Biomedical subjects

Clara D Bloomfield

Publications and source records attributed to Clara D Bloomfield.

At least 37 records · Page 2Linked to original sources

PubMed2005

The tumor suppressor PP2A is functionally inactivated in blast crisis CML through the inhibitory activity of the BCR/ABL-regulated SET protein.

The oncogenic BCR/ABL kinase activity induces and maintains chronic myelogenous leukemia (CML). We show here that, in BCR/ABL-transformed cells and CML blast crisis (CML-BC) progenitors, the phosphatase activity of the tumor suppressor PP2A is inhibited by the BCR/ABL-induced expression of the PP2A inhibitor SET. In imatinib-sensitive and -resistant (T315I included) BCR/ABL+ cell lines and CML-BC progenitors, molecular and/or pharmacological activation of PP2A promotes dephosphorylation of key regulators of cell proliferation and survival, suppresses BCR/ABL activity, and induces BCR/ABL degradation. Furthermore, PP2A activation results in growth suppression, enhanced apoptosis, restored differentiation, impaired clonogenic potential, and decreased in vivo leukemogenesis of imatinib-sensitive and -resistant BCR/ABL+ cells. Thus, functional inactivation of PP2A is essential for BCR/ABL leukemogenesis and, perhaps, required for blastic transformation.

Animals↗

PubMed2005

Molecular heterogeneity and prognostic biomarkers in adults with acute myeloid leukemia and normal cytogenetics.

PURPOSE OF REVIEW: Patients with acute myeloid leukemia (AML) and normal karyotype constitute the single largest cytogenetic group of AML, estimated to account for 45% of adults with de novo AML. This article critically reviews the recent literature that addresses the molecular heterogeneity of this group of patients and how this relates to prognostic stratification and novel therapeutic approaches. RECENT FINDINGS: Four prognostic biomarkers-the internal tandem duplication and point mutations in the FLT3 gene, partial tandem duplication of the MLL gene, mutations of the CEBPA gene, and overexpression of the BAALC gene-have been found to predict outcome in patients with AML and normal cytogenetics. In addition, one study using gene expression profiling identified two subgroups of AML patients with a normal karyotype whose survival differs significantly. Because mutations in FLT3 result in an autophosphorylated, leukemogenesis-driving protein, molecular targeting therapy with a new class of tyrosine kinase inhibitors is being explored in early clinical trials. SUMMARY: Considerable progress has been made in molecular characterization of AML patients with normal cytogenetics. The challenge for the future is to incorporate these biologic discoveries into novel risk-adapted therapeutic strategies that will improve the currently disappointing cure rate (approximately 25-40%) of this group of patients.

Adult↗

PubMed2004

Sequential multiagent chemotherapy is not superior to high-dose cytarabine alone as postremission intensification therapy for acute myeloid leukemia in adults under 60 years of age: Cancer and Leukemia Group B Study 9222.

The Cancer and Leukemia Group B (CALGB) study 9222 tested the hypothesis that treatment intensification of acute myeloid leukemia (AML) in first remission with multiple chemotherapy agents is superior to high-dose cytarabine (HiDAC) alone. We enrolled 474 patients younger than 60 years old with untreated de novo AML. Daunorubicin and cytarabine resulted in complete remission (CR) in 342 patients (72%), and 309 of these patients were randomized to receive one of 2 different intensification regimens. The first regimen consisted of 3 courses of HiDAC. The second regimen consisted of one course of HiDAC, a second course with etoposide and cyclophosphamide, and a third course with diaziquone and mitoxantrone. After a median follow-up time of 8.3 years, the median survival for all randomized patients was 2.8 years (95% CI, 1.9-6.8 years). There was no difference in disease-free survival (DFS) between the 2 regimens (P = .66). The median DFS was 1.1 years (95% CI, 0.9-1.7 years) for patients receiving HiDAC and 1.0 year (95% CI, 0.9-1.3 years) for those receiving multiagent chemotherapy. Cytogenetics was the only pretreatment characteristic prognostic for DFS, but there was no evidence of a differential treatment effect within cytogenetic risk groups. Toxicity was greater with multiagent chemotherapy. These 2 postremission regimens produced similar outcomes.

Acute Disease↗

PubMed2004

Outcome of induction and postremission therapy in younger adults with acute myeloid leukemia with normal karyotype: a cancer and leukemia group B study.

