嵌合抗原受体（CAR）T细胞疗法已经改变了对复发/难治性B细胞急性淋巴细胞白血病（B-ALL）的儿科患者的治疗方法。然而，关于这一人群中进行第二轮CAR-T疗法所面临挑战的数据很少。我们分析了从2019年6月至2023年5月在一个单一中心接受第二轮CAR-T疗法的九名儿科患者的病历。在临床试验过程中，我们评估了包括CRS、CRES、感染、血液毒性和器官损伤在内的不良事件，以及CAR-T的反应。除了一个由于睾丸复发而选择CAR-T治疗的患者外，其余患者因骨髓复发或结合其他部位需进行CAR-T治疗。CART1和CART2的输注剂量没有区别。第一轮CAR-T治疗（CART1）和第二轮CAR-T治疗（CART2）之间的CRS的发生率和分级没有差异。此外，我们发现CART1（3/9，33.3%）的CRES发生率高于CART2（1/9，11.1%）。我们的研究结果显示CART1和CART2之间的IL-2、IL-4、IL-6、IL-10、IFN-γ和TNF-α没有差异，但接受CART1的患者中IL-17A的峰值明显高于接受CART2的患者（p = 0.011）。CART1后早期和晚期感染率高于CART2。根据ANC、血红蛋白和血小板的动态变化，CART后ANC和血小板明显降低。CART1组的重度血小板减少和严重贫血发生率似乎高于CART2组。CART1和CART2的MRD阴性CR率分别为100%和44.4%（p = 0.029）。所有患者在接受CART2后都经历了事件（复发、化疗、移植或死亡），其中一人死亡，三人自动出院，其余五人幸存。尽管CART2的缓解率不及CART1，但在CRS、CRES、感染和器官损伤方面的安全性仍然非常高。因此，CART2仍然是治疗儿科复发性B-ALL的可行选择。 © 2023 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Chimeric antigen receptor (CAR) T-cell therapy has transformed the treatment approach for pediatric patients suffering from relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). However, there was a paucity of data on the challenges associated with second-round CAR-T therapy in this population.Medical records of nine pediatric patients who received second-round CAR-T therapy in a single center from June 2019 to May 2023 were analyzed. Throughout the course of the clinical trial, we evaluated adverse events including CRS, CRES, infections, hematologic toxicity, and organ injury, as well as CAR-T responses.Except for one patient who chose CART therapy due to testicular relapse, the remaining patients had indications for CAR-T therapy due to relapse with bone marrow alone or combined with other site. There were no difference between the transfusion dose of CART1 and CART2. No differences of incidence and grade of CRS was found between the first-round CAR-T therapy (CART1) and second-round CAR-T therapy (CART2). Additionally, we found that the incidence of CRES was higher for CART1(3/9,33.3%) than CART2(1/9,11.1%). Our findings revealed that there were no differences of IL-2, IL-4, IL-6, IL-10, IFN-γ, and TNF-α between CART1 and CART2, but the peak level of IL-17A was significantly higher in patients receiving CART1 compared to those receiving CART2 (p = .011). Early and late infection rates after CART1 were higher than CART2. Based on the dynamic changes of ANC, hemoglobin and platelet, ANC, and platelet were reduced obviously post CART. It seems that the incidences of severe thrombocytopenia and severe anemia were higher in the CART1 group compared to CART2. The MRD-negative CR rates for CART1 and CART2 are 100% and 44.4%, respectively (p = .029). All patients experienced events (relapse, chemotherapy, transplantation, or death) after receiving CART2, including one died, three discharged automatically, and the remaining five patients survived.Although the remission rate of CART2 is not as high as the CART1 due to the severity of the disease, its safety regarding CRS, CRES, infections, and organ injury is still excellent. Therefore, CART2 remains a viable option for treating pediatric relapsed B-ALL.© 2023 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.