Ultrasound Contrast Agents for Inflammation and Angiogenesis

描述（由申请人提供）：定点微泡（MB）已经证明了作为分子成像工具的潜力。在该项目的第一阶段，开发了一个新的目标MB平台。这种MB使目标配体的共价偶联使用硫醚偶联化学。合成了一种新型单链VEGF靶向配体MB。scVEGF MB与内皮细胞VEGF受体结合具有高特异性，不激活VEGFR信号。这些药物在研究中可以作为分子成像探针，并有可能转化为临床应用。我们现在寻求验证该试剂作为药物发现和基础科学分子超声成像的研究工具，并研究其潜在的临床应用。我们假设scVEGF MB可以检测肿瘤生长背景下的血管生成，比非靶向MB、单独b超或光学成像探针具有更高的敏感性和特异性。具体而言，我们将在体外和体内评估靶向微泡浓度与定量声信号之间的关系，在几种癌症小鼠模型中检测scVEGF MB检测血管生成肿瘤的能力，并研究这些药物监测治疗反应的能力。此外，我们将探讨scVEGF MB在前列腺癌活检指导中的潜在效用。声学信号与目标微泡浓度之间的关系将首先在体外利用超声流模使用一种新的实时超声对比量化方案进行分析。我们将在生物发光小鼠肿瘤模型中检验scVEGF MB对血管生成性肿瘤血管的敏感性和特异性，并通过免疫组织化学和生物发光成像验证。将在前列腺癌小鼠模型中检验scVEGF MB作为监测治疗反应的工具的效用。在数周的治疗中，肿瘤体积的变化将使用卡尺进行评估，并与量化的scVEGF MB信号相关。此外，scVEGF MB在监测治疗反应方面的敏感性将与非靶向MB（量化肿瘤血流）和近红外VEGFR2光学成像造影剂进行比较。前列腺活检指导是scVEGF MB的潜在临床应用，我们将评估其在犬疾病模型中的可行性。转到兽医影像中心的犬在标准b超或scVEGF MB引导下进行前列腺活检，检查scVEGF MB引导增强前列腺癌检测的能力。我们预计该项目将能够确定scVEGF MB是否能够1)特异性成像血管生成肿瘤，2)在相关的临床前模型中监测对实验性抗癌治疗的反应，以及3)提高临床环境中活检指导的敏感性。这些研究将验证scVEGF微泡在临床前研究和药物发现环境中作为检测和监测肿瘤发展的产品，并评估该技术在临床环境中的潜力。公共卫生相关性：能够检测癌症分子成分的探针有可能加速药物发现，加强基础研究，并提高临床环境中癌症检测的敏感性。超声成像广泛应用于研究和临床应用，提供了一种不需要电离辐射的成本效益高的实时成像技术。本文提出的肿瘤靶向药物将使超声成像用于癌症分子成像具有比现有技术更高的灵敏度和安全性。

DESCRIPTION (provided by applicant): Site-targeted microbubbles (MB) have demonstrated potential as a molecular imaging tool. A new targeted MB platform was developed in phase I of this project. This MB enables covalent coupling of targeting ligands using thioether conjugation chemistry. MB bearing a novel single-chain VEGF (scVEGF) targeting ligand was synthesized. The scVEGF MB bind with high specificity to endothelial VEGF receptors, and do not activate VEGFR signaling. These agents have application as a molecular imaging probe in a research setting, and have potential for translation to clinical use. We now seek to validate this agent as a research tool for molecular ultrasound imaging in drug discovery and basic science, and to investigate a potential clinical use. We hypothesize that scVEGF MB can detect angiogenesis in the context of tumor growth with greater sensitivity and specificity than non-targeted MB, B-mode ultrasound alone, or optical imaging probes. Specifically, we will evaluate the relationship between targeted microbubble concentration and quantified acoustic signal in vitro and in vivo, examine the ability of scVEGF MB to detect angiogenic tumors in several mouse models of cancer, and investigate the ability of these agents monitor response to therapy. Additionally, we will explore the potential utility of scVEGF MB in the context of prostate cancer biopsy guidance. The relationship between acoustic signal and targeted microbubble concentration will first be analyzed in vitro with an ultrasound flow phantom using a novel real-time ultrasound contrast quantification scheme. The sensitivity and specificity of scVEGF MB for angiogenic tumor vasculature will be examined in a bioluminescent mouse model of cancer, and validated by immunohistochemistry and bioluminescence imaging. The utility of scVEGF MB as a tool for monitoring response to therapy will be examined in a mouse model of prostate cancer. The change in tumor volume over several weeks of treatment will be evaluated using calipers, and correlated to the quantified scVEGF MB signal. Additionally, the sensitivity of scVEGF MB for monitoring treatment response will be compared against non-targeted MB (which quantify tumor blood flow) and a near-infrared VEGFR2 optical imaging contrast agent. Prostate biopsy guidance is a potential clinical application for the scVEGF MB, and we will evaluate feasibility for this in a canine model of the disease. Prostate biopsy of canines referred to a veterinary imaging center will be performed under standard B-mode ultrasound or scVEGF MB guidance, and the ability of scVEGF MB guidance to enhance prostate cancer detection will be examined. We anticipate that this project will enable determination of whether scVEGF MB can 1) specifically image angiogenic tumors, 2) monitor the response to experimental anti-cancer therapies in relevant preclinical models, and 3) increase the sensitivity of biopsy guidance in a clinical setting. These studies will enable validation of scVEGF microbubbles as a product for detecting and monitoring tumor development in a preclinical research and drug discovery setting, and evaluate the potential for this technology in a clinical setting. PUBLIC HEALTH RELEVANCE: Probes able to detect molecular components of cancer have the potential to accelerate drug discovery, enhance basic research, and improve the sensitivity of cancer detection in a clinical setting. Ultrasound imaging is widely used in both research and clinical applications, and provides a cost-effective, real-time imaging technique that does not require ionizing radiation. The tumor-targeted agent proposed here will enable the use of ultrasound imaging for molecular imaging of cancer with greater sensitivity and safety than existing technology.