FLT3 and acute myeloid leukemia: In contrast to the mutual exclusivity of FLT3-ITD and D835 mutations seen in de novo AML (TCGA dataset), 35% of patients in TKI-naive postchemotherapy group and 51.4% of pre-TKI patients in the current cohort harbored both FLT3-ITD and D835 mutations26, suggesting that both chemotherapy and type II FLT3 inhibitor treatment could select drug-resistant FLT3 TKD clones.