急性B淋巴细胞白血病自体CD19 CAR-T制备中CD19 CAR转入体系残留白血病细胞的体外研究

In vitro studies on the transfer of CAR into leukemia cells due to their residue in the autologous CAR-T cell preparation system for acute B-cell acute lymphoblastic leukemia

目的分析复发/难治性急性B淋巴细胞白血病(R/R B-ALL)自体CD19嵌合抗原受体T细胞(CAR-T细胞)制备过程中,培养体系中残留白血病细胞导致CD19 CAR转入白血病细胞的特征和体外杀伤研究。方法①收集30例接受CD19 CAR-T细胞治疗的R/R B-ALL患者及6例健康志愿者外周血单个核细胞(PBMC);②流式细胞术分析R/R B-ALL患者PBMC经CD3磁珠分选后及体外培养过程中体系白血病细胞残留情况;③患者及健康志愿者PBMC CD3+T细胞转染CD19 CAR及CD22 CAR慢病毒,制备CD19 CAR-T、CD22 CAR-T细胞;④复苏Nalm-6细胞株,CD19 CAR慢病毒转染Nalm-6细胞,制备CD19 CAR-Nalm-6细胞,同时转染患者原代ALL细胞;⑤流式细胞术检测转染率;⑥CCK-8法检测细胞增殖;⑦乳酸脱氢酶(LDH)法检测CD19 CAR-T、CD22 CAR-T细胞对Nalm-6细胞及CD19 CAR-Nalm-6细胞杀伤活性。结果①30例接受CD19 CAR-T细胞治疗的R/R B-ALL患者中,2例CD3+T细胞中发现3.32%、2.04%的白血病细胞残留,随体外培养时间延长,在培养第4天,白血病细胞完全消失。②体外培养中CD19 CAR-Nalm-6细胞增殖率高于Nalm-6细胞。③效靶比为1∶1且共培养24、48、72 h,CD19 CAR-T细胞对Nalm-6细胞的杀伤活性高于CD19 CAR-Nalm-6细胞;与CD19 CAR-T细胞相比,CD22 CAR-T细胞对CD19 CAR-Nalm-6细胞的杀伤活性更高。④相同效靶比情况,单独应用CD22 CAR-T细胞对CD19 CAR-Nalm-6细胞的杀伤活性高于CD19 CAR-T联合CD22 CAR-T细胞。结论CD19 CAR-T细胞制备过程中培养体系残留白血病细胞可能会导致CD19 CAR被引入白血病细胞中而导致CD19 CAR-T细胞治疗失败,在细胞制备过程中需要检测培养体系中白血病细胞的残留情况。CD22 CAR-T细胞治疗可作为上述情况的挽救治疗措施之一。

Objective To investigate the characteristics and cytotoxicity in vitro of the residual leukemia cells in the culture system that caused the accidental transfer of CD19 chimeric antigen receptor(CAR)into leukemia cells during the preparation of autologous CD19 CAR-T cells of relapsed/refractory B-cell acute lymphoblastic leukemia.Methods①Peripheral blood mononuclear cells(PBMC)of 30 patients with relapsed/refractory B-cell acute lymphoblastic anemia(R/R B-ALL)who accepted CD19 CAR-T cell therapy and six healthy volunteers were collected.②The residual leukemia cells were analyzed by flow cytometry in the system after the PBMCs of R/R B-ALL patients were sorted by CD3 magnetic beads.③CD3+T cells from patients and healthy volunteers were transfected with CD19 CAR and CD22 CAR lentivirus to prepare CD19 CAR-T and CD22 CAR-T cells.④The Nalm-6 cell line was resuscitated and the Nalm-6 cells with CD19 CAR lentivirus were transfected to prepare CD19 CAR-Nalm-6 cells.The patient's primary ALL cells were transfected with CD19 CAR lentivirus at the same time.⑤The transfection rates were analyzed by flow cytometer,the cell proliferation was analyzed by the CCK-8 method,and the cell-killing activities were detected by the lactate dehydrogenase method.Results①Among the 30 R/R B-ALL patients who received CD19 CAR-T cell therapy,two patients had 2.04%and 3.32%residual leukemia cells in CD3+T cells.After 4 days in culture,the residual leukemia cells disappeared and could not be detected by a flow cytometer with prolonged cultivation in vitro.②The proliferation of CD19 CAR-Nalm-6 cells was higher than that of the Nalm-6 cells.③The killing activity of the CD19 CAR-T cells on Nalm-6 cells was higher than that of the CD19 CAR-Nalm6 cells at a target ratio of 1∶1 on 24,48,72 h,respectively.The cytotoxicity of CD22 CAR-T cells on CD19 CAR-Nalm-6 cells was significantly higher than that of CD19 CAR-T cells.④The cytotoxicity of CD22 CAR-T alone on CD19 CAR-Nalm-6 cells was higher than that of CD19 CAR-T combined with CD22 CAR-T at the same target ratio.Conclusion The residual leukemia cells in the culture system in the preparation of CD19 CAR-T cells may lead to the introduction of CD19 CAR into leukemia cells and results in the failure of the CD19 CAR-T cell therapy.Detecting the residual leukemia cells in the culture system via flow cytometry before transfection with CD19 CAR lentivirus is needed.Thus,CD22 CAR-T cell therapy could be used as one of the salvage treatments.