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Query: UMLS:C0023467 (acute myeloid leukemia)
 35,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Increasing evidence suggests that the biology of acute myeloid leukemia (AML) may differ between older and younger patients, with a higher incidence of antecedent myelodysplasia, unfavorable cytogenetic abnormalities, and multidrug resistance seen in the elderly. Abrogation of apoptosis in response to cytotoxic medications is associated with drug resistance in AML, as is expression of bcl-2, an important anti-apoptotic protein. We hypothesized that blasts from elderly (> or = 55 years) and young adult AML patients might have different levels of apoptotic and cell cycle responses to chemotherapeutic agents, as well as different levels of proliferation and of bcl-2 protein expression. Therefore, we cultured bone marrow leukemia samples from previously untreated elderly (n=33) and young (n=21) AML patients for 48 h and then measured apoptosis, bcl-2 protein levels, cell cycle distributions, and expression of a proliferation marker, proliferating cellular nuclear antigen (PCNA) in multi-parametric flow cytometry assays. In some experiments, leukemia samples were exposed to cytarabine (Ara-C) or daunomycin (DNR) for the last 16-18 h of the culture period. In comparison to samples from young patients, cultured samples from elderly AML patients had a higher fraction of viable cells, as measured by Trypan blue exclusion, higher PCNA expression, and significantly less culture-induced and drug-induced apoptosis. The mean apoptosis after culture was 13% for elderly AML samples, versus 20% for young AML samples (P=0.009). Similarly, the mean apoptosis after Ara-C was lower in elderly than in young AML samples, 13 versus 28% (P=0.001), as was the mean apoptosis after DNR, 15 versus 26% (P=0.012). Diminished apoptotic responses in elderly AML cells were not consistently associated with high bcl-2 levels at thaw or bcl-2 levels increased by culture. These data suggest that new therapies should be developed to overcome abrogated apoptosis, particularly in elderly AML patients.
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PMID:Blasts from elderly acute myeloid leukemia patients are characterized by low levels of culture- and drug-induced apoptosis. 1113 57

Unequivocally, complete remission (CR) is a prerequisite for the cure for acute leukemia. The history of drug therapy for acute leukemia has taught us that only after CR rates exceed 90% can a satisfactorily high cure rate be obtained, as is observed in acute lymphoblastic leukemia in children and acute promyelocytic leukemia (APL). In multicenter studies of adult acute myeloid leukemia (AML), CR rates hardly exceed 80% with currently available cytotoxic drugs, except for a small fraction of patients having AML with t(8;21) or inv(16). CR rates and survival of adult patients with AML in 4 studies by the Japan Adult Leukemia Study Group from 1987 to 1997 do not improve at all when appropriately adjusted. The remarkable effects of all-trans-retinoic acid in APL and STI571 in chronic myeloid leukemia have shown us the direction of cancer therapy in the 21st century. We should shift the paradigm from nonspecific cytotoxic chemotherapy to therapy that specifically targets the genes or gene products that are responsible for leukemogenesis.
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PMID:How high can we increase complete remission rate in adult acute myeloid leukemia? 1118 81

The ORC5L gene encoding a subunit of the human origin recognition complex (ORC) maps to chromosome band 7q22, a region frequently deleted in adult acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Because of its localization within a region that is commonly deleted in patients with myeloid malignancies and because of the implication of its protein product in cell cycle control (DNA replication) and regulation of gene expression (transcriptional silencing), ORC5L appeared to be a candidate tumor suppressor gene for myeloid disorders associated with 7q22 deletions. Polymerase chain reaction amplification and sequencing analysis of the coding region of the remaining ORC5L allele has not revealed any mutations in nine patients with AML or MDS exhibiting 7q22 deletions. Allelic expression analysis indicates that ORC5L is not imprinted. These data suggest that ORC5L does not function as a tumor suppressor in patients with myeloid neoplasms.
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PMID:Mutation analysis of the origin recognition complex subunit 5 (ORC5L) gene in adult patients with myeloid leukemias exhibiting deletions of chromosome band 7q22. 1137 76

