Dynamic multimodal imaging of tumor hypoxia and vascular profiles in glioblastoma

描述（由申请人提供）：多形性胶质母细胞瘤（GBM）是最常见和最致命的颅内癌症，对传统的多模式治疗具有高度抵抗力。这些肿瘤的特征在于严重的血管生成、破坏的血脑屏障（BBB）、血管源性水肿以及缺氧和坏死区域，其已显示与局部肿瘤控制、无病生存和总生存负相关。有相当多的轶事证据表明，肿瘤内缺氧赋予辐射抗性。然而，在缺乏可靠的体内监测方法的情况下，动态肿瘤内氧状态在GBM中仍然未经测试。我们已经开发了一种遗传策略，使用生物发光报告系统来监测肿瘤内缺氧。通过将缺氧诱导因子1a-萤火虫荧光素酶（HIF-1a-ODD-luc）导入各种GBM细胞，包括从患者的新鲜GBM肿瘤中分离并富集细胞表面标记物CD 133的细胞，我们将能够通过生物发光成像（BLI）实时监测原位GBM模型中的肿瘤缺氧。我们还建议开发基于交错T2-（BOLD，血氧水平依赖性）和T1-（组织氧水平依赖性）加权序列的MRI技术，用于评估肿瘤氧合，包括基线缺氧，空间异质性和原位GBM模型对干预措施的反应动力学。此外，将通过动态磁敏感对比（DSC）和动态对比增强（DCE）MRI评估血管灌注、BBB状态与缺氧的相关性。据报道，抗血管生成和化疗药物辅助治疗后，GBM患者的总生存期和无进展生存期最近有所增加。然而，其潜在机制仍不清楚。我们假设，在体内肿瘤缺氧和血管的多模式成像将提高我们的有效抗血管生成的病理生理机制的理解，并进一步促进联合放疗或化疗的优化。该项目的主要目标是整合多模态成像获得的肿瘤缺氧和血管系统的多个参数，以与肿瘤侵袭性相关，并了解抗血管生成治疗临床获益的病理生理机制。影像学表现将与灌注、血管密度、缺氧的组织学和免疫组化研究以及药物的药理学研究相关联。本项目目标的成功实现将加深我们对临床胶质母细胞瘤的认识，并为未来化疗联合放疗的新型临床治疗方案奠定基础。 公共卫生相关性：多形性胶质母细胞瘤（GBM）是最常见和最致命的颅内癌症，对传统的多模式治疗具有高度抵抗力。这些肿瘤的特征在于严重的血管生成、血脑屏障破坏、血管源性水肿以及缺氧和坏死区域，这些已被证明与临床结果呈负相关。我们建议应用生物发光成像（BLI），缺氧报告基因的基础上，和一种新的MRI方法来评估原位GBM模型中肿瘤内缺氧和血管特征的动态变化，并进一步了解抗血管生成剂（如贝伐单抗）的临床益处的病理生理机制。

DESCRIPTION (provided by applicant): Glioblastoma multiform (GBM) is the most common and lethal intracranial cancer, and highly resists to conventional multimodal therapies. These tumors are characterized by profound angiogenesis, disrupted blood-brain-barrier (BBB), vasogenic edema, as well as regions of hypoxia and necrosis, which have been shown to correlate negatively with local tumor control, disease free survival and overall survival. There is considerable anecdotal evidence that intra-tumoral hypoxia confers radiation resistance. However, in the absence of a reliable method of monitoring, in vivo, the dynamic intra-tumoral oxygen status, has remained untested in GBM. We have developed a genetic strategy to monitor intra-tumoral hypoxia using a bioluminescence reporter system. By introducing the Hypoxia-inducible-factor1a-firefly luciferase (HIF-1a-ODD-luc) to various GBM cells including the cells isolated from fresh GBM tumors of patient and enriched for the cell surface marker CD133, we will be able to monitor real-time tumor hypoxia in orthotopic GBM model by bioluminescent imaging (BLI). We also propose to develop MRI techniques based on an interleaved T2- (BOLD, blood oxygen level dependent) and T1- (tissue oxygen level dependent) weighted sequence for assessing tumor oxygenation, including baseline hypoxia, spatial heterogeneity and dynamics of response to interventions in orthotopic GBM model. Moreover, correlation of vascular perfusion, BBB status with hypoxia will be evaluated by dynamic susceptibility contrast (DSC) and Dynamic contrast enhanced (DCE) MRI. Recent gains in overall survival as well as progression free survival of GBM patients have been reported following adjuvant treatment with antiangiogenic and chemotherapeutic agents. However, the underlying mechanisms remain unclear. We hypothesize that in vivo multimodal imaging of tumor hypoxia and vasculature will enhance our understanding of pathophysiological mechanisms of effective antiangiogenesis and further facilitate optimization of combined radiotherapy or chemotherapy. The major goal of this project is to integrate multiple parameters of tumor hypoxia and vasculature acquired by multimodal imaging to correlate with tumor aggressiveness and understand pathophysiological mechanism underlying the clinical benefits from antiangiogenic treatment. The imaging findings will be correlated with histological and immunohistochemical studies of perfusion, vascular density and hypoxia, as well as pharmacological study of drug. Successful accomplishment of the goals of this project will enhance our understanding of clinical glioblastoma and lay the foundation for future novel clinical treatment regimens towards chemotherapy in combination with radiotherapy. PUBLIC HEALTH RELEVANCE: Glioblastoma multiform (GBM) is the most common and lethal intracranial cancer, and highly resists to conventional multimodal therapies. These tumors are characterized by profound angiogenesis, disrupted blood-brain-barrier, vasogenic edema, as well as regions of hypoxia and necrosis, which have been shown to correlate negatively with clinical outcome. We propose to apply bioluminescent imaging (BLI), based on a hypoxia reporter gene, and a novel MRI approach to assessing dynamic change of intra-tumor hypoxia and vascular characteristics in orthotopic GBM models, and to further understand pathophysiological mechanisms underlying the clinical benefits from antiangiogenic agents such as bevacizumab.