嵌合抗原受体T细胞（CAR-T）在血液病治疗中取得巨大成功，但T细胞非肿瘤特异分布和肿瘤微环境免疫抑制等因素严重限制了CAR-T细胞的实体瘤治疗效果。我们曾报道趋化因子及其受体决定T细胞定位、M2肿瘤相关巨噬细胞抑制T细胞功能。前期结果显示，CCR5配体（CCL4与CCL5）在非小细胞肺癌（NSCLC）组织高表达，CAR-T细胞过表达CCR5后的定向运动能力更强；IL-12可诱导M2细胞向抑制肿瘤的M1细胞转化；间皮素在NSCLC肿瘤组织特异高表达，针对该靶点的CAR-T细胞能够杀伤表达间皮素的肺癌细胞、控制PDX肿瘤生长。本项目以NSCLC为模型，以靶向间皮素的3代CAR-T细胞为基础，通过CCR5和IL-12转基因，利用细胞杀伤、增殖、趋化等体外实验以及PDX肿瘤模型研究转基因修饰对CAR-T细胞浸润肿瘤、逆转免疫抑制及清除肿瘤能力的影响。本项目将为CAR-T细胞治疗实体瘤提供新思路。

Chimeric antigen receptor T cells (CAR-T) have shown unprecedented efficacy in treatment of hemapoietic malignancies. However, CAR-T cells fail to induce responses in solid tumor frequently, due to limited infiltration and immune-suppression in tumor microenvironment. In previous reports, we have shown that immune cells and factors intimately affect T cells in tumor microenvironment, such as chemokines and their corresponding receptors determining T cell localization, and type 2 tumor-associated macrophages (M2) roughly inhibiting T cells. Therefore, we hypothesize that patients with solid tumor would benefit from CAR-T cell therapy with increasing specific chemokine receptor expression to enhance tumor-directed migration and compromising inhibitory effects of M2. To address this hypothesis, CAR-T cell modifications are tested in non-small cell lung cancer (NSCLC) model, which is the most representative tumor type with extremely high incidence in China. In NSCLC, mesothelin was exclusively and highly expressed in malignant lesions. The 3rd generation of CAR-T cells targeting mesothelin specifically lysed lung cancer cells and inhibited tumor growth in PDX model. Additionally, higher expressions of CCL4 and CCL5 were noted in tumor tissues, compared with marginal areas. And CAR-T cells with enforced expression of CCR5, the receptor cognizing CCL4 and CCL5, demonstrated improved directional movement. In situ analysis showed dense accumulations of M2 in NSCLC. IL-12 induced immune-inhibitory M2 cells repolarizing to immune-promoting M1 macrophages in vitro. Those data indicated CCR5 and IL-12 may facilitate CAR-T cells to gather and alleviate immune-suppression within tumor, bringing on greater anti-tumor responses. Further in vitro experiments including cell lysis, proliferation and chemotactic migration, and in vivo observations in PDX model, will be performed to check how transduced-CCR5 or/and -IL-12 impact the therapeutic efficiency of CAR-T cells. This project would shed a new light on improving CAR-T cells in solid tumor therapy.