Acute myeloid leukemia with myelodysplasia-related changes are characterized by a specific molecular pattern with high frequency of ASXL1 mutations

To determine whether the distinct and heterogeneous WHO category called "AML with myelodysplasia-related changes" (MRC-AML), presents specific molecular alterations we searched for mutations in genes known to be mutated in malignant myeloid diseases. In 48 MRC-AML patients analyzed, we found 17 mutations in ASXL1 (35%), eight in RUNX1 (17%), seven in TET2 (15%), 12 in IDH (n = 2) or IDH2 (n = 10) (25%), four in DNMT3A (8%), four in NPM1 (8%), and one in FLT3 (2%). Mutations were more frequent in the intermediate cytogenetic (IC) subgroup of 36 patients than in the unfavorable karyotype subgroup, with an average ratio mutations/patients of 1.36 0-3] vs. 0.33 0-2] (P < 0.001). Then, we compared these 36 patients with IC MRC-AML with a control panel of 37 no-MRC-AML patients, who had both IC and no dysplasia. IC MRC-AMLs were associated with higher incidence of ASXL1 mutations (47% vs. 0%, P < 0.001) and lower incidence of DNMT3A (6% vs. 38%, P = 0.001), NPM1 (11% vs. 62%, P < 0.001) and FLT3 (3% vs. 49%, P < 0.001) mutations. No difference was found in the incidence of IDH1/2 or TET2 mutations according to the presence of dysplasia. Complete remission rate after intensive treatment was lower in the MRC-AML group than in the no-MRC-AML group (48% vs. 78%, P = 0.023) and in wild type NPM1 patients (50% vs. 84%, P = 0.009). Our study showed that MRC-AML as defined in the WHO 2008 classification presents a specific mutation pattern characterized by a high frequency of ASXL1 mutations and a low rate of NPM1, FLT3, and DNMT3A mutations.