CEBPA copy number variations in normal karyotype acute myeloid leukemia: Possible role of breakpoint-associated microhomology and chromatin status in CEBPA mutagenesis.

Copy number variations (CNV) in CEBPA locus represent heterogeneous group of mutations accompanying acute myeloid leukemia (AML). The aim of this study was to characterize different CEBPA mutation categories in regard to biological data like age, cytology, CD7, and molecular markers, and identify possible factors affecting their etiology. We report here the incidence of 12.6% of CEBPA mutants in the population of 262 normal karyotype AML (NK-AML) patients. We confirmed that double mutant AMLs presented uniform biological features when compared to single CEBPA mutations and accompanied mostly younger patients. We hypothesized that pathogenesis of distinct CEBPA mutation categories might be influenced by different factors. The detailed sequence analysis revealed frequent breakpoint-associated microhomologies of 2 to 12bp. The analysis of distribution of microhomology motifs along CEBPA gene showed that longer stretches of microhomology at the mutational junctions were relatively rare by chance which suggests their functional role in the CEBPA mutagenesis. Additionally, accurate quantification of CEBPA transcript levels showed that double CEBPA mutations correlated with high-level CEBPA expression, whereas single N-terminal CEBPA mutations were associated with low-level CEBPA expression. This might suggest that high-level CEBPA expression and/or accessibility of CEBPA locus contribute to B-ZIP in-frame duplications.

[Hematological toxicity of radioimmunotherpy with 90Y Ibritumomab]. / Toksycznosc hematologiczna radioimmunoterapii z zastosowaniem 90Y Ibritumomabu.

Radioimmunotherapy with 90Y Ibritumomabu (Zevalin, BSP) is a new method of systemic radiotherapy applicable to B-cell lymphoma patients. It may be delivered as a short outpatient procedure, with few adverse effects other than hematological toxicity. In the paper, we present length and depth of cytopenias, together with the results of additional tests performed to reveal the possible pathomechanisms, based on 102 patients treated at the University Hospital in Krakow.

Long-term outcomes of patients with Chronic Myeloid Leukemia who commenced treatment with imatinib: a 20-year single-centre experience.

We report on long-term outcomes of 267 patients (pts) with chronic myeloid leukemia (CML) treated with imatinib administered as initial therapy. The median follow-up time was 11.4 years. 38 (14.2%) pts attempted to discontinue imatinib therapy after achieving sustained deep molecular response (≥MR4), 15 of them achieved treatment-free remission (TFR). 144 pts (53.9%) have been switched to other TKI during the follow-up period. The estimated OS for 267 pts for 10, 15 and 18 years was 98.8%, 75.6% and 52.1%. According to prognostic scores (Sokal, Euro, ELTS), OS and PFS were significantly better in low-risk pts than in high-risk pts. According to ELTS, low-risk pts have a better chance of achieving MR4 than both intermediate (p = 0.03) and high-risk (p = 0.04) groups. It suggests that a specific ELTS-adapted treatment could help to optimize treatment results. In the study population, imatinib has demonstrated sustained efficacy and an acceptable rate of late toxic effects.

Consolidation with 90Y ibritumomab tiuxetan radioimmunotherapy in mantle cell lymphoma patients ineligible for high dose therapy: results of the phase II multicentre Polish Lymphoma Research Group trial, after 8-year long follow-up.

Polish Lymphoma Research Group performed a phase-II trial to test whether 90Y ibritumomab tiuxetan radioimmunotherapy (Y90) may constitute an alternative consolidation for mantle cell lymphoma patients unfit for high-dose therapy. Forty-six patients were consolidated with Y90 following response to the 1st (n = 34) or 2nd line (n = 12) (immuno)chemotherapy. Majority of the patients had advanced disease (stage IV and presence of B-symptoms in 85% and 70%, respectively) and high MIPI (5.8, range 4-7). Consolidation with Y90 increased the complete remission (CR) rate obtained by the 1st line therapy from 41% to 91% and allowed for median PFS of 3.3 and OS of 6.5 years. In the first relapse, CR rate increased from 16% to 75%, while median PFS and OS totaled 2.2 and 6.5 years, respectively. At 8 years, 30% of patients, consolidated in the 1st line CR were alive, without relapse. Toxicity associated with Y90 is manageable, more severe after fludarabine-based regimens.

Promoter DNA methylation and expression levels of HOXA4, HOXA5 and MEIS1 in acute myeloid leukemia.

