Response to erythropoietic-stimulating agents in patients with chronic myelomonocytic leukemia.

BACKGROUND: The efficacy of erythropoietic-stimulating agents (ESA) in chronic myelomonocytic leukemia (CMML) is unknown. Our objective was to analyze erythroid response (ER) and overall survival (OS) in a series of 94 patients with CMML treated with ESA. METHODS: We analyzed a series of 94 patients with CMML treated with ESA included in the Spanish and Düsseldorf-MDS registries. FINDINGS: ER was observed in 64% of patients and red blood cell (RBC) transfusion independence in 31%. The median duration of ER was 7 months (range, 0-88). CPSS and EPO level were significantly associated with ER in multivariate analysis (P = 0.003). Considering only patients with CPSS low- or intermediate-1-risk group, the absence of RBC transfusion dependence and erythropoietin (EPO) level predicted ER (P = 0.003 and P = 0.008, respectively). In multivariate analysis, only the EPO level retained its prognostic value (P = 0.029). Achievement of ER correlated with a better survival since ER evaluation (P = 0.016). INTERPRETATION: The CPSS and EPO levels are adequate tools to select CMML patients with symptomatic anemia who may benefit from treatment with ESA. A significant ER to ESA is expected in anemic patients with low/intermediate-1 CMML risk by the CPSS and a low endogenous serum EPO level.

Biallelic losses of 13q do not confer a poorer outcome in chronic lymphocytic leukaemia: analysis of 627 patients with isolated 13q deletion.

Losses in 13q as a sole abnormality confer a good prognosis in chronic lymphocytic leukaemia (CLL). Nevertheless, its heterogeneity has been demonstrated and the clinical significance of biallelic 13q deletions remains controversial. We compared the clinico-biological characteristics of a series of 627 patients harbouring isolated 13q deletions by fluorescence in situ hybridization (FISH), either monoallelic (13q × 1), biallelic (13q × 2), or the coexistence of both clones (13qM). The most frequent 13q deletion was 13q × 1 (82·1%), while 13q × 2 and 13qM represented 8·6% and 9·3% of patients respectively. The median percentage of altered nuclei significantly differed across groups: 55%, 72·5% and 80% in 13q × 1, 13q × 2 and 13qM (P < 0·001). However, no significant differences in the clinical outcome among 13q groups were found. From 84 patients with sequential FISH studies, eight patients lost the remaining allele of 13q whereas none of them changed from 13q × 2 to the 13q × 1 group. The percentage of abnormal cells detected by FISH had a significant impact on the five-year cumulative incidence of treatment and the overall survival, 90% being the highest predictive power cut-off. In conclusion, loss of the remaining 13q allele is not enough to entail a worse prognosis in CLL. The presence of isolated 13q deletion can be risk-stratified according to the percentage of altered cells.

A putative "hepitype" in the ATM gene associated with chronic lymphocytic leukemia risk.

Chronic lymphocytic leukemia (CLL) cells are characterized by several chromosomal lesions. Some of these aberrations imply chromosome breaks as a result of unrepaired double strand breaks (DSBs) in the DNA. The ATM (ataxia telangiectasia-mutated) protein is the principal integrator of cellular responses to DSBs. ATM deletion is also an adverse prognostic factor in CLL. Taking this into account, we evaluated if genetic and/or epigenetic variation in the ATM gene may modulate the individual susceptibility to develop CLL. Our case-control association study was performed in a large Spanish population of 1,503 individuals, including 742 patients with CLL and 761 controls. We identified one haplotype within the ATM gene that confers an increased risk of CLL development (OR = 1.33; 95% CI: 1.10-1.60). Two polymorphisms of this ATM haplotype eliminated one CpG site each in Introns 15 and 61, causing changes in DNA methylation pattern. These data provide the first evidence for the existence of a putative "hepitype" in the ATM gene associated with CLL risk.

Prognostic impact of severe thrombocytopenia in low-risk myelodysplastic syndrome.

