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Biomedical subjects

Daniel J DeAngelo

Publications and source records attributed to Daniel J DeAngelo.

At least 19 recordsLinked to original sources
PubMed2006

Chromosome 5q deletion and epigenetic suppression of the gene encoding alpha-catenin (CTNNA1) in myeloid cell transformation.

Interstitial loss of all or part of the long arm of chromosome 5, or del(5q), is a frequent clonal chromosomal abnormality in human myelodysplastic syndrome (MDS, a preleukemic disorder) and acute myeloid leukemia (AML), and is thought to contribute to the pathogenesis of these diseases by deleting one or more tumor-suppressor genes. Although a major commonly deleted region (CDR) has been delineated on chromosome band 5q31.1 (refs. 3-7), attempts to identify tumor suppressors within this band have been unsuccessful. We focused our analysis of gene expression on RNA from primitive leukemia-initiating cells, which harbor 5q deletions, and analyzed 12 genes within the CDR that are expressed by normal hematopoietic stem cells. Here we show that the gene encoding alpha-catenin (CTNNA1) is expressed at a much lower level in leukemia-initiating stem cells from individuals with AML or MDS with a 5q deletion than in individuals with MDS or AML lacking a 5q deletion or in normal hematopoietic stem cells. Analysis of HL-60 cells, a myeloid leukemia line with deletion of the 5q31 region, showed that the CTNNA1 promoter of the retained allele is suppressed by both methylation and histone deacetylation. Restoration of CTNNA1 expression in HL-60 cells resulted in reduced proliferation and apoptotic cell death. Thus, loss of expression of the alpha-catenin tumor suppressor in hematopoietic stem cells may provide a growth advantage that contributes to human MDS or AML with del(5q).

Acute Disease↗
PubMed2006

Gemtuzumab ozogamicin-associated sinusoidal obstructive syndrome (SOS): an overview from the research on adverse drug events and reports (RADAR) project.

Gemtuzumab ozogamicin (GO) was approved for marketing in 2000 by the United States Food and Drug Administration (FDA) for older patients with relapsed acute myeloid leukemia (AML). Four months later, 14 phase II clinical trial participants who received novel GO-containing combination chemotherapy regimens developed an unexpected hepatic toxicity termed sinusoidal obstructive syndrome (SOS) or hepatic veno-occlusive disease (VOD). Investigators associated with the Research on Adverse Drug Events and Reports (RADAR) project reviewed safety reports for GO included in reports of clinical trials and observational studies, interim reports from an FDA mandated Prospective Observational Registry, and the Food and Drug Administration's Adverse Event Reporting System. Medline searches provided incidence estimates of GO-associated SOS and comparative rates of SOS without GO. SOS is characterized by hyperbilirubinemia, painful hepatomegaly, ascites, and sudden weight gain developing at a median of 10 days following GO administration for patients who did not undergo an allogeneic SCT procedure and 13 days following an allogeneic SCT for patients who had previously received GO. Among adult AML patients who received GO in clinical trials, SOS incidence was 3% at doses < or =6 mg/m(2) if administered as monotherapy or in combination with non-hepatotoxic agents versus 28% if administered with thioguanine and 15% when administered as monotherapy at a dose of 9 mg/m(2). Observational studies identified SOS rates between 15% and 40% if an SCT is performed within 3 months of GO administration. The FDA mandated Prospective Observational Registry of patients who receive care at 60 medical centers has identified GO-associated SOS rates of 14% if an SCT is performed and 9% otherwise. Caution is advised when administering GO in routine clinical practice, particularly if administered with other hepatotoxic agents, at doses and schedules more intensive than those approved by the FDA, or within 3 months of a SCT procedure.

Acute Disease↗
PubMed2006

Phase 1 clinical results with tandutinib (MLN518), a novel FLT3 antagonist, in patients with acute myelogenous leukemia or high-risk myelodysplastic syndrome: safety, pharmacokinetics, and pharmacodynamics.

