EUTOS Score Identifies Cases with Poor Outcome in Patients with Early Chronic Phase Chronic Myeloid Leukemia, Though Not Predictive for Optimal Response to Imatinib

Introduction.: The EUTOS score has recently been developed by the European Leukemia-Net (ELN) to predict the achievement of an 18-month complete cytogenetic response (CCyR) and progression-free survival in imatinib-treated early chronic phase (ECP) chronic myeloid leukemia (CML) patients. The score uses the percentage of basophils and spleen size to divide patients in 2 groups of low- and high-risk. Since its publication in 2011, however, there have been conflicting reports about the efficacy of EUTOS score. Moreover, scanty data are available on the power of this scoring system to foresee optimal response to imatinib, as defined by ELN recommendations. Aims and Methods.: To test the power of EUTOS score in predicting achievement of optimal response to imatinib, as defined by ELN, time to imatinib failure (TTF) and progression-free survival (PFS), we evaluated 265 ECP CML patients treated with front-line standard dose imatinib (400 mg daily) at 5 major hematology centres in the north-eastern area of Italy. Partial cytogenetic response (PCyR) and CCyR were defined as 1–35% and 0% Ph+ metaphases, respectively; major molecular response (MMR) was defined as BCR-ABL