We studied the impact of cytogenetics and kind of induction/consolidation therapy on 848 adult acute myeloid leukemia (AML) patients (age 15-83). The patients received three types of induction/consolidation regimen: standard (daunorubicin and cytosine arabinoside (3/7); two cycles); intensive (idarubicin, cytosine arabinoside and etoposide (ICE), plus mitoxantrone and intermediate-dose Ara-C (NOVIA)); and low-dose (low-dose cytosine arabinoside). CR patients under 60 years of age, if an HLA-identical donor was available received allogeneic stem cell transplantation (allo-SCT); otherwise, as part of the program, they underwent autologous (auto)-SCT. CR rates significantly associated with 'favorable' (inv(16), t(8;21)), 'intermediate' ('no abnormality', abn(11q23), +8, del(7q)) and 'unfavorable' (del (5q), -7, abn(3)(q21q26), t(6;9), 'complex' (more than three unrelated cytogenetic abnormalities)) karyotypes (88% vs 65% vs 36%, respectively; P = 0.0001). These trends were confirmed in all age groups. On therapeutic grounds, intensive induction did not determine significant increases of CR rates in any of the considered groups, with respect to standard induction. Low-dose induction was associated with significantly lower CR rates. Considering disease-free survival (DFS), multivariate analysis of the factors examined (including karyotype grouping) showed that only age > 60 years significantly affected outcome. However, in cases where intensive induction was adopted, 'favorable' karyotype was significantly related to longer DFS (P = 0.04). This was mainly due to the favorable outcome of t(8;21) patients treated with intensive induction. Patients receiving allo-SCT had significantly longer DFS (P = 0.005); in particular, allo-SCT significantly improved DFS in the 'favorable' and 'intermediate' groups (P = 0.04 and P = 0.048, respectively). In conclusion our study could provide some guidelines for AML therapy: (1) patients in the 'favorable' karyotype group seem to have a longer DFS when treated with an intensive induction/consolidation regimen, adopted before auto-SCT instead of standard induction; this underlines the importance of reinforcement of chemotherapy, not necessarily based on repeated high-dose AraC cycles. Allo-SCT, independently of induction/consolidation therapy, should be considered an alternative treatment; (2) patients in the 'intermediate' karyotype group should receive allo-SCT; (3) patients in the 'unfavorable' karyotype group should be treated using investigational chemotherapy, considering that even allo-SCT cannot provide a significantly longer DFS, but only a trend to a better prognosis.
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PMID:The prognostic value of cytogenetics is reinforced by the kind of induction/consolidation therapy in influencing the outcome of acute myeloid leukemia--analysis of 848 patients. 1141 75

We are conducting a Phase I trial of a fusion toxin (DT-GM) for the treatment of relapsed or refractory acute myeloid leukemia (AML). The fusion toxin consists of a truncated diphtheria toxin (DT) linked to human granulocyte-macrophage colony stimulating factor (GM). Prior to beginning the Phase I trial, our first goal was to determine whether healthy controls and adult AML patients had preexisting antibodies able to inhibit DT-GM. Sera from 5 of the 9 controls completely neutralized DT-GM by an in vitro bioassay to assess the inhibition of DT-GM. Sera from 43 patients with AML were tested by bioassay and a specific enzymoimmunoassay (EIA) for anti-DT-GM antibodies. Forty-two of 43 samples were positive by EIA, and 5 patients (11.6%) showed complete neutralization of DT-GM in the bioassay. Anti-DT-GM concentrations were significantly higher in samples demonstrating neutralization than in samples demonstrating no neutralization (P = 0.003). In the Phase I trial of DT-GM prior to therapy, none of 28 patients exhibited neutralization by bioassay, but 89% were positive by EIA. After the first course of DT-GM, 23% developed neutralizing antibodies by the bioassay, and 64% of patients exhibited an increase in their anti-DT-GM antibody concentrations by EIA. Further studies are needed to determine the clinical impact of the anti-DT-GM antibodies and whether the neutralization bioassay can be replaced by our EIA.
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PMID:Antibody response to DT-GM, a novel fusion toxin consisting of a truncated diphtheria toxin (DT) linked to human granulocyte-macrophage colony stimulating factor (GM), during a phase I trial of patients with relapsed or refractory acute myeloid leukemia. 1146 48

