胃印戒细胞癌新抗原肽纳米疫苗库构建及抗肿瘤作用评价

Recently, increasing evidence has shown that neoantigen reactive T cells are responsible for tumor regression in patients receiving TIL therapy, immune checkpoint inhibitors, and TCR-modified T cell therapy in both mouse models and clinical settings, thus personalized neoantigen-based immunotherapy is regarded as one of the most important directions for the development of cancer immunotherapy. Our team has been devoted to clinical translational research of personalized cancer immunotherapy for several years. To overcome the potential shortcomings in the identification of neoantigens and its translational application, a neoantigen peptide library was established in this study. Applying multiple neoepitope screening programs, the neoantigen peptide library was designed based on hotspot mutations in gastric signet ring cell carcinoma (SRC) and prevalent HLA types in Chinese population. After personalized immunogenic mutant peptide was identified, neoantigen peptide loaded nano-vaccines was constructed and its dendritic cell-targeting ability and immune boost effect were evaluated in vitro and in MHC humanized mouse. Furthermore, neoantigen-reactive T cells underwent PD-1 gene knock-out, which mediated by CRISPR-Cas9 system, and the antitumor effect and safety were evaluated in PDTX model. The purpose of this study was to develop and optimize a scientific, feasible, and timely manner for personalized cancer immunotherapy. The project presents a technology with great potential for clinical application and promotion for personalized immunotherapy of gastric signet ring cell carcinoma, which was expected to achieve an original technology innovation in the area of cancer immunotherapy.

近年来，不断有研究表明新抗原反应性T细胞是在肿瘤浸润淋巴细胞、免疫检查点抑制剂、TCR工程化T细胞等免疫治疗中介导肿瘤缓解的关键因素。因而，以新抗原为基础的个体化免疫治疗被认为是肿瘤免疫治疗的重要发展方向。申请者多年来致力于个体化免疫治疗的临床转化研究。本项目拟从目前新抗原鉴定和转化应用中存在的潜在缺陷出发，采用多种免疫新抗原表位筛选技术，针对胃印戒细胞癌中高频驱动突变基因的热点突变，设计基于中国人群常见HLA分型的新抗原肽库。利用肽库筛选出患者的个体化新抗原并构建新抗原肽纳米疫苗，在体外及MHC人源化小鼠模型中评估纳米疫苗的DC细胞靶向性和免疫增强作用；此外，在PDTX模型中，评价免疫检查点PD-1分子敲除的新抗原反应性T细胞的抗肿瘤作用及安全性。以期建立一套科学、经济、有效的个体化生物免疫治疗新体系。该项目技术既有鲜明的临床应用潜力，又可以切实推动胃印戒细胞癌个体化免疫治疗的进程。

本项目通过挖掘胃印戒细胞癌患者的基因组变异信息，结合常见肿瘤变异数据库，选择高频突变基因中的热点突变，采用多种新抗原表位筛选工具，设计并制备针对中国人群常见HLA-A*0201、HLA-A*2402和HLA-A*1101 等分型的高亲和力抗原表位肽库。自主构建个体化新抗原肽纳米疫苗，体外验证了新抗原纳米疫苗的淋巴结和DC细胞的靶向性。在小鼠胃癌模型中，构建个体化新抗原纳米疫苗（PNVAC），验证优化纳米疫苗相关参数，证实PNVAC疫苗在体内的预防和治疗性价值，并评估新抗原纳米疫苗联合PD-1阻断后的抗肿瘤作用。这项工作为开发基于新抗原疫苗的癌症免疫治疗提供了一种安全可行的策略。