Imatinib may not be the best choice for planning TFR in CML patients.

Abstract

e19059 Background: Treatment of chronic myeloid leukemia had been revolutionized by the use of Tyrosine kinase inhibitors. Recently, the strategy of treatment free remission had been introduced to ameliorate toxicity and reduce financial burden beside allowing patients who now have similar survival to normal people to achieve some goals as childbearing. Aim of this study: to check the suitability of imatinib as a first line treatment in potential patients in whom treatment free remission will be an ultimate goal. Methods: This study included patients with chronic myeloid leukemia, chronic phase who were treated in King Abdulla Medical city in the period between 2011 and end of 2019. Initial diagnosis was done by bone marrow, cytogenetics, molecular testing for BCR/ABL. Quantitative estimation of BCR-ABL1 was done on peripheral blood every 3 months to follow response which was assessed according to ELN criteria for follow up. Results: 140 patients were included in this study who received imatinib as first line therapy. The male to female ratio was 1.1 and the median age was 42 Y. 17 patients (12.1 %) were > 60 Y at start of treatment. The majority of patients were considered low risk (70.2%) as by EUTOS risk score. Breakpoint region was e13/a2 in 39.3%, e14/a2 in 38.3% and unknown in 22.7% of patients. 62% of patients were compliant with treatment. At the time of analysis, 79 patients (56%) remained on imatinib. 51/140 (36%) stopped it due to failure, 11 due to intolerance (7.9%). Favorable molecular responses were achieved in 67.4%, 53.9% and 50% at 3,6,12 months respectively. Compliance and risk scores were significantly affecting these responses. 54/70 (77%) of those who achieved MMR at 12 months achieved a deep molecular response (M4, M4.5) after a median period of 36 m. 40 patients (57%,74%) of those who achieved MMR, DMR respectively developed DMR lasting for more than 2 years (which is the requirement for TTF). This also reflects 28.5% of the whole group of patients. Conclusions: Although Imatinib continues to be the preferred first line in treating CML, CP yet it might be more suitable to use a second generation TKI if TFR is planned ahead.