Tandutinib (MLN518/CT53518) is a novel quinazoline-based inhibitor of the type III receptor tyrosine kinases: FMS-like tyrosine kinase 3 (FLT3), platelet-derived growth factor receptor (PDGFR), and KIT. Because of the correlation between FLT3 internal tandem duplication (ITD) mutations and poor prognosis in acute myelogenous leukemia (AML), we conducted a phase 1 trial of tandutinib in 40 patients with either AML or high-risk myelodysplastic syndrome (MDS). Tandutinib was given orally in doses ranging from 50 mg to 700 mg twice daily The principal dose-limiting toxicity (DLT) of tandutinib was reversible generalized muscular weakness, fatigue, or both, occurring at doses of 525 mg and 700 mg twice daily. Tandutinib's pharmacokinetics were characterized by slow elimination, with achievement of steady-state plasma concentrations requiring greater than 1 week of dosing. Western blotting showed that tandutinib inhibited phosphorylation of FLT3 in circulating leukemic blasts. Eight patients had FLT3-ITD mutations; 5 of these were evaluable for assessment of tandutinib's antileukemic effect. Two of the 5 patients, treated at 525 mg and 700 mg twice daily, showed evidence of antileukemic activity, with decreases in both peripheral and bone marrow blasts. Tandutinib at the MTD (525 mg twice daily) should be evaluated more extensively in patients with AML with FLT3-ITD mutations to better define its antileukemic activity.

Administration, Oral↗
PubMed2006

Impact of conditioning regimen intensity on outcome of allogeneic hematopoietic cell transplantation for advanced acute myelogenous leukemia and myelodysplastic syndrome.

We reviewed 136 patients with advanced acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS) undergoing allogeneic transplantation to assess the impact of conditioning regimen intensity on outcome. Thirty-nine patients receiving nonmyeloablative stem cell transplantation (NST) were compared with 97 patients receiving myeloablative transplantation. Patients receiving NST were at high risk for treatment-related complications given that they were older, 57 vs 43 years (P < .001), and more likely had received previous or myeloablative transplantation (54% vs 2%; P < .0001). The cumulative risk of relapse was higher for patients after NST (61% vs 38%; P = .02). The 100-day mortality was less after NST (15% vs 32%) Overall survival (OS) at 2 years was 28% for NST and 34% for myeloablative transplantation (P = .89). Progression-free survival (PFS) at 2 years was 20% for NST and 31% for myeloablative transplantation (P = .31). Cox regression analysis showed that the intensity of the conditioning regimen had no effect on either OS or PFS. Despite the high-risk features of patients with advanced AML or MDS undergoing NST, OS and PFS in these patients was similar to those in patients receiving myeloablative transplantation. These results demonstrate that dose intensity plays a significant role in control of disease after transplantation, but that this benefit is negated by increasing treatment-related mortality. These results suggest that NST is a reasonable alternative for patients with advanced AML and MDS at high risk for complications after myeloablative transplantation.

Acute Disease↗
PubMed2006

MPLW515L is a novel somatic activating mutation in myelofibrosis with myeloid metaplasia.

BACKGROUND: The JAK2V617F allele has recently been identified in patients with polycythemia vera (PV), essential thrombocytosis (ET), and myelofibrosis with myeloid metaplasia (MF). Subsequent analysis has shown that constitutive activation of the JAK-STAT signal transduction pathway is an important pathogenetic event in these patients, and that enzymatic inhibition of JAK2V617F may be of therapeutic benefit in this context. However, a significant proportion of patients with ET or MF are JAK2V617F-negative. We hypothesized that activation of the JAK-STAT pathway might also occur as a consequence of activating mutations in certain hematopoietic-specific cytokine receptors, including the erythropoietin receptor (EPOR), the thrombopoietin receptor (MPL), or the granulocyte-colony stimulating factor receptor (GCSFR). METHODS AND FINDINGS: DNA sequence analysis of the exons encoding the transmembrane and juxtamembrane domains of EPOR, MPL, and GCSFR, and comparison with germline DNA derived from buccal swabs, identified a somatic activating mutation in the transmembrane domain of MPL (W515L) in 9% (4/45) of JAKV617F-negative MF. Expression of MPLW515L in 32D, UT7, or Ba/F3 cells conferred cytokine-independent growth and thrombopoietin hypersensitivity, and resulted in constitutive phosphorylation of JAK2, STAT3, STAT5, AKT, and ERK. Furthermore, a small molecule JAK kinase inhibitor inhibited MPLW515L-mediated proliferation and JAK-STAT signaling in vitro. In a murine bone marrow transplant assay, expression of MPLW515L, but not wild-type MPL, resulted in a fully penetrant myeloproliferative disorder characterized by marked thrombocytosis (Plt count 1.9-4.0 x 10(12)/L), marked splenomegaly due to extramedullary hematopoiesis, and increased reticulin fibrosis. CONCLUSIONS: Activation of JAK-STAT signaling via MPLW515L is an important pathogenetic event in patients with JAK2V617F-negative MF. The bone marrow transplant model of MPLW515L-mediated myeloproliferative disorders (MPD) exhibits certain features of human MF, including extramedullary hematopoiesis, splenomegaly, and megakaryocytic proliferation. Further analysis of positive and negative regulators of the JAK-STAT pathway is warranted in JAK2V617F-negative MPD.

