Biomedical subjects

David T Curiel

Publications and source records attributed to David T Curiel.

At least 55 records · Page 3Linked to original sources

PubMed2006

Survivin promoter-based conditionally replicative adenoviruses target cholangiocarcinoma.

Cholangiocarcinoma is a highly malignant neoplasm with no effective treatment. Conditionally replicative adenoviruses (CRAds) represent a promising new modality for the treatment of cancer in general. A key contribution in this regard was the introduction of tumor-selective viral replication for amplification of the initial inoculum in the neoplastic cell population. Under ideal conditions following cellular infection, the viruses replicate selectively in the infected tumor cells and kill the cells by cytolysis, leaving normal cells unaffected. However, to date there have been two limitations to the clinical application of these CRAd agents, i.e. poor viral infectivity and tumor specificity. Here we report the construction of three new CRAd agents, CRAd-S.RGD, CRAd-S.F5/3 and CRAd-S.pk7, in which the tumor specificity is regulated by a tumor-specific promoter, the survivin promoter, and the viral infectivity is enhanced by incorporating a capsid modification (RGD, F5/3 or pk7) in the adenovirus fiber region. These CRAd agents effectively target cholangiocarcinoma cells, induce strong cytoxicity in these cells in vitro and inhibit tumor growth in a murine xenograft model in vivo. In addition, the survivin promoter has extremely low activity both in the non-transformed cell line, HMEC, and in human liver tissue. Our results suggest that the survivin-based CRAds are promising agents for targeting cholangiocarcinoma with low host toxicity. Such results should provide important insights into the identification of novel therapeutic strategies for cholangiocarcinoma.

Adenoviridae↗

PubMed2005

Oncolytic adenoviruses - selective retargeting to tumor cells.

Virotherapy is an approach for the treatment of cancer, in which the replicating virus itself is the anticancer agent. Virotherapy exploits the lytic property of virus replication to kill tumor cells. As this approach relies on viral replication, the virus can self-amplify and spread in the tumor from an initial infection of only a few cells. The success of this approach is fundamentally based on the ability to deliver the replication-competent viral genome to target cells with a requisite level of efficiency. With virotherapy, while a number of transcriptional retargeting strategies have been utilized to restrict viral replication to tumor cells, this review will focus primarily on transductional retargeting strategies, whereby oncolytic viruses can be designed to selectively infect tumor cells. Using the adenoviral vector paradigm, there are three broad strategies useful for viral retargeting. One strategy uses heterologous retargeting ligands that are bispecific in that they bind both to the viral vector as well as to a cell surface target. A second strategy uses genetically modified viral vectors in which a cellular retargeting ligand is incorporated. A third strategy involves the construction of chimeric recombinant vectors, in which a capsid protein from one virus is exchanged for that of another. These transductional retargeting strategies have the potential for reducing deleterious side effects, and increasing the therapeutic index of virotherapeutic agents.

Adenoviridae↗

PubMed2005

Preclinical evaluation of transcriptional targeting strategies for carcinoma of the breast in a tissue slice model system.

INTRODUCTION: In view of the limited success of available treatment modalities for metastatic breast cancer, alternative and complementary strategies need to be developed. Adenoviral vector mediated strategies for breast cancer gene therapy and virotherapy are a promising novel therapeutic platform for the treatment of breast cancer. However, the promiscuous tropism of adenoviruses (Ads) is a major concern. Employing tissue specific promoters (TSPs) to restrict transgene expression or viral replication is an effective way to increase specificity towards tumor tissues and to reduce adverse effects in non-target tissues such as the liver. In this regard, candidate breast cancer TSPs include promoters of the genes for the epithelial glycoprotein 2 (EGP-2), cyclooxygenase-2 (Cox-2), alpha-chemokine SDF-1 receptor (stromal-cell-derived factor, CXCR4), secretory leukoprotease inhibitor (SLPI) and survivin. METHODS: We employed E1-deleted Ads that express the reporter gene luciferase under the control of the promoters of interest. We evaluated this class of vectors in various established breast cancer cell lines, primary breast cancer cells and finally in the most stringent preclinical available substrate system, constituted by precision cut tissue slices of human breast cancer and liver. RESULTS: Overall, the CXCR4 promoter exhibited the highest luciferase activity in breast cancer cell lines, primary breast cancer cells and breast cancer tissue slices. Importantly, the CXCR4 promoter displayed a very low activity in human primary fibroblasts and human liver tissue slices. Interestingly, gene expression profiles correlated with the promoter activities both in breast cancer cell lines and primary breast cancer cells. CONCLUSION: These data suggest that the CXCR4 promoter has an ideal 'breast cancer-on/liver-off' profile, and could, therefore, be a powerful tool in Ad vector based gene therapy or virotherapy of the carcinoma of the breast.

