Reduced-intensity allogeneic stem cell transplantation for patients aged 50 years or older with B-cell ALL in remission: a retrospective study by the Adult ALL Working Group of the Japan Society for Hematopoietic Cell Transplantation.

We retrospectively assessed the outcome and pretransplantation predictors of the outcome in 118 patients aged ≥ 50 years who received fludarabine-containing reduced-intensity allo-SCT (RIST) for B-cell ALL in the first or second CR. Eighty patients received transplants from unrelated donors. Seventy-eight patients were positive for the Ph chromosome. The median follow-up period was 18 months and the 2-year OS rate was 56%. The 2-year cumulative incidence of relapse and non-relapse mortality was 28% and 26%, respectively. The incidence of grades II-IV and III-IV acute GVHD was 46% and 24%, respectively. After 2 years, the incidence of chronic GVHD was 37%. Multivariate analysis of pretransplant factors showed that a higher white blood cell count (≥ 30 × 10(9)/L) at diagnosis (hazard ratio (HR)=2.19, P=0.007) and second CR (HR=2.02, P=0.036) were significantly associated with worse OS, whereas second CR (HR=3.83, P<0.001) and related donor (HR=2.34, P=0.039) were associated with a higher incidence of relapse. Fludarabine-containing RIST may be a promising strategy for older patients with B-cell ALL in their first remission.