Amino Acid Substitution↗
PubMed2005

Failure to define window of time for autologous tumor vaccination in patients with newly diagnosed or relapsed acute lymphoblastic leukemia.

OBJECTIVES: We and others have shown that B cell precursor acute lymphoblastic leukemia cells (ALL) stimulated with CD40 ligand become efficient antigen-presenting cells (APC) capable of expanding autologous, tumor-specific T cells from patients. Translation of these preclinical findings to a novel treatment strategy required four separate issues to be determined: (1) if a CD40-ALL vaccine could be generated for clinical use; (2) whether clinical translation could be achieved; (3) whether the vaccination was safe; and (4) whether a window of time could be identified that would optimize the efficacy of vaccination. PATIENTS AND METHODS: Nine patients with relapsed/refractory ALL were enrolled in a phase I trial of vaccination with autologous CD40-ALL. Immunologic reconstitution was measured in a separate cohort of 23 patients with newly diagnosed ALL. RESULTS: We successfully prepared autologous vaccines for all nine patients in the phase I trial. CD40-ALL were potent APC, capable of stimulating allogeneic and peptide-specific T cells in vitro. Two patients were vaccinated without adverse events. Five patients died or progressed before vaccination, suggesting that rapid disease progression limits vaccination in patients with relapse disease, thus limiting clinical translation. We therefore sought to identify a window of time for vaccination during which this approach might be feasible. To achieve this end, we evaluated immunological reconstitution in newly diagnosed patients with ALL patients. Despite recovery of myelopoiesis, most patients had profound defects in T, B, and natural killer (NK) cell numbers that failed to recover at any point during therapy. CONCLUSION: Autologous tumor vaccination at a time of ALL relapse is not feasible. Alternative strategies for immunotherapy of ALL may require ex vivo generation of antigen specific T cells and adoptive therapy.

Adolescent↗
PubMed2005

The treatment of adolescents and young adults with acute lymphoblastic leukemia.

Intensive chemotherapy regimens for children with acute lymphoblastic leukemia (ALL) have greatly improved, and the majority of children with precursor B-cell ALL are able to achieve a complete remission (CR), with an induction rate approaching 98% and a 5-year estimated event-free survival rate (EFS) of approximately 80%. Although there have been dramatic improvements over the last several decades in both the EFS and overall survival (OS) rates in young children with ALL, the results in adult clinical trials have not kept pace. Current adult treatment regimens result in CR rates in the 80% range, with EFS at 5 years of only 30%-40%. Adolescents and young adults represent a minority of patients enrolled onto either adult or pediatric clinical trials. As a result, little information is available regarding CR, EFS, and OS rates for this age group, and the appropriate treatment regimen for this group of patients remains elusive. Recent studies suggest that young adult patients have far superior outcomes when treated on more intensive pediatric regimens. In addition, new insights into the molecular pathogenesis of T cell ALL have led to new therapeutic strategies.

Adolescent↗
PubMed2005

Review.

Explore the source record for details and available documents.

Burkitt Lymphoma↗
PubMed2004

Comparative outcome of nonmyeloablative and myeloablative allogeneic hematopoietic cell transplantation for patients older than 50 years of age.

Nonmyeloablative stem cell transplantation (NST) is increasingly used in older patients. The impact of the shift from myeloablative transplantation to NST on relapse, transplant complications, and outcome has yet to be fully examined. We performed a retrospective analysis of 152 patients older than 50 years undergoing NST or myeloablative transplantation. Seventy-one patients received nonmyeloablative conditioning, fludarabine (30 mg/m(2)/d x 4) and intravenous busulfan (0.8 mg/kg/d x 4); 81 patients received myeloablative conditioning, primarily cyclophosphamide and total body irradiation. NST patients were more likely to have unrelated donors (58% versus 36%; P = .009), a prior transplant (25% versus 4%; P = < .0001), and active disease at transplantation (85% versus 59%; P = < .001). Despite the adverse characteristics, overall survival was improved in the NST group at 1 year (51% versus 39%) and 2 years (39% versus 29%; P = .056). There was no difference in progression-free survival (2 years, 27% versus 25%; P = .24). The incidence of grade 2 to 4 graft-versus-host disease was similar (28% versus 27%). The nonrelapse mortality rate was lower for NST patients (32% versus 50%; P = .01), but the relapse rate was higher (46% versus 30%; P = .052). Our experience suggests that, in patients over age 50, NST with fludarabine and low-dose busulfan leads to an overall outcome at least as good as that following myeloablative therapy.

