A New Class of Magnetic Nanoparticles for Glioma Targeted Drug Delivery

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Project Summary Glioblastoma is the most common and aggressive malignant brain tumor with extremely poor prognosis. Current standard care for glioblastoma treatment consists of maximal surgical resection followed by chemotherapy and radiation therapy. Unfortunately, it hardly produces long-term control on tumor progression. Due to the highly heterogeneous, infiltrating and recurring natures of glioblastomas, chemotherapy plays a crucial role in clinical management of glioblastomas. However, existing chemotherapies in brain tumor treatment are mostly disappointing, often due to poor delivery of chemotherapy agents stemming from their low water solubility and/or inability of crossing the blood brain barrier (BBB) or blood tumor barrier (BTB). Although nanomaterial-based drug delivery systems have shown advantages by enhancing the delivery efficiency and improving the safety profile of therapeutics over conventional chemotherapy formulations in treating many cancers, their development and applications in brain tumor treatment are largely limited, because of delivery challenges in current nano-delivery systems with sizes of 10-200 nm. Supported by the premises that: 1) ferumoxytol (Feraheme®), an FDA approved iron oxide nanoparticle for treating iron deficiency anemia, can be used for imaging brain tumor with magnetic resonance imaging (MRI) in patients, and 2) our sub-5 nm ultrafine iron oxide nanoparticle (uIONP) can reach brain tumors in the intracranial glioma mouse model to enhance tumors in MRI with T1 contrast, this STTR Phase I project aims to develop a new class of drug-carrying and glioblastoma targeted IONP for delivering highly potent yet water-insoluble chemotherapy agent SN38, the active and much more potent form of chemotherapy agent Irinotecan (CPT-11) used in treating many other cancers in oncology clinic, for treating intracranial brain tumors. We will incorporate our patented amphiphilic poly(ethylene glycol)-block-(allyl glycidyl ether) (PEG-b-AGE) coating polymer for uIONPs to encapsulate hydrophobic SN38, which has not been used for treating brain tumors due to poor intracranial delivery. Tri-peptide RGD with well-documented functions and safety profile is selected as the ligand for functionalizing uIONPs to target αvβ3 integrin overexpressed in glioblastomas. In the proposed project, we will prepare and optimize the RGD-conjugated uIONP with SN38 loading (RGD-uIONP/SN38) with consistent physiochemical and biological properties, including SN38 loading efficiency, surface charge, density of conjugated the targeting ligand, glioblastoma cell targeting, intracellular drug release and cytotoxicity, and stability (Aim 1). We will then use an intracranial mouse model to investigate the blood half-life, biodistribution, clearance, and tumor uptake and intra-tumoral distribution of developed RGD-uIONP/SN38 as well as the stability of this platform in blood and organs in Aim 2, followed by determining the efficacy of RGD- uIONP/SN38 in inhibiting the tumor growth based on MRI in vivo and histopathological analysis. The results will lead to the further development of this system towards clinical translation in the Phase II project.