基于PET成像研究沙利度胺对黑色素瘤血管生成拟态的抑制作用

Vasculogenic mimicry (VM) is a unique type of micro-circulation network inside solid tumor with overall difference from blood vessel, and VM has become a rising and important target in the development of anti-cancer drug. Currently, there are only cell-biological and histo-pathological methods available for the evaluation of anti-VM drug. In vivo and dynamic method for characterizing the process of inhibitory Effect on VM is still required. Positron emission tomography (PET) can monitor biological process and drug effect quantitatively and dynamically, by characterizing the distribution and activity of specific biomarker in a targeted and visual way. In this program, we plan to execute the PET imaging on hetero-xenograft node mouse melanoma model that is classical in VM research, using positron emission nuclide-labelled oligo-peptide tracers that target key biomarkers, such as matrix metalloproteinase-2 (MMP-2) and erythropoietin-producing hepatocellular tyrosine kinase A2 (EphA2), involved in the formation of VM. By quantifying the uptake level of the tracers in tumor, the activity of MMP-2/EphA2 will be evaluated in vivo, in real-time and quantitatively. These results will be validated by histo-pathological assay. Based On these PET method and model drug thalidomide which is able to inhibit VM in melanoma, through investigating the interventional progress of thalidomide on VM in melanoma, an imaging method for the evaluation of inhibitory effect of anti-VM drug will be developed. If this program is implemented, methodological complement would be offered to the researches of anti-tumor drug screening, pharmacodynamics and clinical response, in which VM are focus on.

血管生成拟态（VM）是血管之外的另一种肿瘤微循环体系，是抗肿瘤药物研究的新兴重要靶点。目前评价抗VM药物仅采用细胞生物学和组织病理学方法，药物抑制VM的体内作用过程尚缺少在体、动态评价。而正电子发射断层成像（PET）技术能通过靶向、可视化描述体内特定生物标志物的分布和活性，动态、定量表征生物学过程和药效。本项目拟采用针对VM重要生物标志物（基质金属蛋白酶-2和上皮酪氨酸受体激酶A2）的寡肽类正电子示踪剂，对VM研究中经典的裸鼠移植黑色素瘤模型进行PET成像，通过测定肿瘤的示踪剂摄取水平，在体、实时、定量、可视化表征上述标志物的活性，并采用组织病理学方法予以验证；应用上述PET方法和已知可抑制黑色素瘤VM的模型药物沙利度胺，建立在体、动态评价抗VM药物的影像学方法，表征沙利度胺对黑色素瘤VM的作用规律。本项目的完成将为以VM为靶点的抗肿瘤药物筛选、药效学和临床疗效评价研究提供新的方法学思路。

肿瘤微循环管网（新生血管、血管生成拟态等）是肿瘤细胞保持增殖、侵袭、转移能力所依托的重要组织结构，也是抗肿瘤药的靶点之一。对微循环管网中高表达分子实体的体内分布进行无创、动态、定量成像，不仅能可视化表征肿瘤微环境，还可进行受试者自身对照，更准确地反映抗肿瘤药效。.为制备针对上述靶标的寡肽示踪剂，本项目探索了常用中间体化合物——[18F]氟苯甲醛（FBA）的合成新方法。采用新型原料、反应路线和纯化方法制备了碘盐型FBA前体；还探索了经成肟催化剂5-MA催化，在温和条件下耦联FBA与HYNIC-肽的反应。初步确认目标终产物存在，但反应条件仍需优化。.针对肿瘤微管网典型靶标VEGFR-2，本项目基于其单克隆抗体（简称单抗）构建了[89Zr]锆标记示踪剂89Zr-DFO-Ramucirumab，并在前列腺癌模型中开展正电子发射断层成像（PET）、生物分布（Bio-D）、免疫组织化学（IHC）研究。可知该示踪剂对VEGFR-2有良好特异性和亲和力，其肿瘤摄取高于已报道的类似模态。.同理，本课题还基于靶向程序性死亡配体（PD-L1）单抗构建了示踪剂89Zr-DFO-avelumab，用于乳腺癌模型PET成像。经冷阻断、Bio-D、IHC验证，可知该示踪剂能特异性反映肿瘤组织PD-L1分布，有望用于基于免疫检查点的患者分层和疗效评估。.针对胰腺癌尚缺乏优良分子影像标志物的问题，本课题基于细胞间粘附分子1（ICAM-1）单抗构建了近红外荧光（NIRF）染料和核素双标记示踪剂89Zr-DFO-ICAM-1-IR800，用于对胰腺癌皮下/原位瘤模型进行PET/NIRF成像和Bio-D研究，以及离体器官/瘤体光学成像和IHC验证。结果显示该示踪剂适用于胰腺癌病灶多模态检测和术中导航。.以上研究成果为针对肿瘤微循环管网及其他靶标的病灶发现、疗效监测、药物评价提供了比传统方法更直观、贴切的临床前研究新手段。