Reduced-intensity conditioning for unrelated donor progenitor cell transplantation: long-term follow-up of the first 285 reported to the national marrow donor program.

To determine the long-term outcome of patients undergoing unrelated donor transplantation (URD) after a reduced intensity conditioning (RIC) regimen, we performed a retrospective analysis of the transplant outcomes of the first 5 years of RIC experience as reported to the National Marrow Donor Program (NMDP). Patients were included if they were older than 18 years and had undergone a URD transplant procured through the NMDP from January 1, 1996 until May 31, 2001, with an RIC regimen for a hematologic malignancy. The number of URDs performed using an RIC increased from 59 during 1996 to 1999, to 149 in the year 2000. RIC recipients were older (53 vs. 33 years) and had a higher likelihood of having advanced disease (81% vs. 51%) when compared to patients undergoing a myeloablative conditioning regimen during the same time period. The 5-year survival rate is 23% (95% confidence interval [CI]; 18, 28), whereas the 5 year incidence of progression/relapse is 43.4% (95% CI; 37,49). Prognostic factors for better overall survival on multivariate analysis were earlier disease stage, longer time to transplant from diagnosis, better HLA match, >or=90% performance score, and use of peripheral blood stem cells. This analysis demonstrates that long-term survival and disease control can be obtained with URD progenitor cell transplantation after RIC conditioning. However, only prospective trials will define the optimal role of this therapy in patients with hematologic malignancies. Therefore, URD transplantation with RIC should continue to be explored in the context of clinical trials.