Fludarabine, antithymocyte globulin, and very low-dose busulfan for reduced-intensity conditioning before allogeneic stem cell transplantation in patients with lymphoid malignancies.

This retrospective report compared the results of a reduced-intensity conditioning (RIC) regimen including fludarabine (Flu), and very low-dose oral busulfan (BU) (4 mg/kg total dose) in combination with antithymocyte globulin (ATG) (Flu/ATG/BU) to the classical Flu and low-dose total body irradiation (TBI) (2 Gy) regimen (Flu/TBI) in patients with lymphoid malignancies. With a median follow-up of 42 months, the cumulative incidence of transplant-related mortality (TRM) was 22% in the Flu/ATG/BU group versus 41% in the Flu/TBI group (P = .09). Grade 3-4 acute graft-versus-host disease (aGVHD) and extensive chronic GVHD (cGVHD) incidents were 15% versus 44% (P = .006), and 12% versus 58% (P = .0003), in the Flu/ATG/BU group versus the Flu/TBI group, respectively. The Kaplan-Meier estimate of overall survival (OS) at 2 years was comparable between both groups (71%; 95% confidence interval [CI] 58%-86%, in the Flu/ATG/BU group vs 60%; 95% CI 44%-83%, in the Flu/TBI group, P = .20). The estimate of progression-free survival (PFS) was 63% (95% CI 50%-80%) in the Flu/ATG/BU group versus 52% (95% CI, 36%-76%) in the Flu/TBI group (P = .18), suggesting that reduced-intensity conditioning (RIC) based on Flu, very low-dose BU, and ATG has the potential to induce long-term remissions in patients with lymphoid malignancies.