Hypomethylation and apoptosis in 5-azacytidine-treated myeloid cells

Epigenetic Changes in the HTR8 and 3A-sub E placental Cell Lines Exposed to Bisphenol A and Benzyl Butyl Phthalate

OBJECTIVE

Bisphenol A and phthalate are known endocrine disruptors and capable of inducing epigenetic changes in the human population. However, their impact on the placenta is less well studied. Our objective was to measure the effect of exposure to bisphenol A and benzyl butyl phthalate in first-trimester HTR8-SVneo and third-trimester 3A-sub E trophoblast cells by profiling the DNA methylation pattern of the imprinting control region of the IGF2 (insulin-like growth factor) and H19 genes.

METHODS

Human placental HTR8-SVneo and 3A-sub E cell lines were treated with two sub-lethal concentrations of bisphenol A and benzyl butyl phthalate. Demethylating agent, 5-azacytidine, was used as a positive control. Cells were harvested on post-treatment days 1 and 4. The methylation profile of six CpG dinucleotide sites, part of the CTCF 6 binding site of the IGF2/H19 imprinting control region, was determined by pyrosequencing.

RESULTS

In the first-trimester HTR8-SVneo cell line, we observed a significant increased methylation of the CpG sites 3, 4 when treated with a high concentration of bisphenol A or benzyl butyl phthalate while increased methylation at site 6 for both high and low dose treatment on day 4. Demethylation of the CpG sites 1, 4, and 6 was observed when treated with 5-azacytidine on day 4. In the third-trimester 3A-sub E cell line, no significant changes in the methylation profile were observed under any treatment conditions.

CONCLUSIONS

The results of this study demonstrate the capability of epigenetic changes in human placenta cells induced by bisphenol A and benzyl butyl phthalate. The observed methylation changes only in the first-trimester HTR8-SVneo cells phthalate may reflect a window of epigenetic susceptibility related to these environmental toxicants.

Antileishmanial potentials of azacitidine and along with meglumine antimoniate on Leishmania major: In silico prediction and in vitro analysis

This study aimed to investigate the in vitro and in silico antileishmanial activity of azacitidine (AZA) on Leishmania major promastigotes and amastigotes. The in silico method was used to evaluate the possibility of the interaction of AZA into the binding pocket of inducible nitric oxide synthase (iNOS), a leading defensive oxidative metabolite. Following that, in vitro anti-promastigote, and anti-amastigote activity of AZA was determined using an MTT assay and a macrophage model, respectively. Cytotoxic effects of AZA and meglumine antimoniate (MA) were also assessed by MTT assay on murine macrophages. All experiments were performed in triplicate. The results showed that AZA interacted with Ser133, Gln134, and Lys13 amino acids of iNOS, and the molecular docking score was obtained at -241.053 kcal/mol. AZA in combination with MA significantly (P<0.001) inhibited the growth rate of nonclinical promastigote (IC50 247.6±7.3 μM) and 8.5-fold higher of clinical intramacrophage amastigote stage (29.8±5.3 μM), compared to the untreated group. A significant upsurge of Th1 subsets and transcription genes and a meaningful decline in Th2 cytokines subclasses at the equivalent concentrations of AZA and MA was observed (P<0.001). The apoptosis effect of AZA along with MA was significantly induced on L. major in a dose-dependent manner (P<0.001). The present study demonstrated that AZA possesses antileishmanial activity in in vitro and in silico models. However, AZA combined with MA was more effective than AZA alone in inhibiting the growth rate of promastigotes and amastigotes of L. major. This study indicates that AZA in combination with MA demonstrated a potent antileishmanial mechanism, promoting immune response and enhancing an immunomodulatory role toward the Th1 pathway. This experimental study is a basic study for applying more knowledge about the mechanisms of AZA along with MA in animal models in the future.

High-Risk Acute Myeloid Leukemia: A Pediatric Prospective

Pediatric acute myeloid leukemia is a clonal disorder characterized by malignant transformation of the hematopoietic stem cell. The incidence and the outcome remain inferior when compared to pediatric ALL, although prognosis has improved in the last decades, with 80% overall survival rate reported in some studies. The standard therapeutic approach is a combined cytarabine and anthracycline-based regimen followed by consolidation with allogeneic stem cell transplantation (allo-SCT) for high-risk AML and allo-SCT for non-high-risk patients only in second complete remission after relapse. In the last decade, several drugs have been used in clinical trials to improve outcomes in pediatric AML treatment.

