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Biomedical subjects

Clara D Bloomfield

Publications and source records attributed to Clara D Bloomfield.

At least 19 recordsLinked to original sources

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↗

Clinical relevance of mutations and gene-expression changes in adult acute myeloid leukemia with normal cytogenetics: are we ready for a prognostically prioritized molecular classification?

Recent molecular analyses of leukemic blasts from pretreatment marrow or blood of patients with acute myeloid leukemia (AML) and a normal karyotype, the largest cytogenetic subset (ie, 40%-49%) of AML, have revealed a striking heterogeneity with regard to the presence of acquired gene mutations and changes in gene expression. Multiple submicroscopic genetic alterations with prognostic significance have been discovered, including internal tandem duplication of the FLT3 gene, mutations in the NPM1 gene, partial tandem duplication of the MLL gene, high expression of the BAALC gene, and mutations in the CEBPA gene. Application of gene-expression profiling has also identified a gene-expression signature that appears to separate cytogenetically normal AML patients into prognostic subgroups, although gene-expression signature-based classifiers predicting outcome for individual patients with greater accuracy are needed. These and similar future findings are likely to have a major impact on the clinical management of cytogenetically normal AML not only in prognostication but also in selection of appropriate treatment, since many of the identified genetic alterations already constitute or will potentially become targets for specific therapeutic intervention. In this report, we review prognostic genetic findings in karyotypically normal AML and discuss their clinical implications.

Acute Disease↗

High expression of the ETS transcription factor ERG predicts adverse outcome in acute T-lymphoblastic leukemia in adults.

PURPOSE: In adult T-lymphoblastic leukemia (T-ALL) disease-free survival remains limited to 32% to 46%. The adverse prognosis in T-ALL has not been attributed to cytogenetic or molecular aberrations. We have determined the prognostic impact of the oncogenic transcription factor ERG in T-ALL. PATIENTS AND METHODS: ERG expression was analyzed by real-time polymerase chain reaction (PCR) in 105 adults with newly diagnosed T-ALL treated on the German ALL protocols. Patients were dichotomized at ERG's median expression into low (n = 52) and high (n = 53) expressers. Homeobox (HOX) 11 and HOX11L2 expression was determined by real-time PCR. RESULTS: High ERG expressers compared with low ERG expressers had an inferior overall survival (OS, P = .02; 5-year OS: high ERG 26% v low ERG 58%) and relapse-free survival (RFS, P = .003; 5-year RFS: high ERG 34% v low ERG 72%). On multivariable analysis high ERG expression (P = .005), immunophenotypic subgroups (early v mature v thymic T-ALL; overall P = .04), HOX11L2 positivity (P = .055), and absence of HOX11 (P = .017) were independent adverse risk factors predicting RFS. Patients with high ERG expression had a hazard ratio (HR) for relapse of 3.2. Within the good prognostic subgroup of thymic T-ALL (n = 57), high ERG (HR, 4.1; P = .02) and presence of HOX11L2 (HR, 6.6; P = .008) were independent adverse factors for RFS. CONCLUSION: High expression of ERG is an adverse risk factor in adult T-ALL. Within thymic T-ALL, otherwise classified as standard-risk, high ERG expression-identified patients that were four times more likely to fail long-term RFS. The prognostic impact of ERG may assist treatment stratification and suggest the need of alternative regimens.

Adolescent↗

Adverse prognostic significance of KIT mutations in adult acute myeloid leukemia with inv(16) and t(8;21): a Cancer and Leukemia Group B Study.

