Preclinical Validation of Polyvalent siRNA Gold Nanoparticle Conjugates as anti-G

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PROJECT SUIVIMARY (See instructions): Malignant glioma (MG) represent the most prevalent and lethal primary cancer of the central nervous system. Patients diagnosed with the highest grade MG, grade IV glioblastoma multiforme (GBM), survive for only 9-12 months after diagnosis despite surgical resection and aggressive treatment regimens. Multimodal approaches using radiation with conjunctive chemotherapy (temozolamlde) resulted in only margina increase in patients' survival up to 14.6 months; recurrence is nearly universal and salvage therapies for such progression remain ineffective. An incomplete understanding of how catalogued genetic aberrations dictate phenotypic hallmarks of the disease, particularly intense therapy (apoptosis) resistance, yet florid intratumoral necrogenesis, combined with a highly therapy-resistant cancer stem cell population (brain tumor stem cells, BTSC) as the putative cell-of-origin conspired to make GBM a highly enigmatic and incurable disease. This grant proposal addresses the critical challenges facing the glioma field on multiple levels: (i) To overcome toxicity, insufficient specificity and delivery of targeted therapies (e.g. (R)TK inhibitors), our efforts focus on gene silencing using novel small interfering RNA (siRNA)-conjugated gold nanoparticles (RNA-Au NPs). This alternative and highly promising new agent exhibits enhanced cellular/tissue uptake, reduced offtarget effects and improved biostability and compatibility compared to conventional molecular RNAi and other polymer and nanoconstructs. (ii) This single-entity RNAi nano-reagent will target concomitantly activated RTKs and Bcl2L12 as GBM signature lesions and functionally validated modulators of therapeutic resistance and neurologically debilitating necrogenesis. (iii) We will pre-clinically validate RTK- and Bcl2L12- targeting NPs (RTK-, L12-RNA-Au NPs) in physiologically highly relevant BTSC and derived orthotopic explant model systems, (iv) We will extend our pre-clinical validation efforts from orthotopic xenograft models to studies of tumor regression in a refined, acute onset, highly penetrant GBM mouse model to assess efficacy of RNA-Au NPs in the setting of an intact immune system and a physiologically more relevant tumor microenvironment.