Impact on long-term OS of conditioning regimen in allogeneic BMT for children with AML in first CR: TBI+CY versus BU+CY: a report from the Société Française de Greffe de Moelle et de Thérapie Cellulaire

Allogeneic hematopoietic SCT (HSCT) appears to be an efficient tool to cure high-risk AML in first CR but the choice between BU-based or TBI-based conditioning regimens still remains controversial. In order to analyze the impact of conditioning regimen on long-term survival, we conducted a retrospective analysis from French registry data including all consecutive patients under 18 years old ( n =226) from 1980 to 2004 transplanted for AML in CR1 from sibling ( n =142) or matched unrelated donors and given either TBI-1200 cGy and CY 120 mg/kg (TBI-Cy, n =84) or BU 16 mg/kg and CY 200 mg/kg (BuCy200, n =142). Patient subgroups were comparable for all criteria except for median age at diagnosis and HSCT and for donor type. Both 5-year OS and disease-free survival (DFS) were significantly better in BuCy200 group ( P =0.02 and 0.005, respectively). In multivariate analysis, both HLA matching and BuCy200 appeared as good prognostic factors for treatment-related mortality and DFS. Grade 2–4 acute GvHD and chronic GvHD rates were statistically higher in TBI-Cy group than in Bu-Cy200 one with a RR at 2 ( P =0.002). In total, Bu-Cy200 conditioning regimen gives better outcome compared with TBI-Cy irrespective of the stem cell source and the donor type.