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）可改善生存率，但患有这种致命疾病的患者的复发率为100%。必须确定允许肿瘤细胞在辅助治疗中存活的分子机制，并进行治疗靶向，以改善结果。自噬是一种细胞内过程，其特征在于形成自噬囊泡，所述自噬囊泡隔离细胞质内容物并靶向它们在溶酶体中降解，已经在用TMZ或RT处理的GBM细胞中观察到。临床前研究已经确定，治疗诱导的自噬是一种存活反应，其可以有助于化疗抗性和肿瘤复发。这些研究发现，亲溶酶体抗疟药羟氯喹（HCQ）可以抑制治疗诱导的自噬并增强肿瘤细胞死亡。HCQ的自噬抑制与大的无效自噬囊泡的积累有关，其可以在肿瘤组织和外周血单核细胞（PMBC）中定量。为了将这些临床前研究结果转化为临床获益，将通过脑肿瘤治疗新方法联盟进行I/II期方案测试HCQ与TMZ和RT用于新诊断的GBM。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。本提案中概述的相关研究将测试两个假设：1）可以使用临床可实现剂量的HCQ与TMZ和RT组合的新测定来测量自噬抑制; 2）可以鉴定对自噬抑制剂最敏感的肿瘤的遗传特征。这些假设将通过完成三个特定目标进行测试，这些目标是使用来自参加本临床试验的患者的血液和组织样本：特定目标1是测量PBMC中的自噬抑制。具体目标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。具体目标3是表征控制自噬和在GBM中经常失调的基因的突变状态和拷贝数，并将基因型与存活相关联。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显著影响GBM和其他难治性恶性肿瘤患者的护理，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可增强小鼠模型中的肿瘤消退。该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，该治疗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，这些患者参加了羟氯喹联合标准治疗的多机构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.