PURPOSE: To analyze the prognostic impact of mutated KIT (mutKIT) in core-binding factor acute myeloid leukemia (AML) with inv(16)(p13q22) and t(8;21)(q22;q22). PATIENTS AND METHODS: Sixty-one adults with inv(16) and 49 adults with t(8;21), assigned to postremission therapy with repetitive cycles of higher dose cytarabine were analyzed for mutKIT in exon 17 (mutKIT17) and 8 (mutKIT8) by denaturing high-performance liquid chromatography and direct sequencing at diagnosis. The median follow-up was 5.3 years. RESULTS: Among patients with inv(16), 29.5% had mutKIT (16% with mutKIT17 and 13% with sole mutKIT8). Among patients with t(8;21), 22% had mutKIT (18% with mutKIT17 and 4% with sole mutKIT8). Complete remission rates of patients with mutKIT and wild-type KIT (wtKIT) were similar in both cytogenetic groups. In inv(16), the cumulative incidence of relapse (CIR) was higher for patients with mutKIT (P = .05; 5-year CIR, 56% v 29%) and those with mutKIT17 (P = .002; 5-year CIR, 80% v 29%) compared with wtKIT patients. Once data were adjusted for sex, mutKIT predicted worse overall survival (OS). In t(8;21), mutKIT predicted higher CIR (P = .017; 5-year CIR, 70% v 36%), but did not influence OS. CONCLUSION: We report for the first time that mutKIT, and particularly mutKIT17, confer higher relapse risk, and both mutKIT17 and mutKIT8 appear to adversely affect OS in AML with inv(16). We also confirm the adverse impact of mutKIT on relapse risk in t(8;21) AML. We suggest that patients with core-binding factor AML should be screened for mutKIT at diagnosis for both prognostic and therapeutic purposes, given that activated KIT potentially can be targeted with novel tyrosine kinase inhibitors.

Acute Disease↗

Cancer and leukemia group B leukemia correlative science committee: major accomplishments and future directions.

The Cancer and Leukemia Group B (CALGB) Leukemia Correlative Science Committee (LCSC) has a remarkable history of outstanding productivity and has been at the cutting edge of correlative science for adult leukemia for almost 25 years. Its work, initially focused on the use of immunophenotyping for diagnosis and prognosis of acute lymphoblastic leukemia and acute myeloid leukemia, has, for the last 15 years, focused on the clinical use of cytogenetic and molecular genetic markers in acute myeloid leukemia and acute lymphoblastic leukemia as well as in chronic lymphocytic leukemia. Numerous CALGB LCSC studies have had a major effect on the way we currently diagnose, predict outcome, select appropriate treatment, document complete remission, and monitor residual disease in adults with acute leukemia. In part as a result of the work of the CALGB LCSC, we are increasingly moving toward molecularly targeted therapy in acute and chronic leukemias. In this report, we briefly review those contributions from the CALGB LCSC that have had, or are likely to have in the future, a major effect on how we currently manage leukemia and outline directions of ongoing and future research conducted by the CALGB LCSC.

Adult↗

Independent confirmation of a prognostic gene-expression signature in adult acute myeloid leukemia with a normal karyotype: a Cancer and Leukemia Group B study.

Patients with acute myeloid leukemia (AML) and normal karyotype are classified in an intermediate-risk group, albeit this subset is heterogeneous for clinical outcome. A recent complementary DNA microarray study identified a gene-expression signature that--when used to cluster normal karyotype patients--separated them into 2 prognostically relevant subgroups. We sought the first independent validation of the prognostic value of this signature. Using oligonucleotide microarrays to measure gene expression in samples from uniformly treated adults with karyotypically normal AML, we performed cluster analysis based on the previously identified signature. We also developed a well-defined classification rule using the signature to predict outcome for individual patients. Cluster analysis confirmed the prognostic utility of the signature: patient clusters differed in overall (P = .001) and disease-free (P = .001) survival. The signature-based classifier identified groups with differences in overall (P = .02) and disease-free (P = .05) survival. A strong association of the outcome classifier with the prognostically adverse FLT3 internal tandem duplication (FLT3 ITD) potentially explained the prognostic significance of the signature. However, in the subgroup of patients without FLT3 ITD there was a moderate difference in survival for the classifier-derived groups. Our analysis confirms the applicability of the gene-expression profiling strategy for outcome prediction in cytogenetically normal AML.

