Acute myeloid leukemia (AML) carrying NPM1 mutations and cytoplasmic nucleophosmin (NPMc؉ AML) accounts for about one-third of adult AML and shows distinct features, including a unique gene expression profile. MicroRNAs (miRNAs) are small noncoding RNAs of 19 -25 nucleotides in length that have been linked to the development of cancer. Here, we investigated the role of miRNAs in the biology of NPMc؉ AML. The miRNA expression was evaluated in 85 adult de novo AML patients characterized for subcellular localization/ mutation status of NPM1 and FLT3 mutations using a custom microarray platform. Data were analyzed by using univariate t test within BRB tools. We identified a strong miRNA signature that distinguishes NPMc؉ mutated (n ‫؍‬ 55) from the cytoplasmic-negative (NPM1 unmutated) cases (n ‫؍‬ 30) and includes the up-regulation of miR-10a, miR-10b, several let-7 and miR-29 family members. Many of the down-regulated miRNAs including miR-204 and miR-128a are predicted to target several HOX genes. Indeed, we confirmed that miR-204 targets HOXA10 and MEIS1, suggesting that the HOX upregulation observed in NPMc؉ AML may be due in part by loss of HOX regulators-miRNAs. FLT3-ITD؉ samples were characterized by upregulation of miR-155. Further experiments demonstrated that the up-regulation of miR-155 was independent from FLT3 signaling. Our results identify a unique miRNA signature associated with NPMc؉ AML and provide evidence that support a role for miRNAs in the regulation of HOX genes in this leukemia subtype. Moreover, we found that miR-155 was strongly but independently associated with FLT3-ITD mutations. FLT3-ITD ͉ HOX ͉ NPM1A cute myeloid leukemia (AML) arises from multiple and sequential genetic alterations involving hematopoietic precursors (1). In Ϸ25% of cases, specific chromosomal translocations like the t(8;21), inv(16) or t(15;17) represent the initial events leading to malignant transformation (1) and are associated with a good outcome. In contrast, 40-50% of AMLs have normal karyotype by conventional banding analysis and are characterized by great molecular and clinical heterogeneity (2). Recent work has identified novel molecular abnormalities in normal karyotype AML (NK-AML) that has improved the classification and risk stratification of this large subgroup of patients. Among them, internal tandem duplications in the juxta-membrane domain or mutations in the second tyrosine kinase domain (TKD) of the FLT3 gene have been found in 30-45% of NK-AML (3). Both types of mutations constitutively activate FLT3 and FLT3-ITD mutations have been associated with increased risk of relapse (4). Mutations in the myeloid transcription factor CEBPA have been detected in 10-15% of NK-AML (5) and are associated with favorable prognosis (5, 6).Mutations of the nucleophosmin (NPM1) gene, usually occurring at exon-12 (7) and more rarely at exon-11 (8) represent the most common genetic alteration in AML-NK (50-60% of cases) and account for about one-third of all adult AML (7). This gene encodes for a ubiquitously expressed...

Hematopoietic transcription factors are involved in chromosomal translocations, which generate fusion proteins contributing to leukemia pathogenesis. Analysis of patient's primary leukemia blasts revealed that those carrying the t(8;21) generating AML1/ETO, the most common acute myeloid leukemia-associated fusion protein, display low levels of a microRNA-223 (miR-223), a regulator of myelopoiesis. Here, we show that miR-223 is a direct transcriptional target of AML1/ETO. By recruiting chromatin remodeling enzymes at an AML1-binding site on the pre-miR-223 gene, AML1/ETO induces heterochromatic silencing of miR-223. Ectopic miR-223 expression, RNAi against AML1/ETO, or demethylating treatment enhances miR-223 levels and restores cell differentiation. Here, we identify an additional action for a leukemia fusion protein linking the epigenetic silencing of a microRNA locus to the differentiation block of leukemia.

