OBJECTIVES: Bosutinib a dual Src/Abl tyrosine kinase inhibitor (TKI) demonstrated efficacy in a phase 1/2 study of patients with relapsed/refractory Chronic Myeloid Leukemia (CML). Health utilities were reported in the imatinib IRIS study, but there is limited information from relapsed/refractory CML patients. The objective was to evaluate the effect of bosutinib on health utilities in patients with CML after failure with imatinib. METHODS: Evaluation of patient HRQoL was an exploratory objective in the clinical trial measured using the EQ-5D, which consists of 5-items: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. Each item ranges from 1 (“no problems”) to 3 (“extreme problems”). The EQ-5D was completed at weeks 4, 8, 12 and every 12 weeks thereafter, as well as treatment completion and scored according to the UK tariff. RESULTS: Of the N=570 patients included in the trial, 288 were second line chronic phase (CP 2L) CML, 118 were third line CP patients (3L), 76 were accelerated phase (AP) and 64 blast phase (BP). For 2L patients, the mean utility score at baseline was 0.83 (SD 0.21), and was maintained throughout the course of the study demonstrating a significant improvement at week 36 (mean change from baseline 0.04, p=0.01).  For 3L patients, the mean utility at baseline was 0.80 (SD 0.22), and maintained throughout the study. There were no statistically significant differences from baseline through week 36 in health utility in 3L patients. The mean utility at baseline for advanced patients was 0.78 (SD 0.28) for AP and 0.66 (SD 0.30) for BP patients and was maintained throughout the study. CONCLUSIONS: These data suggest that relapsed/refractory CML patients treated with bosutinib maintain their quality of life throughout the trial regardless of the line of treatment or phase of disease. These results highlight the value of capturing patient HRQoL in CML treatment.