Favorable Outcome in Patients with Acute Myelogenous Leukemia with the Nucleophosmin Gene Mutation Autografted after Conditioning with High-Dose Continuous Infusion of Idarubicin and Busulfan

Mutations of the nucleophosmin gene (NPM1), in the absence of concurrent FLT3-internal tandem duplication (FLT3-ITD) have impressive prognostic value in patients with acute myelogenous leukemia (AML), carrying normal karyotype (NK). In this study we describe treatment results from a series of 19 patients with NPM+/FLT3− autografted in first complete remission (CR) after conditioning with a regimen, named BuI, based on high-dose continuous infusion of idarubicin and Busulfan. Ninety-nine consecutive patients (median age of 54 years) with NK AML autografted in first CR were analyzed. Nineteen of 99 patients (19%) had NPM1 mutation in the absence of FLT3 mutations. The control group, accounting for 80 patients, included 16 cases (15%) with both mutations, 10 (12%) with FLT3/ITD mutation and no NPM mutation, and 54 (68%) in whom neither NPM1 nor FLT3 mutations were detectable. The median overall survival (OS) for the whole patient population was 34 months, the median disease-free survival (DFS) was 22 months. Median OS and DFS were significantly longer for patients with isolated NPM1 mutation as opposed to controls (OS: not reached versus 25 months, P = .02; DFS: not reached versus 16 months, P = .007, respectively). Of interest, patients with isolated NPM1 mutation had a better outcome in terms of either OS or DFS compared to the group of 16 NMP1+/FLT3+ patients. In conclusion, our study suggest that BuI regimen results in favorable clinical outcome in patients with isolated NPM1 mutation, and could be investigated in a randomized study versus other regimes or repeated courses of high dose cytosine-arabinoside.

Key Words: Acute myeloid leukemia, NPM1 mutations, Autologous transplantation, High-dose idarubicin