A pilot study of imatinib, low-dose cytarabine and idarubicin for patients with chronic myeloid leukemia in myeloid blast phase.

Imatinib is the single most effective agent in chronic myelogenous leukemia (CML) in blast phase (BP), inducing hematologic responses in 30 - 50% of patients. However, only a few of these are complete (CHR) and durable. Imatinib is synergistic with idarubicin and cytarabine. We administered imatinib 600 mg/day, cytarabine 10 mg/day subcutaneous, and idarubicin 12 mg/m2 intravenous every 14 days in 19 patients with CML in myeloid BP. Fourteen patients (74%) achieved a hematologic response: CHR in 9 (47%) (3 with complete and 1 with minor cytogenetic responses) and return to chronic phase (RTC) in 5 (26%). Median duration of response was 10 weeks (range, 2 - 89). Six patients received allogeneic stem cell transplantation: 4 CHR, 1 chronic phase and 1 BP. Median survival was 5 months (range, 2 - 20 months). This outpatient regimen is effective and well tolerated and perhaps superior to single-agent imatinib for patients in myeloid BP.