Age-related prognostic impact of different types of DNMT3A mutations in adults with primary cytogenetically normal acute myeloid leukemia.

PURPOSE

To determine the frequency of DNMT3A mutations, their associations with clinical and molecular characteristics and outcome, and the associated gene- and microRNA-expression signatures in primary cytogenetically normal acute myeloid leukemia (CN-AML).

PATIENTS AND METHODS

Four hundred fifteen previously untreated adults were analyzed for DNMT3A mutations and established prognostic gene mutations and expression markers. Gene- and microRNA-expression profiles were derived using microarrays.

RESULTS

Younger (< 60 years; n = 181) and older (≥ 60 years; n = 234) patients had similar frequencies of DNMT3A mutations (35.3% v 33.3%). Missense mutations affecting arginine codon 882 (R882-DNMT3A) were more common (n = 92; 62%) than those affecting other codons (non-R882-DNMT3A). DNMT3A-mutated patients did not differ regarding complete remission rate, but had shorter disease-free survival (DFS; P = .03) and, by trend, overall survival (OS; P = .07) than DNMT3A-wild-type patients. In multivariable analyses, DNMT3A mutations remained associated with shorter DFS (P = .01), but not with shorter OS. When analyzed separately, the two DNMT3A mutation types had different significance by age group. Younger patients with non-R882-DNMT3A mutations had shorter DFS (P = .002) and OS (P = .02), whereas older patients with R882-DNMT3A mutations had shorter DFS (P = .005) and OS (P = .002) after adjustment for other clinical and molecular prognosticators. Gene- and microRNA-expression signatures did not accurately predict DNMT3A mutational status.

CONCLUSION

DNMT3A mutations are frequent in CN-AML, and their clinical significance seems to be age dependent. DNMT3A-R882 mutations are associated with adverse prognosis in older patients, and non-R882-DNMT3A mutations are associated with adverse prognosis in younger patients. Low accuracy of gene- and microRNA-expression signatures in predicting DNMT3A mutation status suggested that the role of these mutations in AML remains to be elucidated.