Phosphoproteomic Characterization of Primary AML Samples and Relevance for Response Toward FLT3-inhibitors

摘要

Kinase hyperactivity is a common driver of acute myeloid leukemia (AML) and serves as a therapeutic target.1 The most frequent activating genetic aberrations in AML are internal tandem duplications (~23%) and tyrosine kinase domain mutations (~7%) of FMS-like tyrosine kinase 3 (FLT3-ITD and FLT3-TKD), and the presence of FLT3-ITD negatively affects survival.2 Combined with chemotherapy, FLT3-Tyrosine Kinase Inhibitor (FLT3-TKI) midostaurin improves overall survival in newly diagnosed FLT3-mutated AML, whereas the single agent gilteritinib proved superior to chemotherapy in relapsed/refractory FLT3-mutated AML.2 The presence of FLT3-ITD is predictive for response to FLT3-TKIs,3 yet 41%–56% of FLT3-WT patients respond to FLT3-TKIs, indicating alternative possibilities of FLT3 pathway activation or TKI off-target effects leading to unexpected treatment response.4 Others have identified genomic and global phosphorylation markers associated with FLT3-TKI response in FLT3-WT AML.5,6 As the primary targets of currently approved FLT3-TKIs are tyrosine (Y) kinases, we hypothesized that the direct evaluation of tyrosine kinome could reveal phosphorylation markers associated with FLT3-TKI response. Therefore, we performed both label-free pY-based and global phosphoproteomics7 in 35 primary AML samples (18 FLT3-WT, 17 FLT3-ITD, details provided in Supplemental Digital Table 1, http://links.lww.com/HS/A167) to identify differential phosphorylation underlying response to the FLT3-TKIs gilteritinib and midostaurin.