摘要目的:探讨多色流式细胞术（MFC）监测微小残留病变（MRD）在 CD19嵌合抗原受体T细胞（CD19-CAR-T 细胞）治疗后桥接异基因造血干细胞移植（allo-HSCT）治疗难治、复发急性B淋巴细胞白血病（r/r B-ALL）患者过程中的意义和价值。方法:收集2019年1月至7月河北燕达陆道培医院收治的r/r B-ALL患者37例，年龄15（6，19）岁，其中男24例，女13例，均为经CD19-CAR-T细胞免疫治疗桥接allo-HSCT治疗的患者。采用多色流式细胞技术以胞浆CD79a抗体设B细胞门监测患者在CART治疗前第0天、治疗后第15天、第28天及移植后骨髓、脑脊液样本、组织样本的MRD值评估肿瘤细胞残存以及肿瘤累及位置，监测CD19阳性B细胞在移植前恢复情况及CD19阳性B细胞恢复距离CAR-T细胞回输天数评估CAR-T细胞实际杀伤效果，同时进行患者各时间点外周血CAR-T细胞计数等。采用Kaplan-Meier法及Log-rank检验分析单因素累积生存差异。结果:（1）37例患者中8例死亡，29例存活。5例患者移植后复发，其中复发患者4例死亡，1例存活。（2）死亡组患者在CAR-T细胞免疫治疗后到桥接移植前MFC-MRD阴性缓解率为5/8，低于存活组28/29（ χ 2=7.540， P=0.006）；回输第15天阴性缓解率为3/8，低于存活组24/29（ χ 2=6.512， P=0.011）；回输第28天阴性缓解率为3/8，低于存活组26/29（ χ 2=10.065， P=0.002）。而死亡组伴髓外MFC-MRD阳性肿瘤浸润率为（7/8）高于存活组（14/29）（ χ 2=3.931， P=0.047）。CAR-T细胞免疫治疗后，死亡组CD19阳性细胞恢复时间即CAR-T细胞可对CD19阳性细胞杀伤时间42.00（30.00，49.00）d短于生存组55.00（41.50，73.50）d（ Z=0.022， P=0.020）。 结论:利用多色流式细胞术检测B-ALL患者微小残留病变发现，在CD19-CAR-T细胞免疫治疗后到桥接allo-HSCT前、回输第15天、回输第28天等时间点，阳性结果均提示预后不良。这一结果为临床进行对症治疗提供一定指导意义。

abstractsObjective:To investigate the significance of multicolor flow cytometry (MFC) monitoring of minimal residual disease (MRD) in the course of allogeneic hematopoietic stem cell transplantation (allo-HSCT) after CD19-chimeric antigen receptor(CAR)-T cell immunotherapy for patients with refractory, relapsed B-cell acute lymphoblastic leukemia (r/r B-ALL).Methods:37 patients with r/r B-ALL admitted to Hebei Yanda Lu Daopei Hospital from January to July 2019, aged 15 (6, 19) years old, including 24 males and 13 females, were treated with CD19-CAR-T cell immunotherapy bridging allo-HSCT. MFC with cytoplasmic CD79a antibody to set up B-cell gates was used to monitor patients′ bone marrow (BM), cerebrospinal fluid (CSF), and tissue samples on day 0 (prior to the CAR-T cell immunotherapy), day 15, day 28 post CAR-T cell immunotherapy, and post transplantation.The MRD values of these samples were analyzed to evaluate the residual tumor cells and metastasis. The killing effect of the CAR-T cells was evaluated by the recovery of CD19+B cells before transplantation and the period between the timepoint when CD19+B cells was recovered and the timepoint when CAR-T cells were infused. Peripheral blood CAR-T cells were counted at different time points. Statistic analysis was performed by Kaplan-Meie assay and Log-rank test to analyze the difference of univariate cumulative survival.Results:(1)Among the 37 patients, 8 died and 29 survived. 5 patients relapsed after transplantation, of which 4 relapsed patients died and 1 survived. (2)MFC MRD negative remission rate of the death group was lower than that of the survival group at the following time points: post-CAR-T therapy and prior to transplantation (5/8 vs. 28/29, χ 2=7.540, P=0.006); day 15 of the CAR-T cell reinfusion (3/8 vs. 24/29, χ 2=6.512, P=0.011); day 28 of the reinfusion (3/8 vs. 276/29, χ 2=10.065, P=0.002). The probability of extramedullary MFC MRD positive tumor infiltration in the death group was higher than that in the survival group(7/8 vs. 14/29, χ 2=3.931, P=0.047). After CAR-T cell immunotherapy, the recovery period of CD19-positive cells in the death group, or the time for CAR-T cells to kill CD19-positive cells, was shorter than that in the survival group [42.00 days(30.00,49.00) vs. 55.00 days(41.50,73.50), Z=0.022, P=0.020]. Conclusion:The positive results of MRD by MFC at the following timepoints may predict unfavorable outcomes, such as post-CAR-T therapy and prior to transplantation, day 15 and 28 of the CAR-T cell immunotherapy, which may provide some guidance for clinical management.