BACKGROUND: Thrombocytopenia is very common in myelodysplastic syndrome (MDS); however, its clinical impact in low-risk patients remains controversial. METHODS: The authors analyzed the incidence and prognostic significance of thrombocytopenia at diagnosis in 2565 de novo MDS patients included in the Spanish MDS Registry. RESULTS: Thrombocytopenia (platelet count <100 × 10(9) /L) was identified in 842 patients (32.8%). Severe thrombocytopenia (platelet count <30 × 10(9) /L) was observed in 7.1% of patients and was significantly associated with a higher-risk World Health Organization subtype (P = .026) and intermediate-2/high-risk International Prognostic Scoring System (IPSS) score (P = .046). Severe thrombocytopenia was the most important prognostic factor and had negative effects on the low/intermediate-1 risk group. Median overall survival of patients with a platelet count <30 and ≥ 30 × 10(9) /L was 16 months and 71 months, respectively (hazard ratio, 4.66; 95% confidence interval, 2.74-7.90; P < .0001). The negative effect of severe thrombocytopenia in low/intermediate-1 risk patients was caused by increased risk of bleeding. CONCLUSIONS: MDS patients with low/intermediate-1 IPSS risk score and severe thrombocytopenia should no longer be regarded as low risk, and must be considered for disease-altering approaches at diagnosis.

Methylation of CpG sites in BCL2 major breakpoint region and the increase of BCL2/JH translocation with aging.

The BCL2 breakage mechanism has been shown to be highly dependent on DNA methylation at the major breakpoint region (MBR) CpG sites. We recently described an increased frequency of BCL2/ JH translocation with aging. It is known that methylation levels change with aging. The present study aimed to determine whether methylation alterations at CpG sites of BCL2 MBR were the cause of increased breakages with aging. We analyzed the methylation levels of three CpG sites on the region by pyrosequencing and studied if methylation levels and/or polymorphisms affecting CpG sites were associated with an increase of translocations. We observed that although the methylation levels of MBR CpG sites were higher in individuals with BCL2/JH translocation, in contrast to our expectations, these levels decreased with the age. Moreover, we show that polymorphisms at those CpG sites leading to absence of methylation seem to be a protective factor for the apparition of translocations.

Genetic variants in miRNA processing genes and pre-miRNAs are associated with the risk of chronic lymphocytic leukemia.

Genome wide association studies (GWAS) have identified several low-penetrance susceptibility alleles in chronic lymphocytic leukemia (CLL). Nevertheless, these studies scarcely study regions that are implicated in non-coding molecules such as microRNAs (miRNAs). Abnormalities in miRNAs, as altered expression patterns and mutations, have been described in CLL, suggesting their implication in the development of the disease. Genetic variations in miRNAs can affect levels of miRNA expression if present in pre-miRNAs and in miRNA biogenesis genes or alter miRNA function if present in both target mRNA and miRNA sequences. Therefore, the present study aimed to evaluate whether polymorphisms in pre-miRNAs, and/or miRNA processing genes contribute to predisposition for CLL. A total of 91 SNPs in 107 CLL patients and 350 cancer-free controls were successfully analyzed using TaqMan Open Array technology. We found nine statistically significant associations with CLL risk after FDR correction, seven in miRNA processing genes (rs3805500 and rs6877842 in DROSHA, rs1057035 in DICER1, rs17676986 in SND1, rs9611280 in TNRC6B, rs784567 in TRBP and rs11866002 in CNOT1) and two in pre-miRNAs (rs11614913 in miR196a2 and rs2114358 in miR1206). These findings suggest that polymorphisms in genes involved in miRNAs biogenesis pathway as well as in pre-miRNAs contribute to the risk of CLL. Large-scale studies are needed to validate the current findings.

Methylation of the nonhomologous end joining repair pathway genes does not explain the increase of translocations with aging.

