Despite recent advances, multiple myeloma (MM) remains incurable, and most patients eventually develop progressive disease. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) offers a potentially curative option in 10%-20% of patients with relapsed or refractory disease. We evaluated the outcome of patients undergoing allo-HSCT with reduced-intensity conditioning (RIC) for relapsed and/or refractory MM at our institution. The study cohort included 51 patients with heavily pretreated, relapsed MM who underwent RIC allo-HSCT between 1996 and 2006. The median time from diagnosis to allo-HSCT was 34 months, and median follow-up in surviving patients was 27 months (range, 3-98 months). Cumulative transplantation-related mortality at 1 year was 25%. Progression-free survival (PFS) and overall survival (OS) at 2 years were 19% and 32%, respectively. The incidences of grade II-IV acute and chronic graft-versus-host disease were 27% and 47%, respectively. At the time of this analysis, 12 patients (24%) were alive, 7 of whom (14%) were in remission for up to 6 years after allo-HSCT. A lower beta2 microglobulin level (<3.3) and previous autologous HSCT were predictive of lower nonrelapse mortality and longer PFS and OS. Our findings indicate that allo-HSCT with RIC is associated with acceptable toxicity and durable remission and survival in relapsed or refractory MM. The use of RIC allo-HSCT earlier in the course of the disease may offer the greatest benefit.
