Find in Library

The significance of <i>FLT3</i>-ITD in acute promyelocytic leukemia (APL) is not well-established. We performed a bi-center retrospective study of 138 APL patients, 59 (42.8%) of whom had <i>FLT3</i>-ITD. APL patients with <i>FLT3</i>-ITD had higher baseline white blood cell counts (WBCs) (<i>p</i> < 0.001), higher hemoglobin, (<i>p</i> = 0.03), higher aspartate aminotransferase (<i>p</i> = 0.001), lower platelets (<i>p</i> = 0.004), lower fibrinogen (<i>p</i> = 0.003), and higher incidences of disseminated intravascular coagulation (<i>p</i> = 0.005), M3v variant morphology (<i>p</i> < 0.001), and the bcr3 isoform (<i>p</i> < 0.001). <i>FLT3</i>-ITD was associated with inferior post-consolidation complete remission (CR) (<i>p</i> = 0.02) and 5-year overall survival (OS) of 79.7%, compared to 94.4% for <i>FLT3</i>-WT (wild-type) (<i>p</i> = 0.02). <i>FLT3</i>-ITD was strongly associated with baseline WBCs ≥ 25 × 10⁹/L (odds ratio (OR): 54.4; 95% CI: 10.4–286.1; <i>p</i> < 0.001). High <i>FLT3</i>-ITD allelic burdens correlated with high-risk (HR) Sanz scores and high WBCs, with every 1% increase in allelic burden corresponding to a 0.6 × 10⁹/L increase in WBC. HR APL was associated with a 38.5% increase in allelic burden compared with low-risk (LR) APL (95% CI: 19.8–57.2; <i>p</i> < 0.001). Our results provide additional evidence that <i>FLT3</i>-ITD APL is a distinct subtype of APL that warrants further study to delineate potential differences in therapeutic approach.