Acute Disease↗

MicroRNA fingerprints during human megakaryocytopoiesis.

microRNAs are a highly conserved class of noncoding RNAs with important regulatory functions in proliferation, apoptosis, development, and differentiation. To discover novel regulatory pathways during megakaryocytic differentiation, we performed microRNA expression profiling of in vitro-differentiated megakaryocytes derived from CD34(+) hematopoietic progenitors. The main finding was down-regulation of miR-10a, miR-126, miR-106, miR-10b, miR-17 and miR-20. Hypothetically, the down-regulation of microRNAs unblocks target genes involved in differentiation. We confirmed in vitro and in vivo that miR-130a targets the transcription factor MAFB, which is involved in the activation of the GPIIB promoter, a key protein for platelet physiology. In addition, we found that miR-10a expression in differentiated megakaryocytes is inverse to that of HOXA1, and we showed that HOXA1 is a direct target of miR-10a. Finally, we compared the microRNA expression of megakaryoblastic leukemic cell lines with that of in vitro differentiated megakaryocytes and CD34(+) progenitors. This analysis revealed up-regulation of miR-101, miR-126, miR-99a, miR-135, and miR-20. Our data delineate the expression of microRNAs during megakaryocytopoiesis and suggest a regulatory role of microRNAs in this process by targeting megakaryocytic transcription factors.

Antigens, CD34↗

Pretreatment cytogenetics add to other prognostic factors predicting complete remission and long-term outcome in patients 60 years of age or older with acute myeloid leukemia: results from Cancer and Leukemia Group B 8461.

We investigated the relative prognostic significance of cytogenetics in 635 adult acute myeloid leukemia (AML) patients 60 years of age or older treated on front-line protocols. Classification trees and tree-structured survival analysis (TSSA) were used to identify important cytogenetic groups, and their prognostic significance was then assessed in multivariable analysis (MVA). Overall, 48.5% achieved complete remission (CR); 6.6% survived at 5 years. Complex karyotypes with at least 3 abnormalities (complex > or = 3) and a group including "rare aberrations" predicted lower CR rates (25% and 30%) versus other patients (56%). Compared with complex > or = 3, the odds of CR were significantly higher for noncomplex karyotypes without rare aberrations on MVA. Cytogenetically, complex > or = 5 predicted inferior disease-free survival on TSSA, remaining significant on MVA together with white blood cell count (WBC), sex, and age. For survival, complex > or = 5, rare aberrations, and core-binding factor (CBF) abnormalities were prognostic (P < .001), with 5-year survivals of 0%, 0%, and 19.4%, respectively, and 7.5% for remaining patients. Together with WBC, marrow blasts, sex, and age, the cytogenetic groups remained significant on MVA. In conclusion, pretreatment cytogenetics adds to other prognostic factors in older AML patients. Patients with complex > or = 5 appear to benefit minimally from current treatment and are better suited for investigational therapy or supportive care.

Acute Disease↗

BAALC expression and FLT3 internal tandem duplication mutations in acute myeloid leukemia patients with normal cytogenetics: prognostic implications.

PURPOSE: Evaluate the impact of BAALC (brain and acute leukemia, cytoplasmic), a gene whose expression has been associated with adverse outcome in acute myeloid leukemia (AML) with normal cytogenetics, and FLT3 internal tandem duplication (ITD) mutations as independent prognostic factors in a larger study. PATIENTS AND METHODS: BAALC expression was determined by real-time reverse transcriptase polymerase chain reaction in pretreatment blood samples of 307 adults <or= 60 years of age with AML with normal cytogenetics. Patients were dichotomized at BAALC's median expression into low and high expressers. The FLT3 ITD mutant:wild-type ratio was determined by fragment analysis. RESULTS: Compared with low-BAALC patients, high-BAALC patients had a higher rate of primary resistant leukemia (16% v 6%; P = .006). High BAALC expression was associated with a higher cumulative incidence of relapse (CIR; P = .018) and an inferior overall survival (OS; 3-year OS, 36% v 54%; P = .001). On multivariable analysis, high BAALC was independently predictive of resistant disease (P = .019), and high BAALC as well as a high FLT3 mutant:wild-type ratio were confirmed as the only factors predicting a high CIR (BAALC, P = .03; FLT3, P = .01) and inferior OS (BAALC, P = .001; FLT3, P = .012). CONCLUSION: This study strengthens BAALC expression as one of the most important prognostic factors in AML patients with normal cytogenetics. BAALC expression and FLT3 mutation status should assist in tailoring induction and postremission therapies.