HOXA genes encode transcription factors, which are crucial for embryogenesis and tissue differentiation and are involved in the early stages of hematopoiesis. Aberrations in HOXA genes and their cofactor MEIS1 are found in human neoplasms, including acute myeloid leukemia (AML). The present study investigated the role of HOXA4, HOXA5 and MEIS1 promoter DNA methylation and mRNA expression in AML. Samples from 78 AML patients and 12 normal bone marrow (BM) samples were included. The levels of promoter DNA methylation were determined using quantitative methylation­specific polymerase chain reaction (PCR; qMSP) and the relative expression levels were measured using reverse transcription quantitative PCR in Ficoll­separated BM mononuclear cells and in fluorescent activated cell sorting­sorted populations of normal hematopoietic progenitors. In total, 38.1 and 28.9% of the patients exhibited high methylation levels of HOXA4 and HOXA5, respectively, compared with the control samples, and MEIS1 methylation was almost absent. An inverse correlation between HOXA4 methylation and expression was identified in a group of patients with a normal karyotype (NK AML). An association between the genes was observed and correlation between the DNA methylation and expression levels of the HOXA gene promoter with the expression of MEIS1 was observed. Patients with favorable chromosomal aberrations revealed a low level of HOXA4 methylation and decreased expression levels of HOXA5 and MEIS1 compared with the NK AML and the adverse cytogenetic risk patients. The NK AML patients with NPM1 mutations exhibited elevated HOXA4 methylation and expression levels of HOXA5 and MEIS1 compared with the NPM1 wild­type patients. Comparison of the undifferentiated BM­derived hematopoietic CD34+CD38low, CD34+CD38+ and CD15+ cells revealed a gradual decrease in the expression levels of these three genes and an increase in HOXA4 promoter methylation. This differentiation­associated variability was not observed in AML, which was classified according to the French­American­British system.

Complex cytogenetics in a case of probably work related MDS/AML.

In the majority of cases of overt acute myeloid leukemia (AML), there is no knowledge about a preleukemic phase of myelodysplastic syndrome (MDS). A few recent case-control studies suggest an association between MDS and several occupations. We report a unique case of MDS/AML related to the patient's work condition with numerous cytostatic agents. The karyotype revealed a spectrum of genetic rearrangements identified by conventional cytogenetics, fluorescence in situ hybridization (FISH) and spectral karyotyping (SKY). We suggest that amplification of chromosomal material may play a greater role in leukemogenesis than has been recognized previously.

ABL-kinase domain point mutation as a cause of imatinib (STI571) resistance in CML patient who progress to myeloid blast crisis.

Imatinib mesylate (STI571) is a major therapeutic advance for the management of chronic myeloid leukaemia (CML), however, a proportion of patients are refractory to it, particularly those in more advanced phases of CML. Different mechanisms of resistance to imatinib are suggested, including point mutations within ABL-kinase domains. A point mutation leading to substitution at the ATP binding site of ABL-kinase and insensitivity to imatinib was detected in our patient treated with imatinib, who progressed to blast crisis. Additionally, clonal evolution could lead to BCR-ABL-independent proliferation. Early detection of ABL-kinase mutation could predict the progression of CML treated with imatinib.

Comparison of promoter DNA methylation and expression levels of genes encoding CCAAT/enhancer binding proteins in AML patients.

CCAAT/enhancer binding proteins (CEBPs) are transcription factors regulating myeloid differentiation. Disturbances of their expression may contribute to leukemogenesis. In this study we compared promoter methylation and expression levels of selected CEBP genes in a group of 78 AML patients, normal bone marrow and hematopoietic precursor cells. CEBPA, CEBPD and CEBPE promoter methylation levels were elevated in 37%, 35.5% and 56.7% of patients. No CEBPZ(DDIT3) methylation was observed. An inverse relationship between CEBPA and CEBPD DNA methylation and expression levels was observed. AML cytogenetic risk groups and patients with particular translocation are characterized by distinct methylation/expression profile of CEBPs encoding genes.

Different prognosis of acute myeloid leukemia harboring monosomal karyotype with total or partial monosomies determined by FISH: retrospective PALG study.

A monosomal karyotype (MK) was identified by banding techniques (BT) in acute myeloid leukemia (AML). However, BT may be insufficient to determine the actual loss of a complete chromosome, especially in complex karyotypes. We have investigated the effect of monosomy type, total (MK-t) and partial (MK-p), reevaluated by FISH, on prognosis. We have found that complete remission rate and probability of overall survival at 1 year was higher in MK-p (n=27) than MK-t (n=15) group (40% vs. 15.4%, P=0.19 and 30% vs. 9%, P=0.046, respectively). Our results indicate for the first time that monosomy type influences the prognosis of MK-AML.