异基因造血干细胞移植（HCT）后白血病复发患者的存活率较低，主要原因是毒性和疾病进展。二次HCT通常是唯一的治愈治疗选择。我们回顾性研究了我们两个机构（MSKCC-美国；乌得勒支-荷兰）对无关脐带血移植（CBT）治疗移植后复发的经验。使用Kaplan-Meier方法评估总生存率（OS）和事件无进展生存率（EFS），使用Fine-Gray的竞争风险方法评估与治疗相关的死亡率（TRM）和复发情况。 2009年至2021年间，26名<21岁的患者接受了第二（n=24）或第三（n=2）个带有CB移植物的HCT。 HCT1时的中位年龄为11.5（范围：0.9-17.7）岁，所有患者均接受了髓毒性细胞清除治疗。自HCT1到复发的中位时间为12.8（范围5.5-189）个月。在CBT时，患者的中位年龄为13.5（范围1.4-19.1）岁。诊断为AML：13例；ALL：4例；MDS：5例；JMML：2例；CML：1例；混合表型急性白血病：1例。十六名患者（62%）处于晚期，要么是CR>2，要么是有活动性疾病。自HCT1到CBT的中位时间为22.2（范围7-63.2）个月。所有患者在CBT后移植成功。十三名患者发生了急性GvHD；其中7例为III或IV级。在46.6（范围17.4-155）个月的中位随访期后，3年OS为69.2%（95% CI 53.6-89.5%），3年EFS为64.9%（95% CI 48.8-86.4%）。有8名患者死亡，其中3例为AML复发，5例为毒性导致的死亡（呼吸衰竭[n=4]，GvHD[n=1]），死亡发生在CBT后中位时间为7.7（范围5.9-14.4）个月。3年期治疗相关死亡发生率为19.2%（95% CI 4.1-34.4%）。值得注意的是，所有TRM事件发生在2015年之前接受移植的患者身上；在2015年之后接受CBT的16名患者中没有观察到与毒性相关的死亡。3年期复发发生率为15.9%（95% CI 1.6-30.2%），对于这些高危患者来说，该比例非常低。 CB移植在首次HCT后复发的小儿白血病患者中的存活情况非常令人鼓舞，过去十年TRM较低。在移植后复发的患者中，CBT应被视为相对安全的挽救治疗选择。 版权所有 © 2023 Troullioud Lucas, Boelens, Prockop, Curran, Bresters, Kollen, Versluys, Bierings, Archer, Davis, Klein, Kernan, Lindemans and Scaradavou.

Patients with leukemia relapse after allogeneic hematopoietic cell transplant (HCT) have poor survival due to toxicity and disease progression. A second HCT often offers the only curative treatment.We retrospectively reviewed our bi-institutional experience (MSKCC-USA; Utrecht-NL) with unrelated cord blood transplantation (CBT) for treatment of post-transplant relapse. Overall survival (OS) and event-free survival (EFS) were evaluated using the Kaplan-Meier method, treatment-related mortality (TRM) and relapse were evaluated using the competing risk method by Fine-Gray.Twenty-six patients age < 21 years received a second (n=24) or third (n=2) HCT with CB grafts during the period 2009-2021. Median age at first HCT (HCT1) was 11.5 (range: 0.9-17.7) years and all patients received myeloablative cytoreduction. Median time from HCT1 to relapse was 12.8 (range 5.5-189) months. At CBT, median patient age was 13.5 (range 1.4-19.1) years. Diagnoses were AML: 13; ALL: 4, MDS: 5, JMML: 2; CML: 1; mixed phenotype acute leukemia: 1. Sixteen patients (62%) were in advanced stage, either CR>2 or with active disease. Median time from HCT1 to CBT was 22.2 (range 7-63.2) months. All patients engrafted after CBT. Thirteen patients developed acute GvHD; 7 had grade III or IV. With a median survivor follow-up of 46.6 (range 17.4-155) months, 3-year OS was 69.2% (95% CI 53.6-89.5%) and 3-year EFS was 64.9% (95% CI 48.8-86.4%). Eight patients died, 3 of AML relapse and 5 due to toxicity (respiratory failure [n=4], GvHD [n=1]) at a median time of 7.7 (range 5.9-14.4) months after CBT. Cumulative incidence of TRM at 3 years was 19.2% (95% CI 4.1-34.4%). Notably, all TRM events occurred in patients transplanted up to 2015; no toxicity-related deaths were seen in the 16 patients who received CBT after 2015. Cumulative incidence of relapse was 15.9% (95% CI 1.6-30.2%) at 3 years, remarkably low for these very high-risk patients.Survival was very encouraging following CB transplants in pediatric patients with recurrent leukemia after first HCT, and TRM has been low over the last decade. CBT needs to be strongly considered as a relatively safe salvage therapy option for post-transplant relapse.Copyright © 2023 Troullioud Lucas, Boelens, Prockop, Curran, Bresters, Kollen, Versluys, Bierings, Archer, Davis, Klein, Kernan, Lindemans and Scaradavou.