PURPOSE: Evaluate the outcome of induction and postremission therapy in adults younger than 60 years with normal cytogenetics acute myeloid leukemia (AML). PATIENTS AND METHODS: In 490 patients, induction included cytarabine and daunorubicin (AD) or cytarabine and escalated doses of daunorubicin and etoposide +/- PSC-833 (ADE/ADEP). Intensification included one cycle of high-dose cytarabine (HDAC) followed by etoposide/cyclophosphamide and mitoxantrone/diaziquone (group I), three HDAC cycles (group II), four intermediate-dose cytarabine (IDAC) or HDAC cycles (group III), or one HDAC/etoposide cycle and autologous stem-cell transplantation (ASCT; group IV). RESULTS: Of 350 patients receiving AD, 73% achieved complete remission (CR), compared with 82% of 140 receiving ADE/ADEP (P = .04). Splenomegaly was associated with a lower CR rate (P < .001), and ADE/ADEP, with a higher CR rate in younger patients (P = .005). The 5-year disease-free survival (DFS) rate was 28% each for intensification groups I and II, compared with 41% and 45% for groups III and IV, respectively (P = .02). The 5-year cumulative incidence of relapse (CIR) was 62% and 67% for groups I and II, respectively, compared with 54% and 44% for groups III and IV, respectively (P = .049). The type of postremission intensification remained significant for DFS and CIR in multivariable analysis. CONCLUSION: In younger adults with normal cytogenetics AML, splenomegaly predicts a lower CR rate, and the postremission strategies of either four cycles of I/HDAC or one cycle of HDAC/etoposide followed by ASCT are associated with improved DFS and reduced relapse compared with therapies that include fewer cycles of cytarabine or no transplantation.

Acute Disease↗

PubMed2004

Dose escalation studies of cytarabine, daunorubicin, and etoposide with and without multidrug resistance modulation with PSC-833 in untreated adults with acute myeloid leukemia younger than 60 years: final induction results of Cancer and Leukemia Group B Study 9621.

PURPOSE: P-glycoprotein (Pgp) is strongly inhibited by PSC-833. A chemotherapy dose-escalation study was performed with PSC-833 in patients younger than 60 years with untreated acute myeloid leukemia. Clinical rather than pharmacokinetic end points were used to develop two induction therapies containing drugs susceptible to Pgp-mediated efflux and associated with comparable toxicities at the maximum-tolerated doses. PATIENTS AND METHODS: A total of 410 patients were enrolled. Fifteen induction regimens containing variable doses of daunorubicin (DNR) and etoposide (ETOP) and fixed doses of cytarabine were evaluated with (ADEP) or without (ADE) a fixed dose of PSC-833. RESULTS: Doses selected for phase III testing were DNR 90 mg/m(2) and ETOP 100 mg/m(2) in ADE, and DNR and ETOP each 40 mg/m(2) in ADEP. Intolerable mucosal toxicity occurred at higher doses of ADEP. Although the design of this study precludes direct comparisons, there was an apparent advantage for receiving ADEP with respect to disease-free and overall survival in patients < or = 45 years old, despite the significantly lower doses of DNR and ETOP given in ADEP compared with ADE. CONCLUSION: A large clinical data set was used to develop induction regimens containing two drugs susceptible to Pgp-mediated efflux, with and without an inhibitor of Pgp function. The chosen doses have comparable antileukemia activity and toxicity, making them suitable for use in a phase III comparative study of induction chemotherapy for patients with acute myeloid leukemia younger than 60 years. That trial will also clarify whether patients < or = 45 years old are especially likely to benefit from Pgp inhibition during induction therapy.

Acute Disease↗

PubMed2004

Adult de novo acute myeloid leukemia with t(6;11)(q27;q23): results from Cancer and Leukemia Group B Study 8461 and review of the literature.