Adenoviridae↗

PubMed2005

Generation and selection of targeted adenoviruses embodying optimized vector properties.

The utility of adenovirus serotype 5 (Ad5)-based vectors for gene therapy applications would be improved by cell-specific targeting. However, strategies to redirect Ad5 vectors to alternate cellular receptors via replacement of the capsid fiber protein have often resulted in structurally unstable vectors. In view of this, we hypothesized that the selection of modified adenoviruses during their rescue and propagation would be a straightforward approach that guarantees the generation of functional, targeted vectors. Based on our first generation fiber-fibritin molecule, several new chimeric fibers containing variable amounts of fibritin and the Ad5 fiber shaft were analyzed via a new scheme for Ad vector selection. Our selected chimera, composed of the entire Ad5 fiber shaft fused to the 12th coiled-coil segment of fibritin, is capable of efficient capsid incorporation and ligand display. Moreover, transduction by the resultant vector is independent of the expression of the native Ad5 receptor. The incorporation of the Fc-binding domain of Staphylococcus aureus protein A at the carboxy terminus of this chimeric fiber facilitates targeting of the vector to a variety of cellular receptors by means of coupling with monoclonal antibodies. In addition, we have concluded that Ad5 vectors incorporating individual targeting ligands require individual optimization of the fiber-fibritin chimera, which may be accomplished by selecting the optimal fiber-fibritin variant at the stage of rescue of the virus in cells of interest, as described herein.

Adenoviridae↗

PubMed2005

Gene transfer to carcinoma of the breast with fiber-modified adenoviral vectors in a tissue slice model system.

Successful adenoviral (Ad) vector-mediated strategies for breast cancer gene therapy and virotherapy have heretofore been hindered by low transduction efficiency. This has recently been understood to result from a relative paucity of expression of the primary adenovirus receptor, coxsackie-adenovirus-receptor (CAR), on primary tumor cells. To further investigate this issue, we evaluated the expression of CAR on breast cancer cell lines as well as primary breast cancer cells. With the exception of one patient sample, CAR expression was notably higher in the tumor cells from patients compared to CAR expression in the tumor cell lines. Furthermore, we explored CAR-independent targeting strategies to breast cancer tissue by exploring a panel of infectivity-enhanced Ad vectors, which contain CAR-independent targeting motifs for their utility in breast cancer gene therapy and virotherapy. These targeting motifs included Ad 3 knob (Ad5/3), canine Ad serotype 2 knob (Ad5CAV-2), RGD (Ad5.RGD), polylysine (Ad5.pK7), or both RGD and polylysine (Ad5.RGD.pK7), and were tested using the breast cancer tissue slice model, which is the most stringent substrate system available. Of all the tested tropism modified Ad vectors, Ad5/3 exhibited the highest transductional efficiency in breast cancer. These preclinical results suggest that Ad5/3 is the most useful modification to achieve higher clinical efficacy of breast cancer gene therapy and virotherapy.

Adenoviridae↗

PubMed2005

A new targeting approach for breast cancer gene therapy using the heparanase promoter.

Gene therapy with adenoviral (Ad) vectors is a promising new approach in the treatment of cancer. Strategies to restrict adenoviral-mediated transgene expression are important to avoid gene transfer into normal cells. Heparanase (HPR) is overexpressed in breast cancer but downregulated in differentiated normal tissue. Expression of the HPR gene was evaluated in breast cancer cells. Biodistribution and liver tropism was evaluated in a mouse model. HPR is highly expressed in breast cancer tissue. The HPR promoter retained its fidelity in an adenovirus context and was activated in breast cancer cells but showed low activity in normal breast cells and the murine liver. We conclude that the HPR pathway is a promising target for the development of breast cancer directed gene therapy strategies.

