1. ¹Department of Pediatrics, Columbia University, New York, NY, USA
2. ²Department of Pediatric Hematology/Oncology, Mount Sinai Medical Center, New York, NY, USA
3. ³Department of Surgery, Immunogenetics and Transplantation Laboratory, University of California, San Francisco, CA, USA
4. ⁴Department of Pathology, Columbia University, New York, NY, USA
5. ⁵Department of Biostatistics, Columbia University, New York, NY, USA
6. ⁶Department of Medicine, Columbia University, New York, NY, USA

Correspondence: Dr MS Cairo, Division of Pediatric Hematology and Blood and Marrow Transplantation, Departments of Pediatrics, Medicine and Pathology, Morgan Stanley Children's Hospital of New York-Presbyterian, Columbia University, 3959 Broadway, CHN 10-03, New York, NY 10032, USA. E-mail: mc1310@columbia.edu

⁷These authors contributed equally to this work and should be considered co-primary or first authors.

Received 27 February 2007; Revised 7 June 2007; Accepted 21 June 2007; Published online 30 July 2007.

Abstract

There is a significant amount of morbidity and mortality following myeloablative umbilical cord blood transplantation (UCBT). Reduced intensity (RI) conditioning offers an alternative to myeloablative conditioning before UCBT. We investigated RI-UCBT in 21 children and adolescents with malignant (n=14), and non-malignant diseases (n=7). RI conditioning consisted of fludarabine (150–180 mg/m²) with either busulfan (8 mg/kg)+rabbit antithymocyte globulin (R-ATG; n=16) or cyclophosphamide+R-ATGetoposide (n=5). Human leukocyte antigen match: 4/6 (n=13), 5/6 (n=5) and 6/6 (n=3). The median total nucleated cell and CD34⁺ cell dose per kilogram were 3.58 10⁷ and 2.54 10⁵, respectively. The median time for neutrophil and platelet engraftment was 17.5 and 52 days, respectively. There were six primary graft failures (chronic myelogenous leukemia (CML), -thalassemia, hemophagocytic lymphohistiocytosis (HLH) and myelodysplastic syndrome (MDS)). The probability of developing grade II to grade IV acute graft-versus-host disease (GVHD) and chronic GVHD was 28.6 and 16.7%, respectively. Incidence of transplant-related mortality (TRM) was 14%. The 5 years overall survival (OS) in all patients was 59.8%. The 5 years OS for patients with average versus poor-risk malignancy was 77.8 versus 22.2% (P=0.03). RI-UCBT may result in graft failure in specific high-risk chemo-naïve patients (CML, -thalassemia, HLH and MDS), but in more heavily pretreated pediatric and adolescent recipients results in rapid engraftment and may be associated with decreased severe GVHD and TRM.