Outcomes of UCB (unrelated cord blood) transplantation are equivalent to matched-sibling hematopoietic stem cell transplantation (HSCT) in children with high-risk acute lymphocytic leukemia (ALL)

Abstract

8563 Background: HSCT is commonly used for pediatric ALL patients with early relapse or other high-risk features. Given the lack of matched-sibling donors and multiple advantages of UCB as a stem cell source (less GVHD, rapid availability), we compared the outcomes of high-risk pediatric ALL patients that underwent HSCT at Children's Memorial Hospital (since 1992) with UCB (4–5/6 HLA match) or HLA-matched sibling transplant (6/6 HLA match). Methods: Patients included: ALL CR2 patients who relapsed <36 mos from diagnosis and ALL CR1 patients with at least 1 high-risk feature (unfavorable karyotype, poor response to induction, age<1 yr, WBC>100,000 at diagnosis). 25% of CR1 patients in both groups had 2 or more high-risk features. Cytoreduction, which was the same in both groups, consisted of TBI 150cGy × 8 (d-9 to-6), VP-16 1g/m2 over 24hr (d-5 to-4), and cyclophosphamide 60 mg/kg/day (d-4 to-2). GVHD prophylaxis: CSA, short-course MTX, and for UCB ATG d +1, +3, +5, +7. Three of the matched-sibling grafts were T-cell depleted. Results: There were 23 matched-sibling (20 BM/3 PBSC) and 26 UCB recipients. Both groups had equivalent high-risk factors. Engraftment took longer in UCB recipients. 100d TRM and GVHD rates were equal in both groups. 3 yr EFS was 60% in both groups. Age, gender, degree of HLA-matching (for UCB), and acute/chronic GVHD did not affect EFS. Conclusions: In pediatric patients with high-risk ALL being considered for HSCT, outcome of matched-sibling HSCT and UCB transplant is equivalent with regards to TRM, GVHD, and EFS. UCB should be considered an equivalent stem cell source to use in this group when a HLA-matched sibling is not available. No significant financial relationships to disclose.