Adenoviridae↗

PubMed2005

Ovarian cancer targeted adenoviral-mediated mda-7/IL-24 gene therapy.

OBJECTIVE: We have previously shown that adenoviral-mediated melanoma differentiation-associated gene-7 (Ad.mda-7) therapy induces apoptosis in ovarian cancer cells. However, the apoptosis induction was low and directly correlated with infectivity of Ad.mda-7. The objective of this study was to derive ovarian cancer targeted infectivity-enhanced adenoviral vectors encoding mda-7 and evaluate their enhancement in therapeutic efficacy for ovarian carcinoma. METHODS: Infectivity-enhanced adenoviral vectors encoding mda-7 Ad.RGD.mda-7 and Ad.RGD.pK7.mda-7 were derived by incorporation of RGD and or RGD and Pk7 motifs in the fiber knobs by genetic modification. Viruses were validated by PCR for presence of mda-7 and by Western blot for expression of MDA-7 protein. To test the enhancement of therapeutic efficacy of these viruses, a panel of human ovarian carcinoma cells, OV-4, HEY, SKOV3, SKOV3.ip1, were infected by either Ad.mda-7 or Ad.RGD.mda-7 and Ad.RGD.pK7.mda-7 or their respective control viruses and the cell killing was evaluated by crystal violet staining in vitro. Further, therapeutic efficacy was evaluated in vivo using human ovarian cancer xenograft mouse models. RESULTS: Both Ad.RGD.pK7.mda-7 and Ad.RGD.mda-7 showed significant increase in cell killing in vitro compared to unmodified Ad.mda-7 with Ad.RGD.pK7.mda-7 showing highest cell killing. Further, Ad.RGD.pK7.mda-7 showed a significant increase in survival of mice bearing human ovarian cancer xenografts compared to Ad.mda-7 and other control groups. CONCLUSION: Infectivity-enhanced Ad.RGD.mda-7 and Ad.RGD.pK7.mda-7 viruses significantly enhanced ovarian cancer tumor cell killing in vitro. Significant prolongation of survival by Ad.RGD.pK7.mda-7 in murine ovarian cancer models demonstrates the high clinical translational potential of these viruses for ovarian cancer therapy.

Adenocarcinoma↗

PubMed2005

Reovirus sigma1 fiber incorporated into adenovirus serotype 5 enhances infectivity via a CAR-independent pathway.

Adenovirus serotype 5 (Ad5) has been used for gene therapy with limited success because of insufficient infectivity in cells with low expression of the primary receptor, the coxsackie and adenovirus receptor (CAR). To enhance infectivity in tissues with low CAR expression, tropism expansion is required via non-CAR pathways. Serotype 3 Dearing reovirus utilizes a fiber-like sigma1 protein to infect cells expressing sialic acid and junction adhesion molecule 1 (JAM1). We hypothesized that replacement of the Ad5 fiber with sigma1 would result in an Ad5 vector with CAR-independent tropism. We therefore constructed a fiber mosaic Ad5 vector, designated as Ad5-sigma1, encoding two fibers: the sigma1 and the wild-type Ad5 fiber. Functionally, Ad5-sigma1 utilized CAR, sialic acid, and JAM1 for cell transduction and achieved maximum infectivity enhancement in cells with or without CAR. Thus, we have developed a new type of Ad5 vector with expanded tropism, possessing fibers from Ad5 and reovirus, that exhibits enhanced infectivity via CAR-independent pathway(s).

Adenoviridae↗

PubMed2005

Genetic incorporation of HSV-1 thymidine kinase into the adenovirus protein IX for functional display on the virion.

