Outcome of reduced-intensity allogeneic hematopoietic stem cell transplantation for multiple myeloma.

We retrospectively evaluated single-institute outcomes of allogeneic hematopoietic stem cell transplantation (allo-HSCT) with a reduced-intensity conditioning regimen consisting of fludarabine (125 mg/m²) and melphalan (140 mg/m²) for multiple myeloma. Twenty-three patients (median age: 46 years) were evaluated. Stem cell sources were bone marrow or peripheral blood stem cells from siblings (n = 4) and bone marrow from unrelated donors (n = 19). For graft-versus-host disease prophylaxis, cyclosporine A or tacrolimus with short-term methotrexate was given. Disease status at time of transplant was complete response in four patients, very good partial or partial response in 13, and stable or progressive disease in six. The median follow-up period of 7 survivors at analysis was 73.2 months (range 46.0-158.9 months). During the follow-up, disease recurrence or progression was observed in 21 patients, and was primary causes of death in 88% of the patients. The 5-year overall survival and progression-free survival rates were 38.6% (95% CI 19.3-57.7%) and 5.4% (95% CI 0.4-21.6%), respectively. Although allo-HSCT with this conditioning could be safely performed, further refinement of this approach aiming at more effective eradication of myeloma cells is clearly warranted.