Recent advances in myelodysplastic syndromes

Epigenetic Regulation of Genomic Stability by Vitamin C

DNA methylation plays an important role in the maintenance of genomic stability. Ten-eleven translocation proteins (TETs) are a family of iron (Fe²⁺) and α-KG -dependent dioxygenases that regulate DNA methylation levels by oxidizing 5-methylcystosine (5mC) to generate 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC). These oxidized methylcytosines promote passive demethylation upon DNA replication, or active DNA demethylation, by triggering base excision repair and replacement of 5fC and 5caC with an unmethylated cytosine. Several studies over the last decade have shown that loss of TET function leads to DNA hypermethylation and increased genomic instability. Vitamin C, a cofactor of TET enzymes, increases 5hmC formation and promotes DNA demethylation, suggesting that this essential vitamin, in addition to its antioxidant properties, can also directly influence genomic stability. This review will highlight the functional role of DNA methylation, TET activity and vitamin C, in the crosstalk between DNA methylation and DNA repair.

Reprogramming the Epigenome With Vitamin C

The erasure of epigenetic modifications across the genome of somatic cells is an essential requirement during their reprogramming into induced pluripotent stem cells (iPSCs). Vitamin C plays a pivotal role in remodeling the epigenome by enhancing the activity of Jumonji-C domain-containing histone demethylases (JHDMs) and the ten-eleven translocation (TET) proteins. By maintaining differentiation plasticity in culture, vitamin C also improves the quality of tissue specific stem cells derived from iPSCs that are highly sought after for use in regenerative medicine. The ability of vitamin C to potentiate the activity of histone and DNA demethylating enzymes also has clinical application in the treatment of cancer. Vitamin C deficiency has been widely reported in cancer patients and has recently been shown to accelerate cancer progression in disease models. Therapies involving high-dose vitamin C administration are currently gaining traction in the treatment of epigenetic dysregulation, by targeting aberrant histone and DNA methylation patterns associated with cancer progression.

Health care utilization and risk of infection and bleeding among patients with myelodysplastic syndromes with/without transfusions, and with/without active therapy

This study utilized claims data from a national US commercial health insurer to examine rates of cytopenia-related complications (significant bleeding, infection) and health care utilization (emergency room visits, inpatient hospitalizations) among patients with myelodysplastic syndromes (MDS) within predefined periods of transfusion activity and active therapy. Periods with no transfusions, regardless of relationship to treatment intervention, were associated with lower rates of cytopenia-related complications. These data suggest that eliminating or reducing the need for transfusions may help to reduce MDS-related medical problems, and treatment toward that goal should be considered in patients with MDS needing transfusions.

Four- and five-color flow cytometry analysis of leukocyte differentiation pathways in normal bone marrow: a reference document based on a systematic approach by the GTLLF and GEIL

BACKGROUND

The development of multiparameter flow cytometry (FCM) and increasingly sophisticated analysis software has considerably improved the exploration of hematological disorders. These tools have been widely applied in leukaemias, lymphomas, and myelodysplasias, yet with very heterogeneous approaches. Consequently, there is no extensive reference document reporting on the characteristics of normal human bone marrow (BM) in multiparameter FCM. Here, we report a reference analysis procedure using relevant antibody combinations in normal human BM.

METHODS

A first panel of 23 antibodies, constructed after literature review, was tested in four-color combinations (including CD45 in each) on 30 samples of BM. After evaluation of the data, a second set of 22 antibodies was further applied to another 35 BM samples. All list-modes from the 65 bone marrow samples were reviewed collectively. A systematised protocol for data analysis was established including biparametric representations and color codes for the three major lineages and undifferentiated cells.

RESULTS

This strategy has allowed to obtain a reference atlas of relevant patterns of differentiation antigens expression in normal human BM that is available within the European LeukemiaNet. This manuscript describes how this atlas was constructed.

CONCLUSIONS

Both the strategy and atlas could prove very useful as a reference of normality, for the determination of leukemia-associated immunophenotypic patterns, analysis of myelodysplasia and, ultimately, investigation of minimal residual disease in the BM.

