Allogeneic stem cell transplantation in the myelodysplastic syndromes: interim results of outcome following reduced-intensity conditioning compared with standard preparative regimens

Conventional allogeneic stem cell transplantation (SCT) for myelodysplastic syndrome (MDS) is associated with excessive procedure-related mortality. The outcome following volunteer-unrelated donor (VUD) or sibling allogeneic SCT was therefore evaluated in 23 MDS patients conditioned with reduced-intensity regimens (fludarabine/busulphan/Campath-1H) because of advanced age (48 vs 37 years, P = 0.002) and/or co-morbidity (19 vs 3, P < 0.0001) which precluded conventional transplantation, and compared with 29 treated with standard protocols [busulphan/cyclophosphamide (Bu/Cy); Bu/Cy/total-body irradiation/Campath-1G]. Graft-versus-host disease (GVHD) prophylaxis comprised of cyclosporine/methotrexate. One hundred per cent donor engraftment (variable number tandem repeat analysis/cytogenetics/fluorescence in situ hybridization) was achieved in 18/19 (95%) evaluable patients receiving reduced-intensity regimens, although six (32%) have subsequently shown mixed chimaerism. Reduced-intensity conditioning was associated with significantly reduced duration of aplasia, less mucositis, fever, antibiotic, analgesia, parenteral nutrition use, less acute and chronic GVHD, and lower early procedure-related mortality [two (9%) vs nine (31%), P < 0.05]. Six patients relapsed (two standard, four reduced-intensity) and two (reduced-intensity) experienced late graft failure. The 2 year actuarial overall/disease-free survival (OS/DFS) was 48/39% in the reduced-intensity arm and 44/44% in the standard group. The 2 year non-relapse mortality was 31% and 50% respectively. In VUD recipients, OS was superior in the reduced-intensity arm (49% vs 34%). Predictors of DFS included good/intermediate-risk karyotype, low/intermediate-1 International Prognostic Scoring system score, human leucocyte antigen compatibility and attainment of complete remission. Our data demonstrates that VUD or sibling allogeneic SCT following reduced-intensity conditioning is feasible in high-risk MDS patients considered unsuitable for standard transplantation and is associated with comparable 3.5 year DFS to those receiving conventional regimens.