To compare single-agent gemtuzumab ozogamicin (GO) with best supportive care (BSC) including hydroxyurea as first-line therapy in older patients with acute myeloid leukemia unsuitable for intensive chemotherapy. Patients and MethodsIn this trial, patients at least 61 years old were centrally randomized (1:1) to receive either a single induction course of GO (6 mg/m 2 on day 1 and 3 mg/m 2 on day 8) or BSC. Patients who did not progress after GO induction could receive up to eight monthly infusions of the immunoconjugate at 2 mg/m 2 . Randomization was stratified by age, WHO performance score, CD33 expression status, and center. The primary end point was overall survival (OS) by intention-to-treat analysis. ResultsA total of 237 patients were randomly assigned (118 to GO and 119 to BSC). The median OS was 4.9 months (95% CI, 4.2 to 6.8 months) in the GO group and 3.6 months (95% CI, 2.6 to 4.2 months) in the BSC group (hazard ratio, 0.69; 95% CI, 0.53 to 0.90; P = .005); the 1-year OS rate was 24.3% with GO and 9.7% with BSC. The OS benefit with GO was consistent across most subgroups, and was especially apparent in patients with high CD33 expression status, in those with favorable/ intermediate cytogenetic risk profile, and in women. Overall, complete remission (CR [complete remission] + CRi [CR with incomplete recovery of peripheral blood counts]) occurred in 30 of 111 (27%) GO recipients. The rates of serious adverse events (AEs) were similar in the two groups, and no excess mortality from AEs was observed with GO. ConclusionFirst-line monotherapy with low-dose GO, as compared with BSC, significantly improved OS in older patients with acute myeloid leukemia who were ineligible for intensive chemotherapy. No unexpected AEs were identified and toxicity was manageable.J Clin Oncol 34.

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Purpose Cytarabine plays a pivotal role in the treatment of patients with acute myeloid leukemia (AML). Most centers use 7 to 10 days of cytarabine at a daily dose of 100 to 200 mg/m2 for remission induction. Consensus has not been reached on the benefit of higher dosages of cytarabine. Patients and Methods The European Organisation for Research and Treatment of Cancer (EORTC) and Gruppo Italiano Malattie Ematologiche dell' Adulto (GIMEMA) Leukemia Groups conducted a randomized trial (AML-12; Combination Chemotherapy, Stem Cell Transplant and Interleukin-2 in Treating Patients With Acute Myeloid Leukemia) in 1,942 newly diagnosed patients with AML, age 15 to 60 years, comparing remission induction treatment containing daunorubicin, etoposide, and either standard-dose (SD) cytarabine (100 mg/m2 per day by continuous infusion for 10 days) or high-dose (HD) cytarabine (3,000 mg/m2 every 12 hours by 3-hour infusion on days 1, 3, 5, and 7). Patients in complete remission (CR) received a single consolidation cycle containing daunorubicin and intermediate-dose cytarabine (500 mg/m2 every 12 hours for 6 days). Subsequently, a stem-cell transplantation was planned. The primary end point was survival. Results At a median follow-up of 6 years, overall survival was 38.7% for patients randomly assigned to SD cytarabine and 42.5% for those randomly assigned to HD cytarabine (log-rank test P = .06; multivariable analysis P = .009). For patients younger than age 46 years, survival was 43.3% and 51.9%, respectively (P = .009; multivariable analysis P = .003), and for patients age 46 to 60 years, survival was 33.9% and 32.9%, respectively (P = .91). CR rates were 72.0% and 78.7%, respectively (P < .001) and were 75.6% and 82.4% for patients younger than age 46 years (P = .01) and 68.3% and 74.8% for patients age 46 years and older (P = .03). Patients of all ages with very-bad-risk cytogenetic abnormalities and/or FLT3-ITD (internal tandem duplication) mutation, or with secondary AML benefitted from HD cytarabine. Conclusion HD cytarabine produces higher remission and survival rates than SD cytarabine, especially in patients younger than age 46 years.

