Clinicopathologic and genetic characterization of nonacute NPM1-mutated myeloid neoplasms

Abstract

NPM1-mutated myeloid neoplasms (NPM1+ MNs) with <20% blood or bone marrow blasts are rare and have been previously shown in limited case series to exhibit an aggressive clinical course. We assembled the largest cohort of NPM1+ MN cases to date (n = 45) and compared it with NPM1- MN (n = 95) and NPM1+ de novo acute myeloid leukemia (AML; n = 119) patients. Compared with NPM1- MN, NPM1+ MN were associated with younger age (P = .007), a normal karyotype (P < .0001; noninternal tandem duplication, P = .01) were less frequent in NPM1+ MN than in NPM1+ AML. In multivariable analyses performed in patients with myelodysplastic syndrome only, total mutation count (hazard ratio [HR], 1.3; P = .05), NPM1 mutation (HR, 3.6; P = .02), TP53 mutation (HR, 5.2; P = .01), and higher International Prognostic Scoring System-R score (HR, 1.7; P = .0003) were independently associated with shorter overall survival, whereas stem cell transplant conferred a favorable effect (HR, 0.1; P < .0001). These data suggest that NPM1+ MN are biologically distinct from NPM1- MN. Similar to NPM1+ AML, patients with NPM1-mutated myelodysplastic syndrome may benefit from more intensive therapeutic regimens.