Nonmyeloablative stem cell transplantation (NST) is increasingly used in older patients. The impact of the shift from myeloablative transplantation to NST on relapse, transplant complications, and outcome has yet to be fully examined. We performed a retrospective analysis of 152 patients older than 50 years undergoing NST or myeloablative transplantation. Seventy-one patients received nonmyeloablative conditioning, fludarabine (30 mg/m 2 /d ؋ 4) and intravenous busulfan (0.8 mg/kg/d ؋ 4); 81 patients received myeloablative conditioning, primarily cyclophosphamide and total body irradiation. NST patients were more likely to have unrelated donors (58% versus 36%; P ‫؍‬ .009), a prior transplant (25% versus 4%; P ‫؍‬ < .0001), and active disease at transplantation (85% versus 59%; P ‫؍‬ < .001). Despite the adverse characteristics, overall survival was improved in the NST group at 1 year (51% versus 39%) and 2 years (39% versus 29%; P ‫؍‬ .056). There was no difference in progression-free survival (2 years, 27% versus 25%; P ‫؍‬ .24). The incidence of grade 2 to 4 graft-versushost disease was similar (28% versus 27%). The nonrelapse mortality rate was lower for NST patients (32% versus 50%; P ‫؍‬ .01), but the relapse rate was higher (46% versus 30%; P ‫؍‬ .052). Our experience suggests that, in patients over age 50, NST with fludarabine and low-dose busulfan leads to an overall outcome at least as good as that following myeloablative therapy. (Blood.

To assess the effect of related versus unrelated donors on outcomes in patients following T-cell-depleted (TCD) allogeneic BMT, we compared engraftment, GVHD, relapse rates, and survival in BMT patients who received CD6+ TCD marrow from HLA-matched related donors (MRD) with those in patients who received CD6+ TCD marrow from unrelated donors (URD). A total of 170 consecutive patients (120 with related donors, 50 with unrelated donors) were analyzed. The 2 groups were similar in age, sex, prior cytomegalovirus exposure, and stage of disease at the time of transplantation. GVHD prophylaxis was identical in the 2 groups, with TCD as the only method of GVHD prophylaxis. The total number of nucleated, CD34+, CD33+, and CD6+ cells infused did not significantly differ between the 2 groups. The median day to reach 500 x 10(6) neutrophils/L was 12 days for both related (range, 8-22 days) and unrelated (range, 9-23 days) graft recipients (P = .92). Incidence of grades 2 through 4 acute GVHD was higher in URD than in MRD recipients (42% versus 20%, P = .004). According to multivariable analysis results, donor source was the single most important factor influencing GVHD (P = .01). The 2-year estimated risk of relapse was 45.9% in MRD recipients compared to 25.7% in URD recipients (P = .06). Multivariable analysis revealed that the 2 most pertinent factors adversely affecting overall survival were advanced disease stage (P = .0002) and age greater than 50 years (P = .0003) at transplantation. There was no difference in relapse-free survival in URD and MRD recipients. We conclude that for patients undergoing TCD-BMT, use of unrelated marrow is associated with a higher risk of GVHD and other transplantation-related complications. However, these adverse events do not lead to inferior probability of relapse-free survival because they are accompanied by a reduction in relapse rates.