Adenoviral vectors have been exploited for a wide range of gene therapy applications. Direct genetic modification of the adenovirus capsid proteins has been employed to achieve alteration of vector tropism. We have defined the carboxy-terminus of the minor capsid protein pIX as a locus capable of presenting incorporated ligands on the virus capsid surface. Thus, we sought to exploit the possibility of incorporating functional proteins at pIX. In our current study, we incorporated the herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) within pIX to determine if a larger protein of this type could retain functionality in this context. Our study herein clearly demonstrates our ability to rescue viable adenoviral particles that display functional HSV-1 TK as a component of their capsid surface. DNA packaging and cytopathic effect were not affected by this genetic modification to the virus, while CAR-dependent binding was only marginally affected. Using an in vitro [3H]-thymidine phosphorylation assay, we demonstrated that the kinase activity of the protein IX-TK fusion protein incorporated into adenoviral virions is functional. Analysis of cell killing after adenovirus infection showed that the protein IX-TK fusion protein could also serve as a therapeutic gene by rendering transduced cells sensitive to gancyclovir. Using 9-[4-[18F]-fluoro-3-(hydroxymethyl)butyl]guanine ([18F]-FHBG; a positron-emitting TK substrate), we demonstrated that we could detect specific cell binding and uptake of adenoviral virions containing the protein IX-TK fusion protein at 1 h post-infection. Our study herein clearly demonstrates our ability to rescue viable adenoviral particles that display functional HSV-1 TK as a component of their capsid surface. The alternative display of HSV-1 TK on the capsid may offer advantages with respect to direct functional applications of this gene product. In addition, the determination of an expanded upper limit of incorporable proteins on pIX highlights its unique utility as a locus for placement of functional vector constructs.

Amino Acid Sequence↗

PubMed2005

MDA-7/IL-24 regulates proliferation, invasion and tumor cell radiosensitivity: a new cancer therapy?

The novel cytokine MDA-7/IL-24 was identified by subtractive hybridization in the mid-1990s as a cytokine whose expression increased during the induction of terminal differentiation, and that was either not expressed or was present at low levels in tumor cells compared to non-transformed cells. Multiple studies from several laboratories have subsequently demonstrated that expression of IL-24 in tumor cells, but not in non-transformed cells, causes their growth arrest and ultimately cell death. In addition, IL-24 has been noted to be a radiosensitizing cytokine, which in part is due to the generation of reactive oxygen species (ROS) and causing endoplasmic reticulum stress. Recent publications of Phase I trial data have shown that a recombinant adenovirus to express MDA-7/IL-24 (Ad.mda-7 (INGN 241)) was safe and had tumoricidal effects in patients, which argues that IL-24 may have therapeutic value. This review describes what is known about the impact of IL-24 on tumor cell biology in addition to approaches that may enhance the toxicity of this novel cytokine.

Animals↗

PubMed2005

High efficiency transduction of dendritic cells by adenoviral vectors targeted to DC-SIGN.

Dendritic cells (DCs) are a central element in the development of antigen-specific immune responses. The lack of a specific and efficient technique for the in vivo delivery of antigens to DCs remains a major obstacle limiting a vaccine's ability to induce an effective immune response. The efficacy of adenoviral (Ad) vectors in this regard can be enhanced through alterations in vector tropism such that DC-targeted transduction is achieved. Here, the efficiency of DC transduction by Ad vectors retargeted to DC-specific ICAM-3 grabbing nonintegrin (DC-SIGN) was studied and compared to that of Ad vectors retargeted through CD40. A comparable and significant enhancement of gene transfer to monocyte derived DCs (MDDCs) was accomplished by means of an Ad vector harboring the Fc-binding domain of Staphylococcus aureus protein A in combination with antibodies to DC-SIGN or to CD40 or with fused complexes of human Ig-Fc with their natural ligands, i.e., ICAM-3 or CD40L, respectively. Whereas CD40-targeted Ad transduction resulted in a more profound phenotypic DC maturation, DC-SIGN- and CD40-targeted Ad both induced similar levels of IL-12 secretion. These data demonstrate the usefulness of DC-SIGN as a DC-restricted targeting motif for Ad-mediated vaccination strategies.

Adenoviridae↗

PubMed2005

A fiber-modified, secretory leukoprotease inhibitor promoter-based conditionally replicating adenovirus for treatment of ovarian cancer.

