A639 ment regimens for chronic myeloid leukemia. If further research were funded, studies should examine a combination of natural history, treatment, and quality of life parameters, especially the effectiveness of first-line TKI treatment.Objectives: The first goal was to adapt an existing Austrian decision-analytic model for chronic myeloid leukemia (CML) treatment to the US-American health care context. Secondly, we updated the model with new data and further treatment strategies to identify the most effective and most cost-effective strategy for the treatment of CML patients with different sequential tyrosine kinase inhibitors (TKIs). MethOds: We evaluated 18 different treatment strategies within the US-American setting in terms of survival, quality-adjusted survival and costs. For model parameters, data from literature, a US-American expert survey, the Utah Cancer Registry, and economic data from a US-American database were used. Evaluated treatment strategies included imatinib, dasatinib, nilotinib, bosutinib, ponatinib, stem-cell transplantation and chemotherapy. The Markov state-transition model was analyzed as a cohort simulation over a lifelong time horizon, a third-party payer perspective was adopted and a discount rate of 3% was used. Additionally, several deterministic and probabilistic sensitivity analyses were conducted. Results: Imatinib without second-line TKI resulted in an incremental cost-utility ratio (ICUR) of $148,700/QALY gained (incremental cost-effectiveness ratio (ICER) of $128,800/Lys) compared to baseline strategy 'chemotherapy'. Imatinib with second-line nilotinib yielded an ICUR of $217,100/QALY gained (ICER $242,200/ LY) compared to imatinib without second-line TKI. Imatinib followed by secondline bosutinib had an ICUR of $331,300/QALY gained (ICER $265,100/LY) compared to imatinib followed by second-line nilotinib. Imatinib with second-line dasatinib produced an ICUR of $343,200/QALY gained (ICER $279,600/LY) compared to imatinib with second-line bosutinib. All remaining strategies were excluded due to dominance. ICURs and ICERs obtained from the probabilistic sensitivity analysis deviated up to 6.5% (2.5%) compared to base-case ICURs (ICERs). cOnclusiOns: Based on our analysis and current treatment guidelines, we recommend imatinib followed by second-line nilotinib as the most cost-effective treatment strategy. Our model results may support clinicians and patients in CML treatment decision making.