Image-guided Ultrasound-triggered Tumor Therapy

描述(由申请人提供)：超声波为影像引导治疗提供了一种独特的方法。首先，使用回声对比成像检测肿瘤血管。接下来，应用聚焦的、更高强度的超声脉冲序列来激活对比剂/药物载体材料，并在辐射区域释放治疗剂。在这一应用中，我们提出了新一代超声触发药物载体材料的设计和评价。药物载体微泡和脂质体结构将被应用于将抗肿瘤药物或血栓生成酶释放到肿瘤血管中。将实现药物在肿瘤内的选择性沉积。靶向对肿瘤的细胞毒作用和靶向血栓形成将导致肿瘤的生长和凋亡受到限制。特定靶点(R21阶段)：1.制备靶向微泡药物载体，并从脂质体、附着在微泡上的脂质体和微泡载体中进行超声介导的模型染料标志物的释放。评价脂质体/颗粒膜成分、结构、相变温度和超声强度、频率和脉冲特性对释放效率的影响，以实现最佳释放。2.评价微泡/脂质体/药物构建物在细胞培养中对激活的内皮细胞的靶向性，评价药物释放、凝胶和内皮细胞的沉积。3.体外研究超声介导的微泡/脂质体/酶结构的“触发”激活；评估释放和治疗酶的有效性以转化底物。4.通过超声应用焦点的图像引导靶向，评估超声能量按需破坏体内皮下肿瘤内微泡药物载体系统的能力。特异性靶点(R33期)：1.研究微泡和构建的微泡-脂质体的急性毒性、生物分布、血管行为和靶向性，比较微泡和微泡-脂质体的壳层回声成像、荧光和放射性标记以及药物载体颗粒的含量。2.通过超声成像、放射性标记和荧光标志物的生物分布、体内荧光光学成像、组织组织学和长期存活动物研究，研究微泡、脂质体/复合体和包裹的细胞毒剂在电离辐射领域的体内蓄积。3.超声激活凝血酶药物载体结构；在活体显微镜下选择性地在模型血管区域释放凝血酶。监测血液和微泡在靶组织中的流动。4.展示了在照射实体肿瘤的过程中，通过超声波触发的凝血酶从肿瘤血管区域选择性地释放的凝血酶本身以及与细胞毒性药物负载颗粒相结合来阻止肿瘤的生长。治疗后监测肿瘤内血流。对药物载体配方和超声激活参数进行最终优化。

DESCRIPTION (provided by applicant): Ultrasound offers a unique approach to image-guided therapy. First, tumor vasculature is detected using echo contrast imaging. Next, focused, higher-intensity ultrasound pulse sequence is applied to activate contrast/drug carrier material and release the therapeutic agent in the insonated area. In this application we propose the design and evaluation of a new generation of ultrasound-triggered drug carrier materials. Drug carrier microbubbles and liposome constructs will be applied to release antitumor agents or thrombus-generating enzyme into tumor vasculature. Selective drug deposition in the tumor mass will be achieved. Targeted cytotoxic effect on the tumor and targeted thrombosis will result in restriction of tumor growth and apoptosis. Specific aims (R21 Phase): 1. Prepare targetable microbubble drug delivery constructs and perform ultrasound-mediated release of model dye markers from liposomes, liposomes attached to microbubbles, and microbubble carriers. Evaluate release efficacy as a function of liposome/particle membrane composition, structure, phase transition temperature and ultrasound intensity, frequency and pulse characteristics to achieve optimal release. 2. Evaluate targetability of microbubble/liposome/drug constructs to activated endothelium in cell culture, assess drug release, gel and endothelial cell culture deposition. 3. Study ultrasound-mediated "triggering" activation of microbubble/liposome/enzyme constructs in vitro; evaluate release and therapeutic enzyme availability to convert the substrate. 4. Assess the ability of ultrasound energy to destroy microbubble drug carrier systems in an in vivo subcutaneous tumor on demand with image-guided targeting of ultrasound application focus. Specific aims (R33 Phase): 1. Study acute toxicity, biodistribution, vascular behavior and targeting of microbubbles and microbubble-liposomes constructs in a mouse model after intravenous administration comparing echo imaging, fluorescence and radioactive labeling of shells and contents of drug carrier particles. 2. Investigate in vivo accumulation of microbubbles, liposomes/complexes, and encapsulated cytotoxic agents in the areas of insonation, by ultrasound imaging, biodistribution of radiolabeled and fluorescent markers, fluorescence in vivo optical imaging, and tissue histology, as well as longer-term survival animals studies. 3. Perform ultrasound activation of thrombin drug carrier constructs; release thrombin selectively in the areas of model vasculature during intravital microscopy. Monitor blood and microbubble flow through target tissue. 4. Demonstrate arrest of tumor growth by ultrasound-triggered release of thrombin from microbubble constructs selectively in the areas of tumor vasculature during insonation of a solid tumor, per se and in combination with cytotoxic drug-loaded particles. Monitor blood flow within the tumor after treatment. Perform final optimization of the drug carrier formulation and ultrasound activation parameters.