Revisiting fetal hemoglobin inducers in beta-hemoglobinopathies: a review of natural products, conventional and combinatorial therapies

Beta-hemoglobinopathies exhibit a heterogeneous clinical picture with varying degrees of clinical severity. Pertaining to the limited treatment options available, where blood transfusion still remains the commonest mode of treatment, pharmacological induction of fetal hemoglobin (HbF) has been a lucrative therapeutic intervention. Till now more than 70 different HbF inducers have been identified. The practical usage of many pharmacological drugs has been limited due to safety concerns. Natural compounds, like Resveratrol, Ripamycin and Bergaptene, with limited cytotoxicity and high efficacy have started capturing the attention of researchers. In this review, we have summarized pharmacological drugs and bioactive compounds isolated from natural sources that have been shown to increase HbF significantly. It primarily discusses recently identified synthetic and natural compounds, their mechanism of action, and their suitable screening platforms, including high throughput drug screening technology and biosensors. It also delves into the topic of combinatorial therapy and drug repurposing for HbF induction. Overall, we aim to provide insights into where we stand in HbF induction strategies for treating β-hemoglobinopathies.

5-Azacytidine depletes HSCs and synergizes with an anti-CD117 antibody to augment donor engraftment in immunocompetent mice

Depletion of hematopoietic stem cells (HSCs) is used therapeutically in many malignant and nonmalignant blood disorders in the setting of a hematopoietic cell transplantation (HCT) to eradicate diseased HSCs, thus allowing donor HSCs to engraft. Current treatments to eliminate HSCs rely on modalities that cause DNA strand breakage (ie, alkylators, radiation) resulting in multiple short-term and long-term toxicities and sometimes even death. These risks have severely limited the use of HCT to patients with few to no comorbidities and excluded many others with diseases that could be cured with an HCT. 5-Azacytidine (AZA) is a widely used hypomethylating agent that is thought to preferentially target leukemic cells in myeloid malignancies. Here, we reveal a previously unknown effect of AZA on HSCs. We show that AZA induces early HSC proliferation in vivo and exerts a direct cytotoxic effect on proliferating HSCs in vitro. When used to pretreat recipient mice for transplantation, AZA permitted low-level donor HSC engraftment. Moreover, by combining AZA with a monoclonal antibody (mAb) targeting CD117 (c-Kit) (a molecule expressed on HSCs), more robust HSC depletion and substantially higher levels of multilineage donor cell engraftment were achieved in immunocompetent mice. The enhanced effectiveness of this combined regimen correlated with increased apoptotic cell death in hematopoietic stem and progenitor cells. Together, these findings highlight a previously unknown therapeutic mechanism for AZA which may broaden its use in clinical practice. Moreover, the synergy we show between AZA and anti-CD117 mAb is a novel strategy to eradicate abnormal HSCs that can be rapidly tested in the clinical setting.

Labeling and measuring stressed mitochondria using a PINK1-based ratiometric fluorescent sensor

Mitochondria are essential organelles that carry out a number of pivotal metabolic processes and maintain cellular homeostasis. Mitochondrial dysfunction caused by various stresses is associated with many diseases such as type 2 diabetes, obesity, cancer, heart failure, neurodegenerative disorders, and aging. Therefore, it is important to understand the stimuli that induce mitochondrial stress. However, broad analysis of mitochondrial stress has not been carried out to date. Here, we present a set of fluorescent tools, called mito-Pain (mitochondrial PINK1 accumulation index), which enable the labeling of stressed mitochondria. Mito-Pain uses PTEN-induced putative kinase 1 (PINK1) stabilization on mitochondria and quantifies mitochondrial stress levels by comparison with PINK1-GFP, which is stabilized under mitochondrial stress, and RFP-Omp25, which is constitutively localized on mitochondria. To identify compounds that induce mitochondrial stress, we screened a library of 3374 compounds using mito-Pain and identified 57 compounds as mitochondrial stress inducers. Furthermore, we classified each compound into several categories based on mitochondrial response: depolarization, mitochondrial morphology, or Parkin recruitment. Parkin recruitment to mitochondria was often associated with mitochondrial depolarization and aggregation, suggesting that Parkin is recruited to heavily damaged mitochondria. In addition, many of the compounds led to various mitochondrial morphological changes, including fragmentation, aggregation, elongation, and swelling, with or without Parkin recruitment or mitochondrial depolarization. We also found that several compounds induced an ectopic response of Parkin, leading to the formation of cytosolic puncta dependent on PINK1. Thus, mito-Pain enables the detection of stressed mitochondria under a wide variety of conditions and provides insights into mitochondrial quality control systems.

