Autophagy inhibition as a therapeutic strategy for glioblastoma mutliforme

描述（由申请人提供）：尽管通过在辅助放射治疗（RT）中添加替莫唑胺（TMZ）来改善新诊断的多形性胶质母细胞瘤（GBM）的生存率，但这种致命疾病的患者的复发率为100%。允许肿瘤细胞在辅助治疗中存活的分子机制必须被确定和治疗靶向以改善结果。在TMZ或rt治疗的GBM细胞中，观察到自噬是一种细胞内过程，其特征是形成自噬囊泡，将细胞质内容物隔离并靶向溶酶体降解。临床前研究已经确定，治疗诱导的自噬是一种生存反应，可能导致化疗耐药和肿瘤复发。这些研究发现抗疟药羟氯喹（HCQ）可抑制治疗诱导的自噬，促进肿瘤细胞死亡。HCQ对自噬的抑制与肿瘤组织和外周血单核细胞（PMBC）中大量无效自噬囊泡的积累有关。为了将这些临床前研究结果转化为临床益处，将通过脑肿瘤治疗新方法联盟进行HCQ联合TMZ和RT治疗新诊断的GBM的I/II期试验。这项9个中心CTEP批准的临床试验将在一年内招募88-94名患者。本提案中概述的相关研究将验证两个假设：1)在临床可实现的剂量下，HCQ与TMZ和RT联合使用，可以使用一种新的检测方法来测量自噬抑制；2)确定最易受自噬抑制剂影响的肿瘤的遗传特征。这些假设将通过使用该临床试验患者的血液和组织样本来完成三个特定目标来验证：特定目标1是测量pbmc中的自噬抑制。具体目的2是表征HCQ的药代动力学特征，并将其与自噬抑制的测量相关联。具体目的3是表征控制自噬的基因的突变状态和拷贝数，这些基因在GBM中经常失调，并将基因型与生存联系起来。从这些研究中获得的知识将为HCQ或其他新型自噬抑制剂的未来临床试验和临床前研究提供基础。这一长期目标有可能对GBM和其他难治性恶性肿瘤患者的护理产生重大影响，并与NCI将最先进的癌症治疗纳入临床实践的使命直接相关。公共卫生相关性：羟基氯喹抑制治疗诱导的自噬增强小鼠模型中的肿瘤消退。本提案描述了相关研究，旨在了解自噬抑制作为一种治疗策略的作用，该策略使用来自新诊断的多形性胶质母细胞瘤患者的生物组织，这些患者参加了一项多机构的I/II期临床试验，羟氯喹联合标准治疗。从这些相关研究中获得的知识有可能影响脑肿瘤和其他难治性癌症患者的治疗。

DESCRIPTION (provided by applicant): Despite improvements in survival achieved by the addition of temozolomide (TMZ) to adjuvant radiation therapy (RT) for newly diagnosed glioblastoma multiforme (GBM), patients with this deadly disease experience a 100% recurrence rate. Molecular mechanisms that allow tumor cells to survive adjuvant therapy must be identified and therapeutically targeted to improve outcomes. Autophagy, an intracellular process characterized by the formation of autophagic vesicles that sequester cytoplasmic contents and target them for degradation in lysosomes has been observed in GBM cells treated with TMZ or RT. Preclinical studies have determined that therapy-induced autophagy is a survival response that can contribute to chemotherapy resistance and tumor recurrence. These studies found that the lysosomotropic antimalarial hydroxychloroquine(HCQ) can inhibit therapy-induced autophagy and enhance tumor cell death. Autophagy inhibition with HCQ is associated with an accumulation of large ineffective autophagic vesicles which can be quantified in both tumor tissue and peripheral blood mononuclear cells (PMBC). In order to translate these preclinical findings into clinical benefit, a phase I/II protocol testing HCQ with TMZ and RT for newly diagnosed GBM will be conducted through the New Approaches to Brain Tumor Therapy consortium. This 9-center CTEP- approved clinical trial will enroll 88-94 patients in one year. The correlative studies outlined in this proposal will test two hypotheses: 1) autophagy inhibition can be measured using a novel assay at clinically achievable doses of HCQ in combination with TMZ and RT; and 2) the genetic characteristics of tumors most susceptible to autophagy inhibitors can be identified. These hypotheses will be tested through the completion of three specific aims using blood, and tissue samples from patients enrolled on this clinical trial: Specific aim 1 is to measure autophagy inhibition in PBMCs. Specific aim 2 is to characterize the pharmacokinetic profile of HCQ and correlate this to measurements of autophagy inhibition. Specific aim 3 is to characterize the mutational status and copy number of genes that control autophagy and are frequently dysregulated in GBM, and correlate genotype to survival. The knowledge gained from these studies will provide the basis for proposals of future clinical trials and preclinical investigations of HCQ, or other novel autophagy inhibitors. This long-term objective has the potential to significantly impact the care of patients with GBM and other treatment-refractory malignancies and is immediately relevant to the NCI mission of incorporating of state-of-the-art cancer treatments into clinical practice. PUBLIC HEALTH RELEVANCE: The inhibition of therapy-induced autophagy with hydroxychloroquine enhances tumor regression in mouse models. This proposal describes correlative studies designed to understand the role of autophagy inhibition as a therapeutic strategy using biological tissue from patients with newly diagnosed glioblastoma multiforme enrolled on a multi- institution phase I/II trial of hydroxychloroquine in combination with standard therapy. The knowledge gained from these correlative studies has the potential to impact the treatment of patients with brain tumors and other treatment-refractory cancers.