BACKGROUND: Acute myeloid leukemia (AML) with t(6;11)(q27;q23) is a well established but rare entity, and few studies have reported the full clinical, hematologic, and outcome data of patients with this disease. METHODS: To characterize the features of t(6;11) AML, the authors searched the Cancer and Leukemia Group B (CALGB) cytogenetic database comprising 2667 adults with newly diagnosed, de novo AML and identified 16 patients (0.6%) with t(6;11). A review of the literature identified 33 adults with de novo t(6;11) AML for whom survival data were available. RESULTS: CALGB patients had a median age of 45 years (range, 22-65 years) and commonly presented with French-American-British (FAB) subtype M4 or M5 (81%). Gingival involvement at presentation was common (31%). All patients with gingival involvement had FAB M4. Compared with other patients with M4 AML in the CALGB database (n = 429), patients with M4 and t(6;11) (n = 7) had a higher frequency of gingival hypertrophy at presentation (71% vs. 17%, P = 0.003). Patients with t(6;11) were more likely to be African American (P = 0.02) and to die during induction (P = 0.03) than those without t(6;11). The complete response (CR) rate was 69% (11 of 16 patients), and CR duration was short (median, 9 months). The estimated probability of 2-year survival was 13%. Both long-term survivors received allogeneic stem cell transplantation. The estimated probability of 2-year survival of patients reported in the literature was 15%. CONCLUSIONS: Although the patient sample was small, the authors suggested that investigational approaches, including allogeneic transplantation, be considered for adults with t(6;11) AML.

Acute Disease↗

PubMed2004

Abnormal cytogenetics at date of morphologic complete remission predicts short overall and disease-free survival, and higher relapse rate in adult acute myeloid leukemia: results from cancer and leukemia group B study 8461.

PURPOSE: As most patients with acute myeloid leukemia (AML) with morphologic complete remission (CR) ultimately relapse, better predictors for outcome are needed. Recently, Cheson et al suggested using cytogenetic remission (CRc) as part of the criteria for CR. To our knowledge, ours is the first relatively large study evaluating the usefulness of CRc attained immediately following induction chemotherapy. PATIENTS AND METHODS: We included AML patients treated on Cancer and Leukemia Group B front-line studies with cytogenetic samples obtained at diagnosis and at the first day of documented CR following induction. Patients with abnormal cytogenetics at diagnosis, and normal cytogenetics at CR (NCR; n = 103) were compared with those with abnormal cytogenetics both at diagnosis and at CR (ACR; n = 15) for overall survival (OS), disease-free survival (DFS), and cumulative incidence of relapse (CIR). Cox proportional hazards models determined the prognostic significance of cytogenetics at CR, adjusting for other covariates. RESULTS: Clinical features were similar for both groups, with the exception of favorable cytogenetics [t(8;21), inv(16)/t(16;16), t(15;17)] at diagnosis, which was more frequent (P =.03) in the NCR group. Median follow-up was 3.1 years (range, 1.0 to 11.4 years). ACR patients had significantly shorter OS (P =.006) and DFS (P =.0001), and higher CIR (P =.0001). In multivariable models, the NCR and ACR groups were predictors for OS (P =.03), DFS (P =.02), and CIR (P =.05). The relative risk of relapse or death was 2.1 times higher for ACR patients than for NCR patients (95% CI, 1.1 to 3.9). CONCLUSION: Our data suggest that converting to normal karyotype at the time of first CR is an important prognostic indicator and support the use of CRc as a criterion of CR in AML.

Acute Disease↗

PubMed2004

Intensive chemotherapy with and without cranial radiation for Burkitt leukemia and lymphoma: final results of Cancer and Leukemia Group B Study 9251.

BACKGROUND: The objective of the current study was to evaluate the efficacy of intensive chemotherapy with and without cranial radiation for central nervous system (CNS) prophylaxis in adults with Burkitt leukemia or lymphoma. METHODS: Patients received 18 weeks of therapy. Prophylactic cranial radiation (2400 centigrays) and 12 doses of triple intrathecal chemotherapy were administered to the first cohort of patients. A subsequent cohort received the same therapy, with the exceptions that intrathecal therapy was reduced to six doses and radiotherapy was administered only to high-risk individuals. RESULTS: The median follow-up durations were 6.8 years in Cohort 1 and 4.1 years in Cohort 2. Three occurrences of transverse myelitis, 2 severe neuropathies, 3 cases of aphasia, and 1 case of blindness were documented in the first cohort of 52 patients (Cohort 1). In the subsequent cohort of 40 patients (Cohort 2), none of these occurrences were observed, and patients experienced less neurologic toxicity overall (61% vs. 26%; P=0.001). Responses were similar, and the 3-year event-free survival rate was 0.52 (95% confidence interval, 0.38-0.65) for Cohort 1 and 0.45 (0.29-0.60) for Cohort 2. CONCLUSIONS: Intensive, short-duration chemotherapy with less intensive CNS prophylaxis led to control at this sanctuary site with little neurotoxicity and may be curative for adults with Burkitt leukemia or lymphoma.