PURPOSE: The use of conditionally replicating adenoviruses (CRAD) is dependent on molecular differences between tumor cells and nontumor cells. Transcriptional targeting of CRAD replication via tumor-specific promoters is an effective way to control replication regulation. Genetic fiber pseudotyping is an approach for circumventing low expression of the primary adenovirus serotype 5 (Ad5) receptor by using the distinct adenovirus serotype 3 (Ad3) receptor for entry into and subsequent killing of ovarian cancer cells. EXPERIMENTAL DESIGN: In this study, we constructed a fiber-modified CRAD containing the secretory leukoprotease inhibitor (SLPI) promoter to control viral replication via the E1A gene (Ad5/3SLPI). To evaluate the liver toxicity of chimeric 5/3 fiber-modified CRADs, we compared Ad5/3SLPI with Ad5/3Cox-2L, a CRAD with E1A under control of the Cox-2 promoter, and Ad5/3Delta24, a CRAD that replicates in cancer cells inactive in the retinoblastoma/p16 pathway by use of an in vivo hepatotoxicity model and by a model system that uses slices of human liver. RESULTS: We show efficient viral replication and oncolysis of Ad5/3SLPI in both multiple ovarian cancer cell lines and primary tumor cell spheroids as well as therapeutic efficacy in an orthotopic mouse model of peritoneal carcinomatosis. Ad5/3SLPI showed significantly decreased liver toxicity compared with other 5/3 fiber-modified control vectors examined. CONCLUSIONS: In summary, Ad5/3SLPI is a promising vector candidate for treating metastatic ovarian cancer and showed robust virus replication, oncolysis, and in vivo therapeutic efficacy. Ad5/3SLPI showed comparatively low liver toxicity and therefore holds potential for patient use in the clinic.

Adenoviridae↗

PubMed2005

In vivo analysis of a genetically modified adenoviral vector targeted to human CD40 using a novel transient transgenic model.

BACKGROUND: Retargeting is necessary to overcome the limitations of adenovirus (Ad)-based gene therapy vectors. To this end, we previously constructed an adenovirus with the fiber knob domain replaced by a fibritin trimerization motif fused to the CD40 ligand (Ad5Luc.FF/CD40L). We demonstrated the utility of this fiber replacement strategy for targeting CD40 (hCD40) on human dendritic cells in vitro. The in vivo targeting capacity of this virus, however, is unknown, and there is a limited repertoire of animal models that present hCD40 at an accessible site. Therefore, a new animal model for evaluating CD40-targeted vectors is required. METHODS: We constructed a recombinant adenovirus that expresses hCD40 under transcriptional control of the flt-1 promoter (AdflthCD40). Expression of hCD40 was validated both in vitro and in transgenic mice expressing the human coxsackie adenovirus receptor (hCAR mice). We then evaluated the targeting efficiency of Ad5Luc.FF/CD40L to hCD40 expressed in the pulmonary vasculature of the hCAR mice. RESULTS: Infection of flt-1-positive cells with AdflthCD40 resulted in abundant hCD40 expression in vitro, which could subsequently be targeted by Ad5Luc.FF/CD40L. In vivo administration of AdflthCD40 to hCAR mice resulted in hCD40 expression in the pulmonary vasculature, which was successfully targeted with systemically administered Ad5Luc.FF/CD40L. CONCLUSIONS: This is the first data showing that genetically modified Ad5Luc.FF/CD40L can successfully target hCD40 in vivo. Our data also establishes the utility of transcriptionally targeted, Ad-mediated transient expression of human target molecules in the pulmonary vasculature of hCAR mice as models for in vivo analysis of targeted gene therapy vectors.

Animals↗

PubMed2005

Promoter-controlled infectivity-enhanced conditionally replicative adenoviral vectors for the treatment of gastric cancer.

