Tyrosine Kinase Inhibitor Dosing Patterns in Elderly Patients With Chronic Myeloid Leukemia

Abstract

IntroductionTyrosine kinase inhibitors (TKIs) improve the survival rate of patients with chronic myeloid leukemia (CML). However, elderly patients often experience adverse events and require dose adjustments, leading to dose interruptions or treatment discontinuation. We therefore investigated TKI dosing patterns and subsequent outcomes in elderly CML patients. Patients and MethodsUsing the National Health Information Database, we identified patients with CML aged ≥ 70 years who were prescribed TKIs (imatinib, dasatinib, nilotinib, or radotinib) during 2007-2013. Data on age, sex, prescribed medication, and date of death were extracted. ResultsAmong the 378 patients, the median age was 75 (range, 70-92) years; the median follow-up period was 53 (range, 1-133) months. Imatinib, dasatinib, nilotinib, and radotinib were prescribed to 324 (85.7%), 110 (29.1%), 93 (24.6%), and 15 (4.0%) patients, respectively. In 42 patients (12.2%), the initial dose was lower than the recommended dose for chronic-phase CML. At last follow-up, 249 patients (65.9%) were receiving a reduced dose. The mean ± standard deviation dose densities of imatinib, dasatinib, nilotinib, and radotinib were 207 ± 121.6, 29 ± 26.7, 235 ± 197, and 123 ± 95.4 mg/day, respectively. The estimated 5-year overall survival probability was 61.0%. Initial TKI dose or dose reduction within first year did not affect the overall survival (P = .0571 and .1826, respectively). ConclusionDose reduction was observed in 65.9% of the patients at their last visit; except for imatinib, TKI dose densities were < 50% of the recommended dose for the chronic phase. Therefore, the recommended TKI doses might be too high for elderly patients with CML.