Prognostic impact of WT1 mutations in cytogenetically normal acute myeloid leukemia: a study of the German-Austrian AML Study Group.

To evaluate the incidence and clinical impact of WT1 gene mutations in younger adult patients with cytogenetically normal acute myeloid leukemia (CN-AML), sequencing of the complete coding region was performed in diagnostic samples from 617 patients who were treated on 3 German-Austrian AML Study Group protocols. WT1 mutations were identified in 78 (12.6%) of the 617 patients; mutations clustered in exon 7 (54 of 78) and exon 9 (13 of 78), but also occurred in exons 1, 2, 3, and 8.

Gene mutations and response to treatment with all-trans retinoic acid in elderly patients with acute myeloid leukemia. Results from the AMLSG Trial AML HD98B.

Background: In a previous randomized trial, AML HD98B, we showed that administration of all-trans retinoic acid in addition to intensive chemotherapy improved the outcome of older patients with acute myeloid leukemia. The objectives of this study were to evaluate the prognostic impact of gene mutations and to identify predictive genetic factors for the all-trans retinoic acid treatment effect.

Design And Methods: Data from mutation analyses of the NPM1, CEBPA, FLT3, and MLL genes were correlated with outcome in patients 61 years and older treated within the AML HD98B trial.

Stem cell transplantation in children: how to design a new study.

In contrast to adults, 50% or more of medicines used in children have never been actually studied in the paediatric population in the European Union community (EU). Under the impression that compliance with good clinical practice (GCP) requirements will lead to an improved quality of clinical trials, the ratification of the EU Directive 2001/20/EG now imposes the same GCP regulations demanded for commercial clinical trials on non-commercial trials or so-called investigator-initiated trials (IITs). Although it is desirable that all clinical trials comply with ICH-GCP, ensuring that an IIT conforms creates a significant burden for the principal investigator, turning an IIT into a substantial logistic, administrative and financial enterprise.

Mutations and treatment outcome in cytogenetically normal acute myeloid leukemia.

Background: Mutations occur in several genes in cytogenetically normal acute myeloid leukemia (AML) cells: the nucleophosmin gene (NPM1), the fms-related tyrosine kinase 3 gene (FLT3), the CCAAT/enhancer binding protein alpha gene (CEPBA), the myeloid-lymphoid or mixed-lineage leukemia gene (MLL), and the neuroblastoma RAS viral oncogene homolog (NRAS). We evaluated the associations of these mutations with clinical outcomes in patients.

Methods: We compared the mutational status of the NPM1, FLT3, CEBPA, MLL, and NRAS genes in leukemia cells with the clinical outcome in 872 adults younger than 60 years of age with cytogenetically normal AML.

Gene-expression profiling identifies distinct subclasses of core binding factor acute myeloid leukemia.

Core binding factor (CBF) leukemias, characterized by either inv(16)/t(16;16) or t(8;21), constitute acute myeloid leukemia (AML) subgroups with favorable prognosis. However, there exists substantial biologic and clinical heterogeneity within these cytogenetic groups that is not fully reflected by the current classification system. To improve the molecular characterization we profiled gene expression in a large series (n = 93) of AML patients with CBF leukemia [(inv (16), n = 55; t(8;21), n = 38)].

JAK2V617F mutations as cooperative genetic lesions in t(8;21)-positive acute myeloid leukemia.

Significant progress has been made in identifying genetic lesions that are causally implicated in the pathogenesis of acute myeloid leukemia (AML). These insights improve our understanding of the genetic basis of the disease, a prerequisite for the development of novel therapeutic approaches.

Stem cell transplantation in children with infantile osteopetrosis is associated with a high incidence of VOD, which could be prevented with defibrotide.

Malignant infantile osteopetrosis (MIOP) is a rare hereditary disorder of osteoclast function, which can be reversed by hematopoietic stem cell transplantation (SCT). We observed a high incidence of hepatic veno-occlusive disease (VOD) in transplanted patients and explored the prevention of this complication by using defibrotide (DF) as a prophylaxis. Twenty children with MIOP were consecutively transplanted in our center between 1996 and 2005.