The Gruppo Italiano Malattie Ematologiche dell'Adulto (GIMEMA) 0496 protocol, through the central handling of bone marrow samples at presentation, allowed us to combine cytogenetic and molecular information on a large series of adults with acute lymphoblastic leukemia (ALL) treated homogeneously, enabling us to define as broadly as possible their genetic profile and to determine the impact on outcome of the cytogenetic-molecular signature. Of 414 patients centrally processed, 325 were considered for the categorization into the following cytogeneticmolecular subgroups: normal, t(9;22)/ BCR-ABL, t(4;11)/MLL-AF4, t(1;19)/E2A-PBX1, 9p/p15-p16 deletions, 6q deletions, miscellaneous structural abnormalities, and hyperdiploid. The inclusion into each subgroup was based on a hierarchical approach: molecular abnormalities with adverse prognosis had precedence over karyotypic changes with less-defined prognosis and the latter over ploidy. Patients without abnormalities and those with isolated 9p/p15-p16 deletions showed a relatively favorable outcome (median disease-free survival [DFS], > 3 years). The t(9;22)/BCR-ABL, t(4;11)/MLL-AF4, t(1; 19)/E2A-PBX1 defined a group with dismal prognosis (median DFS, 7 months), whereas 6q deletions, miscellaneous aberrations, and hyperdiploidy predicted an intermediate prognosis (median DFS, 19 months). This study highlights the importance of a combined cytogenetic-molecular profiling of adult ALL at presentation as a critical independent determinant of their outcome, providing further evidence of the necessity of a risk-adapted therapeutic algorithm for an optimal management of these patients. (Blood. 2005;105: 3434-3441)

Epigenetic alterations of chromatin due to aberrant histone deacetylase (HDAC) activity and transcriptional silencing of all-trans retinoic acid (ATRA) pathway are events linked to the pathogenesis of acute myeloid leukemia (AML) that can be targeted by specific treatments. A pilot study was carried out in eight refractory or high-risk AML patients not eligible for intensive therapy to assess the biological and therapeutic activities of the HDAC inhibitor valproic acid (VPA) used to remodel chromatin, followed by the addition of ATRA, to activate gene transcription and differentiation in leukemic cells. Hyperacetylation of histones H3 and H4 was detectable at therapeutic VPA serum levels (z50 Mg/mL) in blood mononuclear cells from seven of eight patients. This correlated with myelomonocytic differentiation of leukemic cells as revealed by morphologic, cytochemical, immunophenotypic, and gene expression analyses. Differentiation of the leukemic clone was proven by fluorescence in situ hybridization analysis showing the cytogenetic lesion +8 or 7qÀ in differentiating cells. Hematologic improvement, according to established criteria for myelodysplastic syndromes, was observed in two cases. Stable disease and disease progression were observed in five and one cases, respectively. In conclusion, VPA-ATRA treatment is well tolerated and induces phenotypic changes of AML blasts through chromatin remodeling. Further studies are needed to evaluate whether VPA-ATRA treatment by reprogramming differentiation of the leukemic clone might improve the response to chemotherapy in leukemia patients. (Cancer Res 2006; 66(17): 8903-11)

Acute myeloid leukemia (AML) with mutated NPM1 usually carries normal karyotype (NK), but it may harbor chromosomal aberrations whose significance remains unclear. We addressed this question in 631 AML patients with mutated/ cytoplasmic NPM1. An abnormal karyotype (AK) was present in 93 of 631 cases (14.7%), the most frequent abnormalities being ؉8, ؉4, ؊Y, del(9q), ؉21. Chromosome aberrations in NPM1-mutated AML were similar to, but occurred less frequently than additional chromosome changes found in other AML with recurrent cytogenetic abnormalities according to WHO classification. Four of the 31 NPM1-mutated AML patients karyotyped at different time points had NK at diagnosis but AK at relapse: del(9q) (n ‫؍‬ 2), t(2;11) (n ‫؍‬ 1), inv(12) (n ‫؍‬ 1). NPM1-mutated AML with NK or AK showed overlapping morphologic, immunophenotypic (CD34 negativity), and gene expression profile (down-regulation of CD34 and up-regulation of HOX genes). No difference in survival was observed among NPM1-mutated AML patients independently of whether they carried a NK or an AK, the NPM1-mutated/FLT3-ITD negative cases showing the better prognosis. Findings in our patients point to chromosomal aberrations as secondary events, reinforce the concept that NPM1 mutation is a founder genetic lesion, and indicate that NPM1-mutated AML should be clinically handled as one entity, irrespective of the karyotype. (Blood. 2009;114: 3024-3032)