Genome-wide analysis toward the epigenetic aetiology of myelodysplastic syndrome disease progression and pharmacoepigenomic basis of hypomethylating agents drug treatment response.

Myelodysplastic syndromes (MDS) consist of a group of hematological malignancies characterized by ineffective hematopoiesis, cytogenetic abnormalities, and often a high risk of transformation to acute myeloid leukemia (AML). So far, there have been only a very limited number of studies assessing the epigenetics component contributing to the pathophysiology of these disorders, but not a single study assessing this at a genome-wide level. Here, we implemented a generic high throughput epigenomics approach, using methylated DNA sequencing (MeD-seq) of LpnPI digested fragments to identify potential epigenomic targets associated with MDS subtypes. Our results highlighted that PCDHG and ZNF gene families harbor potential epigenomic targets, which have been shown to be differentially methylated in a variety of comparisons between different MDS subtypes. Specifically, CpG islands, transcription start sites and post-transcriptional start sites within ZNF124, ZNF497 and PCDHG family are differentially methylated with fold change above 3,5. Overall, these findings highlight important aspects of the epigenomic component of MDS syndromes pathogenesis and the pharmacoepigenomic basis to the hypomethylating agents drug treatment response, while this generic high throughput whole epigenome sequencing approach could be readily implemented to other genetic diseases with a strong epigenetic component.

Fetal hemoglobin induction in azacytidine responders enlightens methylation patterns related to blast clearance in higher-risk MDS and CMML.

BACKGROUND: As new treatment options for patients with higher-risk myelodysplastic syndromes are emerging, identification of prognostic markers for hypomethylating agent (HMA) treatment and understanding mechanisms of their delayed and short-term responses are essential. Early fetal hemoglobin (HbF) induction has been suggested as a prognostic indicator for decitabine-treated patients. Although epigenetic mechanisms are assumed, responding patients' epigenomes have not been thoroughly examined. We aimed to clarify HbF kinetics and prognostic value for azacytidine treated patients, as well as the epigenetic landscape that might influence HbF re-expression and its clinical relevance. RESULTS: Serial HbF measurements by high-performance liquid chromatography (n = 20) showed induction of HbF only among responders (p = 0.030). Moreover, HbF increase immediately after the first azacytidine cycle demonstrated prognostic value for progression-free survival (PFS) (p = 0.032, HR = 0.19, CI 0.24-1.63). Changes in methylation patterns were revealed with methylated DNA genome-wide sequencing analysis (n = 7) for FOG-1, RCOR-1, ZBTB7A and genes of the NuRD-complex components. Targeted pyrosequencing methodology (n = 28) revealed a strong inverse correlation between the degree of γ-globin gene (HBG2) promoter methylation and baseline HbF levels (p = 0.003, rs = - 0.663). A potential epigenetic mechanism of HbF re-expression in azacytidine responders was enlightened by targeted methylation analysis, through hypomethylation of site -53 of HBG2 promoter (p = 0.039, rs = - 0.504), which corresponds to MBD2-NuRD binding site, and to hypermethylation of the CpG326 island of ZBTB7A (p = 0.05, rs = 0.482), a known HbF repressor. These changes were associated to blast cell clearance (pHBG2 = 0.011, rs = 0.480/pZBTB7A = 0.026, rs = 0.427) and showed prognostic value for PFS (pZBTB7A = 0.037, HR = 1.14, CI 0.34-3.8). CONCLUSIONS: Early HbF induction is featured as an accessible prognostic indicator for HMA treatment and the proposed potential epigenetic mechanism of HbF re-expression in azacytidine responders includes hypomethylation of the γ-globin gene promoter region and hypermethylation of the CpG326 island of ZBTB7A. The association of these methylation patterns with blast clearance and their prognostic value for PFS paves the way to discuss in-depth azacytidine epigenetic mechanism of action.

Allogeneic Hematopoietic Stem Cell Transplantation for Mixed or Overlap Myelodysplastic/Myeloproliferative Disorders.

Chronic myelomonocytic leukemia (CMML) and the remaining, less frequent hybrid, mixed, or overlap myelodysplastic syndromes/myeloproliferative neoplasms (MDSs/MPNs) are difficult to treat neoplastic hematological disorders, exhibiting substantial clinical and prognostic heterogeneity, for which clear therapeutic guidelines or effective treatment options are still missing. CMML has an overall survival ranging from a few months to several years. Although patients with proliferative or dysplastic features may benefit from hydroxyurea and hypomethylating agent treatment, respectively, none of these treatments can establish long-term remission and prevent the inevitable transformation to acute leukemia. Novel targeted treatment approaches are emerging but are still under investigation. Therefore, currently, allogeneic stem cell transplantation (allo-SCT) remains the only treatment modality with a curative potential, but its widespread application is limited, due to significant morbidity and mortality associated with the procedure, especially in the elderly and in patients with comorbidities. Recognition of patient eligibility for allo-SCT is crucial, and the procedure should be addressed to patients with a good performance status without severe comorbidities and mainly to those in intermediate- to high-risk category, with a suitable stem cell donor available. The issues of best timing for performing transplantation, patient and donor eligibility, the type of conditioning regimen, and the outcomes after various allo-SCT procedures are the topics of this review.

High Frequency of Post-Transfusion Microchimerism Among Multi-Transfused Beta-Thalassemic Patients.