Acute Disease↗
PubMed2004

After chronic myelogenous leukemia: tyrosine kinase inhibitors in other hematologic malignancies.

Tyrosine kinases phosphorylate proteins on tyrosine residues, producing a biologic signal that influences many aspects of cellular function including cell growth, proliferation, differentiation, and death. Constitutive or unregulated activity through mutation or overexpression of these enzymes is a common pathologic feature in many acute and chronic leukemias. Inhibition of tyrosine kinases represents a strategy to disrupt signaling pathways that promote neoplastic growth and survival in hematologic malignancies and likely in other neoplasias as well. This review focuses on tyrosine kinases that have been implicated in the pathogenesis of hematologic diseases other than chronic myelogenous leukemia and discusses the evidence for the use of small molecules to target these kinases.

Animals↗
PubMed2004

Patients with acute myeloid leukemia and an activating mutation in FLT3 respond to a small-molecule FLT3 tyrosine kinase inhibitor, PKC412.

Leukemic cells from 30% of patients with acute myeloid leukemia (AML) have an activating mutation in the FLT3 (fms-like tyrosine kinase) gene, which represents a target for drug therapy. We treated 20 patients, each with mutant FLT3 relapsed/refractory AML or high-grade myelodysplastic syndrome and not believed to be candidates for chemotherapy, with an FLT3 tyrosine kinase inhibitor, PKC412 (N-benzoylstaurosporine), at a dose of 75 mg 3 times daily by mouth. The drug was generally well tolerated, although 2 patients developed fatal pulmonary events of unclear etiology. The peripheral blast count decreased by 50% in 14 patients (70%). Seven patients (35%) experienced a greater than 2-log reduction in peripheral blast count for at least 4 weeks (median response duration, 13 weeks; range, 9-47 weeks); PKC412 reduced bone marrow blast counts by 50% in 6 patients (2 of these to < 5%). FLT3 autophosphorylation was inhibited in most of the Corresponding patients, indicating in vivo target inhibition at the dose schedule used in this study. PKC412 is an oral tyrosine kinase inhibitor with clinical activity in patients with AML whose blasts have an activating mutation of FLT3, suggesting potential use in combination with active agents, such as chemotherapy.

Adult↗
PubMed2004

Extended follow-up of patients treated with imatinib mesylate (gleevec) for chronic myelogenous leukemia relapse after allogeneic transplantation: durable cytogenetic remission and conversion to complete donor chimerism without graft-versus-host disease.

PURPOSE: Over the last several years, donor lymphocyte infusions have become the standard approach for patients with chronic myelogenous leukemia (CML) who relapse after allogeneic stem cell transplantation (SCT). Recent reports indicate that imatinib mesylate (Gleevec) can induce remissions in these patients as well. Less is known about the extent and durability of these responses. EXPERIMENTAL DESIGN: We studied 15 patients treated with imatinib for recurrent CML after SCT, 10 patients with stable phase CML (SP-CML), 1 with accelerated phase (AP-CML), and 4 with blast phase (BP-CML). The dose of imatinib was 600 mg (n = 10) or 400 mg (n = 5) daily. Patients were followed for hematological, cytogenetic, and molecular response. A susbset of responders was followed for changes in donor-derived hematopoietic chimerism. RESULTS: Of the 10 patients with SP-CML, all achieved a hematological response. Within 3 months, five of these patients had achieved a complete cytogenetic response (CCR). By six months, 9 of 10 patients had achieved CCR. The BCR-ABL transcript could not be detected by reverse transcription-PCR in 7 of these 9 patients. Patients who achieved CCR showed evidence of conversion to complete donor chimerism. No patient developed graft-versus-host disease. With a median follow up of 25 months, all patients are alive and 9 of 10 patients remain in CCR. Only one of the 5 patients with AP/BP-CML achieved a complete cytogenetic response. CONCLUSIONS: We find that imatinib is well tolerated in patients with SP-CML who relapse after SCT. Responses were rapid, durable, and associated with conversion to full donor chimerism without graft-versus-host disease. Imantinib was far less effective in patients who relapsed with AP/BP-CML. Imatinib should be evaluated as either an alternative or as an adjunct to donor lymphocyte infusions for patients with SP-CML who relapse after SCT.

Adult↗
PubMed2004

Identifying and characterizing a novel activating mutation of the FLT3 tyrosine kinase in AML.

