EZH2 mutational status predicts poor survival in myelofibrosis

Guglielmelli, P., Biamonte, F., Score, J., Hidalgo-Curtis, C., Cervantes, F., Maffioli, M., Fanelli, T., Ernst, T., Winkelman, N., Jones, A. V., Zoi, K., Reiter, A., Duncombe, A., Villani, L., Bosi, A., Barosi, G., Cross, N. C. P. and Vannucchi, A. M. (2011) EZH2 mutational status predicts poor survival in myelofibrosis. Blood, 118 (19), 5227-5234. (doi:10.1182/blood-2011-06-363424).

Abstract

We genotyped 370 subjects with primary myelofibrosis (PMF) and 148 with postpolycythemia vera/postessential thrombocythemia (PPV/PET) MF for mutations of EZH2. Mutational status at diagnosis was correlated with hematologic parameters, clinical manifestations, and outcome. A total of 25 different EZH2 mutations were detected in 5.9% of PMF, 1.2% of PPV-MF, and 9.4% of PET-MF patients; most were exonic heterozygous missense changes. EZH2 mutation coexisted with JAK2V617F or ASXL1 mutation in 12 of 29 (41.4%) and 6 of 27 (22.2%) evaluated patients; TET2 and CBL mutations were found in 2 and 1 patients, respectively. EZH2-mutated PMF patients had significantly higher leukocyte counts, blast-cell counts, and larger spleens at diagnosis, and most of them (52.6%) were in the high-risk International Prognostic Score System (IPSS) category. After a median follow-up of 39 months, 128 patients (25.9%) died, 81 (63.3%) because of leukemia. Leukemia-free survival (LFS) and overall survival (OS) were significantly reduced in EZH2-mutated PMF patients (P = .028 and P < .001, respectively); no such impact was seen for PPV/PET-MF patients, possibly due to the low number of mutated cases. In multivariate analysis, survival of PMF patients was predicted by IPSS high-risk category, a < 25% JAK2V617F allele burden, and EZH2 mutation status. We conclude that EZH2 mutations are independently associated with shorter survival in patients with PMF.

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Contributors

Author: N. C. P. Cross

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