OBJECTIVETo examine the incidence and clinical significance of NPM1 mutations in childhood acute myeloid leukemia (AML) patients.

METHODSNPM1 mutations of 70 newly diagnosed childhood AML were detected by high resolution melting (HRM) analysis on the LightCycler 480. The incidence and clinical significance were analyzed.

RESULTSNPM1 mutations were identified in 32 (45.7%) of the 70 AML children. There was no significant difference in clinical characteristics between patients with or without NPM1 mutation, but patients with NPM1 mutation had a higher platelet count (P = 0.013). There was also no significant difference in NPM1 mutation between normal and abnormal karyotype groups. In AML-ETO or PML-RARα positive groups, the incidence of NPM1 mutations was significant lower (P = 0.048). There was no significant difference in response rates after induction therapy (P = 0.217), but the complete remission (CR) rate was higher in the NPM1-mutated group (81.3%). There was a trend toward higher event-free survival (EFS) and overall survival (OS) rates in the NPM1 mutated patients than that in wild NPM1 patients (EFS = 53.8% vs 41.4%, OS = 52.7% vs 39.2%), but the difference was not statistically significant (P = 0.374 and 0.380).

CONCLUSIONNPM1 mutations were relatively common in our cohort of AML patients. There was no significant difference in clinical characteristics between patients with and without NPM1 mutation. The NPM1 mutation patients group seemed to have better therapy response, but the difference was not statistically significant.