Bone marrow as stem cell source for allogeneic HLA-identical sibling transplantation following reduced-intensity preparative regimen

OBJECTIVE: Reduced-intensity conditioning regimens (RIC) and peripheral blood stem cells (PBSC) are increasingly used for allogeneic stem cell transplantation (allo-BMT). RIC has been shown to allow engraftment with minimal early transplant-related mortality (TRM). However, in the context of RIC, the use of bone marrow (BM) as stem cell source is still little evaluated. PATIENTS AND METHODS: In this report, we analyzed the outcome of 32 high-risk patients with hematological malignancies who received an HLA-identical sibling allo-BMT after RIC including fludarabine, busulfan, and anti-thymocyte globulin (ATG). RESULTS: Sustained neutrophil and platelet recovery occurred at a median of 13 days (range, 10-19) and 17 days (range, 0-45) respectively. Early and durable full donor chimerism could be established as soon as the first month after allo-BMT. Also, a sustained and early CD8(+) T-cell recovery was observed, but the CD4(+) T-cell compartment remained profoundly low. The cumulative incidences of grade II-IV acute GVHD and chronic GVHD were 26% (95% CI, 11-41%) and 31% (95% CI, 15-47%) respectively. The overall cumulative incidence of TRM was 28% (95% CI, 12-44%) occurring mainly in patients aged over 50. In this setting, GVHD showed a protective effect on disease progression or relapse with better progression-free survival for patients with GVHD as compared to patients without GVHD (p=0.03). CONCLUSIONS: Collectively, these results confirm that the use of BM grafts for RIC is feasible with durable donor engraftment and no detrimental GVHD.