Chromosome translocations are especially frequent in human lymphomas and leukemias but are insufficient to drive carcinogenesis. Indeed, several of the so-called tumor specific translocations have been detected in peripheral blood of healthy individuals, finding a higher frequency of some of them with aging. The inappropriate repair of DNA double strand breaks by the nonhomologous end joining (NHEJ) pathway is one of the reasons for a translocation to occur. Moreover, fidelity of this pathway has been shown to decline with age. Although the mechanism underlying this inefficacy is unknown, other repair pathways are inactivated by methylation with aging. In this study, we analyzed the implication of NHEJ genes methylation in the increase of translocations with the age. To this aim, we determined the relationship between translocations and aging in 565 Spanish healthy individuals and correlated these data with the methylation status of 11 NHEJ genes. We found higher frequency of BCL2-JH and BCR-ABL (major) translocations with aging. In addition, we detected that two NHEJ genes (LIG4 and XRCC6) presented age-dependent promoter methylation changes. However, we did not observe a correlation between the increase of translocations and methylation, indicating that other molecular mechanisms are involved in the loss of NHEJ fidelity with aging.

Complex, not monosomal, karyotype is the cytogenetic marker of poorest prognosis in patients with primary myelodysplastic syndrome.

PURPOSE: Complex karyotype (CK) is the poorest risk factor in patients with myelodysplastic syndrome (MDS). It has recently been reported that monosomal karyotype (MK) worsens the prognosis of patients with CK. PATIENTS AND METHODS; We analyzed 1,054 adult patients with MDS with an abnormal karyotype from the Spanish Registry of MDS. The aim of the study was to describe the incidence, characteristics, and prognosis of MK; the main end points were overall survival (OS) and leukemia-free survival. RESULTS: MK was identified in 172 patients (16%), most of whom (88%) presented with CK. Variables significantly associated with OS were age (hazard ratio [HR], 1.90; P < .001), bone marrow (BM) blast percentage (HR, 1.05; P < .001), hemoglobin level (HR, 1.71; P < .001), platelet count (HR, 1.41; P < .001), karyotype complexity (CK [three abnormalities]: HR, 1.81; P = .003; very CK [> three abnormalities]: HR, 2; P < .001), and abnormalities of chromosome 5 and/or 7 (HR, 1.89; P < .001). Variables significantly related to the risk of transformation to acute myeloid leukemia (AML) were higher BM blast percentage (HR, 1.12; P < .001) and karyotype complexity (CK: HR, 2.53; P = .002; very CK: HR, 2.77; P < .001). CONCLUSION: After accounting for karyotype complexity, MK was not associated with OS or evolution to AML. In conclusion, these results demonstrate that the prognostic value of MK in MDS is not independent and is mainly the result of its strong association with number of chromosomal abnormalities.

High mitochondrial DNA stability in B-cell chronic lymphocytic leukemia.

BACKGROUND: Chronic Lymphocytic Leukemia (CLL) leads to progressive accumulation of lymphocytes in the blood, bone marrow, and lymphatic tissues. Previous findings have suggested that the mtDNA could play an important role in CLL. METHODOLOGY/PRINCIPAL FINDINGS: The mitochondrial DNA (mtDNA) control-region was analyzed in lymphocyte cell DNA extracts and compared with their granulocyte counterpart extract of 146 patients suffering from B-Cell CLL; B-CLL (all recruited from the Basque country). Major efforts were undertaken to rule out methodological artefacts that would render a high false positive rate for mtDNA instabilities and thus lead to erroneous interpretation of sequence instabilities. Only twenty instabilities were finally confirmed, most of them affecting the homopolymeric stretch located in the second hypervariable segment (HVS-II) around position 310, which is well known to constitute an extreme mutational hotspot of length polymorphism, as these mutations are frequently observed in the general human population. A critical revision of the findings in previous studies indicates a lack of proper methodological standards, which eventually led to an overinterpretation of the role of the mtDNA in CLL tumorigenesis. CONCLUSIONS/SIGNIFICANCE: Our results suggest that mtDNA instability is not the primary causal factor in B-CLL. A secondary role of mtDNA mutations cannot be fully ruled out under the hypothesis that the progressive accumulation of mtDNA instabilities could finally contribute to the tumoral process. Recommendations are given that would help to minimize erroneous interpretation of sequencing results in mtDNA studies in tumorigenesis.