Impact of different fludarabine doses in the fludarabine-based conditioning regimen for unrelated bone marrow transplantation

Abstract

Abstract To compare the effect of fludarabine (Flu) dose, the clinical outcomes of patients who received Flu and busulfan (FB; n = 1647) or melphalan (Flu with melphalan (FM); n = 1162) conditioning for unrelated bone marrow transplantation were retrospectively analyzed using Japanese nationwide registry data. In the FB group, high-dose Flu (180 mg/m2; HFB) and low-dose Flu (150/125 mg/m2; LFB) were given to 1334 and 313 patients, respectively. The three-year overall survival (OS) rates were significantly higher in the HFB group than in the LFB group (49.5% vs. 39.2%, p < 0.001). In the HFB and LFB groups, the cumulative incidences were 30.4% and 36.6% (p = 0.058) for three-year relapse. In the multivariate analysis for OS and relapse, Flu dose was identified as an independent prognostic factor (hazard ratio: 0.83, p = 0.03; hazard ratio: 0.80, p = 0.043). In the FM group, high-dose Flu (180 mg/m2; HFM) and low-dose Flu (150/125 mg/m2; LFM) were given to 118 and 1044 patients, respectively. The OS and relapse did not differ significantly between the HFM and LFM groups. These findings suggest that high-dose Flu was associated with favorable outcomes in the FB group but not in the FM group.