Ovarian cancer is the leading cause of death from gynecological malignancies in the USA with an overall five-year survival rate of 50%. The NIH panel on ovarian cancer concluded that """"""""innovative approaches to the treatment of advanced primary as well as recurrent ovarian cancer must be identified and studied"""""""". This conclusion supports the research proposed in this application. The purpose of this project is to draw on the advances made in molecular biology, polymer science, chemotherapy, and photodynamic therapy to develop a novel therapeutic modality, which will be potentially more effective than existing therapeutic agents in ovarian cancer treatment. Clinical data indicate that the therapeutic use of nanosized (5-20 nm) water- soluble polymer-anticancer drug conjugates appears to be a novel and successful strategy for cancer treatment. The advantages of polymer-bound drugs (when compared to low-molecular weight drugs) are: a) active uptake by fluid-phase pinocytosis (non-targeted polymer-bound drug) or receptor-mediated endocytosis (targeted polymer-bound drug);b) increased active accumulation of the drug at the tumor site by targeting;c) increased passive accumulation of the drug at the tumor site by the enhanced permeability and retention effect;d) long-lasting circulation in the bloodstream;e) decreased non-specific toxicity of the conjugated drug;f) decreased immunogenicity of the targeting moiety;f) immuno-protecting and immunomobilizing activities;and g) and modulation of the cell signaling and apoptotic pathways. The main aim of the proposed research is to design new, effective macromolecular therapeutics for the treatment of cancer. Macromolecular therapeutics based on conjugates of N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers with Biologic Response Modifiers, 4-hydroxyphenyl retinamide and all- trans-retinoic acid, and conjugates with anticancer drugs, geldanamycin, 2,5-bis(6-hydroxymethyl-2- thienyl)furan, and mesochlorin e6 will be designed and synthesized. A novel therapeutic modality will be developed: pretreatment of cancer cells with macromolecular retinoids will lead to differentiation of cancer cells resulting in enhanced susceptibility to chemotherapy and/or photodynamic therapy. The pretreatment will be followed by administration of a polymer-bound chemotherautic agent and a polymer-bound photosensitizer. Combinatorial chemistry approaches will be used to identify human ovarian carcinoma CD47 binding peptides. A secondary library will be constructed based on results of alanine scanning. This will permit to select peptides with high binding affinity. Multivalent peptide-targeted conjugates will be designed and evaluated. Mechanism of action of macromolecular therapeutics will be studied in detail. The results will provide a basis for the design of double-targeted conjugates - to the receptor expressed at the plasma membrane and to a subcellular location identified for each particular drug by mechanistic studies. The concept of double-targeted macromolecular therapeutics provides a new paradigm for the design of efficient anticancer drugs for the treatment of ovarian cancer.
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