Imatinib mesylate as first-line therapy in patients with chronic myeloid leukemia in accelerated phase and blast phase: a retrospective analysis.

INTRODUCTION: Imatinib is a bcr-abl tyrosine kinase inhibitor which has revolutionized the treatment for chronic myeloid leukemia (CML). Even though there is much data on CML chronic phase, there is limited data on imatinib-naοve advanced phase CML.

MATERIALS AND METHODS: We retrospectively analysed 90 patients with advanced phase CML (accelerated phase [AP]: 51 and blast crisis [BC]: 39), patients who received imatinib as frontline therapy.

RESULTS: The median age of presentation in CML-AP and CML-BC were 32 years (12-61) and 39 years (8-59), respectively. Imatinib at 600 mg/day was initiated within 2 weeks of diagnosis. Median time to complete hematological response in both CML-AP and CML-BC was 3 months (CML-AP: 1-9 months and CML-BC: 1-14 months). At 6 months 30 (59%) CML-AP and 15 (38%) CML-BC patients achieved major cytogenetic response (MCyR), of them 24 (47%) and 10 (25.6%) being the complete cytogenetic response, respectively. At a median follow-up of 41 months, the median overall survival in CML-AP was 61 months, but in CML-BC it was 14 months. The median progression-free survival and event-free survival were 30 months and 23 months in CML-AP and 14 and 12 months in CML-BC, respectively. On univariate analysis, performance status (PS), spleen size, and MCyR predicted survival in AP, whereas in BC, platelet count, PS, and early MCyR were predictive. Non-hematologic and hematologic adverse events were observed in 80% and 60% of patients, respectively. Dose was reduced in 10% of patients for grade IV toxicity and interrupted in 30% for grade III toxicity.

CONCLUSION: Front-line imatinib is an option in advanced phases of CML especially in CML-AP in low-resource countries, where stem cell transplantation and alternate TKIs are not available.