ENGRAFTMENT FAILURE FOLLOWING BONE-MARROW TRANSPLANTATION IN CHILDRENWITH THALASSEMIA MAJOR USING BUSULFAN AND CYCLOPHOSPHAMIDE CONDITIONING

Thirteen children older than 3 years of age with beta-thalassemia majo r underwent allogeneic bone marrow transplantation (BMT) from a full h uman leukocyte antigen (HLA) matched sibling donor in a single institu tion. These patients received busulfan (Bu) 26 mg/kg followed by cyclo phosphamide (Cy) 200 mg/kg for conditioning. Eight of the 13 patients (Group I) engrafted and have a median age of 13 years (range 5-15 year s). The five patients (Group 2) who failed to engraft have a median ag e of 6 years (range 3-8 years). The association with the following fac tors was found to be statistically significant. age (older in Group 1) , duration of nadir of White blood count (WBC) of less than or equal t o.1 x 10(9)/L (long er in Group I), and the dose of Bu administered to each patient calculated on the basis of body surface area (higher dos e in Group 1). The high late of engraftment failure (5 out of 13) may be related to the suboptimal systemic exposure of Bu in younger childr en leading to inadequate Done marrow ablation when the standard dose o f 16 mg/kg is used.