FLT3 Clonal Evolution in Patients With Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogeneous group of hematological diseases. According to the Taiwan Cancer Registry Annual Report, 859 new AML cases were diagnosed in Taiwan in 2018, with an age-standardized incidence rate of 3.06 in males and 2.18 in females per 100,000 person-years. The FMS-like tyrosine kinase 3 gene (FLT3) affects the proliferation and differentiation of stem cells or hematopoietic progenitor cells. FLT3 mutations are found in 25-30% of newly diagnosed AML patients and are considered a negative prognostic factor, remaining significant even after intensive chemotherapy and/or stem cell transplant. Two critical issues for ensuring timely targeted therapy for FLT3+ patients are the speed of FLT3 test turnaround and the use of tests at key time points. Rapid turnaround times are necessary for early intervention, with European LeukemiaNet (ELN) recommending results within 3 days. However, it's unclear if this is achievable in real-world settings. FLT3 mutation status evolves, with 15-25% of patients losing and 13% acquiring the mutation at relapse. Despite guidelines recommending FLT3 testing at diagnosis and relapse, there is no consensus in Taiwan on its importance and timing. Some observational studies on AML in Taiwan have been conducted but provide limited information on the timing and turnaround of FLT3 testing in real-world practice. This study will describe the current FLT3 testing landscape, including turnaround time and timing of tests among adult relapsed/refractory (R/R) AML patients at NTUH. It will also investigate the clinical characteristics and survival outcomes of both adult R/R AML and newly diagnosed AML patients.