Adult↗

Chromosome aberrations, gene mutations and expression changes, and prognosis in adult acute myeloid leukemia.

Pretreatment clinical features and prognosis of patients with acute myeloid leukemia (AML) are strongly influenced by acquired genetic alterations in leukemic cells, which include microscopically detectable chromosome aberrations and, increasingly, submicroscopic gene mutations and changes in gene expression. Cytogenetic findings separate AML patients into three broad prognostic categories: favorable, intermediate and adverse. The cytogenetic-risk classifications differ somewhat for younger adult patients and those aged 60 years or older. In many instances, patients with specific cytogenetic findings, e.g., those with a normal karyotype or those with either t(8;21)(q22;q22) or inv(16)(p13q22)/t(16;16)(p13;q22) [collectively referred to as core-binding factor (CBF) AML] can be further subdivided into prognostic categories based on the presence or absence of particular gene mutations or changes in gene expression. Importantly, many of these molecular genetic alterations constitute potential targets for risk-adapted therapies. In this article, we briefly review major cytogenetic prognostic categories and discuss molecular genetic findings of prognostic significance in two of the largest cytogenetic groups of patients with AML, namely AML with a normal karyotype and CBF AML.

Acute Disease↗

Quantitative real-time RT-PCR monitoring of BCR-ABL in chronic myelogenous leukemia shows lack of agreement in blood and bone marrow samples.

Molecular monitoring of the BCR-ABL transcript in chronic myelogenous leukemia (CML) using quantitative RT-PCR provides clinicians with important diagnostic and prognostic information. To determine whether molecular detection and monitoring of CML is comparable using peripheral blood (PB) and bone marrow (BM) aspirate samples, we performed a prospective study using quantitative real-time RT-PCR (QRT-PCR) of paired PB and BM samples from 41 patients with CML entered onto a single Cancer and Leukemia Group B (CALGB) treatment study. QRT-PCR analysis of PB and BM samples was performed prior to initiation of, and during, treatment with homoharringtonine and cytarabine on a CALGB study for previously untreated CML. Statistical analyses demonstrated good agreement of PB and BM pre-treatment samples. However, using the Bland-Altman statistical method that measures true agreement between PB and BM values, we found that there was only modest agreement of BCR-ABL measurements in PB and BM for samples obtained during treatment. PB values obtained during treatment tended to be lower than the corresponding BM values [average difference = -0.37 (p<0.001) in 36 paired samples] and the 95% limits of agreement ranged from -1.23 to 0.48. Nevertheless, our study demonstrates that BM and PB QRT-PCR values followed a similar trend during treatment (Spearman correlation coefficient, 0.83; 95% CI, 0.70, 0.96). Our data suggest that, quantitatively, PB and BM measurements of BCR-ABL are frequently disparate. Since BM values tended to be higher than PB values, BM sampling provides the most accurate assessment of minimal residual disease (MRD). Based on these results, we caution against interchanging BM with PB sampling for MRD monitoring during treatment of CML since this may lead to misinterpretation of treatment results.

Antineoplastic Combined Chemotherapy Protocols↗

Overexpression of the ETS-related gene, ERG, predicts a worse outcome in acute myeloid leukemia with normal karyotype: a Cancer and Leukemia Group B study.