Newly identified c-KIT receptor tyrosine kinase ITD in childhood AML induces ligand-independent growth and is responsive to a synergistic effect of imatinib and rapamycin.

Activating mutations of c-KIT lead to ligand-independent growth. Internal tandem duplications (ITDs) of exon 11, which encodes the juxtamembrane domain (JMD), are constitutively activating mutations found in 7% of gastrointestinal stromal tumors (GISTs) but have not been described in childhood acute myeloid leukemia (AML). DNA and cDNA from 60 children with AML were screened by polymerase chain reaction (PCR) for mutations of the JMD.

Organisational learning and self-adaptation in dynamic disaster environments.

This paper examines the problems associated with inter-organisational learning and adaptation in the dynamic environments that characterise disasters. The research uses both qualitative and quantitative methods to investigate whether organisational learning took place during and in the time in between five disaster response operations in Turkey. The availability of information and its exchange and distribution within and among organisational actors determine whether self-adaptation happens in the course of a disaster response operation.

Mutant nucleophosmin (NPM1) predicts favorable prognosis in younger adults with acute myeloid leukemia and normal cytogenetics: interaction with other gene mutations.

To assess the prognostic relevance of mutations in the NPM1 gene encoding a nucleocytoplasmic shuttle protein in younger adults with acute myeloid leukemia (AML) and normal cytogenetics, sequencing of NPM1 exon 12 was performed in diagnostic samples from 300 patients entered into 2 consecutive multicenter trials of the AML Study Group (AMLSG). Treatment included intensive double-induction therapy and consolidation therapy with high cumulative doses of high-dose cytarabine. NPM1 mutations were identified in 48% of the patients including 12 novel sequence variants, all leading to a frameshift in the C-terminus of the nucleophosmin 1 (NPM1) protein.

Gemtuzumab ozogamicin (Mylotarg) in children with refractory or relapsed acute myeloid leukemia.

Background: Gemtuzumab ozogamicin (GO) is an immunoconjugate consisting of the CD33 antibody and calicheamicin, a potent cytotoxic agent. Developed for targeted treatment of CD33-positive AML, studies in adults showed its efficacy in relapsed and refractory AML.

Patients And Method: We report 12 children with multiple relapsed or refractory AML receiving GO as compassionate use.

Critical role for Kit-mediated Src kinase but not PI 3-kinase signaling in pro T and pro B cell development.

The Kit receptor functions in hematopoiesis, lymphocyte development, gastrointestinal tract motility, melanogenesis, and gametogenesis. To investigate the roles of different Kit signaling pathways in vivo, we have generated knock-in mice in which docking sites for PI 3-kinase (KitY719) or Src kinase (KitY567) have been mutated. Whereas steady-state hematopoiesis is normal in KitY719F/Y719F and KitY567F/Y567F mice, lymphopoiesis is affected differentially.

Defibrotide in the treatment of children with veno-occlusive disease (VOD): a retrospective multicentre study demonstrates therapeutic efficacy upon early intervention.

Veno-occlusive disease (VOD) of the liver is a complication observed particularly in patients undergoing hematopoietic stem cell transplantation (HSCT). Defibrotide (DF) is a polydeoxyribonucleotide with aptameric activity on endothelium. We evaluated in a retrospective analysis the efficacy of DF in pediatric patients developing hepatic VOD after HSCT.

Gastrointestinal stromal tumors in a mouse model by targeted mutation of the Kit receptor tyrosine kinase.

Oncogenic Kit mutations are found in somatic gastrointestinal (GI) stromal tumors (GISTs) and mastocytosis. A mouse model for the study of constitutive activation of Kit in oncogenesis has been produced by a knock-in strategy introducing a Kit exon 11-activating mutation into the mouse genome based on a mutation found in a case of human familial GIST syndrome. Heterozygous mutant KitV558Delta/+ mice develop symptoms of disease and eventually die from pathology in the GI tract.