Adolescent↗

PubMed2004

Repetitive cycles of high-dose cytarabine benefit patients with acute myeloid leukemia and inv(16)(p13q22) or t(16;16)(p13;q22): results from CALGB 8461.

PURPOSE: To study the impact of repetitive (three to four courses) versus a single course of high-dose cytarabine (HDAC) consolidation therapy on outcome of patients with acute myeloid leukemia (AML) and inv(16)(p13q22) or t(16;16)(p13;q22). PATIENTS AND METHODS: We examined the cumulative incidence of relapse (CIR), relapse-free survival (RFS), and overall survival (OS) for 48 adults younger than 60 years with inv(16)/t(16;16) who had attained a complete remission on one of four consecutive clinical trials and were assigned to receive HDAC consolidation therapy. Twenty-eight patients were assigned to either three or four courses of HDAC, and 20 patients were assigned to one course of HDAC followed by alternative intensive consolidation therapy. RESULTS: Pretreatment features were similar for the two groups. The CIR was significantly decreased in patients assigned to receive three to four cycles of HDAC compared with patients assigned to one course (P=.03; 5-year CIR, 43% v 70%, respectively). The difference in RFS also approached statistical significance (P=.06). In a multivariable analysis that adjusted for potential confounding covariates, only treatment assignment (three to four cycles of HDAC) predicted for superior RFS (P=.02). The OS of both groups was similar (P=.93; 5-year OS, 75% for the three to four cycles of HDAC group v 70% for the one cycle of HDAC group), reflecting a high success rate with stem-cell transplantation salvage treatment administered among patients in both treatment groups. CONCLUSION: We conclude that, in AML patients with inv(16)/t(16;16), repetitive HDAC therapy decreases the likelihood of relapse compared with consolidation regimens including less HDAC.

Acute Disease↗

PubMed2004

Acute myeloid leukemia with complex karyotypes and abnormal chromosome 21: Amplification discloses overexpression of APP, ETS2, and ERG genes.

Molecular mechanisms of leukemogenesis have been successfully unraveled by studying genes involved in simple rearrangements including balanced translocations and inversions. In contrast, little is known about genes altered in complex karyotypic abnormalities. We studied acute myeloid leukemia (AML) patients with complex karyotypes and abnormal chromosome 21. High-resolution bacterial artificial chromosome (BAC) array-based comparative genomic hybridization disclosed amplification predominantly in the 25- to 30-megabase (MB) region that harbors the APP gene (26.3 MB) and at position 38.7-39.1 MB that harbors the transcription factors ERG and ETS2. Using oligonucleotide arrays, APP was by far the most overexpressed gene (mean fold change 19.74, P = 0.0003) compared to a control group of AML with normal cytogenetics; ERG and ETS2 also ranked among the most highly expressed chromosome 21 genes. Overexpression of APP and ETS2 correlated with genomic amplification, but high APP expression occurred even in a subset of AML patients with normal cytogenetics (10 of 64, 16%). APP encodes a glycoprotein of unknown function previously implicated in Alzheimer's disease, but not in AML. We hypothesize that APP and the transcription factors ERG and ETS2 are altered by yet unknown molecular mechanisms involved in leukemogenesis. Our results highlight the value of molecularly dissecting leukemic cells with complex karyotypes.

Acute Disease↗

PubMed2004

Differences in prognostic factors and outcomes in African Americans and whites with acute myeloid leukemia.

Whites have a more favorable prognosis than African Americans for a number of cancers. The relationship between race and outcome is less clear in acute myeloid leukemia (AML). Using data from 7 Cancer and Leukemia Group B studies initiated from 1985 to 1997, we conducted a retrospective cross-sectional analysis of 2570 patients (270 African American and 2300 white) with de novo AML who received induction chemotherapy. African Americans were younger than whites (48 versus 54 years, P <.001). African Americans also had different cytogenetic risk group distributions than whites (P <.001): they were more commonly classified in the favorable (23% versus 14%) and unfavorable (31% versus 23%) groups, and less commonly classified in the intermediate group (47% versus 63%). African American men had a lower complete remission (CR) rate (54%, compared with 64% for white men, 65% for white women, and 70% for African American women, P =.001) and a worse overall survival compared with all other patients (P =.004), when known risk factors are taken into account. African Americans and whites with AML differ with respect to important prognostic factors. African American men have worse CR rates and overall survival than whites and African American women, and should be considered a poor-risk group.