The FLT3 receptor is activated by juxtamembrane insertion mutations and by activation loop point mutations in patients with acute myeloid leukemia (AML). In a systematic tyrosine kinase gene exon resequencing study, 21 of 24 FLT3 exons were sequenced in samples from 53 patients with AML, 9 patients with acute lymphoblastic leukemia (ALL), and 3 patients with myelodysplasia samples. Three patients had novel point mutations at residue N841 that resulted in a change to isoleucine in 2 samples and to tyrosine in 1 sample. Introduction of FLT3-N841I cDNA into Ba/F3 cells led to interleukin-3 (IL-3)-independent proliferation, receptor phosphorylation, and constitutive activation of signal transducer and activator of transcription 5 (STAT5) and extracellular regulatory kinase (ERK), suggesting that the N841I mutation confers constitutive activity to the receptor. An FLT3 inhibitor (PKC412) inhibited the growth of Ba/F3-FLT3N841I cells (IC(50) 10 nM), but not of wild-type Ba/F3 cells cultured with IL-3. PKC412 also reduced tyrosine phosphorylation of the mutant receptor and inhibited STAT5 phosphorylation. Examination of the FLT3 autoinhibited structure showed that N841 is the key residue in a hydrogen-bonding network that likely stabilizes the activation loop. These results suggest that mutations at N841 represent a significant new activating mutation in patients with AML and that patients with such mutations may respond to small-molecule FLT3 inhibitors such as PKC412.

Adult↗
PubMed2003

Prior gemtuzumab ozogamicin exposure significantly increases the risk of veno-occlusive disease in patients who undergo myeloablative allogeneic stem cell transplantation.

Gemtuzumab ozogamicin (GO), a monoclonal antibody used in the treatment of acute myelogenous leukemia (AML) has been linked to the development of venoocclusive disease (VOD). We conducted a retrospective study of 62 patients with previously treated AML/MDS (myelodysplastic syndrome) who underwent allogeneic stem cell (SC) transplantation at our institution from December 2000 to October 2002 to determine whether GO exposure prior to allogeneic SC transplantation increases the risk of developing VOD. Fourteen patients received GO prior to SC transplantation. Of 62 patients, 13 (21%) developed VOD; 9 (64%) of 14 with prior GO exposure developed VOD compared with 4 (8%) of 48 without prior GO exposure (P <.0001). Logistic regression controlling for sex, disease status, donor type, and graft-versus-host disease prophylaxis identified prior treatment with GO as a significant risk factor for VOD (odds ratio [OR], 21.6; 95% confidence interval [CI], 4.2-112.2]. Nine of 10 patients who underwent SC transplantation 3.5 months or less following GO developed VOD compared with none of 4 patients who underwent SC transplantation more than 3.5 months from GO administration. Three of 14 patients who received GO prior to SC transplantation died of VOD. We conclude that patients undergoing SC transplantation within a short interval from GO administration are at increased risk of developing VOD.

Acute Disease↗
PubMed2003

A tyrosine kinase created by fusion of the PDGFRA and FIP1L1 genes as a therapeutic target of imatinib in idiopathic hypereosinophilic syndrome.

BACKGROUND: Idiopathic hypereosinophilic syndrome involves a prolonged state of eosinophilia associated with organ dysfunction. It is of unknown cause. Recent reports of responses to imatinib in patients with the syndrome suggested that an activated kinase such as ABL, platelet-derived growth factor receptor (PDGFR), or KIT, all of which are inhibited by imatinib, might be the cause. METHODS: We treated 11 patients with the hypereosinophilic syndrome with imatinib and identified the molecular basis for the response. RESULTS: Nine of the 11 patients treated with imatinib had responses lasting more than three months in which the eosinophil count returned to normal. One such patient had a complex chromosomal abnormality, leading to the identification of a fusion of the Fip1-like 1 (FIP1L1) gene to the PDGFRalpha (PDGFRA) gene generated by an interstitial deletion on chromosome 4q12. FIP1L1-PDGFRalpha is a constitutively activated tyrosine kinase that transforms hematopoietic cells and is inhibited by imatinib (50 percent inhibitory concentration, 3.2 nM). The FIP1L1-PDGFRA fusion gene was subsequently detected in 9 of 16 patients with the syndrome and in 5 of the 9 patients with responses to imatinib that lasted more than three months. Relapse in one patient correlated with the appearance of a T674I mutation in PDGFRA that confers resistance to imatinib. CONCLUSIONS: The hypereosinophilic syndrome may result from a novel fusion tyrosine kinase - FIP1L1-PDGFRalpha - that is a consequence of an interstitial chromosomal deletion. The acquisition of a T674I resistance mutation at the time of relapse demonstrates that FIP1L1-PDGFRalpha is the target of imatinib. Our data indicate that the deletion of genetic material may result in gain-of-function fusion proteins.

Adult↗