Testing the NKT cell hypothesis in lenalidomide-treated myelodysplastic syndrome patients

Myelodysplastic syndrome (MDS) comprises a group of clonal bone marrow disorders characterized by ineffective hematopoiesis and increased predisposition to acute myeloid leukemia. The causes of MDS remain poorly defined, but several studies have reported the NKT cell compartment of patients with MDS is deficient in number and functionally defective. In support of a central role for NKT cells, a pilot clinical study reported that lenalidomide (an approved treatment for MDS) increased NKT cell numbers in patients with MDS, and several in vitro studies showed lenalidomide specifically promoted NKT cell proliferation and cytokine production. We tested this in a much larger study and confirm a moderate in vitro augmentation of some NKT cell functions by lenalidomide, but find no impact on the NKT cell compartment of patients treated with lenalidomide, despite a consistently positive clinical response. We further show that the frequency and cytokine production of NKT cells is normal in patients with MDS before treatment and remains stable throughout 10 months of lenalidomide therapy. Collectively, our data challenge the concept that NKT cell defects contribute to the development of MDS, and show that a clinical response to lenalidomide is not dependent on modulation of NKT cell frequency or function.

Epigenetic inactivation of tumour suppressor gene KLF11 in myelodysplastic syndromes*

The identification of aberrantly hypermethylated genes may lead to the development of new diagnostic markers and the identification of novel targets of epigenetic therapy in myelodysplastic syndromes (MDS). We therefore investigated the methylation status of transcription factor genes KLF5, KLF11, and MAFB, shown to be aberrantly methylated in myelogeneous leukaemia cells, in a series of 115 MDS patient as well as in 25 control subjects. Using quantitative high-resolution pyrosequencing methodology, KLF11, MAFB, and KLF5 were shown for the first time to be hypermethylated in 17 (15%), 8 (7%), and 2 (1.7%) cases, respectively, but not in any of the patients with an isolated 5q-deletion. Patient samples harbouring KLF11 methylation displayed reduced KLF11 mRNA expression and KLF11 hypermethylation correlated with a high International Prognostic Scoring System score (P < 0.05). In conclusion, epigenetic inactivation and subsequent transcriptional repression of the KLF11 gene is quite frequent in MDS. Patients with an isolated 5q-deletion seem to harbour a distinct epigenetic profile.

Epidermodysplasia Verruciformis Associated with Myelodysplastic Syndrome: An Intriguing Association

Background:

Epidermodysplasia verruciformis (EV) is a rare genodermatosis characterized by massive infection with human papillomaviruses (HPVs) and development of skin cancer. Myelodysplastic syndromes (MDSs) are a group of chronic conditions that involve dysplastic hematopoiesis, peripheral blood cytopenias, and a high incidence of progression into leukemia.

Methods:

We describe the intriguing association of these two premalignant conditions (EV and MDS) in one patient. These diagnoses were confirmed by histopathologic examination and cytogenetic abnormalities of bone marrow cells.

Results:

The patient presented initially with clinical features typical of EV and impairment of cell-mediated immunity. In the skin lesions, HPVs 23 and 25 were identified by nested polymerase chain reaction. Six years later, he had recurrent episodes of mucosal bleeding with fever, weakness, and fatigue. At this time, severe refractory anemia and neutropenia were observed, and bone marrow smears showed hypercellularity with abnormal dysplastic megakaryocytes. The cytogenetic pattern showed abnormalities involving trisomy of chromosomes 8 and 21. The patient received a diagnosis of the indolent subtype of MDS.

Conclusions:

Through the observation of our patient and review of the literature, we hypothesized that the pathomechanisms, including the role of oncogenes and cytokines, are connected to the progression to malignancy in these settings.

Cell cycle and apoptosis regulatory gene expression in the bone marrow of patients with de novo myelodysplastic syndromes (MDS)

Deregulation of cell cycle and apoptosis pathways are known contributors to the pathogenesis of myelodysplastic syndromes (MDS). However, the underlying mechanisms are not fully clarified. The aim of our study was to examine mRNA expression levels of cell cycle and apoptosis regulatory genes, as well as the percentage of apoptotic and S phase cells and to correlate the findings with clinical characteristics and prognosis. Sixty patients with MDS, classified according to FAB (17 RA, five RARS, 19 RAEB, nine RAEBT, ten CMML) and WHO (ten RA, three RARS, seven RCMD, two RCMD-RS, 11 RAEBI, eight RAEBII, ten CMML, and nine AML) were included in the study. We found increased expression of anti-apoptotic bclxL and mcl1 genes and decreased expression of p21 gene in MDS patients. Moreover, we found increased expression of anti-apoptotic mcl1 gene in patients with higher than Intermediate-1 IPSS group. Multivariate analysis confirmed that combined expression of apoptotic caspases 8, 3, 6, 5, 2, 7, and Granzyme B was decreased in MDS patients. Regarding cell cycle regulatory genes expression, we demonstrated increased expression of cyclin D1 in patients with CMML Increased combined expression of cyclins B, C, D1, and D2 was found in patients with cytogenetic abnormalities. The two pathways seem to be interconnected as shown by the positive correlation between CDKs 1, 2, 4, p21 and the level of apoptosis and positive correlation between apoptotic caspase 3 expression and the percentage of S phase cells. In conclusion, our study showed altered expression of genes involved in apoptosis and cell cycle in MDS and increased expression of cyclin D1 in patients with CMML.

