VEGFR2靶向超声造影定量分析评价小鼠胰腺癌的抗肿瘤治疗效果的实验研究

Our previous studies have demonstrated that quantitative analysis of tumor blood perfusion with contrast-enhanced ultrasound (CEUS) using untargeted agent (SonoVue) could evaluate the early effect of antiangiogenic therapy, and showed the potential to monitor changes of blood kinetics in tumors during chemotherapy in animal models as well as in clinical trials. However, untargeted CEUS provided poor assessment of anticancer therapies in pancreatic adenocarcinoma due to the tumor's hypoenhancement. Specific approach is required for this purpose..The combination of cytotoxic drug with an antiangiogenic agent( a molecule-targeted drug) in pancreatic adenocarcinoma has been extensively investigated recently. However, it is still lack of a simple and reproducible imaging approach to effectively monitor the effecacy of the combined treatment. .Vascular endothelial growth factor receptor 2 (VEGFR2) is overexpressed in pancreatic carcinoma, which has been used as a target in CEUS offering a noninvasive method for evaluating angiogenesis in tumors. We will apply this method to quantitatively evaluate the response of pancreatic carcinoma to different anticancer therapies (olive oil; gemcitabine; bevacizumab; combination bevacizumab with gemcitabine) in a mouse model. .We will analyze quantitative parameters of VEGFR2-targeted CEUS, and their correlations with changes in tumor size, microvessel density and levels of VEGFR2 expression in tumors in response to different therapies using quantitative immunofluorescent method. We also compare it with untargeted CEUS to explore the potential of targeted CEUS for anticancer therapy study in animal model and clinical trial of pancreatic carcinoma.

我们前期的研究显示非靶向超声造影定量分析组织的血流灌注能有效评价抗血管生成药物的疗效，动物实验和临床研究也观察到超声造影定量参数能反映化疗后肿瘤血流灌注的改变。然而，该非靶向超声造影显示胰腺癌为低血供病灶，在胰腺癌的治疗和监测中作用有限。细胞毒药物和抗血管生成药物联合治疗进展期胰腺癌的研究正在进程中，目前尚未建立简单有效，可重复使用的评价方法。鉴于胰腺腺癌中血管内皮生成因子受体2（VEGFR2）高表达，本课题采用VEGFR2靶向超声造影成像技术来评价鼠胰腺癌对不同干预组（对照组、吉西他滨组、贝伐单抗组以及吉西他滨联合贝伐单抗组）的治疗反应。通过与非靶向超声造影成像的对照，研究不同治疗组靶向超声造影定量参数与肿瘤体积的改变，微血管CD34和VEGFR2的免疫荧光定量表达水平等相关性，研究靶向超声造影定量参数监测不同药物干预的有效性及优势，为胰腺癌的实验和临床研究提供有效、无创的影像学方法。

肿瘤的化疗疗效评价对决策肿瘤的治疗方案有重要的价值。由于化疗后肿瘤细胞的消失与肿瘤体积的减少并不完全一致，肿瘤的病理组织学改变早于临床监测到的变化，不能被常规的影像学技术所反映，而该变化可能引起组织硬度的微弱变化。目前的超声弹性成像技术能进行组织弹性的半定量值或弹性量化值，弹性成像也已经为临床运用于鉴别乳腺肿、甲状腺、前列腺占位的良恶性，有研究表明乳腺癌的硬度与新辅助化疗的效果相关，但是有价值的研究鲜见文献报道。.我们的研究分别采用准静态压缩的弹性成像技术和实时剪切波弹性成像技术评价裸鼠MCF-7乳腺癌对治疗组（顺铂和紫杉醇）和对照组的治疗反应，分析两组弹性参数与肿瘤体积的改变，肿瘤的细胞密度及Van Gieson染色获得的肿瘤内部胶原蛋白含量定量等相关性，比较治疗前后超声弹性参数的变化，研究超声弹性成像参数监测药物干预的有效性及优势。.我们的结果显示应用顺铂和紫杉醇治疗后，裸鼠MCF-7乳腺癌的硬度显著增加，肿瘤的细胞密度显著减少，胶原蛋白染色面积比值显著增加。采用准静态压缩的弹性成像技术获得的弹性值在裸鼠MCF-7乳腺癌治疗前两组的Strain Ratio无显著差异，治疗后出现显著差异，Strain Ratio与肿瘤的细胞密度成负相关，与肿瘤内胶原蛋白染色面积比值成正相关。实时剪切波弹性成像技术获得的肿瘤的弹性均值(KPa),标准差(KPa)及与肝脏相比的Strain Ratio，在治疗前无显著的差异，治疗后两组之间有显著的差异。.我们的研究表明准静态压缩的弹性成像技术和剪切波弹性成像技术均能反映化疗引起肿瘤的病理组织学变化，能对于裸鼠MCF-7乳腺癌进行化疗疗效的评价，剪切波弹性成像技术评价裸鼠MCF-7乳腺癌进行化疗疗效更优。