Multifunctional nanoparticles to improve treatment of human glioblastoma

描述(申请人提供)：多功能纳米颗粒改善人类胶质母细胞瘤的治疗这项研究的长期目标是开发新的治疗方法，以改善成人多形性胶质母细胞瘤(GBM)患者的临床结果，GBM是人类最常见和致命的原发脑瘤。最近的临床试验表明，在术后治疗期间使用甲基化药物替莫唑胺(TMZ)可显著提高GBM患者的存活率。尽管TMZ联合放射治疗现在是治疗GBM的当代标准，但由于O6-甲基鸟嘌呤-DNA甲基转移酶(MGMT)介导的耐药性，大多数GBM没有反应，MGMT是一种DNA修复蛋白，限制了TMZ的放射增敏和细胞毒作用。我们小组和其他人最近的研究表明，可以通过用DNA修复抑制剂消除MGMT活性来克服GBM对TMZ的耐药性。然而，DNA修复抑制剂的药代动力学较差，如血脑屏障通透性差、半衰期短、骨髓产生有害副作用等，阻碍了其临床应用。我们建议开发一种多功能纳米颗粒(NP)，它可以将DNA抑制剂特异性地输送到GBM细胞，以规避耐药和限制治疗的全身毒性。我们的多学科团队开发了由聚乙二醇接枝壳聚糖(聚乙二醇壳聚糖)的可生物降解聚合物外壳包裹的氧化铁核心组成的NPs原型。核壳结构与近红外荧光团Cy5.5和靶向配体氯毒素(CTX)偶联。这种NP系统的每一个元素都赋予了一种属性，使其成为图像引导药物输送载体的极佳候选者。在本研究中，抑制剂以共价方式附着在NP的外壳上，通过二硫键交联，并可通过谷胱甘肽介导的靶细胞胞浆中的还原来快速降解，从而释放有效载荷，但不是在血液中。该项目包括以下具体目标：(1)缓蚀剂衍生纳米颗粒的制备和表征；(2) NPs对人GBM细胞的治疗效果评价，以及NPs的体内毒性和血脑屏障通透性；(3)NPs对人GBM异种移植模型的治疗作用研究。我们的纳米粒结合了促进药物装载、在运输过程中保护药物、穿透血脑屏障、促进细胞内快速释放和赋予肿瘤特异性的功能。此外，纳米粒的每一种成分材料都具有生物相容性，并具有多种功能。这一策略将GBM癌症生物学前沿研究的进展与肿瘤成像和治疗方面的先进纳米技术相结合，以规避治疗阻力。拟议工作的成功完成可能会产生一种新的治疗剂，可以很容易地投入临床试验，因为我们的NP专门设计用于提高目前治疗GBM的标准的疗效。这项研究的扩展的健康相关性是，具有血脑屏障穿透能力的NPs也可能有助于向各种肿瘤的脑转移瘤输送治疗剂。

DESCRIPTION (provided by applicant): Multifunctional nanoparticles to improve treatment of human glioblastoma The long-term objective of this research is to develop novel therapeutic approaches to improve the clinical outcome of adult patients with glioblastoma multiforme (GBM), the most common and lethal human primary brain tumor. Recent clinical trials have demonstrated that administration of the methylating agent temozolomide (TMZ) during post-operative therapy significantly increases survival of GBM patients. Although TMZ in combination with radiation is now the contemporary standard of care for GBMs, the majority of GBMs are not responsive due to the resistance mediated by O6-methylguanine-DNA methyltransferase (MGMT), a DNA repair protein that limits the radiosensitizing and cytotoxic effects of TMZ. Recent studies from our group and others suggest that the resistance of GBMs to TMZ can be overcome by ablating MGMT activity with DNA repair inhibitors. However, the clinical utility of DNA repair inhibitors have been hindered by their poor pharmacokinetics such as poor permeability of the blood-brain barrier (BBB), a short half-life, and bone marrow producing deleterious side-effects. We propose to develop a multifunctional nanoparticle (NP) that can deliver DNA inhibitors specifically to GBM cells to circumvent treatment-resistance and treatment-limiting systemic toxicity. Our multidisciplinary team has developed prototype NPs consisting of an iron oxide core surrounded by a shell of a biodegradable polymer of polyethylene glycol grafted chitosan (PEG-chitosan). The core-shell structure is conjugated with the near-infrared fluorophore Cy5.5 and the targeting ligand chlorotoxin (CTX). Each element of this NP system confers a property that makes it an excellent candidate as an image-guided drug delivery vehicle. In this study, inhibitors are covalently attached to the outer shell of the NP tht is crosslinked by disulfide linkage and can be rapidly degraded by glutathione-mediated reduction in cytosol of target cells to release the payload but not in blood. The project includes the following Specific Aims: (1) Fabrication and characterization of inhibitor derivatized NPs; (2) Assessment of therapeutic effects of NPs on human GBM cells, and in vivo toxicity and BBB permeation of NPs; (3) Study of therapeutic efficacy of NPs in an orthotopic GBM xenograft model of human GBM. Our NPs incorporate features that facilitate drug loading, protect drug during transport, penetrate the BBB, facilitate rapid intracellular release, and confer tumor specificity. Moreover, each component material of the NP is biocompatible and assumes multiple functions. This strategy combines the advances in forefront research of GBM cancer biology with advanced nanotechnology in tumor imaging and therapeutics to circumvent the resistance to treatment. Successful completion of the proposed work may produce a novel therapeutic agent that can be readily brought to clinical trial as our NP is expressly designed to improve the efficacy of the current standard of care for GBM. The expanded health relevance of this research is that the NPs with BBB penetration ability may also facilitate the delivery of therapeutic agents to brain metastases from a variety of tumors.