Combined therapy of CAR-IL-15/IL-15Rα-T cells and GLIPR1 knockdown in cancer cells enhanced anti-tumor effect against gastric cancer.

BACKGROUND: Chimeric antigen receptor (CAR) T cell therapy has shown remarkable responses in hematological malignancies with several approved products, but not in solid tumors. Patients suffer from limited response and tumor relapse due to low efficacy of CAR-T cells in the complicated and immunosuppressive tumor microenvironment. This clinical challenge has called for better CAR designs and combined strategies to improve CAR-T cell therapy against tumor changes. METHODS: In this study, IL-15/IL-15Rα was inserted into the extracellular region of CAR targeting mesothelin. In-vitro cytotoxicity and cytokine production were detected by bioluminescence-based killing and ELISA respectively. In-vivo xenograft mice model was used to evaluate the anti-tumor effect of CAR-T cells. RNA-sequencing and online database analysis were used to identify new targets in residual gastric cancer cells after cytotoxicity assay. CAR-T cell functions were detected in vitro and in vivo after GLI Pathogenesis Related 1 (GLIPR1) knockdown in gastric cancer cells. Cell proliferation and migration of gastric cancer cells were detected by CCK-8 and scratch assay respectively after GLIPR1 were overexpressed or down-regulated. RESULTS: CAR-T cells constructed with IL-15/IL-15Rα (CAR-ss-T) showed significantly improved CAR-T cell expansion, cytokine production and cytotoxicity, and resulted in superior tumor control compared to conventional CAR-T cells in gastric cancer. GLIPR1 was up-regulated after CAR-T treatment and survival was decreased in gastric cancer patients with high GLIPR1 expression. Overexpression of GLIPR1 inhibited cytotoxicity of conventional CAR-T but not CAR-ss-T cells. CAR-T treatment combined with GLIPR1 knockdown increased anti-tumor efficacy in vitro and in vivo. CONCLUSIONS: Our data demonstrated for the first time that this CAR structure design combined with GLIPR1 knockdown in gastric cancer improved CAR-T cell-mediated anti-tumor response.

[Effect of Special Structure Bi-Specific Chimeric Antigen Receptor T Cell on Tumor Cells].

OBJECTIVE: To explore and design a novel bi-specific chimeric antigen receptor (CAR) structure. To obtain the corresponding CAR-T cells and verify killing effects on tumor cells in vitro and in vivo. METHODS: Five kinds of bi-specific CAR structures including humanized CD19 scFv and CD79b scFv, CD8 hinge & TM-4-1BB-CD3ζ and/or CD3ε chain intracellular regions were constructed and prepared. CAR-19-79b cells were obtained. Five kinds of CAR-T cells were co-incubated with the 3M-CD19-CD79b-Luc target cells. Luciferase assay and ELISA were used to detecte the killing ability of these five groups of CAR-T cells and the secretion of cytokines and compared. The optimal structure of CAR-T cells was used to treat the leukemia mouse model constructed by Daudi-Luc cells. And the treatment efficacy was evaluated. At the same time, other targets were used in this structure. With the same methods, the stability and effectiveness of the structure were verified. RESULTS: CAR-19-79b-T cells were cultured for 7 days, the expression rates of CAR-19 and CAR-79b were 21.6%-36.3% and 21.7%-37.8%, respectively. The killing rates of 5 kinds of CAR-19-79b-T cells prepared by T cells from 3 healthy donors on 3M-CD19-CD79b-Luc cells were significantly higher than those of the T cell control group at the effect-target ratio of 10∶1. Among them, the killing rates of CAR-19-79b-T cells with No. III and No. IV structures were the strongest. After co-incubation with 3M-CD19-CD79b-Luc target cells, the amount of IFN-γ and TNF-α secreted by CAR-T cells with CAR IV and CARV structures was the lowest. And there was no significance between the two groups (P>0.05). CAR IV cells with remarkable killing effect and low secretion factor had obvious therapeutic effect on Daudi-Luc leukemia mice, extending the survival period of mice to 64 days. And all mice in the T cell control group died at 41.0±2.4 days. The CAR-19-BCMA-T and CAR-19-22-T with the same structure showed significant killing ability and low cytokine expression levels. CONCLUSION: A novel bi-specific CAR structures was successfully designed, which could efficiently kill the corresponding tumor cells and secrete less cytokines (such as TNF-α, IFN-γ). Moreover, it shows obvious therapeutic effect on Daudi lymphoma mouse model. The bi-specific CAR structure shows good killing specificity and safety.

Tumor-killing effects of CD19 and CD22 bi-specific CAR-T cells on tumor cells / 中国肿瘤生物治疗杂志

@#[摘 要] 目的：设计并制备一种分别靶向B细胞表面抗原CD19和CD22的CAR-T细胞，检测其对肿瘤细胞的体内外杀伤效果。方法：将含有人源化 CD19 ScFv的二代CAR分子和带有CD3ε链作为共刺激结构域的CD22 ScFv CAR分子以P2A自剪切肽连接，序列连接于慢病毒载体pLTR-CMV-MCS中，以HEK-293T细胞包装相应的慢病毒载体，感染健康志愿者提供的T细胞制备CAR-19-22-T细胞，同时以相同二代结构分别构建单靶向CAR-T细胞作为参照。构建表达荧光素酶、CD19和/或CD22的前列腺癌3M细胞（靶细胞）。将各种CAR-T细胞与靶细胞共同培养，采用荧光素酶化学发光法和ELISA法检测其对靶细胞的杀伤能力和细胞因子的分泌水平。通过尾静脉注射Raji-Luc细胞构建NOD-SCID免疫缺陷小鼠白血病模型，分别注射各组CAR-T细胞进行治疗并评估其疗效。结果：培养7 d的CAR-19-22-T细胞的CAR-19表达率为13.7%，CAR-22表达率为14.3%。CAR-19-22-T细胞在10∶1效靶比时，对3M-CD19-Luc、3M-CD22-Luc和3M-CD19-CD22-Luc细胞的杀伤率均显著高于T细胞[（78.1±14.4）% vs （11.1±4.3）%、（46.7±10.7）% vs （12.4±2.7）%、（90.5±4.3）% vs （14.3±3.7）%，均P<0.01]；与3M-CD19-Luc、3M-CD22-Luc、3M-CD19-CD22-Luc靶细胞共培养后，CAR-19-22-T细胞IFN-γ、TNF-α和IL-2水平均显著低于CAR-19-T和CAR-22-T细胞（P<0.05或P<0.01）。CAR-19-22-T细胞对移植Raji-Luc细胞模型小鼠治疗效果明显，其生存期显著长于T细胞组（P<0.01），与CAR-19-T组和CAR-22-T组荷瘤小鼠比较差异均无统计学意义（均P>0.05）。结论：成功设计并制备了一种双靶点CAR-19-22-T细胞，其能够有效杀伤表达CD19和/或CD22抗原的肿瘤细胞，对Raji-Luc细胞的白血病模型小鼠有显著的治疗效果。