Long-term survival in refractory acute myeloid leukemia after sequential treatment with chemotherapy and reduced-intensity conditioning for allogeneic stem cell transplantation.

A sequential regimen of chemotherapy, reduced-intensity conditioning (RIC) for allogeneic stem cell transplantation (SCT), and prophylactic donor lymphocyte transfusion (pDLT) was studied in 103 patients with refractory acute myeloid leukemia (AML). According to published criteria, refractoriness was defined by primary induction failure (PIF; n = 37), early (n = 53), refractory (n = 8), or second (n = 5) relapse. Chemotherapy consisted of fludarabine (4 x 30 mg/m(2)), cytarabine (4 x 2 g/m(2)), and amsacrine (4 x 100 mg/m(2)), followed 4 days later by RIC, comprising 4 Gy total body irradiation (TBI), cyclophosphamide, and antithymocyte globulin. Patients without graft-versus-host disease (GvHD) at day +120 received pDLT in escalating doses. Patients' median age was 51.8 years. Before conditioning, 99 patients had active disease, 3 were aplastic, 1 was in second complete remission (CR2). Forty-one patients had family donors, 62 had unrelated donors. With a 25-month median follow-up, overall survival (OS) at 1, 2, and 4 years was 54%, 40%, and 32%; the respective leukemia-free survival (LFS) was 47%, 37%, and 30%. Patients with PIF showed a 2-year OS of 62.5%. OS was 87% in 17 patients receiving pDLT. One-year cumulative incidence of leukemic death and non-relapse-mortality was 28.7% and 17.2%. In a multivariate analysis, more than 2 courses of prior chemotherapy were the strongest predictor for poor outcome (P = .007; HR = 3.01 [OS]; P = .002; HR = 3.25 [LFS]). These results indicate a high activity of the regimen in refractory AML.