食管鳞癌PD-1单抗有效率低，耐药机制不明，肿瘤体细胞突变在塑造免疫微环境介导耐药中起重要作用。我们前期发现食管鳞癌RBPJL-p.P476S突变在临床耐药灶中与T细胞缺乏共存，在体外抑制T细胞的趋化和增殖，在体内抑制PD-1单抗的疗效，并鉴定出食管鳞癌分泌的IL-16是该突变负调控的关键细胞因子。提示食管鳞癌中该突变通过下调IL-16抑制T细胞的免疫功能而介导PD-1单抗的耐药。本项目拟采用定点突变、基因过表达/敲降、表达谱测序、流式分析等技术，在肿瘤细胞与T细胞共培养/肿瘤细胞上清处理T细胞的体外体系、PBMCs-CDX NSG小鼠体内模型中，阐明RBPJL-p.P476S突变对T细胞免疫功能的影响及所依赖的信号通路和分子机制，并验证RBPJL-p.P476S突变介导免疫治疗的耐药和探索逆转耐药的靶向联合治疗，本项目的开展将为食管鳞癌免疫治疗的获益人群定位和联合治疗提供潜在的新思路。

The effective rate of PD-1 antibody in esophageal squamous cell carcinoma is low, while the mechanism of resistance is unknown. Tumor somatic mutations play an important role in immunotherapy resistance through shaping the immune microenvironment. In our previous work, we revealed the coexistence of RBPJL-p.P476S mutation with a lack of T cell infiltration in resistant tumor lesion, RBPJL-p.P476S mutation inhibited T cell chemotaxis and proliferation in vitro and impaired anti-tumor effect of PD-1 antibody in vivo. The key cytokine secreted by tumor cells was identified to be IL-16, which is down-regulated by RBPJL-p.P476S mutation. These results suggested that RBPJL-p.P476S mutation may mediate the inhibition of T cell immune function through down-regulating the secretion of IL-16 in esophageal squamous cell carcinoma. In our further work, the techniques including site-directed mutagenesis, gene overexpression/knockdown, gene expression profiling, flow cytometry will be applied. The in vitro system of co-culture of T cells with tumor cells and T cells exposed to conditioned medium, and the in vivo model of PBMC-CDX NSG mouse will be adopted. This study will be conducted to clarify the impact of RBPJL-p.P476S mutation on the immune function of T cells and the signal pathway and mechanism which is involved. It will also testify the impact on immunotherapy by RBPJL-p.P476S mutation depending on the signal axis, and explore the resistance-reversing effect of combined target therapy. The successful conduction of the present study will shed potential new light on the strategy of patient selection and combination regimens in immunotherapy of esophageal squamous cell carcinoma.