BACKGROUND: Gastric cancer is the fourth most common malignancy worldwide. Adenoviral vectors (Ads) have been applied for gene therapy of various cancers because of their high transduction efficiency. However, the infectivity of gastrointestinal cancer cells is poor due to the limited expression of the Coxsackie-adenovirus receptor (CAR). In addition, few tumor-specific promoters (TSPs) have been characterized for this type of cancer. To overcome these problems, we proposed TSP-driven conditionally replicating adenoviruses (CRAds) with fiber modification for virotherapy of gastric cancer. METHODS: We assessed the expression profile of eight TSPs in gastric cancer cell lines and evaluated promising candidates in the context of CRAd cytocidal effect. Next, infectivity enhancement by fiber modifications was analyzed in the gastric cancer cell lines. Finally, we combined the TSP-driven CRAds of choice with the fiber modifications to augment the killing effect. RESULTS: Out of the eight TSPs, the midkine (MK) and cyclooxygenase-2 (Cox-2M and Cox-2L) promoters showed high transcriptional activity in gastric cancer cells. When these promoters were used in a CRAd context, Cox-2 CRAds elicited the strongest cytocidal effect. The greatest infectivity enhancement was observed with adenoviral vectors displaying 5/3 chimeric fibers. Likewise, Cox-2 CRAds with 5/3 chimeric fibers showed the strongest cytocidal effect in gastric cancer cell lines. Therefore, Cox-2 CRAds with 5/3 chimeric fiber modification showed good selectivity and infectivity in gastric cancer cells to yield enhanced oncolysis. CONCLUSIONS: Cox-2 CRAds with 5/3 chimeric fiber modification are promising for virotherapy of gastric cancer.

Adenoviridae↗

PubMed2005

Selective rat lung endothelial targeting with a new set of monoclonal antibodies to angiotensin I-converting enzyme.

We demonstrated previously that monoclonal antibody (mAb) 9B9 to angiotensin-converting enzyme (ACE) accumulates selectively in the rat lung after systemic injection and thus is a powerful tool for immunotargeting therapeutic agents/genes to the lung microvasculature. Bearing in mind the tremendous research and therapeutic potential of lung immunotargeting via ACE, we generated a novel set of mAbs to rat ACE in order to enhance the repertoire of mAbs suitable for targeting drugs/genes to the rat lung. Five new mAbs recognizing different epitopes on rat ACE were examined for their efficacy to bind rat ACE both in vitro and in vivo. Gene delivery into cultured rat lung endothelial cells increased 30-50-fold after coating modified adenoviruses (containing Ig-binding domain) with mAbs to rat ACE. Radiolabeled mAbs specifically accumulated in the lung after systemic injection. mAb 1A2, 4H3 and 2E1 demonstrated the highest efficacy of lung uptake-around 50% of injected dose per gram of tissue; for mAb 1A2, the selectivity of lung uptake (ratio of lung to blood radioactivity) was 205. The effect of the mAbs on ACE shedding was epitope-specific: injection of mAb 1A2 and 4H3 did not change lung ACE activity, whereas injection of mAb 2E1 and 9B9 decreased rat lung ACE activity by 20%. None of the tested mAbs inhibited ACE activity in vitro. A new set of mAbs to rat ACE demonstrated highly efficient and selective lung accumulation and thus have the potential for targeting drugs/genes to the pulmonary vasculature in different rat models of lung diseases.

Adenoviridae↗

PubMed2005

Oncolytic adenoviral therapy in gallbladder carcinoma.

BACKGROUND: Oncolytic adenoviral therapy is a promising new approach for cancer treatment. The aim of this study was to improve the conditionally replicative adenoviruses (CRAds) for gallbladder cancer therapy by modifying the fiber-knob region for infectivity enhancement and by incorporating tumor-specific promoters (TSPs) for enhanced specificity. METHODS: For promoter-controlled replication, in vitro efficacy of eight TSPs was investigated in two gallbladder cancer cell lines (NOZ and OCUG-1). Infectivity enhancement was analyzed by two different fiber modifications: Arg-Gly-Asp (RGD) incorporation into the HI loop (RGD modification) and a chimeric construct with a serotype 5 shaft and a serotype 3 knob (5/3 fiber modification). Comparisons were made by infectivity analysis and cytotoxicity assays in vitro, followed by tumor suppressive effects tested in vivo. RESULTS: Among TSPs, highest potency was exhibited by the cyclooxygenase-2 (COX-2), Midkine, and vascular endothelial growth factor promoters in both cell lines tested. Fiber chimera (Ad5/3Luc1) conferred significant enhancement of Ad infectivity in comparison with unmodified and RGD-modified vectors. COX-2 CRAds demonstrated selective cytocidal effect in gallbladder cancer cells in vitro. COX-2 promoter-based Ad5/3 CRAds showed significantly enhanced tumor-suppressive effect compared with nonreplicative and RGD-modified CRAd vectors in vivo. CONCLUSIONS: The 5/3 fiber-modified, COX-2 promoter-driven CRAds may prove to be a new agent for the treatment of gallbladder carcinoma.