BACKGROUND: Transfusion-associated microchimerism implies the presence of allogeneic hematopoietic cells in an individual, following the transfusion of a blood product. It is a transfusion-related adverse effect/long-term consequence, which has not been well-investigated among regularly transfused patients with thalassemia. PATIENTS AND METHODS: We investigated 64 regularly transfused, homozygous ß-thalassemic patients and 21 never-transfused healthy volunteer blood donors (controls) for the presence of microchimerism in their sera, using real-time PCR targeting circulating allogeneic, both, Human Leukocyte Antigen-DR isotype (HLA-DR) and non-HLA alleles. The investigation was longitudinally repeated in patient subsets for more than 2 years. Results were correlated with clinical and laboratory parameters, peripheral blood lymphocyte immunophenotype, blood storage time, and donor's gender to identify potential contributing factors for microchimerism generation. RESULTS: Overall, microchimerism was detected in 52 of the 64 patients (81.2%) and in 6 of the 21 controls (28.5%, p = 0.0001). Forty-four patients (68.7%) exhibited long-term microchimerism (persisted for more than 6 months), confirmed at all time-points investigated. Microchimerism was more frequent among elderly, women, splenectomized and more heavily transfused patients, and among those who exhibit higher serum ferritin levels. In these patients, a distinct descending pattern of CD16dim+CD56dim+ natural killer (NK)-cells (p < 0.001) and an ascending pattern of CD4+CD25brightCD127- regulatory T-cells (p = 0.022) for increasing allelic burden were noticed, suggesting the establishment of recipient immune tolerance against the donor-derived chimeric alleles. Both splenectomized and non-splenectomized thalassemic patients exhibited the same trend. The storage time of transfused blood products and donor/gender mismatch had no impact on the development of microchimerism. DISCUSSION-CONCLUSIVE REMARKS: Transfusion-associated microchimerism appears to be a very common complication among multi-transfused thalassemic patients. The potential clinical consequences of this phenomenon remain as yet unclear. Immune tolerance attributed to disease itself and to repeated transfusions might at least in part explain its appearance.

Evaluation of a Bone Marrow Dysmyelopoiesis Immunophenotypic Index for the Diagnosis and Prognosis of Myelodysplastic Syndromes.

BACKGROUND: Myelodysplastic Syndromes (MDS) are a group of clonal hematopoietic stem cell disorders with significant heterogeneity in their clinical presentation and the prognosis of the patients. Several attempts have been made to incorporate flow cytometry (FC) findings into the diagnostic and/or prognostic criteria of dysplasia, but bone marrow (BM) aspirate morphology evaluation remains the gold-standard for diagnosis. The purpose of this study was to provide a diagnostic tool for MDS that relies on BM immunophenotyping and objectifies the interpretation of FC analysis and to validate its capacity to discriminate MDS from other causes of cytopenias. METHODS: To that purpose, a mathematical formula was developed which incorporates granulocytic maturation markers and the percentage of selected myeloid populations and translates them into a single parameter that quantifies the maturation and differentiation defects of BM granulocytes, named Dysmyelopoiesis Index (DMI). Bone marrow samples from 84 MDS patients and 47 non-MDS cytopenic patients were analyzed with FC and DMI was calculated for every patient. RESULTS: DMI detected clonal dysplasia with 84.5% sensitivity and 93.6% specificity, identified as MDS 77.2% of low grade patients and revealed multilineage dysplasia for a number of RA and RARS cases. It discriminated prognostic subgroups of MDS patients (P< .005) and negatively correlated with IPSS (r= - .472, P= .000), WPSS (r= - .481, P= .000) and IPSS-R (r= -.395, P= .000). CONCLUSIONS: DMI represents an accurate quantification of dysmyelopoiesis and an effective stand-alone diagnostic test for MDS, facilitating FC analysis and daily clinical practice.

The association between alcohol and tobacco use among elementary and high school students in Crete, Greece.

BACKGROUND: Tobacco and alcohol use during adolescence have potential long term health consequences and a possibility of future addiction. METHODS: This cross sectional study took place in 2007 among a convenience sample of 981 adolescents from public elementary and high schools in Eastern Crete, Greece. Following parental consent, an anonymous structured questionnaire including information on personal and family use of alcohol and tobacco was distributed. RESULTS: Among the entire study population, cigarette experimentation was found to be associated with current alcohol use, with an Adjusted Odds Ratio (aOR) of 38.8; (95%C.I: 5.33-58.2) and with having a smoker in the immediate family (aOR 10.3; 95%C.I: 3.14-34.0). Among the subset of elementary school children, cigarette smoking was strongly associated with current alcohol use aOR 9.7; (95%C.I: 2.12-44.3), while the association between smoking experimentation and sibling and parental alcohol use was statistically significant within the entire population (however not among elementary students) with an aOR of 2.76 (95%C.I: 1.24-6.15) and aOR 3.66, (95%C.I: 1.97-6.81) respectively. The elementary child's gender was not found to be associated with cigarette experimentation among this study population. CONCLUSIONS: Strong associations were found between alcohol use and tobacco experimentation. The potential parental influence on consequent adolescent tobacco and alcohol use was also noted. Potential community based interventions, if launched in Greece, should take the role of the Greek family into account.