基于PDX模型的实体瘤Dasatinib敏感预测标志物的发现研究

In recent years, dasatinib, an oral available multi-target tyrosine kinase inhibitor, has been tested for its efficacy in several types of solid tumors beyond its original application in CML. However, the response ratio of dasatinib in clinical patients was limited in unselected populations, so it's of urgent need to identify the appropriate predictive bimarkers for dasatinib. In this study, we designed to take advantage of the next-generation sequence technology and SNP array to analyze the genomic background and explore the potential predictive biomarkers for dasatinib in patient derived xenograft models which obtained sensitivity to dasatinib. Then, the correlation and underlied molecular mecanisms of drug sensitivity and biomarkers will be tested in vitro and in vivo. Finally, the predict power of these potential biomarkers will be examined in a seprate and independent group of patient derived xenograft models whose expression of these biomarkers are positive, which mimic the clinical one-arm adaptive trials. The aim of this study is to find out several clinical applicable predictive biomkers to select the most responsive subpopulations for more successful personalized medicine of dasatinib in clinic.

近年来，口服多靶点药物Dasatinib在实体瘤中的应用受到广泛关注，但不合适的病人选择严重制约了其临床疗效，因此开发Dasatinib敏感预测标志物是目前亟需解决的关键问题。本课题以前期所获得的对Dasatinib敏感的PDX动物模型为研究对象，拟通过外显子组测序或芯片杂交技术检测敏感模型组织基因组遗传背景特征筛选潜在敏感标志物，进一步通过系统的体内外实验进行相关性验证和获得敏感性的机制探讨，在此基础上，通过另一组PDX模型筛选出标志物阳性群体进行贴近临床式的标志物阳性选择性试验(one-arm adaptive trial)，以考察标志物是否具有独立的预测能力。通过本研究旨在获得数个具有临床潜在应用价值的敏感标志物，为Dasatinib在实体瘤病人中选择合适的敏感人群进行个体化治疗提供理论依据和相关的检测指标。

本项目的主要研究内容为寻找Dasatininb在实体肿瘤中的敏感预测标志物，在本项基金资助下，共主要开展了以下两部分的研究内容。首先，通过一定规模的肿瘤细胞系和PDX模型筛选，我们发现肾癌是所有实体肿瘤中对Dasatinib响应最为敏感的肿瘤类型。Dasatinib通过诱导G1/S阻滞抑制肾癌细胞增殖。 进一步机制研究发现Dasatinib通过靶向Src激酶（抑制其磷酸化）并进而通过JNK 通路调节LATS-YAP1功能信号轴，促进YAP1从核内转位到胞浆（上调p-YAP1），阻断YAP1核内的转录功能从而最终抑制肾癌细胞增殖。一系列的体内外实验进一步证明，Src-JNK-LATS-YAP1这一功能轴的调控异常会导致Dasatinib的原发性及获得性耐药的产生。这一发现提示，p-Src/p-YAP1功能轴可以有效指示Dasatinib在肾癌中的敏感性及作用机制，并可作为临床肾癌病人遴选的潜在敏感预测标志物。同时，我们针对Dasatinib在肝癌中的应用也进行了研究，发现EphA5是其在肝癌细胞中的主要作用靶点。Dasatinib单用对肝癌细胞无效，但与ALK及FGFR抑制剂联用后可有效抑制肝癌细胞增殖，这一结果在裸鼠移植瘤模型及PDX模型中均得到了有效验证。这一发现提示，EphA5可以作为Dasatinib在肝癌中的预测标志物，用于临床联合用药病人的选择。