Phase II evaluation of an intensified induction therapy with standard daunomycin and cytarabine followed by high dose cytarabine for adults with previously untreated acute myeloid leukemia: a Southwest Oncology Group study (SWOG-9500).

Induction therapy for acute myeloid leukemia (AML) usually consists of 7 days of cytarabine at 100-200 mg/m(2)/day and an anthracycline. Such combinations produce complete response (CR) rates of 60-80% in patients with de novo AML. On the basis of a previous report, suggesting a higher CR rate using a regimen of standard daunomycin and cytarabine followed by 3 days of high-dose cytarabine (HDAC), 101 eligible patients received this regimen in a phase II trial. Sixty patients [59%, 95% confidence interval (CI) 49-69%] achieved a CR, and 10 patients died of infection during induction. Although cytogenetic risk group affected overall survival (P = 0.0016) and relapse-free survival (P = 0.0043), it had no impact on CR rate (P = 0.63). Patients received postremission therapy with repetitive courses of alternate day high-dose cytarabine; this was associated with considerable toxicity and the majority of patients could not receive all of the scheduled postremission therapy. The estimated median survival was 23 months (95% CI 15-34 months), and the estimated probability of surviving 5 years was 34% (95% CI 24-43%). The results of this intensive induction regimen were similar to that seen in previous trials and were not as promising as reported in the previous pilot study.