To evaluate the clinical efficacy of umbilical cord blood transplantation (UCBT) on patients with high-risk acute leukemia.

The clinical data of 14 patients with high-risk acute leukemia who got UCBT in the Department of Hematology of Zhongda Hospital Affiliated to Southeast University from March 2014 to April 2016 were retrospectively analyzed. Pretransplant disease status: 6 patients got first complete remission (CR1) after chemotherapy, 4 cases got second complete remission (CR2) after chemotherapy, 4 patients were in the state of disease progression (non-remission after incipience or recurrence). Ten patients received single cord blood transplantation and 4 patients received double cord blood transplantation. 12 patients were pretreated with myeloablative and were not treated with anti-thymocyte globulin (ATG), and 2 HLA 4/6 matched patients received ATG. All the patients received both cyclosporin and mycophenolate mofetil(MMF) to prevent acute graft-versus-host disease (GVHD). The relationship between the number of transfused CD34⁺ cells and implantation time of platelet, and the relationship between incidence rate of GVHD and compatibility of cord blood were both analysed by Spearman rank correlation. Influencing factors of overall survival (OS) were also analysed by Spearman rank correlation. Two-year accumulative and 3-year probability of OS, leukemia-free-survival (LFS), GVHD-free/ relapse-free survival (GRFS) were evaluated by Kaplan-Meier method.

The median follow-up time was 27.5 months (1-42 months) up to October 2017. Four patients died during the follow-up period (2 patients died of relapse and 2 patients died of infection). One case died of facial soft tissue infection 40 days after transplantation, and the other 13 cases got neutrophil implantation within 30 days after transplantation. The median time of neutrophil implantation was 17 days (11-29 d). Platelets were implanted in 12 cases within 60 days after transplantation, and the median time of platelet implantation was 33 days (25-59 d). The number of transfused CD34⁺ cells was related to the time of platelet implantation (r=-0.62, P<0.05). The incidence of acute GVHD was associated with the compatibility of cord blood (r=-0.55, P<0.05). The number of CMV-DNA copies in urine increased in 100 days after transplantation, and the median duration was 22 days (6-50 d). Three patients whose protopathy was acute lymphoblastic leukemia suffered a relapse after transplantation. Ten patients got CR1 or CR2 before transplantation, among which 9 patients did not relapse during follow-up. The median KPS score was 95 points (80-100 points) at 6 months after transplantation, and the median time of withdrawal cyclosporine, MMF and corticosteroid after transplantation was 113, 35 and 116 days respectively. The results of Kaplan-Meier method showed that the 2-year accumulative and 3-year probability of OS, LFS and GRFS of patients were all 72%. The mortality related to transplantation was 14.2%. The related factors affecting OS were the time of granulocyte implantation after transplantation (r=-0.70, P < 0.05), and the state of the disease before transplantation (r=-0.67, P < 0.05).

UCBT is an alternative choice for high-risk acute leukaemia patients who lack other source of stem cells. Patients with high implantation rate, low GVHD and relapase incidence and high GFRS can stop taking immunosuppressant in the early stage after transplantation, which can improve the quality of long-term survival of patients.