A retrospective analysis of 110 patients with juvenile myelomonocytic leukemia found that single-unit, unrelated donor umbilical cord blood transplantation resulted in a 5-year disease-free survival rate of 44%. “Our data document that a significant proportion of children with this disease, especially when transplanted from donors with limited HLA-disparity, can be cured with [umbilical cord blood transplantation], thus indicating that this type of allograft, can represent a suitable option” for children with juvenile myelomonocytic leukemia who have neither a related or an unrelated donor of hematopoietic stem cells, concluded an international team of investigators in Blood.
Multivariate analysis revealed that factors predicting better disease-free survival included age younger than 1.4 years at diagnosis (hazard ratio [HR] = 0.42, P = .005), 0 to 1 HLA disparities in the donor/recipient pair (HR = 0.4, P = .009), and karyotype other than monosomy 7 (HR = 0.5, P = .02), the investigators reported. “Monosomy of chromosome 7 was the most frequent cytogenetic abnormality, found in 24% of patients,” they noted.
Unique Myeloproliferative Disorder
A unique clonal myeloproliferative disorder, juvenile myelomonocytic leukemia typically occurs in infancy and early childhood. The median age of patients included in the analysis was 1.4 at diagnosis and 2.2 at transplantation.
“The median survival time of children with [juvenile myelomonocytic leukemia] without transplantation has been shown to be only 10 to 12 months,” according to the study report. Therefore, the researchers noted, the relatively short time needed to find a suitable cord blood unit might make umbilical cord blood transplantation an attractive option for these patients.
Treatment and Outcome
Chemotherapy was administered to 88 patients before transplantation, and splenectomy was performed in 28. All but eight patients received myeloablative conditioning; cyclosporine plus steroids was the most common prophylaxis against graft-vs-host disease, the investigators reported.
“Eighteen children (16%) were transplanted with a 6/6 matched donor, 47 (43%) from a donor with a single disparity, and 39 (35%) from a donor with two (36 patients) or three disparities (3 patients); data on HLA compatibility were missing in 6 patients (5.5%),” they noted.
At a median follow-up of 64 months, the 5-year cumulative incidence of transplantation-related mortality was 22%, and the relapse incidence was 33%. The investigators concluded that umbilical cord blood transplantation may cure a “relevant proportion” of children with juvenile myelomonocytic leukemia, but disease recurrence remains the major cause of treatment failure, warranting strategies to reduce relapse incidence. ■
Locatelli F, et al: Blood, August 7, 2013 (early release online).