A genome-wide screening for loss of heterozygosity (LOH), a marker for possible involvement of tumor suppressor genes, was conducted in 53 children with de novo acute myelogenous leukemia (AML). A total of 177 highly polymorphic microsatellite repeat markers were used in locus-specific polymerase chain reactions. This comprehensive allelotyping employed flow-sorted cells from diagnostic samples and whole-genome amplification of DNA from small, highly purified samples. Nineteen regions of allelic loss in 17 patients (32%) were detected on chromosome arms 1q, 3q, 5q, 7q (n = 2), 9q (n = 4), 11p (n = 2), 12p (n = 3), 13q (n = 2), 16q, 19q, and Y. The study revealed a degree of allelic loss underestimated by routine cytogenetic analysis, which failed to detect 9 of these LOH events. There was no evidence of LOH by intragenic markers for p53, Nf1, or CBFA2/AML1. Most lymphocytes lacked the deletions, which were detected only in the leukemic myeloid blast population. Analysis of patients' clinical and biologic characteristics indicated that the presence of LOH was associated with a white blood cell count of 20 x 10(9)/L or higher but was not correlated with a shorter overall survival. The relatively low rate of LOH observed in this study compared with findings in solid tumors and in pediatric acute lymphoblastic leukemia and adult AML suggests that tumor suppressor genes are either infrequently involved in the development of pediatric de novo AML or are inactivated by such means as methylation and point mutations. Additional study is needed to determine whether these regions of LOH harbor tumor suppressor genes and whether specific regions of LOH correlate with clinical characteristics. (Blood. 2001;98:1188-1194)
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PMID:Loss of heterozygosity in childhood de novo acute myelogenous leukemia. 1149 69

p15 and p16 are tumor suppressor genes that have 5' CpG islands and both are subject to hypermethylation associated with their transcriptional inactivation in hematological malignancies. In this study, we used sodium bisulfite sequencing to obtain a complete map of the 5-methylcytosine status of 80 CpGs covering approximately 900 bp in the 5' p15 CpG island, and 53 CpGs covering approximately 700 bp in the 5' p16 CpG island in the hematopoietic cell lines HL60, KG-1, and KG-1a, two normal human bone marrow samples (NBM), and eight cytosine arabinoside (ara-C)-resistant adult acute myeloid leukemia (AML) patients. We found methylation of the p15 CpG island in 75% of the AML cases studied spread throughout the 5' region analyzed but only minimal methylation of p15 in NBM. Further, the p16 CpG island was not aberrantly methylated in NBM or the eight AML patients studied. Two distinct modes of p15 methylation in AML were identified, variegated and complete. Interestingly, KG-1 and KG-1a model the methylation of p15 observed in AML, where KG-1 methylation is variegated and KG-1a methylation is complete. Both KG-1 and KG-1a had no detectable p15 mRNA or protein. These results demonstrate that rather than continuous increases in p15 methylation, surprisingly two punctuated modes of aberrant p15 methylation, variegated and complete, were observed in vitro and in vivo. Thus aberrant methylation of tumor suppressor genes is not a binary switch but in the case of p15 occurs in two independent and stable states.
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PMID:KG-1 and KG-1a model the p15 CpG island methylation observed in acute myeloid leukemia patients. 1153 26

The purpose of this study was to characterize the pharmacokinetics of gemtuzumab ozogamicin (Mylotarg; Wyeth-Ayerst Laboratories, St. Davids, PA) in patients with acute myeloid leukemia (AML) in first relapse. Gemtuzumab ozogamicin is an antibody-chemotherapeutic conjugate characterized as antibody-targeted chemotherapy, consisting of an engineered human anti-CD33 antibody (hP67.6) linked to a potent cytotoxic agent, N-acetyl-gamma calicheamicin DMH. The pharmacokinetics of gemtuzumab ozogamicin was evaluated in 59 adult AML patients in first relapse, enrolled in a phase II study. Plasma was collected following each dose at specified times, and the pharmacokinetics was characterized by measures of hP67.6, total calicheamicin derivatives, and unconjugated calicheamicin derivatives. After administration of the first 9 mg/m2 dose of gemtuzumab ozogamicin, the pharmacokinetic parameters (mean +/- SD) of hP67.6 following the first dose were as follows: peak plasma concentration, 2.86 +/- 1.35 mg/L; AUC, 123 +/- 105 mg x h/L; t 1/2, 72.4 +/- 42.0 hours; and clearance, 0.265 +/- 0.229L/h. Increased concentrations were observed after the second dose and are believed to be due to a decrease in clearance by CD33-positive blast cells, a result of the reduced tumor burden following the first dose. The concentration profiles of calicheamicin followed the same time course as hP67.6, evidence that calicheamicin remained conjugated to the antibody and delivered to leukemic cells. No relationship was found between plasma concentration and response at the recommended dose. The pharmacokinetics of gemtuzumab ozogamicin has been characterized in AML patients receiving doses at the proposed therapeutic level.
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PMID:Pharmacokinetics of gemtuzumab ozogamicin, an antibody-targeted chemotherapy agent for the treatment of patients with acute myeloid leukemia in first relapse. 1169 53