Acute Disease↗

PubMed2004

Prognostic importance of TLX1 (HOX11) oncogene expression in adults with T-cell acute lymphoblastic leukaemia.

The activation of oncogenic transcription factors defines distinct molecular subsets of T-cell acute lymphoblastic leukaemia and has prognostic relevance in children. We investigated the prognostic effect of the expression levels of eight oncogenic transcription factors--TLX1 (HOX11), TLX3 (HOX11L2), TAL1, TAL2, LYL1, OLIG2 (BHLHB1), LMO1, and LMO2--in 52 adults with T-cell acute lymphoblastic leukaemia. The leukaemia-specific survival rate for the 16 TLX1-positive patients was 88% (90% CI 73-100%), compared with 56% (42-70%) for all other cases (p=0.019). Only the TLX1 oncogene expression subgroup showed difference in leukaemia-specific survival. Our results suggest that overexpression of TLX1 confers a good outlook for adults with T-cell acute lymphoblastic leukaemia. Furthermore, our findings lead to questions about whether stem-cell transplantation in first remission is necessary for effective treatment of patients in the low-risk subgroup of patients with TLX1 oncogene expression.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Cytogenetics in acute leukemia.

Cytogenetic analyses in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) have revealed a great number of non-random chromosome abnormalities. In many instances, molecular studies of these abnormalities identified specific genes implicated in the process of leukemogenesis. The more common chromosome aberrations have been associated with specific laboratory and clinical characteristics, and are now being used as diagnostic and prognostic markers guiding the clinician in selecting the most effective therapies. Specific chromosome aberrations and their molecular counterparts have been included in the World Health Organization classification of hematologic malignancies, and together with morphology, immunophenotype and clinical features are used to define distinct disease entities. However, the prognostic importance of less frequent recurrent aberrations in AML and ALL, both primary and secondary, is still to be determined. This review summarizes current views on clinical relevance of major cytogenetic findings in adult AML and ALL.

Adolescent↗

PubMed2004

Additional cytogenetic abnormalities in adults with Philadelphia chromosome-positive acute lymphoblastic leukaemia: a study of the Cancer and Leukaemia Group B.

We analysed the nature and prognostic significance of secondary cytogenetic changes in 111 newly diagnosed adults with acute lymphoblastic leukaemia (ALL) and t(9;22)(q34;q11.2) or its variants. Secondary aberrations were seen in 75 (68%) patients. They included, in order of descending frequency: +der(22)t(9;22), +21, abnormalities of 9p, high hyperdiploidy (>50 chromosomes), +8, -7, +X and abnormalities resulting in loss of material from 8p, gain of 8q, gain of 1q and loss of 7p. Eighty patients (72%) had > or =1 normal metaphase in their karyotype. There were four balanced and 12 unbalanced translocations previously unreported in ALL with t(9;22). The t(2;7)(p11;p13) and der(18)t(8;18)(q11.2;p11.2) were seen in two cases each, and have never before been reported in haematological malignancy. All but four patients were treated on front-line Cancer and Leukaemia Group B clinical protocols. The presence of -7 as a sole secondary abnormality was associated with a lower complete remission (CR) rate (P = 0.004), while the presence of > or =3 aberrations was associated with a higher CR rate (P = 0.009) and +der(22)t(9;22) with a higher cumulative incidence of relapse (P = 0.02). It will be of interest to see if newly diagnosed t(9;22)-positive adult ALL patients with these and other secondary aberrations respond differently to treatment regimens that include imatinib mesylate.

Adult↗

PubMed2004

Prognostic significance of additional cytogenetic abnormalities in newly diagnosed patients with Philadelphia chromosome-positive chronic myelogenous leukemia treated with interferon-alpha: a Cancer and Leukemia Group B study.