Mechanism of action of lenalidomide in hematological malignancies

Immunomodulatory drugs lenalidomide and pomalidomide are synthetic compounds derived by modifying the chemical structure of thalidomide to improve its potency and reduce its side effects. Lenalidomide is a 4-amino-glutamyl analogue of thalidomide that lacks the neurologic side effects of sedation and neuropathy and has emerged as a drug with activity against various hematological and solid malignancies. It is approved by FDA for clinical use in myelodysplastic syndromes with deletion of chromosome 5q and multiple myeloma. Lenalidomide has been shown to be an immunomodulator, affecting both cellular and humoral limbs of the immune system. It has also been shown to have anti-angiogenic properties. Newer studies demonstrate its effects on signal transduction that can partly explain its selective efficacy in subsets of MDS. Even though the exact molecular targets of lenalidomide are not well known, its activity across a spectrum of neoplastic conditions highlights the possibility of multiple target sites of action.

Venous thromboembolism in myelodysplastic syndrome patients receiving lenalidomide: results from postmarketing surveillance and data mining techniques

BACKGROUND AND OBJECTIVES

Multiple myeloma treatment with lenalidomide-based regimens is associated with risk of venous thromboembolism (VTE), particularly during concomitant use with erythropoiesis-stimulating agents (ESAs). The risk of VTE in myelodysplastic syndrome (MDS) patients treated with lenalidomide is not well characterized and the background risk in untreated patients is not known. This study set out to determine the reporting rate of VTE in MDS patients on lenalidomide in the two years of postmarketing experience in the US, and to investigate whether there is a disproportional signal of VTE in MDS patients on lenalidomide by screening the US FDA Adverse Event Reporting System (AERS) safety database.

METHODS

The MDS population exposed to lenalidomide was obtained from RevAssist, the company's proprietary restrictive distribution programme. VTE reports were identified from the company's postmarketing surveillance safety database. The FDA AERS database was used for disproportionality analysis, and signal scores computed using three algorithms: multi-item gamma Poisson shrinker (MGPS), proportional reporting ratio (PRR), and reporting odds ratios (ROR).

RESULTS

A total of 7764 MDS patients were prescribed lenalidomide during the first two years of commercial use in the US. VTE representing deep vein thrombosis and pulmonary embolism was reported in 41 patients, a reporting rate of 0.53%. The computed signal scores did not exceed the statistical threshold for identification of a significant disproportional signal for VTE in MDS reports involving use of lenalidomide without concomitant use of ESAs. However, a disproportional signal of VTE was detected in MDS reports where lenalidomide was concurrently used with ESAs.

CONCLUSION

The VTE reporting rate for MDS patients receiving lenalidomide during the first two years of postmarketing exposure was low (0.53%). Disproportionality analysis demonstrated a statistically meaningful association of VTE with lenalidomide concomitantly used with ESAs in MDS patients, but the association was not statistically significant when lenalidomide was used in the absence of ESAs.

Neighborhood socioeconomic status influences the survival of elderly patients with myelodysplastic syndromes in the United States

The potential role of socioeconomic status (SES) in the survival of patients with myelodysplastic syndromes (MDS) has not been evaluated. We conducted the first study to assess the prognostic role of neighborhood SES among a cohort of 2,118 patients (age >/= 66 years) who were diagnosed with incident MDS in the United States during 2001-2002. Principal component analysis was used to develop a summary SES score by combining multiple measures of neighborhood SES. The score was then used to classify the census tract each patient resided in into a category of high, medium, or low SES. Hazard ratios (HRs) were estimated using multivariate Cox proportional hazard models. After adjusting for age, gender, comorbidities, and histological subtypes, compared with MDS patients lived in high-SES census tracts, those resided in medium (HR = 1.14, 95% CI: 1.01-1.30) and low (HR = 1.17, 95% CI: 1.02-1.34) SES census tracts had significantly increased the risks of death. The impact of SES on survival was more apparent for patients with refractory anemia with ringed sideroblasts-patients residing in medium (HR = 1.85, 95% CI: 1.17-2.91) and low (HR = 2.06, 95% CI: 1.27-3.37) census tracts had a nearly two-fold increased the risk of mortality, compared with those living in high-SES census tracts. In conclusion, this population-based study suggests that neighborhood SES status is a significant and independent determinant of survival among elderly patients with MDS in the United States.

