Randomized comparison of cyclophosphamide-total body irradiation versus busulfan-cyclophosphamide conditioning in autologous bone marrow transplantation for acute myeloid leukemia

Purpose: This prospective trial of autologous bone marrow transplantation for acute myeloid leukemia was undertaken to compare the outcome using two different preparative regimens. Methods and Materials: Between October 1987 and April 1993, 35 patients with acute myeloid leukemia in first n = 12) or greater (n = 23) remission were stratified by remission status and randomized to undergo 4-hydroperoxycyclosphamide purged autologous bone marrow transplantation after either cyclosphamide (120 mg/kg) and total body irradiation (1320 Gy in eight fractions over 4 days) (CY/TBI), or busulfan (16 mg/kg) and cyclophosphamide (200 mg/kg) (BU/CY) conditioning. Results: At 2 years, overall survival and disease-free survival were 39% (95% confidence intervals (CI) 22-57%) and 36% (95% CI 19-52%), respectively. Patients in first complete had a significantly better outcome with a 2-year disease free survival of 57% (95% CI 28-86%) compared to others at 24% (95% CI 6-43%, log rank p = 0.048). For patients conditioned with CY/TBI, the estimated 2-year disease-free survival was 50% compared to 24% for patients conditioned with BU/VY (log rank p = 0.12). Estimated 2-year relapse rates were 43% vs. 70% (log rank p = 0.17), respectively. For patients in first remission no differences in disease-free survival (2-year estimates 67% vs 50%, log rank p = 0.69), between the two regimens were observed. For patients in greater than first complete remission there was a trend towards improved disease-free survival in the CY/TBI arm (2-year estimates 42% vs 9%, log rank p = 0.06). There were no differences in time to white blood cell count (WBC) engraftment, absolute neutrophil count of > 500, incidence of bacteremias, or median time to hospital discharge between the two regimens. Acute toxicities were similar. Interstitial pneumonitis developed in two patients (one on each arm), while veno occlusive disease developed in three BU/CY patients, but none of the CY/TBI patients (log rank p = 0.07). Conclusions: Cyclosphamide-total body irradiation provided an equivalent or better outcome to BU/CY, particularly in advanced patients, and should remain in the standard by which new regimens are judged. The high relapse rate with both regimes, especially patients who were in greater than in first complete remission, emphasizes the need for early transplant and for new strategies to improve outcome.