A novel molecular mechanism of primary resistance to FLT3-kinase inhibitors in AML

Abstract Currently, FLT3 tyrosine kinase inhibitors (TKIs) are emerging as the most promising drug therapy to overcome the dismal prognosis of acute myelogenous leukemia (AML) patients harboring internal tandem duplications (ITDs) of FLT3. However, up-front drug resistance occurs in approximately 30% of patients, and molecular mechanisms of resistance are poorly understood. Here, we have uncovered a novel mechanism of primary resistance to FLT3 TKIs in AML: an FLT3 receptor harboring a nonjuxtamembrane ITD atypically integrating into the β-2 sheet of the first kinase domain (FLT3_ITD627E) induces dramatic up-regulation of the anti-apoptotic myeloid cell leukemia 1 protein (MCL-1). Using RNA…