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Fludarabine, Busulfan and Melphalan Conditioning in Pediatric Myeloid Malignancies Undergoing Hematopoietic Stem Cell Transplantation
Methods: Retrospective review of pediatric patients with myeloid malignancies who underwent HSCT at our institution from September 2005 to September 2010.
Results: There were 19 patients who underwent HSCT in the time period. Median age is 5 (range, 1-20) years. There were 15 patients in CR1, 2 patients in CR2 and 2 patients not in CR. Patients received Fludarabine (120mg/m2) + Busulfan, weight-based dosing + Melphalan 140mg/m2 (15 patients) decreased to 70 mg/m2 (3 patients), and 1 infant with weight adjusted dose with Cyclosporine + ATG + MTX as GVHD prophylaxis. Average length of stay from Day 0 to discharge is 28 (range, 17-51) days. All patients achieved neutrophil recovery at median 14 (range, 10-46) days. All patients achieved > 95% chimerism (D+21) and 100% (D+100). Regimen-related toxicities were CTC grade 2-3 mucositis (89%), seizures (10%) and sinusoidal obstruction syndrome (SOS) (15%). Decreasing the Melphalan dose did not decrease the occurrence of mucositis and SOS in the 3 patients. Busulfan pharmacokinetics was not measured; all patients received phenytoin prophylaxis at therapeutic levels. The 100-day TRM is 0%. Overall, 47% had grade 1-2 aGVHD, 21 % grade 3-4 aGVHD and 76% had cGVHD. The 2-year overall survival (OS) & EFS for the 15 patients in CR 1 are 93%, and 80% respectively. Both of the patients not in CR died of disease.
Conclusion: In our limited number of patients, we found FluBuMel to have excellent engraftment rates with very low TRM. However, there were high occurrence of toxicities, particularly mucositis and SOS.