Through the hard work of a large number of investigators, the biology of acute myeloid leukemia (AML) is becoming increasingly well understood, and as a consequence, new therapeutic targets have been identified and new model systems have been developed for testing novel therapies. How these new therapies can be most effectively studied in the clinic and whether they will ultimately improve cure rates are questions of enormous importance. In this article, Dr. Jacob Rowe presents a summary of the current state-of-the-art therapy for adult AML. His contribution emphasizes the fact that AML is not a single disease, but a number of related diseases each distinguished by unique cytogenetic markers which in turn help determine the most appropriate treatment. Dr. Jerald Radich continues on this theme, emphasizing how these cytogenetic abnormalities, as well as other mutations, give rise to abnormal signal transduction and how these abnormal pathways may represent ideal targets for the development of new therapeutics. A third contribution by Dr. Frederick Appelbaum describes how AML might be made the target of immunologic attack. Specifically, strategies using antibody-based or cell-based immunotherapies are described including the use of unmodified antibodies, drug conjugates, radioimmunoconjugates, non-ablative allogeneic transplantation, T cell adoptive immunotherapy and AML vaccines. Finally, Dr. John Dick provides a review of the development of the NOD/SCID mouse model of human AML emphasizing both what it has taught us about the biology of the disease as well as how it can be used to test new therapies. Taken together, these reviews are meant to help us understand more about where we are in the treatment of AML, where we can go and how we might get there.
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PMID:Acute myeloid leukemia. 1172 79

In order to determine whether granulocyte colony-stimulating factor (G-CSF) alone initiated during steady state was able to mobilize peripheral blood stem cells (PBSC) in acute myeloid leukemia (AML) and to assess predictive factors for engraftment after autologous PBSC transplantation, we studied 49 successive adult AML patients for whom autologous transplantation was planned between July 1994 and November 1998. G-CSF was used as priming agent and was initiated at least 4 weeks after the last day of chemotherapy, while neutrophil count was >0.5 x 10(9)/l and platelet count was >30 x 10(9)/l. A median of three aphereses was performed resulting in a median collection of 14.8 x 10(8) nucleated cells/kg containing 7.7 x 10(8) mononuclear cells/kg, 47.1 x 10(4) CFU-GM/kg, and 3.8 x 10(6) CD34+ cells/kg. A significant correlation was observed between nucleated cell, mononuclear cell, and CFU-GM yields, while no correlation was found with CD34+ cell yield. Recruitment was not significantly different in patients with CD34+ leukemic cells at the time of initial diagnosis when compared to that of those presenting with CD34- blastic cells. Thirty-three patients actually underwent transplantation. Reasons for not autografting were inadequate stem cell harvest (ten patients), early relapse (two patients), prolonged neutropenia (one patient), organ failure (two patients), or patient refusal (one patient). Median time to achieve a neutrophil count greater than 0.5 x 10(9)/l and platelet count >50 x 10(9)/l untransfused was 13 and 36 days, respectively. A predictive factor for a shorter period neutropenia and a shorter thrombopenia was a higher count of harvested nucleated cells (p < 0.01 and p = 0.02, respectively). A higher count of harvested cells was also a predictive factor for less red cell and platelet transfusions (p=0.03 and p=0.02, respectively). The number of CD34+ harvested PBSC was not predictive for engraftment. We conclude that PBSC mobilization with G-CSF alone initiated in steady state is a feasible, safe, and suitable procedure for harvesting cells in sight of autologous transplantation in adult acute myeloid leukemia.
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PMID:Autologous transplantation in acute myeloid leukemia: peripheral blood stem cell harvest after mobilization in steady state by granulocyte colony-stimulating factor alone. 1173 69


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