Induction of long-term remission of a relapsed childhood B-acute lymphoblastic leukemia with rituximab chimeric anti-CD20 monoclonal antibody and autologous stem cell transplantation.

Childhood B-cell neoplasms account for approximately 2% of childhood acute lymphoblastic leukemia (ALL). The short but intensive chemotherapy yields a currently 75% to 85% event-free survival. The prognosis for children with relapsed disease is considered to be dismal.

Nonmyeloablative allogeneic hematopoietic stem cell transplantation for treatment of Dyskeratosis congenita.

We describe the treatment of a 10-year-old girl with autosomal recessive Dyskeratosis congenita (DC), neutropenia, thrombocytopenia and combined immunodeficiency by nonmyeloablative hematopoietic stem cell transplantation. The conditioning regimen consisted of fludarabine 30 mg/m(2)/day (days -5, -4, -3) and 2 Gy TBI (0.07 Gy/min; day 0).

Gemtuzumab ozogamicin: first clinical experiences in children with relapsed/refractory acute myeloid leukemia treated on compassionate-use basis.

Gemtuzumab ozogamicin (GO; Mylotarg) was developed to treat CD33(+) acute myeloid leukemia (AML). To date, only studies in adults and preliminary data from a phase 1 study in children have been reported. We report data on 15 children with relapsed/refractory CD33(+) AML who were treated with GO monotherapy on compassionate use basis (4-9 mg/m(2) up to 3 courses).

Serum granulocyte colony-stimulating factor levels are not increased in patients with autoimmune neutropenia of infancy.

Objective: To assess the role of granulocyte colony-stimulating factor (G-CSF) in autoimmune neutropenia (AIN).

Design: Serum G-CSF levels were measured in 57 children with AIN. Two different G-CSF-dependent assays were used: a solid-phase "sandwich" enzyme-linked immunosorbent assay and a proliferation assay.

Downregulation of c-kit expression in human endothelial cells by inflammatory stimuli.

In recent studies we have shown that the expression of stem cell factor (SCF) in human endothelial cells is regulated by inflammatory processes. Gram-negative bacteria, interleukin-1 (IL-1), and lipopolysaccharide were able to upregulate the expression of SCF in human umbilical vein endothelial cells (HUVEC) (Blood 83:2836, 1994). Interestingly enough c-kit, the receptor of SCF, is coexpressed on HUVEC, suggesting an autoregulatory mechanism.

Effects of bone marrow fibroblasts on the proliferation and differentiation of myeloid leukemic cell lines.

The effects of normal bone marrow fibroblasts (BM FB) on proliferation and differentiation of 10 myeloid leukemic cell lines were investigated in a serum-free co-culture system. The proliferation of three of the cell lines was supported by BM FB. Three of the myeloid cell lines were inhibited 40-70%.

Differential regulation of stem cell factor mRNA expression in human endothelial cells by bacterial pathogens: an in vitro model of inflammation.

Production of hematopoietic growth factors by endothelial cells plays a pivotal role during inflammatory processes. Stem cell factor (SCF) is known to be expressed constitutively in endothelial cells. To investigate the regulation of this cytokine expression by inflammatory stimuli, we cocultured human umbilical vein endothelial cells (HUVEC) with various gram-negative bacterial strains (Escherichia coli, Yersinia enterocolitica, Chlamydia trachomatis, and Neisseria meningitidis, respectively).

Regulation of the density of the stem cell factor receptor (c-kit) by tumor necrosis factor alpha on a human myeloid cell line.

The GM/SO cell line bears a high level of stem cell factor receptors (SCF-R) i.e. c-kit protein, and therefore constitutes a potential model for studying the regulation of this crucial receptor on myeloid cells.