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.

BCR/ABL genes and leukemic phenotype: from molecular mechanisms to clinical correlations.

The Philadelphia chromosome (Ph), a minute chromosome that derives from the balanced translocation between chromosomes 9 and 22, was first described in 1960 and was for a long time the only genetic lesion consistently associated with human cancer. This chromosomal translocation results in the fusion between the 5' part of BCR gene, normally located on chromosome 22, and the 3' part of the ABL gene on chromosome 9 giving origin to a BCR/ABL fusion gene which is transcribed and then translated into a hybrid protein. Three main variants of the BCR/ABL gene have been described, that, depending on the length of the sequence of the BCR gene included, encode for the p190(BCR/ABL), P210(BCR/ABL), and P230(BCR/ABL) proteins. These three main variants are associated with distinct clinical types of human leukemias. Herein we review the data on the correlations between the type of BCR/ABL gene and the corresponding leukemic clinical features. Lastly, drawing on experimental data, we provide insight into the different transforming power of the three hybrid BCR/ABL proteins.