Adenoviridae↗

PubMed2005

Adenoviruses with an RGD-4C modification of the fiber knob elicit a neutralizing antibody response but continue to allow enhanced gene delivery.

OBJECTIVE: The purpose of this study was to investigate the effect of preexisting neutralizing antibody (NAbs) in naive mice and the effect of induced NAbs in mice immunized with either an RGD or nonmodified Ad5 vector on the transduction efficiency of adenoviral vectors. METHODS: BALB/c mice were immunized with Ad5LucRGD, with the unmodified Ad5Luc1, or with Opti-MEM intraperitoneally (ip) from one to three times. Sera were collected on day 27 and serially diluted to block Ad5Luc1 or Ad5LucRGD prior to infection of SKOV3.ip1 human ovarian carcinoma cells with these same vectors. Forty-eight hours post Ad infection, a luciferase assay was performed to determine the titer of NAbs. RESULTS: Luciferase assay data showed that the gene transfer efficacy of Ad5LucRGD was 1.56-fold higher than Ad5Luc1 in the presence of serum from naive mice. In the presence of serum from Ad5Luc1-challenged mice, the transduction efficiency of Ad5LucRGD was 3.27-fold higher (single challenge) and 4.2-fold higher (triple challenge) than Ad5Luc1. In the presence of serum from Ad5LucRGD-challenged mice, the transduction efficiency of Ad5LucRGD was 2.24-fold higher (single challenge) and 2.53-fold higher (triple challenge) than Ad5Luc1. CONCLUSION: The RGD-modified human Ad vectors appear to be less recognizable than unmodified Ad to preexisting NAbs in mouse models. RGD-modified Ad vectors also appear to elicit a relatively lower level of NAbs that may also contribute to the higher gene transduction efficiency of these modified vectors. Therefore, RGD-modified Ad vectors may be reagents of clinical utility in the context of preformed anti-Ad immunity and in the setting of repetitive dosing.

Adenoviridae↗

PubMed2005

Antiangiogenic cancer gene therapy by adeno-associated virus 2-mediated stable expression of the soluble FMS-like tyrosine kinase-1 receptor.

Antiangiogenic gene transfer has the potential to be more efficacious than protein-based therapies or pharmacotherapies for the control of solid tumor growth, invasion and metastasis. For a sustained antiangiogenic effect, a vector capable of long-term expression without vector-associated immunity or toxicity is advantageous. The present study evaluated the potential of a recombinant adeno-associated virus-2 (rAAV) encoding the human soluble FMS-like tyrosine kinase receptor 1 (sFlt-1), which functions by both sequestering vascular endothelial growth factor (VEGF) and forming inactive heterodimers with other membrane-spanning VEGF receptors, in vitro and in vivo. Results indicated significant growth inhibitory activity of the transgenic factor in a human umbilical vein endothelial cell proliferation assay in vitro and protection against the growth of an angiogenesis-dependent human ovarian cancer cell line, SKOV3.ip1, xenograft in vivo with increased disease-free survival. Stable expression of the secretory factor and transgene persistence were confirmed by immunohistochemistry and in situ hybridization analyses, respectively. Increased therapeutic effects on both the growth index of the implanted tumor cells and tumor-free survival also correlated with an increasing dose of the vector used. These studies indicate that rAAV-mediated sFlt-1 gene therapy may be a feasible approach for inhibiting tumor angiogenesis, particularly as an adjuvant/therapy.

Angiogenesis Inhibitors↗