Article

Biology and outcome of childhood acute megakaryoblastic leukemia: A single institution's experience

Department of Hematology-Oncology, St Jude Children's Research Hospital, Memphis, TN 38105, USA.
Blood (Impact Factor: 10.45). 06/2001; 97(12):3727-32. DOI: 10.1182/blood.V97.12.3727
Source: PubMed

ABSTRACT

To describe the clinical and biologic features of pediatric acute megakaryoblastic leukemia (AMKL) and to identify prognostic factors, experience at St Jude Children's Research Hospital was reviewed. Of 281 patients with acute myeloid leukemia treated over a 14-year period, 41 (14.6%) had a diagnosis of AMKL. Six patients had Down syndrome and AMKL, 6 had secondary AMKL, and 29 had de novo AMKL. The median age of the 22 boys and 19 girls was 23.9 months (range, 6.7-208.9 months). The rate of remission induction was 60.5%, with a 48% rate of subsequent relapse. Patients with Down syndrome had a significantly higher 2-year event-free survival (EFS) estimate (83%) than did other patients with de novo AMKL (14%) or with secondary AMKL (20%; P < or =.038). Among patients who had de novo AMKL without Down syndrome, 2-year EFS was significantly higher after allogeneic bone marrow transplantation (26%) than after chemotherapy alone (0%; P =.019) and significantly higher when performed during remission (46%) than when performed during persistent disease (0%; P =.019). The 5-year survival estimates were significantly lower for de novo AMKL (10%) than for other forms of de novo AML (42%; P <.001). Treatment outcome is very poor for patients with AMKL in the absence of Down syndrome. Remission induction is the most important prognostic factor. Allogeneic transplantation during remission offers the best chance of cure; in the absence of remission, transplantation offers no advantage over chemotherapy alone. (Blood. 2001;97:3727-3732)

Download full-text

Full-text

Available from: Bassem I Razzouk
  • Source
    • "AMegL has a bimodal age distribution with peaks in children age 1–3 and adults in their fifties and sixties [4]. AMegL comprises 3– 10% of all AML cases in children and carries a poor prognosis, except in children with Down Syndrome (DS) whom have an excellent prognosis [5] [6] [7]. In fact, AMegL is the most common form of AML in children with DS and is 400-fold more likely than in other children [7] [8] [9] [10] [11]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Acute megakaryocytic leukemia (AMegL) is a biologically heterogenous subtype of acute myeloid leukemia (AML) that arises from megakaryocytes. Improvements in the accuracy of diagnosing AMegL as well as interest in the molecular analysis of leukemias have led to an increased amount of data available on this rare AML subtype. In this review, we will analyze the diverse molecular features unique to AMegL and how they have influenced the development of novel treatment strategies, including polyploidization. The review will also consider the data available on clinical outcomes in AMegL and how it is a poor individual prognostic factor for AML. Finally, the role of allogeneic hematopoietic stem cell transplant in AMegL will be explored. Copyright © 2015. Published by Elsevier Ltd.
    Preview · Article · Jul 2015 · Blood reviews
  • Source
    • "Particularly children with Down syndrome (DS), i.e. trisomy 21, have a 400-fold increased risk [11] to develop acute megakaryoblastic leukemia (AMKL). Patients with DS-AMKL have an excellent prognosis with 5-year overall survival rates of about 80%, while non-DS-AMKL patients have poor survival rates of only 14% to 34% despite high intensity chemotherapy [12,13]. The molecular mechanisms underlying this AML subtype remain incompletely understood. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background Long non-coding RNAs (lncRNAs) are recognized as pivotal players during developmental ontogenesis and pathogenesis of cancer. The intronic microRNA (miRNA) clusters miR-99a ~ 125b-2 and miR-100 ~ 125b-1 promote progression of acute megakaryoblastic leukemia (AMKL), an aggressive form of hematologic cancers. The function of the lncRNA hostgenes MIR99AHG (alias MONC) and MIR100HG within this ncRNA ensemble remained elusive. Results Here we report that lncRNAs MONC and MIR100HG are highly expressed in AMKL blasts. The transcripts were mainly localized in the nucleus and their expression correlated with the corresponding miRNA clusters. Knockdown of MONC or MIR100HG impeded leukemic growth of AMKL cell lines and primary patient samples. The development of a lentiviral lncRNA vector to ectopically express lncRNAs without perturbing their secondary structure due to improper termination of the viral transcript, allowed us to study the function of MONC independent of the miRNAs in cord blood hematopoietic stem and progenitor cells (HSPCs). We could show that MONC interfered with hematopoietic lineage decisions and enhanced the proliferation of immature erythroid progenitor cells. Conclusions Our study reveals an unprecedented function of lncRNAs MONC and MIR100HG as regulators of hematopoiesis and oncogenes in the development of myeloid leukemia.
    Full-text · Article · Jul 2014 · Molecular Cancer
  • Source
    • "Hence, studies examining the basis for the relative chemotherapy resistance of these subgroups may lead to improvements in therapy. The significantly higher cure rates of DS AMKL patients, who almost uniformly harbor somatic mutations in the GATA1 gene, suggested that GATA1 may play a critical role in chemotherapy response and resistance [3,5–9]. This is also supported by studies which established an association between high expression levels of GATA1 and a poorer prognosis in adult AML [12,13]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: It has been previously shown that acute myeloid leukemia (AML) patients with higher levels of GATA1 expression have poorer outcomes. Furthermore, pediatric Down syndrome (DS) patients with acute megakaryocytic leukemia (AMKL), whose blast cells almost universally harbor somatic mutations in exon 2 of the transcription factor gene GATA1, demonstrate increased overall survival relative to non-DS pediatric patients, suggesting a potential role for GATA1 in chemotherapy response. In this study, we confirmed that amongst non-DS patients, GATA1 transcripts were significantly higher in AMKL blasts compared to blasts from other AML subgroups. Further, GATA1 transcript levels significantly correlated with transcript levels for the anti-apoptotic protein Bcl-xL in our patient cohort. ShRNA knockdown of GATA1 in the megakaryocytic cell line Meg-01 resulted in significantly increased cytarabine (ara-C) and daunorubicin anti-proliferative sensitivities and decreased Bcl-xL transcript and protein levels. Chromatin immunoprecipitation (ChIP) and reporter gene assays demonstrated that the Bcl-x gene (which transcribes the Bcl-xL transcripts) is a bona fide GATA1 target gene in AMKL cells. Treatment of the Meg-01 cells with the histone deacetylase inhibitor valproic acid resulted in down-regulation of both GATA1 and Bcl-xL and significantly enhanced ara-C sensitivity. Furthermore, additional GATA1 target genes were identified by oligonucleotide microarray and ChIP-on-Chip analyses. Our findings demonstrate a role for GATA1 in chemotherapy resistance in non-DS AMKL cells, and identified additional GATA1 target genes for future studies.
    Full-text · Article · Jul 2013 · PLoS ONE
Show more