PURPOSE: To test the prognostic significance of ETS-related gene (ERG) expression in cytogenetically normal primary acute myeloid leukemia (AML). PATIENTS AND METHODS: Pretreatment blood samples from 84 cytogenetically normal AML patients aged less than 60 years, who were characterized for BAALC expression, FLT3 internal tandem duplication (ITD), and MLL partial tandem duplication (PTD) and uniformly treated on Cancer and Leukemia Group B 9621 protocol, were analyzed for ERG expression by real-time reverse transcriptase polymerase chain reaction. Patients were divided into quartiles according to ERG levels and were compared for clinical outcome. High-density oligonucleotide arrays were used to identify genes differentially expressed between high and low ERG expressers. RESULTS: With a median follow-up of 5.7 years, patients with the upper 25% of ERG expression values had a worse cumulative incidence of relapse (CIR; P < .001) and overall survival (OS; P = .011) than the remaining patients. In a multivariable analysis, high ERG expression (P < .001) and the presence of MLL PTD (P = .027) predicted worse CIR. With regard to OS, an interaction was observed between expression of ERG and BAALC (P = .013), with ERG overexpression predicting shorter survival only in low BAALC expressers (P = .002). ERG overexpression was an independent prognostic factor even when the unfavorable group of FLT3 ITD patients lacking an FLT3 wild-type allele was included. High ERG expression was associated with upregulation of 112 expressed-sequenced tags and named genes, many of which are involved in cell proliferation, differentiation, and apoptosis. CONCLUSION: ERG overexpression in AML patients with normal cytogenetics predicts an adverse clinical outcome and seems to be associated with a specific molecular signature.

Acute Disease↗

Prognostic factors and outcome of core binding factor acute myeloid leukemia patients with t(8;21) differ from those of patients with inv(16): a Cancer and Leukemia Group B study.

PURPOSE: Because both t(8;21) and inv(16) disrupt core binding factor (CBF) in acute myeloid leukemia (AML) and confer relatively favorable prognoses, these cytogenetic groups are often treated similarly. Recent studies, however, have shown different gene profiling for the two groups, underscoring potential biologic differences. Therefore, we sought to determine whether these two cytogenetic groups should also be considered separate entities from a clinical standpoint. PATIENTS AND METHODS: We analyzed 144 consecutive adults with t(8;21) and 168 with inv(16) treated on Cancer and Leukemia Group B front-line studies. We compared pretreatment features, probability of achieving complete remission (CR), overall survival (OS) and cumulative incidence of relapse (CIR) between the two groups. RESULTS: With a median follow-up of 6.4 years, for CBF AML as a whole, the CR rate was 88%, 5-year OS was 50% and CIR was 53%. After adjusting for covariates, patients with t(8;21) had shorter OS (hazard ratio [HR] = 1.5; P = .045) and survival after first relapse (HR = 1.7; P = .009) than patients with inv(16). Unexpectedly, race was an important predictor for t(8;21) AML, in that nonwhites failed induction more often (odds ratio = 5.7; P = .006) and had shorter OS than whites when certain secondary cytogenetic abnormalities were present. In patients with t(8;21) younger than 60 years, type of induction also correlated with relapse risk. For inv(16) AML, secondary cytogenetic abnormalities (especially +22) and male sex predicted better outcome. CONCLUSION: When the prognostic impact of race, secondary cytogenetic abnormalities, sex, and response to salvage treatment is considered, t(8;21) and inv(16) AMLs seem to be distinct clinical entities and should be stratified and reported separately.

Acute Disease↗

Phase I study of oblimersen sodium, an antisense to Bcl-2, in untreated older patients with acute myeloid leukemia: pharmacokinetics, pharmacodynamics, and clinical activity.

