUMEN
We demonstrate a novel method of concentrating radiation for tumor imaging or killing. The rat sodium/iodide symporter gene (rNIS) was cloned into a retroviral vector for transfer into cancer cells to mimic the iodide uptake of thyroid follicular cells. In vitro iodide transport shows that the symporter functions similarly in rNIS-transduced tumor cells and rat thyroid follicular cells. rNIS-transduced and control nontransduced (NV) human A375 melanoma xenografts established in vivo in athymic nude mice were imaged using a gamma camera after i.p. injections of 123I. The rNIS-transduced human A375 melanoma tumors are visually distinguishable from and accumulate significantly more radionuclides than NV tumors. In vitro clonogenic assays confirm efficacy and clearly show that rNIS-transduced A375 human melanoma, BNL.1 ME murine transformed liver, CT26 murine colon carcinoma, and IGROV human ovarian carcinoma can be selectively killed by the induced accumulation of 131I. Thus, NIS-based gene therapy may have both diagnostic and therapeutic applications for cancer.