Multifunctional nanoparticles to improve treatment of human glioblastoma

本研究的长期目标是开发新的治疗方法，以改善多形性胶质母细胞瘤（GBM）成人患者的临床结果，GBM是最常见和致命的人类原发性脑肿瘤。最近的临床试验表明，在术后治疗期间给予甲基化剂替莫唑胺（TMZ）可显著增加GBM患者的存活率。虽然TMZ与放射联合治疗现在是GBM的当代标准治疗，但由于O 6-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的放射增敏作用和细胞毒性作用。我们小组和其他人最近的研究表明，GBM对TMZ的耐药性可以通过DNA修复抑制剂消除MGMT活性来克服。然而，DNA修复抑制剂的临床应用受到其不良药代动力学的阻碍，例如血脑屏障（BBB）的渗透性差、半衰期短和骨髓产生有害副作用。我们建议开发一种多功能纳米颗粒（NP），可以将DNA抑制剂特异性地递送到GBM细胞，以规避治疗耐药性和治疗限制性全身毒性。我们的多学科团队已经开发出原型纳米粒子，其由聚乙二醇接枝壳聚糖（PEG-壳聚糖）的可生物降解聚合物的外壳包围的氧化铁核心组成。核-壳结构与近红外荧光团Cy5.5和靶向配体氯毒素（CTX）缀合。该NP系统的每个元素赋予一种特性，使其成为图像引导药物递送载体的优秀候选者。在这项研究中，抑制剂共价连接到NP的外壳上，NP通过二硫键交联，并且可以通过谷胱甘肽介导的靶细胞胞质溶胶还原而快速降解，以释放有效载荷，但不会在血液中。该项目包括以下具体目标：（1）制备和表征抑制剂衍生的纳米颗粒;（2） 评估NP对人GBM细胞的治疗效果，以及NP的体内毒性和BBB渗透;（3）研究NP在人GBM的原位GBM异种移植模型中的治疗功效。我们的纳米颗粒具有促进药物装载、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特征。此外，NP的每种组分材料都是生物相容的，并具有多种功能。该策略将GBM癌症生物学前沿研究的进展与肿瘤成像和治疗学中的先进纳米技术相结合，以规避对治疗的耐药性。成功完成拟议的工作可能会产生一种新的治疗剂，可以很容易地带到临床试验，因为我们的NP是明确设计的，以提高目前的标准治疗GBM的疗效。这项研究的扩展的健康相关性是具有BBB穿透能力的NP也可以促进治疗剂从各种肿瘤向脑转移的递送。

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.