Unrelated donor bone marrow transplantation using a chemotherapy-only preparative regimen for adults with high-risk acute myelogenous leukemia

Limited data are available for adults undergoing unrelated donor (URD) BMT for AML using chemotherapy-only preparative regimens. Previous studies incorporated irradiation, included adults and children, and excluded secondary leukemia. Herein we report long-term outcomes for adults with poor-prognostic AML receiving a novel regimen of busulfan (16 mg/kg), cytarabine (8,000 mg/m(2)), and cyclophosphamide (120 mg/kg) (BAC), followed by URD BMT. From June 1995 through October 2001, 45 adults were enrolled. Adverse features included unfavorable cytogenetics (49%), secondary AML (47%), leukemia at transplant (42%), and extramedullary disease (16%). At time of BMT, 23 were in remission (12 CR1) while 22 had leukemia. Four (9%) died early. Acute and chronic GVHD rates were 44 and 67%, respectively. Seventeen (38%) were disease-free 52 months post-BMT; 13 were leukemia-free (eight CR1) at transplant. Eleven relapsed. Three-year DFS and OS were 42 and 46%, respectively. DFS and OS were longer, and relapses less, for those in CR at time of BMT. Secondary leukemia, cytogenetics, cell dose, and GVHD did not influence outcome. In poor-risk AML, BAC provided cytoreduction comparable to reported TBI-containing regimens, when administered for URD BMT. With decreasing treatment-related mortality, it is justified to proceed early to URD BMT for patients with poor prognostic features.