Busulfan plus etoposide as a preparative regimen for autologous bone marrow transplantation for acute myelogenous leukemia: an update

We have used a new preparative regimen prior to autologous bone marrow transplantation in patients in remission of acute myelogenous leukemia (AML). Sixty-two patients were treated with preparative chemotherapy consisting of 1 mg/kg of busulfan every 6 hours for 4 days (total dose 16 mg/kg) on days -7 to -4 followed by an intravenous infusion of 60 mg/kg of etoposide on day -3. Autologous bone marrow that had been purged with 4-hydroperoxycyclophosphamide was infused on day 0. Thirty-five of the treated patients were in first remission, 21 were in second or third remission, and six had primary refractory AML and required aggressive salvage regimens to achieve remission. Among patients in first remission, one treatment-related death and five relapses have occurred. With a median follow-up of 25 months, the actuarial relapse rate is 19% +/- 8% and the disease-free survival rate is 79% +/- 8% at 3 years. The 16 patients with favorable FAB subtypes (M3 or M4E0) showed an excellent response to this treatment protocol, with no relapses after median follow-up of 35 months. Among patients in second or third remission, there were five treatment-related deaths and five relapses. With a median follow-up of 41 months, the actuarial relapse rate is 30% +/- 11% and the disease-free survival rate is 52% +/- 11% at 3 years. Four of six primary refractory patients died during treatment and one remains in remission with short follow-up. These preliminary data indicate that aggressive preparative regimens followed by the infusion of purged autologous bone marrow may be a promising approach to improving the clinical outcome of adult patients with AML.