Reduction in multi-lineage and erythroid progenitors distinguishes myelodysplastic syndromes from non-malignant cytopenias

We studied the diagnostic role of CFC assays in myelodysplastic syndromes (MDS) using CFC data from bone marrow (BM) and peripheral blood (PB) of 221 MDS patients, 51 patients with non-malignant causes of cytopenia and/or dysplasia and 50 normal controls. A consistent decrease in BM but not PB multi-lineage and erythroid progenitor frequencies was seen in patients with MDS compared to controls (P<0.05). Automated distinction showed a sensitivity of 87+/-6% and a specificity of 71+/-11% in classifying MDS patients. In conclusion, a defect in early hematopoietic progenitor activity, in particular erythroid activity, distinguishes MDS from non-MDS.

Update on the therapy for myelodysplastic syndrome

The myelodysplastic syndromes (MDS) are a diverse group of clonal hematopoietic stem cell disorders characterized by cytopenias. Patients have a risk of developing acute leukemia though most succumb to complications of low blood counts. Over the past decade many novel treatments have been developed and investigation of new agents is ongoing. In this article, we discuss the classification and prognostic systems that are used in MDS, the agents available for treatment of MDS as well as review supportive and palliative care options for patients who are not candidates for, or opt against, newer treatment strategies.

Sporadic epithelial ovarian cancer: clinical relevance of BRCA1 inhibition in the DNA damage and repair pathway

Among the most promising pathways for molecular targets in sporadic epithelial ovarian cancer (SEOC) are those involving the BRCA1 protein. Because somatic mutations in BRCA1 are rare in SEOC, it was originally postulated that BRCA1 plays a limited role in the pathogenesis of this disease. However, inactivation of BRCA1 through various mechanisms is a relatively frequent event in ovarian cancer. This is important because BRCA1 is involved in the cellular response to DNA damage and repair and has an essential role in the maintenance of genomic stability. The BRCA1 tumor suppressor protein is known to interact with genes and proteins known collectively as the BRCA1 pathway, and defects in this pathway are believed to be a driving force for cancer progression. As a result, there is compelling evidence to suggest that the dysfunction of BRCA1 may be a central mechanism in all ovarian carcinogenesis, and this has clinical and molecular significance beyond the management of patients with hereditary ovarian cancer. The aim of this review is to evaluate the evidence for BRCA1 dysfunction in SEOC and to link this dysfunction to a defective DNA repair pathway and ultimately the promotion of genomic instability and tumorigenesis. Furthermore, we advocate the continued need to study BRCA1 and its pathway by prospectively correlating clinicopathologic data with molecular aberrations. This will determine whether BRCA1 has relevance as a predictive and prognostic marker in SEOC and whether aberrations in the BRCA1 pathway warrant further study as potential therapeutic targets.

The role of azacitidine in the treatment of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a heterogeneous group of hematopoietic disorders characterized by ineffective hematopoiesis and potential transformation to acute myeloid leukemia. Supportive care including transfusions and growth factors remained the mainstay of treatment for decades; however, further understanding of the biology behind these diseases led to the investigation of novel agents. As hypermethylation of tumor suppressor genes, such as p15, was believed to play a key role in the pathogenesis of these diseases, hypomethylating agents were investigated. Azacitidine is one of two hypomethylating agents used in the treatment of MDS, and the first approved by US FDA. In preclinical studies, azacitidine demonstrated hypomethylating/differentiating activity with low concentration, whereas high concentration was associated with cytotoxic effects. In clinical trials, azacitidine not only improved the cytopenias associated with MDS but also delayed leukemic transformation, improved quality of life and improved overall survival in many patients so treated. Azacitidine was the first agent noted to change the natural history of the disease. Further studies are underway evaluating the role of azacitidine pre- and post-transplantation, in combination with other agents, as well as in treatment of acute myeloid leukemia patients who are not good candidates for intensive chemotherapy. Azacitidine is also likely to be studied in the treatment of other malignant conditions. Although both subcutaneous and intravenous administrations have been approved, oral azacitidine is presently under investigation.