[Research progress of the side effect and application prospects of CAR-T cells in the treatment of malignant tumors]

[Analysis of local reactions and efficacy of CD19 chimeric antigen receptor-modified T cells therapy in recurrent/refractory B-cell lymphoma with >7.5 cm lesions]

目的

观察病灶>7.5 cm的复发/难治B细胞非霍奇金淋巴瘤（R/R NHL）患者CD19嵌合抗原受体T细胞（CAR-T细胞）治疗的肿瘤局部反应及疗效。

方法

以2018年8月至2020年5月接受CD19 CAR-T细胞治疗的病灶>7.5 cm的32例R/R NHL患者为研究对象，流式细胞仪检测CD19CAR-T细胞的体内扩增情况；酶联免疫吸附测定法检测患者外周血中细胞因子水平；观察全身不良反应及肿瘤局部反应，分析总有效率（ORR）及总生存（OS）情况。

结果

① 32例患者CAR-T细胞治疗后，13例获得完全缓解（CR）（40.63％），10例获得部分缓解（PR）（31.25％），ORR为71.88％。② 23例有效患者均发生细胞因子释放综合征（CRS），其中1～2级13例，3～4级10例；而疾病稳定+疾病进展（SD+PD）组9例患者CRS均为1～2级（P＝0.030）。③共15例（46.9％）患者发生肿瘤局部反应，其中CR 9例、PR 5例、SD 1例，肿瘤局部反应包括：浅表肿物直径增大且伴红肿热痛；深部肿物表现为腹痛、腹胀、憋气以及肿瘤局部疼痛、烧灼，瘤体增大或伴局部水肿；肿瘤局部出现渗出性病变，可见于腹腔、胸膜腔等。④有效组CD19 CAR-T细胞峰值高于SD+PD组［16.8％（5.3％～48.2％）对2.9％（1.5％～5.7％），z＝−4.297，P<0.001］，有效组中出现肿瘤局部反应患者CD19 CAR-T细胞峰值高于未出现肿瘤局部反应患者［22.2％（10.5％～48.2％）对12.6％（5.3％～21.6％），z＝−3.213，P＝0.001］，多发肿块组CD19 CAR-T细胞峰值高于单发肿块组［35.8％（1.5％～48.2％）对16.8％（10.5％～18.5％），z＝−2.023，P＝0.040］。⑤肿瘤局部反应出现和瘤体缩小时间，均较全身不良反应时间延迟。⑥有效患者中出现肿瘤局部反应者OS率高于未出现肿瘤局部反应者，但差异无统计学意义（75.0％对34.6％，P＝0.169）。

结论

病灶>7.5 cm的R/R NHL患者CD19 CAR-T细胞治疗，近一半出现肿瘤局部反应，发生时间迟于全身不良反应开始的时间。临床试验注册：中国临床试验注册中心（ChiCTR1800018059）

EGLIF-CAR-T Cells Secreting PD-1 Blocking Antibodies Significantly Mediate the Elimination of Gastric Cancer

Objective

To investigate the anti-tumor effects of programmed cell death protein 1 (PD-1) scFv-secreting EGFR-chimeric antigen receptor-modified (CAR)-T cells against gastric cancer.

Methods

Second-generation EGFR-CAR-T cells and fourth-generation PD-1 scFv-secreting EGFR-CAR-T cells were engineered. The anti-tumor activities of chimeric antigen receptor-modified (CAR)-T cells were analyzed in vitro by long-term co-culture with gastric cancer cells. The tumor scavenging capacity in vivo was evaluated in xenograft and PDX mouse models.

Results

EGFR-CAR-T cells secreting PD-1 scFv showed enhanced long-term tumor cell killing capacity in vitro. These cells also showed significant anti-tumor effect in the subcutaneous xenograft model of gastric cancer as well as in the PDX model, and autocrine PD-1 antibody secretion significantly increased tumor infiltration of the CAR-T cells.

Conclusion

EGFR-CAR-T cells secreting PD-1 scFv are highly effective against gastric cancer and offer new insights into anti-cancer immunotherapy.

[Targeting BCMA in multiple myeloma using chimeric antigen receptor-engineered T cells]

Objective: To construct the BCMA-CAR using the B-cell maturation antigen (BCMA) specific ligand APRIL as antigen binding region and to validate the effect of BCMA-CAR modified T cells (BCMA-CAR-T) on myeloma cells. Methods: The BCMA-CAR was constructed using the BCMA specific ligand APRIL as antigen binding domain and 4-1BB as the costimulatory domain. The specific cytotoxicity against BCMA(+) myeloma cell lines and primary multiple myeloma (MM) cells in vitro were evaluated. In addition, BCMA(+) myeloma xenograft mouse model was established to assess the anti-tumor effect of BCMA-CAR-T cell therapy in vivo. Results: BCMA-CAR-T cells could specifically kill BCMA(+) myeloma cell lines (For BCMA-CAR-T cells, BCMA(+) cells are almost undetectable in the E∶T ratio of 1∶4) and MM patients' bone marrow mononuclear cells (the proportion of residual cells in BCMA-CAR-T and vector-T groups was 16.0% vs 66.85%, P=0.003) with significant degranulation (CAR-T and vector-T cells cocultured with MM1.S, H929 and U266 had degranulation levels of 33.30% vs 5.62%, 16.97% vs 2.95% and 25.87% vs 2.97%, respectively, P<0.001) and cytokines release (P<0.01) in vitro. In a human BCMA(+) myeloma xenograft mouse model, BCMA-CAR-T cells could significantly prolong the survival of mice (The median survival time of mice treated with BCMA-CAR-T and vector-T cells was 87.5 days and 67.5 days, respectively, P<0.001) . Conclusion: The ligand-based BCMA-CAR-T cells could be a promising strategy for BCMA(+) multiple myeloma treatment.