Mutations in CCAAT/enhancer binding protein α (CEBPA) are seen in 5% to 14% of acute myeloid leukemia (AML) and have been associated with a favorable clinical outcome. Most AMLs with CEBPA mutations simultaneously carry 2 mutations (CEBPAdouble-mut), usually biallelic, whereas single heterozygous mutations (CEBPAsingle-mut) are less frequently seen. Using denaturing high-performance liquid chromatography and nucleotide sequencing, we identified among a cohort of 598 newly diagnosed AMLs a subset of 41 CEBPA mutant cases (28 CEBPAdouble-mut and 13 CEBPA single-mut cases) CEBPAdouble-mut associated with a unique gene expression profile as well as favorable overall and event-free survival, retained in multi-variable analysis that included cytoge-netic risk, FZT3-ITD and NPM1 mutation, white blood cell count, and age. In contrast, CEBPA single-mut AMLs did not express a discriminating signature and could not be distinguished from wild-type cases as regards clinical outcome. These results demonstrate significant underlying heterogeneity within CEBPA mutation-positive AML with prognostic relevance.

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Erasmus MC: University Medical Center Rotterdam

Wouters, B., Löwenberg, B., Erpelinck, C., van Putten, W., Valk, P., & Delwel, R. (2009). Double CEBPA mutations, but not single CEBPA mutations, define a subgroup of acute myeloid leukemia with a distinctive gene expression profile that is uniquely associated with a favorable outcome. Blood, 113(13), 3088–3091. doi:10.1182/blood-2008-09-179895