Secondary cytogenetic abnormalities at diagnosis of Philadelphia chromosome-positive (Ph+) chronic myelogenous leukemia (CML) have been associated with an inferior outcome in reported series of largely chemotherapy-treated patients. To date, no study has specifically focused on the prognostic significance of secondary karyotypic abnormalities, detected at the time of diagnosis, in interferon (IFN)-alpha treated patients. We compared the outcome of 29 newly diagnosed Ph+ CML patients with additional abnormalities to that of 234 sole Ph+ patients, treated on CALGB protocols with IFN-alpha alone or together with IFN-gamma or low-dose cytarabine. Complete and partial cytogenetic responses were achieved in 20 and 19% of sole Ph+ patients, compared to 23 and 18%, respectively, of patients with additional abnormalities (P=1.00). None of 4 patients with 'high-risk' secondary abnormalities [+8, +Ph and i(17)(q10)], for whom follow-up cytogenetic samples were available, achieved a cytogenetic response. With a median follow-up of 11.3 years, the median overall survival (OS) was 6.0 years for sole Ph+ patients compared to 7.5 years for patients with additional abnormalities (P=0.70), with corresponding 8-year OS of 36 and 38%, respectively. On multivariable analysis, only age (P<0.001) and white blood cell count (P=0.02) were associated with outcome. We conclude that, with the possible exception of +8, +Ph and i(17)(q10), additional chromosomal abnormalities at diagnosis are not associated with inferior outcome in Ph+ CML patients treated with IFN-alpha-based therapy.

Adolescent↗

PubMed2003

Revised recommendations of the International Working Group for Diagnosis, Standardization of Response Criteria, Treatment Outcomes, and Reporting Standards for Therapeutic Trials in Acute Myeloid Leukemia.

An International Working Group met to revise the diagnostic and response criteria for acute myelogenous leukemia originally published in 1990, as well as to provide definitions of outcomes and reporting standards to improve interpretability of data and comparisons among trials. Since the original publication, there have been major advances in our understanding of the biology and molecular genetics of acute leukemia that are clinically relevant and warrant incorporation into response definitions. Differences from the 1990 recommendations included a category of leukemia-free state, new criteria for complete remission, including cytogenetic and molecular remissions and remission duration. Storage of viable blasts for correlative studies is important for future progress in the therapy of these disorders.

Clinical Trials as Topic↗

PubMed2003

A pilot study of high-throughput, sequence-based mutational profiling of primary human acute myeloid leukemia cell genomes.

In this pilot study, we used primary human acute myeloid leukemia (AML) cell genomes as templates for exonic PCR amplification, followed by high-throughput resequencing, analyzing approximately 7 million base pairs of DNA from 140 AML samples and 48 controls. We identified six previously described, and seven previously undescribed sequence changes that may be relevant for AML pathogenesis. Because the sequencing templates were generated from primary AML cells, the technique favors the detection of mutations from the most dominant clones within the tumor cell mixture. This strategy represents a viable approach for the detection of potentially relevant, nonrandom mutations in primary human cancer cell genomes.

Case-Control Studies↗

PubMed2003

Expression analyses identify MLL as a prominent target of 11q23 amplification and support an etiologic role for MLL gain of function in myeloid malignancies.

MLL amplification was recently recognized as a recurrent aberration in acute myeloid leukemia (AML) and myelodys-plastic syndrome (MDS), associated with adverse prognosis and karyotype complexity. Here we present detailed results of fluorescence in situ hybridization (FISH) and expression analyses of MLL and 5 selected 11q candidate oncogenes (CBL, DDX6, ETS1, FLI1, and PLZF) in 31 patient samples and one cell line with 11q23 gain. FISH analyses revealed that the 11q23 amplicon invariably encompassed MLL, DDX6, ETS1, and FLI1, whereas expression analyses identified MLL and DDX6 as the most differentially expressed genes among samples with and without 11q23 copy gain or amplification. In MLL-amplified samples, a significant transcriptional up-regulation of MEIS1, PROML1, ADAM10, NKG2D, and ITPA was noted. Further analyses, designed to elucidate a possible role of the 11q overexpressed genes (MLL, DDX6, FLI1, and ETS1) in unselected MDS and AML samples, revealed a significant upregulation of MLL in MDS. Our findings confirm the MLL gene as a prominent target of 11q23 amplification and provide further evidence for an etiologic role for MLL gain of function in myeloid malignancies. In addition, our results indicate that the transcriptional program associated with MLL rearrangements and MLL overexpression displays significant similarities.

Adult↗