Clinical significance of chromatin-spliceosome acute myeloid leukemia: a report from the Northern Italy Leukemia Group (NILG) randomized trial 02/06.

Secondary acute myeloid leukemia (sAML) after myelodysplastic or myeloproliferative disorders is a high-risk category currently identified by clinical history or specific morphological and cytogenetic abnormalities. However, in the absence of these features, uncertainties remain to identify the secondary nature of some cases otherwise defined as de novo AML. To test whether a chromatin-spliceosome (CS) mutational signature might better inform the definition of the de novo AML group, we analyzed a prospective cohort of 413 newly diagnosed AML patients enrolled into a randomized clinical trial (NILG AML 02/06) and provided with accurate cytogenetic and molecular characterization. Among clinically defined de novo AML, 17.6% carried CS mutations (CS-AML) and showed clinical characteristics closer to sAML (older age, lower white blood cell counts and higher rate of multilineage dysplasia). Outcomes in this group were adverse, more similar to those of sAML as compared to de novo AML (overall survival, 30% in CS-AML and 17% in sAML vs 61% in de novo AML, P<0.0001; disease free survival, 26% in CS-AML and 22% in sAML vs 54% of de novo AML, P<0.001) and independently confirmed by multivariable analysis. Allogeneic transplant in first complete remission improved survival in both sAML and CS-AML patients. In conclusion, these findings highlight the clinical significance of identifying CS-AML for improved prognostic prediction and potential therapeutic implications. (NILG AML 02/06: ClinicalTrials.gov Identifier: NCT00495287).

CEBPA-double-mutated acute myeloid leukemia displays a unique phenotypic profile: a reliable screening method and insight into biological features.

Mutations in CCAAT/enhancer binding protein α (CEBPA) occur in 5-10% of cases of acute myeloid leukemia. CEBPA-double-mutated cases usually bear biallelic N- and C-terminal mutations and are associated with a favorable clinical outcome. Identification of CEBPA mutants is challenging because of the variety of mutations, intrinsic characteristics of the gene and technical issues. Several screening methods (fragment-length analysis, gene expression array) have been proposed especially for large-scale clinical use; although efficient, they are limited by specific concerns. We investigated the phenotypic profile of blast and maturing bone marrow cell compartments at diagnosis in 251 cases of acute myeloid leukemia. In this cohort, 16 (6.4%) patients had two CEBPA mutations, whereas ten (4.0%) had a single mutation. First, we highlighted that the CEBPA-double-mutated subset displays recurrent phenotypic abnormalities in all cell compartments. By mutational analysis after cell sorting, we demonstrated that this common phenotypic signature depends on CEBPA-double-mutated multi-lineage involvement. From a multidimensional study of phenotypic data, we developed a classifier including ten core and widely available parameters. The selected markers on blasts (CD34, CD117, CD7, CD15, CD65), neutrophil (SSC, CD64), monocytic (CD14, CD64) and erythroid (CD117) compartments were able to cluster CEBPA-double-mutated cases. In a validation set of 259 AML cases from three independent centers, our classifier showed excellent performance with 100% specificity and 100% sensitivity. We have, therefore, established a reliable screening method, based upon multidimensional analysis of widely available phenotypic parameters. This method provides early results and is suitable for large-scale detection of CEBPA-double-mutated status, allowing gene sequencing to be focused in selected cases.

The human NPM1 mutation A perturbs megakaryopoiesis in a conditional mouse model.

The NPM1 mutation is the most frequent genetic alteration thus far identified in acute myeloid leukemia (AML). Despite progress in the clinical and biological characterization of NPM1-mutated AML, the role of NPM1 mutation in leukemogenesis in vivo has not been fully elucidated. We report a novel mouse model that conditionally expresses the most common human NPM1 mutation (type A) in the hematopoietic compartment. In Npm1-TCTG/WT;Cre(+) mice, the NPM1 mutant localized in the cytoplasm (NPMc(+)) of bone marrow (BM) cells. The mutant mice developed no AML after 1.5-year follow-up. However, NPMc(+) expression determined a significant platelet count reduction and an expansion of the megakaryocytic compartment in the BM and spleen. Serum thrombopoietin levels overlapped in mutant vs control mice, and BM cells from Npm1-TCTG/WT;Cre(+) mice formed more megakaryocytic colonies in vitro. Moreover, we demonstrated the up-regulation of microRNAs (miRNAs; miR-10a, miR-10b, and miR-20a) inhibiting megakaryocytic differentiation along with increased expression of HOXB genes. Notably, these findings mimic those of human NPM1-mutated AML, which also exhibits a similar miRNA profile and expansion of the megakaryocytic compartment. Our mouse model provides evidence that the NPM1 mutant affects megakaryocytic development, further expanding our knowledge of the role of NPM1 mutant in leukemogenesis.

High Throughput Molecular Characterization of Normal Karyotype Acute Myeloid Leukemia in the Context of the Prospective Trial 02/06 of the Northern Italy Leukemia Group (NILG).

