Influence of FLT3‐internal tandem duplication allele burden and white blood cell count on the outcome in patients with intermediate‐risk karyotype acute myeloid leukemia

BACKGROUND: In patients with acute myeloid leukemia (AML), testing for fms‐like tyrosine kinase‐3 ( FLT3 )–internal tandem duplication ( FLT3 ‐ITD) and nucleophosmin‐1 ( NPM1 ) mutations can allow for further prognostic subclassification, but less is known about the effects of FLT3 ‐ITD allele burden and presenting white blood cell count (WBC) within molecular subgroups. METHODS: The authors retrospectively assessed 206 adult patients who had AML with an intermediate‐risk karyotype and who received treatment on a uniform induction and consolidation chemotherapy regimen. RESULTS: The presenting WBC was a prognostic factor for survival only in patients who had an FLT3 ‐ITD mutation. On multivariate analysis, after correcting for age, WBC, secondary AML, and blast percentage, nucleophosmin‐1 ( NPM1 )‐mutated/ FLT3 ‐ITD–negative patients had superior overall survival compared with patients in the other molecular subgroups. Patients who had FLT3 ‐ITD mutations had an inferior overall survival compared with patients who had NPM1 wild‐type/ FLT3 ‐negative disease, and patients who had low or intermediate levels of the FLT‐ITD of mutant allele had overall and disease‐free survival similar to those in patients who had high‐level mutations. CONCLUSIONS: NPM1 and FLT3 ‐ITD status, age, WBC, and secondary AML were identified as important prognostic variables that can help to risk stratify patients with AML who have intermediate‐risk cytogenetics. FLT3 allele burden had no significant influence on outcomes after correcting for other variables. Cancer 2012. © 2012 American Cancer Society.