PURPOSES: Pharmacologic downregulation of Bcl-2, an antiapoptotic protein overexpressed in cancer, might increase chemosensitivity in acute myeloid leukemia (AML). Herein, we investigated the feasibility of this approach in untreated elderly AML patients by administering oblimersen sodium (G3139), an 18-mer phosphorothioate antisense to Bcl-2, during induction and consolidation treatments. PATIENTS AND METHODS: Untreated patients with primary or secondary AML (stratified to cohort 1 or 2, respectively) who were > or = 60 years received induction with G3139, cytarabine, and daunorubicin at one of two different dose levels (45 and 60 mg/m2) and, on achievement of complete remission (CR), consolidation with G3139 and high-dose cytarabine. An enzyme-linked immunosorbent assay (ELISA)-based assay was used to measure plasma and intracellular concentrations (IC) of G3139. Bcl-2 mRNA and protein levels were quantified by real-time reverse transcriptase polymerase chain reaction and ELISA, respectively, in bone marrow samples collected before induction treatment and after 72 hours of G3139 infusion, prior to initiation of chemotherapy. RESULTS: Of the 29 treated patients, 14 achieved CR. With a median follow-up of 12.6 months, seven patients had relapsed. Side effects of this combination were similar to those expected with chemotherapy alone and were not dose limiting at both dose levels. After 72-hour G3139 infusion, Bcl-2/ABL mRNA copies were decreased compared with baseline (P = .03) in CR patients and increased in nonresponders (NRs; P = .05). Changes in Bcl-2 protein showed a similar trend. Although plasma pharmacokinetics did not correlate with disease response, the median IC of the antisense was higher in the CR patients compared with NRs (17.0 v 4.4 pmol/mg protein, respectively; P = .05). CONCLUSION: G3139 can be administered safely in combination with intensive chemotherapy, and the degree of Bcl-2 downmodulation may correlate with response to therapy.

Aged↗

The MLL partial tandem duplication: evidence for recessive gain-of-function in acute myeloid leukemia identifies a novel patient subgroup for molecular-targeted therapy.

MLL (ALL-1) chimeric fusions and MLL partial tandem duplications (PTD) may have mechanistically distinct contributions to leukemogenesis. Acute myeloid leukemia (AML) blasts with the t(9;11)(p22; q23) express MLL-AF9 and MLL wild-type (WT) transcripts, while normal karyotype AML blasts with the MLL(PTD/WT) genotype express MLL PTD but not the MLL WT. Silencing of MLL WT in MLL(PTD/WT) blasts was reversed by DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors, and MLL WT induction was associated with selective sensitivity to cell death. Reduction of MLL PTD expression induced MLL WT and reduced blast colony-forming units, supporting opposing functions for MLL PTD and MLL WT whereby the MLL PTD contributes to the leukemic phenotype via a recessive gain-of-function. The coincident suppression of the MLL WT allele with the expression of the MLL PTD allele, along with the functional data presented here, supports the hypothesis that loss of WT MLL function via monoallelic repression contributes to the leukemic phenotype by the remaining mutant allele. These data from primary AML and the pharmacologic reversal of MLL WT silencing associated with a favorable alteration in the threshold for apoptosis suggest that these patients with poor prognosis may benefit from demethylating or histone deacetylase inhibitor therapy, or both.

Acute Disease↗

Acute myeloid leukemia with deletion 9q within a noncomplex karyotype is associated with CEBPA loss-of-function mutations.

To assess the prevalence of mutations in the CEBPA gene, which encodes the myeloid transcription factor CEBPA in specific cytogenetic subgroups, we initially studied 125 patients with acute myeloid leukemia (AML). Five of the eight patients with del(9q) as the sole aberration or in combination with a single additional abnormality other than t(8;21) had CEBPA mutations associated with loss of CEBPA function. Consequently, 41 additional del(9q) cases were analyzed; nine had CEBPA loss-of-function mutations. The overall prevalence of CEBPA loss-of-function mutations in cases with del(9q) in a noncomplex karyotype was 41% (14 of 34 patients), whereas none of the patients who had a del(9q) in a complex karyotype (n = 7) or together with a t(8;21) (n = 10) demonstrated mutant CEBPA. We have shown for the first time that AML with del(9q) in the context of a noncomplex karyotype is strongly associated with CEBPA loss-of-function mutations. Loss of a critical segment of 9q, most likely in 9q22, and disruption of CEBPA function possibly cooperate in the pathogenesis of del(9q) AML.

Acute Disease↗