By way of a Next-Generation Sequencing NGS high throughput approach, we defined the mutational profile in a cohort of 221 normal karyotype acute myeloid leukemia (NK-AML) enrolled into a prospective randomized clinical trial, designed to evaluate an intensified chemotherapy program for remission induction. NPM1, DNMT3A, and FLT3-ITD were the most frequently mutated genes while DNMT3A, FLT3, IDH1, PTPN11, and RAD21 mutations were more common in the NPM1 mutated patients (p < 0.05). IDH1 R132H mutation was strictly associated with NPM1 mutation and mutually exclusive with RUNX1 and ASXL1. In the whole cohort of NK-AML, no matter the induction chemotherapy used, by multivariate analysis, the achievement of complete remission was negatively affected by the SRSF2 mutation. Alterations of FLT3 (FLT3-ITD) and U2AF1 were associated with a worse overall and disease-free survival (p < 0.05). FLT3-ITD positive patients who proceeded to alloHSCT had a survival probability similar to FLT3-ITD negative patients and the transplant outcome was no different when comparing high and low-AR-FLT3-ITD subgroups in terms of both OS and DFS. In conclusion, a comprehensive molecular profile for NK-AML allows for the identification of genetic lesions associated to different clinical outcomes and the selection of the most appropriate and effective treatment strategies, including stem cell transplantation and targeted therapies.

Randomized trial comparing standard vs sequential high-dose chemotherapy for inducing early CR in adult AML.

Here we evaluated whether sequential high-dose chemotherapy (sHD) increased the early complete remission (CR) rate in acute myelogenous leukemia (AML) compared with standard-intensity idarubicin-cytarabine-etoposide (ICE) chemotherapy. This study enrolled 574 patients (age, 16-73 years; median, 52 years) who were randomly assigned to ICE (n = 286 evaluable) or sHD (2 weekly 3-day blocks with cytarabine 2 g/m2 twice a day for 2 days plus idarubicin; n = 286 evaluable). Responsive patients were risk-stratified for a second randomization. Standard-risk patients received autograft or repetitive blood stem cell-supported high-dose courses. High-risk patients (and standard-risk patients not mobilizing stem cells) underwent allotransplantation. CR rates after 2 induction courses were comparable between ICE (80.8%) and sHD (83.6%; P = .38). sHD yielded a higher single-induction CR rate (69.2% vs 81.5%; P = .0007) with lower resistance risk (P < .0001), comparable mortality (P = .39), and improved 5-year overall survival (39% vs 49%; P = .045) and relapse-free survival (36% vs 48%; P = .028), despite greater hematotoxicity delaying or reducing consolidation blocks. sHD improved the early CR rate in high-risk AML (odds ratio, 0.48; 95% confidence interval [CI], 0.31-0.74; P = .0008) and in patients aged 60 years and less with de novo AML (odds ratio, 0.46; 95% CI, 0.27-0.78; P = .003), and also improved overall/relapse-free survival in the latter group (hazard ratio, 0.70; 95% CI, 0.52-0.94; P = .01), in standard-risk AML, and postallograft (hazard ratio, 0.61; 95% CI, 0.39-0.96; P = .03). sHD was feasible, effectively achieved rapid CR, and improved outcomes in AML subsets. This study is registered at www.clinicaltrials.gov as #NCT00495287.

Simple, rapid and accurate molecular diagnosis of acute promyelocytic leukemia by loop mediated amplification technology.

The diagnostic work-up of acute promyelocytic leukemia (APL) includes the cytogenetic demonstration of the t(15;17) translocation and/or the PML-RARA chimeric transcript by RQ-PCR or RT-PCR. This latter assays provide suitable results in 3-6 hours. We describe here two new, rapid and specific assays that detect PML-RARA transcripts, based on the RT-QLAMP (Reverse Transcription-Quenching Loop-mediated Isothermal Amplification) technology in which RNA retrotranscription and cDNA amplification are carried out in a single tube with one enzyme at one temperature, in fluorescence and real time format. A single tube triplex assay detects bcr1 and bcr3 PML-RARA transcripts along with GUS housekeeping gene. A single tube duplex assay detects bcr2 and GUSB. In 73 APL cases, these assays detected in 16 minutes bcr1, bcr2 and bcr3 transcripts. All 81 non-APL samples were negative by RT-QLAMP for chimeric transcripts whereas GUSB was detectable. In 11 APL patients in which RT-PCR yielded equivocal breakpoint type results, RT-QLAMP assays unequivocally and accurately defined the breakpoint type (as confirmed by sequencing). Furthermore, RT-QLAMP could amplify two bcr2 transcripts with particularly extended PML exon 6 deletions not amplified by RQ-PCR. RT-QLAMP reproducible sensitivity is 10(-3) for bcr1 and bcr3 and 10(-)2 for bcr2 thus making this assay particularly attractive at diagnosis and leaving RQ-PCR for the molecular monitoring of minimal residual disease during the follow up. In conclusion, PML-RARA RT-QLAMP compared to RT-PCR or RQ-PCR is a valid improvement to perform rapid, simple and accurate molecular diagnosis of APL.