The proposed research describes the development of adenovirus-based gene delivery vectors for the targeted ablation of advanced bladder cancer disease. Bladder cancer is the second most common cancer of the urogenital tract with over 68,000 new cases and 14,000 deaths in 2008. The majority of bladder cancers in the US are transitional cell carcinomas (TCC), although squamous cell carcinomas (SCC) and adenocarcinomas also occur. Superficial lesions are removed surgically by transurethral resection but since residual lesions have a high risk of recurrence (>80%) and progression (~50%), patients receive additional intravesical therapy. Long-term follow up shows that one-third of the patients who initially had superficial lesions die of bladder cancer. Radical cystectomy is the only therapeutic choice for recurrent superficial cancer or muscle invasive bladder cancer. Disease that has invaded beyond the muscle wall, spreads via the lymphatic system forming metastases in liver, lung or bone. Multimodal therapy of advanced tumors results in only 20-40% survival at 5 years. Thus, effective treatment strategies aimed at reducing the recurrence and progression of superficial bladder cancer, as well as improving therapeutic outcome in patients with advanced disease, are needed. Gene therapy using adenoviruses is a powerful approach for delivering exogenous genes that transcribe toxic proteins leading to the ablation of cancer cells. While this is an attractive approach, low expression of the Coxsackie-Adenovirus receptor (CAR) in advanced bladder cancer cells results in poor transduction of cancer cells but not normal hepatocytes, which results in liver toxicity of systemically delivered adenoviruses. In addition, immunogenicity of adenoviruses is a cause for concern. It is necessary to develop novel approaches for efficacious gene therapy of bladder cancer disease. We propose a hybrid system based on polymer-antibody immunoconjugates or PICs, and adenoviruses (Ad) for the targeted ablation of bladder cancer cells. Novel cationic polymers will be conjugated to anti-EGFR antibodies in order to target the Epidermal Growth Factor Receptor (EGFR), which is over-expressed on advanced bladder cancer cells. PICs will be complexed with Ad-GFP and Ad-TRAIL viruses and the in vitro transduction efficacy of the resulting PIC-adenovirus hybrids (PAHs) will be evaluated using bladder cancer cell lines. Cell lines that capture the advanced bladder cancer phenotype will be employed in the proposed studies. AdGFP-based PAHs will be used to determine infectivity (using GFP expression). AdTRAIL-based PAHs will be investigated for their apoptosis-inducing efficacy following the expression of TRAIL, which has been shown to demonstrate selectivity for inducing apoptosis in cancer cells. Three PICs selected from these in vitro experiments will be employed in an orthotopic animal model of bladder cancer to study the biodistribution and anti-tumor efficacy of the PAH. It is anticipated that the proposed strategy will result in the identification of novel therapeutics for the safe, effective, and targeted ablation of bladder cancer disease.
The overall aim of the proposed research is to develop highly effective adenovirus-based gene delivery methods for the ablation of advanced bladder cancer disease. Advanced bladder cancer disease accounts for over 68,000 new cases and 14,000 deaths every year in the United States. We hypothesize that polymer-immunoconjugates (PICs) can be employed in order to selectively target malignant bladder tissue and overcome the limitations associated with currently existing adenoviral cancer gene therapy systems.
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