High-dose cytarabine and daunorubicin as consolidation therapy for acute myeloid leukemia in first remission: long-term follow-up and results.

In an effort to increase the proportion of patients with acute myeloid leukemia (AML) remaining in continued complete remission (CCR), we administered intensive postremission consolidation therapy with high-dose cytarabine (Ara-C) and daunorubicin. Eighty-seven patients, with a median age of 38 years (range, 7 to 71), received consolidation therapy after first complete remission was obtained with standard induction chemotherapy that included conventional doses of Ara-C. Consolidation therapy consisted of from one to three cycles of high-dose Ara-C (3 g/m2 intravenously [IV] over 1 hour every 12 hours for 12 doses) followed by daunorubicin (30 mg/m2/d IV bolus for 3 days). After completion of the high-dose Ara-C and daunorubicin, no further therapy was administered. Myelosuppression encountered with consolidation resulted in a median duration of neutropenia and thrombocytopenia of 3 weeks. Four patients (5%) died during consolidation due to infection and/or hemorrhage; 59% of patients experienced severe but nonfatal infectious or extramedullary organ toxicity. With a median follow-up of more than 3.5 years from diagnosis, the proportion of patients, by Kaplan-Meier product-limit estimate, remaining in CCR is 49% (95% confidence limits, 37% to 61%). In a Cox multivariate analysis, only age significantly (P less than .001) influenced the probability of remaining in CCR. The probability of remaining in CCR was 83%, 50%, and 23% for age groups of 25 or less, 26 to 45, and more than 45 years, respectively. These survival curves all have stable long-term plateaus, suggesting cure. In this study, the administration of brief, intensive nonmarrow ablative chemotherapy resulted in a large proportion of patients with AML remaining in CCR, results similar to those reported with allogeneic bone marrow transplantation. Relapse of acute leukemia was still the major reason for therapy failure, suggesting that more effective or additional postremission therapy will be required to further improve the likelihood of cure especially for older patients.