Treatment Intensification With Either Fludarabine, AraC, G-CSF and Idarubicin, or Cladribine Plus Daunorubicin and AraC on the Basis of Residual Disease Status in Older Patients With AML: Results From the NCRI AML18 Trial

PURPOSE: To evaluate the survival benefit of chemotherapy intensification in older patients with AML who have not achieved a measurable residual disease (MRD)-negative remission.

METHODS: Five hundred twenty-three patients with AML (median age, 67 years; range, 51-79) without a flow cytometric MRD-negative remission response after a first course of daunorubicin and AraC (DA; including 165 not in remission) were randomly assigned between up to two further courses of DA or intensified chemotherapy-either fludarabine, cytarabine, granulocyte colony-stimulating factor and idarubicin (FLAG-Ida) or DA with cladribine (DAC).

RESULTS: Overall survival (OS) was not improved in the intensification arms (DAC v DA: hazard ratio [HR], 0.74 [95% CI, 0.55 to 1.01]; P = .054; FLAG-Ida v DA: HR, 0.86 [95% CI, 0.66 to 1.12]; P = .270); OS at 3 years was 34%, 46%, and 42% for DA, DAC, and FLAG-Ida, respectively. Early deaths and other adverse events were more frequent with FLAG-Ida (9% day 60 deaths v 4% after DA or DAC; P = .032). Of patients entering random assignment, 131 had MRD unknown status. In this subgroup of patients lacking evidence of residual leukemia by flow cytometry, there was no detectable survival advantage from intensification. A planned sensitivity analysis excluding these patients demonstrated a survival benefit for both DAC (HR, 0.66 [95% CI, 0.46 to 0.93]; P = .018) and FLAG-Ida (HR, 0.72 [95% CI, 0.53 to 0.98]; P = .035); OS at 3 years was 30%, 46%, and 46% for DA, DAC, and FLAG-Ida, respectively. There was a concordant reduction in relapse (DAC v DA: HR, 0.66 [95% CI, 0.45 to 0.98]; P = .039; FLAG-Ida v DA: HR, 0.70 [95% CI, 0.49 to 0.99]; P = .042). DAC benefit was maintained when survival was censored for transplant (P = .042).

CONCLUSION: In this study of older patients with AML considered fit and with evidence of residual disease after first induction, chemotherapy intensification improved survival. DAC intensification was better tolerated than FLAG-Ida.