新辅助放化疗联合手术是治疗局部晚期食管鳞癌的重要模式。临床发现，新辅助放化疗疗效在食管鳞癌患者存在异质性；放化疗后残余肿瘤细胞比例与患者预后密切相关。根据肿瘤克隆进化及肿瘤异质性理论，放化疗可促使肿瘤细胞发生克隆进化；放化疗前后肿瘤基因组学特征可能与原发或继发治疗耐受相关。本研究中，我们拟通过全外显子组测序，比较新辅助放化疗前后食管鳞癌组织基因组特征的差异，阐明新辅助放化疗驱动的食管鳞癌克隆进化；分析放化疗前后食管鳞癌基因突变与放化疗敏感性的关系，联合前期新辅助放化疗转录组学数据，寻找潜在的食管鳞癌放化疗敏感性相关基因突变，通过CRIPSR-Cas9技术构建特异基因定点突变的食管鳞癌细胞系，在细胞-动物-分子三个层次阐明该基因突变影响食管鳞癌放和（或）敏感性的作用与机制，在食管鳞癌组织验证该突变与患者放化疗敏感性及预后的相关性，为寻找新的食管鳞癌放化疗敏感性分子标志物奠定基础。

Neoadjuvant chemoradiotherapy (neo-CRT) is an important strategy for advanced esophageal squamous cell carcinoma (ESCC) treatment. Clinical practice found that neo-CRT response is heterogeneous, and the percent of tumor cells after neo-CRT determines ESCC patients’ prognoses. According to the theory of tumor clonal evolution and tumor heterogeneity, CRT could promote tumor clonal evolution, and the genome characteristics of pre- and post-CRT tumor tissues could be related to primary or secondary therapy resistance. In this study, we are going to compare differences of genomic characteristics between pre- and post-neo-CRT ESCC samples with whole exome sequencing, so as to illuminate the ESCC clonal evolution driven by neo-CRT. Furthermore, potential gene mutations related to ESCC CRT response are intended to be identified by analyzing the current exome and previous transcriptome data of pre- and post-neo-CRT ESCC samples. By generating ESCC cells containing site-specific mutation via CRISPR-Cas9, we will verify the role of specific gene mutation on ESCC chemo- and (or) radio-sensitivity by in vitro and in vivo studies, and further explore the underlying molecular mechanisms, which will be further validated by analyzing the relationship between specific gene mutation and ESCC CRT response in clinical samples. This study would lay foundation for identifying useful predictive markers for ESCC neo-CRT response.