[Prognostic significance of early assessment of minimal residual disease in acute myeloid leukemia with mutated NPM1 patients].

Objective: To explore prognostic significance of early assessment of minimal residual leukemia (MRD) in adult patients with de novo acute myeloid leukemia (AML) with mutated NPM1. Methods: The response, NPM1 mutated transcript level after induction chemotherapy and the first 2 cycles of consolidation chemotherapy, disease-free survival (DFS) and overall survival (OS) in 137 patients with AML with NPM1 mutations of A, B and D were retrospectively analyzed. Results: Data of 137 patients were collected, 67 were male, the median age was 49 years (16-67 years) , 107 (78.1%) had normal karyotype, 57 (41.6%) had positive FLT3-ITD mutation, the median NPM1 mutated transcript level at diagnosis was 84.1%. Among the 134 evaluable patients, 115 (85.8%) achieved a complete remission (CR) . Multivariate analyses revealed that WBC<100×10(9)/L ( OR =0.3, 95% CI 0.1-0.9, P =0.027) and first induction therapy with "IA10" protocol ( OR =0.3, 95% CI 0.1-0.8, P =0.015) were factors associated with achieving a CR. With a median follow-up period of 24 months (range, 2 to 91 months) in 77 survived CR patients, the probabilities of DFS and OS at 3 years were 48.0% and 63.9%, respectively. Multivariate analyses showed that positive FLT3-ITD ( HR =3.2, 95% CI 1.6-6.7, P =0.002) , high MRD level after 2 cycles of consolidation chemotherapy (NPM1 mutation transcript level <3-log reduction from the individual baseline, HR =23.2, 95% CI 7.0-76.6, P <0.001) and chemotherapy or autologous hematopoietic stem cell transplantation (auto-HSCT) rather than allogeneic HSCT (allo-HSCT) ( HR =2.6, 95% CI 1.0-6.6, P =0.045) were the unfavorable factors affecting DFS, high MRD level at the time of achieving the first CR (NPM1 mutation transcript level <2-log reduction from the individual baseline, OR =2.5, 95% CI 1.0-6.1, P =0.040) and after 2 cycles of consolidation chemotherapy ( HR =4.5, 95% CI 2.0-10.3, P <0.001) were the unfavorable factors affecting OS. Furthermore, DFS and OS rates at 3 years in those receiving chemotherapy or auto-HSCT were 39.7% and 59.1%, respectively; positive FLT3-ITD and high MRD level after 2 cycles of consolidation chemotherapy were independent factors associated with both shorter DFS ( HR =3.5, 95% CI 1.6-7.6, P =0.002 and HR =8.9, 95% CI 3.8-20.7, P <0.001) and OS ( HR =2.7, 95% CI 1.1-6.9, P =0.036 and HR =3.1, 95% CI 1.2-8.0, P =0.021) ; meanwhile, high MRD level at the time of achieving the first CR associated with shorter OS ( HR =3.1, 95% CI 1.2-8.0, P =0.022) . Conclusion: Positive FLT3-ITD mutation and high MRD level after induction or consolidation chemotherapy associated with poor outcomes in AML patients with mutated NPM1.