Autophagy inhibition as a therapeutic strategy for glioblastoma mutliforme

描述(由申请人提供)：尽管在新诊断的多形性胶质母细胞瘤(GBM)的辅助放射治疗(RT)中加入替莫唑胺(TMZ)可提高存活率，但这种致命疾病的患者复发率为100%。必须确定使肿瘤细胞在辅助治疗中存活的分子机制，并在治疗上有针对性地改善结果。在经TMZ或RT处理的GBM细胞中，观察到自噬是一种细胞内过程，其特征是形成自噬小泡，隔离细胞质内容物并将其靶向于溶酶体内的降解。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，溶酶促性型抗疟药羟基氯喹(HCQ)可以抑制治疗诱导的自噬，并增强肿瘤细胞的死亡。HCQ对自噬的抑制与大量无效的自噬小泡的积累有关，这些小泡在肿瘤组织和外周血单核细胞(PMBC)中都可以被量化。为了将这些临床前的发现转化为临床益处，将通过新的脑肿瘤治疗方法联盟进行一项I/II阶段的方案，用TMZ和RT测试新诊断的GBM的HCQ。这项9中心CTEP批准的临床试验将在一年内招募88-94名患者。这项提案中概述的相关研究将检验两个假设：1)可以使用一种新的检测方法，在临床可达到的剂量下，结合TMZ和RT来测量自噬抑制；以及2)可以确定最容易受到自噬抑制剂影响的肿瘤的遗传特征。这些假说将通过使用血液和参加临床试验的患者的组织样本来完成三个特定目标来验证：特定目标1是测量PBMCs的自噬抑制。具体目标2是描述HCQ的药代动力学特征，并将其与自噬抑制的测量相关联。具体目标3是描述控制自噬的基因的突变状态和拷贝数，这些基因经常在GBM中失控，并将基因与生存相关。从这些研究中获得的知识将为未来的临床试验和HCQ或其他新型自噬抑制剂的临床前研究提供建议的基础。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：羟氯喹抑制治疗诱导的自噬增强了小鼠模型中的肿瘤消退。这项建议描述了相关研究，旨在了解自噬抑制作为一种治疗策略的作用，使用新诊断的多形性胶质母细胞瘤患者的生物组织，这些患者参加了羟基氯喹与标准治疗相结合的多机构I/II期试验。从这些相关研究中获得的知识有可能影响脑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.