COMBINED ULTRASOUND/MOLECULAR ANALYSIS OF TUMOR RESPONSE TO VEGF BLOCKADE

描述（由申请人提供）：组织学不良的肾母细胞瘤（WT）和转移性疾病的儿童继续经历高死亡率。这些患者迫切需要新的治疗方法。我们最近报告了I期数据，表明抗血管内皮生长因子（VEGF）抗体贝伐珠单抗（BV）在难治性儿科肿瘤中具有出色的耐受性。由于这种疗法已在成人癌症中得到验证，因此它可能为侵袭性WT患者提供有吸引力的选择;然而，缺乏临床评估肿瘤反应的方法。这对于儿科癌症患者来说是一个特别关键的问题，长期的肿瘤控制是他们的目标。在我们以前的研究中，我们报道了实验WT最初被VEGF抑制剂显著抑制。然而，与临床观察结果一致，即用BV治疗的成人几乎所有进展，我们发现，如果持续治疗，即使是高度反应性的异种移植物也会恢复生长。对VEGF阻断的耐药机制知之甚少，耐药的临床终点仍不明确。来自我们实验室和其他实验室的新数据表明，VEGF抑制后的肿瘤表现出缺血性损伤的特征，包括诱导损伤反应途径和血管重塑。此外，基因表达、血管组装和灌注的明显变化在急性和慢性两种情况下都发生。例如，我们以前报道过VEGF抑制可在24小时内引起分支血管系统的显著损失和缺血，而长期阻断导致血管重塑、血流恢复和肿瘤进展。血管损伤反应的关键分子标志物包括血管生成所必需的基因家族成员，包括整联蛋白（α V β 3）、VEGF受体（VEGFR-1和-2）和Notch家族成员（Jagged-1），以及缺氧反应的介质（如考克斯-2）。高频超声是一种新兴技术，可以提供WT血管对VEGF抑制剂的解剖、功能和生理反应的快速和纵向评估。此外，新可用的商业扫描仪对超声造影剂（微泡）回波特征的优异灵敏度促进了实体瘤中血管结构的可视化、血流的定量和内皮生物标志物的分子成像。然而，这项技术仍处于起步阶段，进一步开发长循环和靶向微泡对于实现其作为评估血管结构和功能动态变化的手段的全部潜力至关重要。特别是，开发一个适合临床护理点使用的平台至关重要。在这些研究中，我们将使用高频超声，在实验WT的特定背景下，并使用新型微泡工具和超声成像技术，研究VEGF阻断期间的血管重塑。我们在这些研究中的目标是将WT血管生成中的急性和慢性分子变化与超声揭示的高度定量和敏感的结构和流动特征以及血管生物标志物表达模式相关联。公共卫生相关性：我们的最终目标是开发一种创新的超声技术，以监测和指导临床侵袭性肾母细胞瘤（WT）儿童的抗血管生成治疗。我们将开发这项技术，同时探索在血管内皮生长因子（VEGF）的初始和慢性阻断期间肿瘤血管的变化。我们假设WT血管生成的分子变化与无创超声显示的血管变化相关。

DESCRIPTION (provided by applicant): Children with unfavorable histology Wilms tumor (WT) and metastatic disease continue to experience high mortality rates. These patients urgently require new therapies. We have recently reported Phase I data indicating excellent tolerance of the anti-vascular endothelial growth factor (VEGF) antibody bevacizumab (BV) in refractory pediatric tumors. Because this therapy has been validated in adult cancers, it may provide an attractive option for patients with aggressive WT; however, methods of assessing tumor response clinically are lacking. This is a particularly critical issue for pediatric cancer patients, in whom long-term tumor control is the goal. In our previous studies, we reported that experimental WT were initially strikingly suppressed by VEGF inhibitors. Yet consistent with clinical observations that adults treated with BV virtually all progress, we found that even highly responsive xenografts resumed growth if treatment was sustained. The mechanism of resistance to VEGF blockade is poorly understood, and clinical endpoints of resistance remain undefined. Emerging data from our lab and others suggests that tumors subjected to VEGF inhibition exhibit features of ischemic injury, including induction of damage response pathways and vessel remodeling. Further, distinct changes in gene expression, vascular assembly, and perfusion occur both acutely and chronically. For example, we have previously reported that VEGF inhibition can cause striking loss of branching vasculature and ischemia by 24 hours, whereas long-term blockade results in vessel remodeling, recovery of flow, and tumor progression. Key molecular markers of the response to vessel injury include members of gene families that are essential to angiogenesis, including integrins (alphaVbeta3), VEGF receptors (VEGFR-1 and -2), and Notch family members (Jagged-1), and mediators of the response to hypoxia (such as COX-2). High frequency ultrasound is an emerging technology that can provide rapid and longitudinal assessment of the anatomic, functional, and physiological response of WT vasculature to VEGF inhibitors. Further, the excellent sensitivity of newly available commercial scanners to sonographic contrast agents (microbubble) echo-signatures facilitates visualization of vessel architecture, quantification of blood flow, and molecular imaging of endothelial biomarkers in solid tumors. Yet this technology is still in its infancy, and further development of long-circulating and targeted microbubbles is critical for realizing its full potential as a means of evaluating dynamic changes in vessel structure and function. In particular, it is essential to develop a platform suitable for clinical point-of-care use. In these studies, we will investigate vascular remodeling during VEGF blockade using high frequency ultrasound, in the specific context of experimental WT, and using novel microbubble tools and ultrasound imaging techniques. Our goal in these studies is to relate acute and chronic molecular changes in WT angiogenesis with highly quantitative and sensitive architectural and flow characteristics and vascular biomarker expression patterns revealed by ultrasound. PUBLIC HEALTH RELEVANCE: Our ultimate goal is to develop an innovative ultrasound technique to monitor and guide anti-angiogenic therapy for children with clinically aggressive Wilms tumors (WT). We will develop this technology while exploring tumor vascular changes during initial and chronic blockade of vascular endothelial growth factor (VEGF). We hypothesize that molecular changes in WT angiogenesis can be correlated with vascular changes revealed by noninvasive ultrasound.