Autologous blood stem cell transplantation for acute myeloblastic leukemia in first complete remission. Intensification therapy before transplantation does not prolong disease-free survival

Abstract

BACKGROUND AND OBJECTIVE: To compare the clinical results of two consecutive therapeutic protocols including autologous blood stem cell transplantation (ABSCT) for patients with de novo acute myeloblastic leukemia (AML) in first complete remission (CR1). DESIGN AND METHODS: Between November 1989 and January 1997, 50 patients with AML in CR1 underwent ABSCT using two consecutive protocols. In the first one (Group A, 25 patients) peripheral blood stem cells (PBSC) were collected after induction and consolidation chemotherapy courses, and ABSCT was performed immediately thereafter. In the subsequent 25 patients (Group B), PBSC were collected after consolidation alone, and a further chemotherapy course with intermediate dose cytarabine (Ara-C 1 g/m2/12 h x3 days) and mitoxantrone (12 mg/m2/d x3 days) was administered as early intensification. The conditioning regimen consisted of busulfan (16 mg/kg) and cyclophosphamide (200 mg/kg) in every case. RESULTS: Hematopoietic engraftment was slightly quicker in Group B, with median times to reach 0.5 x 10(9) neutrophils/L and 20 x 10(9) platelets/L being 13 and 12 days in Group A and 12 and 11 days in Group B, respectively. There were three graft failures (8%) (2 in Group A and 1 in Group B) and three transplant-related deaths (8%) (2 in Group A and 1 in Group B). No significant differences were observed between the groups in terms of relapse (64% at 4-years in Group A and 81% in Group B). Likewise, the actuarial 4-year disease-free survival (DFS) was not significantly different between the two groups (32% v 18%). INTERPRETATION AND CONCLUSIONS: Our study confirms that AML patients in CR1 receiving ABSCT have rapid engraftment with low mortality. However, autologous transplants with PBSC collected after consolidation chemotherapy were still associated with a high rate of relapse (RR). This RR was not apparently reduced by the administration of intermediate dose Ara-C before transplantation.