Umbilical cord blood transplantation from unrelated donors offers a reasonable chance of cure for children with juvenile myelomonocytic leukemia, particularly in those diagnosed before age 2 years and where there is greater immunologic compatibility between donor and recipient.
A retrospective analysis of data from 110 children with juvenile myelomonocytic leukemia given single-unit, unrelated donor umbilical cord blood transplantation (UCBT) showed a 5-year disease-free survival rate of 44%, according to data published in Blood (2013;122:2135-41 [doi:10.1182/blood-2013-03-491589]).
"Our data document that a significant proportion of children with this disease, especially when receiving transplants from donors with limited HLA [human leukocyte antigens] disparity, can be cured with UCBT, thus indicating that this allograft can represent a suitable option for children with juvenile myelomonocytic leukemia lacking either a related donor or [an] unrelated donor of hematopoietic stem cells," wrote Dr. Franco Locatelli from the University of Pavia, Rome, and his colleagues.
"Compared with bone marrow transplantation, advantages of UCBT are represented by lower incidence and severity of graft-versus-host disease, easier procurement, and prompter availability of cord blood, and the possibility of using donors showing HLA disparities with the recipient," they said.
Patients’ median age at diagnosis was 1.4 years, and at transplantation was 2.2 years. While 16% of units were HLA matched with the recipient, 43% of units had one HLA disparity and 35% had two or three HLA disparities. Data on HLA compatibility were missing in 6 patients (6%).
The study found that children aged younger than 1.4 years at diagnosis had significantly better disease-free survival rates (hazard ratio, 0.42), while those who had one or no HLA disparities with the donor also had better survival rates (HR, 0.43).
Platelet recovery was achieved in 76 children, with the median time of 44 days required to reach a platelet count greater than 20 x 109/L, and by day 180, the cumulative incidence of platelet recovery was 71% plus or minus 6%.
A total of 28 children underwent splenectomy before transplantation, 88 received chemotherapy, 8 were given a reduced-intensity conditioning regimen, and the remainder were treated with myeloablative regimens. Nineteen children also received total body irradiation.
Disease recurrence was the major cause of treatment failure, with a 5-year cumulative incidence of relapse of 33% in the median follow-up period of 64 months.
Twenty-four children died of transplant-attributable causes during the follow-up period, while 45 patients were diagnosed with grade II to IV acute graft-versus-host disease.
The researchers noted an increased risk of transplantation-related mortality among those with monosomy 7 karyotype, and those who did not receive cytotoxic treatment before transplantation.
The authors declared they had no financial conflicts of interest.