Purpose: The goal of this study was to evaluate whether the addition of a purine analog, cladribine or fludarabine, to the standard induction regimen affects the outcome of adult patients with acute myeloid leukemia (AML).
Patients and methods: A cohort of 652 untreated AML patients with median age 47 years (range, 17 to 60 years) were randomly assigned to receive one of three induction regimens: DA (daunorubicin plus cytarabine), DAC (DA plus cladribine), or DAF (DA plus fludarabine). Postremission treatment was the same for all arms.
Results: Complete remission rate in the DAC arm was higher compared with the DA arm (67.5% v 56%; P = .01) as a consequence of reduced incidence of resistant disease (21% v 34%; P = .004). There was no significant difference in early outcome between the DAF and DA arms. The probability of overall survival was improved for the DAC arm (45% ± 4% at 3 years) compared with the DA arm (33% ± 4%; P = .02), and leukemia-free survival was comparable. Long-term outcome did not differ significantly for the comparison of the DAF and DA arms. A survival advantage of the DAC arm over the DA arm was observed among patients age 50 years or older (P = .005), those with initial leukocyte count above 50 × 10(9)/L (P = .03), and those with unfavorable karyotype (P = .03). DAF revealed a significant advantage over DA in patients with adverse karyotype (P = .02).
Conclusion: The addition of cladribine to the standard induction regimen is associated with increased rate of complete remission and improved survival of adult patients with AML.