High-throughput analyses and Bayesian network modeling highlight novel epigenetic Adverse Outcome Pathway networks of DNA methyltransferase inhibitor mediated transgenerational effects

A number of epigenetic modulating chemicals are known to affect multiple generations of a population from a single ancestral exposure, thus posing transgenerational hazards. The present study aimed to establish a high-throughput (HT) analytical workflow for cost-efficient concentration-response analysis of epigenetic and phenotypic effects, and to support the development of novel Adverse Outcome Pathway (AOP) networks for DNA methyltransferase (DNMT) inhibitor-mediated transgenerational effects on aquatic organisms. The model DNMT inhibitor 5-azacytidine (5AC) and the model freshwater crustacean Daphnia magna were used to generate new experimental data and served as prototypes to construct AOPs for aquatic organisms. Targeted HT bioassays (DNMT ELISA, MS-HRM and qPCR) in combination with multigenerational ecotoxicity tests revealed concentration-dependent transgenerational (F0-F3) effects of 5AC on total DNMT activity, DNA promoter methylation, gene body methylation, gene transcription and reproduction. Top sensitive toxicity pathways related to 5AC exposure, such as apoptosis and DNA damage responses were identified in both F0 and F3 using Gaussian Bayesian network modeling. Two novel epigenetic AOP networks on DNMT inhibitor mediated one-generational and transgenerational effects were developed for aquatic organisms and assessed for the weight of evidence. The new HT analytical workflow and AOPs can facilitate future ecological hazard assessment of epigenetic modulating chemicals.

Overcoming Glucocorticoid Resistance in Acute Lymphoblastic Leukemia: Repurposed Drugs Can Improve the Protocol

Glucocorticoids (GCs) are a central component of multi-drug treatment protocols against T and B acute lymphoblastic leukemia (ALL), which are used intensively during the remission induction to rapidly eliminate the leukemic blasts. The primary response to GCs predicts the overall response to treatment and clinical outcome. In this review, we have critically analyzed the available data on the effects of GCs on sensitive and resistant leukemic cells, in order to reveal the mechanisms of GC resistance and how these mechanisms may determine a poor outcome in ALL. Apart of the GC resistance, associated with a decreased expression of receptors to GCs, there are several additional mechanisms, triggered by alterations of different signaling pathways, which cause the metabolic reprogramming, with an enhanced level of glycolysis and oxidative phosphorylation, apoptosis resistance, and multidrug resistance. Due to all this, the GC-resistant ALL show a poor sensitivity to conventional chemotherapeutic protocols. We propose pharmacological strategies that can trigger alternative intracellular pathways to revert or overcome GC resistance. Specifically, we focused our search on drugs, which are already approved for treatment of other diseases and demonstrated anti-ALL effects in experimental pre-clinical models. Among them are some “truly” re-purposed drugs, which have different targets in ALL as compared to other diseases: cannabidiol, which targets mitochondria and causes the mitochondrial permeability transition-driven necrosis, tamoxifen, which induces autophagy and cell death, and reverts GC resistance through the mechanisms independent of nuclear estrogen receptors (“off-target effects”), antibiotic tigecycline, which inhibits mitochondrial respiration, causing energy crisis and cell death, and some anthelmintic drugs. Additionally, we have listed compounds that show a classical mechanism of action in ALL but are not used still in treatment protocols: the BH3 mimetic venetoclax, which inhibits the anti-apoptotic protein Bcl-2, the hypomethylating agent 5-azacytidine, which restores the expression of the pro-apoptotic BIM, and compounds targeting the PI3K-Akt-mTOR axis. Accordingly, these drugs may be considered for the inclusion into chemotherapeutic protocols for GC-resistant ALL treatments.

Epigenetic Modifiers in Myeloid Malignancies: The Role of Histone Deacetylase Inhibitors

Myeloid hematological malignancies are clonal bone marrow neoplasms, comprising of acute myeloid leukemia (AML), the myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML), the myeloproliferative neoplasms (MPN) and systemic mastocytosis (SM). The field of epigenetic regulation of normal and malignant hematopoiesis is rapidly growing. In recent years, heterozygous somatic mutations in genes encoding epigenetic regulators have been found in all subtypes of myeloid malignancies, supporting the rationale for treatment with epigenetic modifiers. Histone deacetylase inhibitors (HDACi) are epigenetic modifiers that, in vitro, have been shown to induce growth arrest, apoptotic or autophagic cell death, and terminal differentiation of myeloid tumor cells. These effects were observed both at the bulk tumor level and in the most immature CD34⁺38⁻ cell compartments containing the leukemic stem cells. Thus, there is a strong rationale supporting HDACi therapy in myeloid malignancies. However, despite initial promising results in phase I trials, HDACi in monotherapy as well as in combination with other drugs, have failed to improve responses or survival. This review provides an overview of the rationale for HDACi in myeloid malignancies, clinical results and speculations on why clinical trials have thus far not met the expectations, and how this may be improved in the future.

Comprehensive mapping of the effects of azacitidine on DNA methylation, repressive/permissive histone marks and gene expression in primary cells from patients with MDS and MDS-related disease

Azacitidine (Aza) is first-line treatment for patients with high-risk myelodysplastic syndromes (MDS), although its precise mechanism of action is unknown. We performed the first study to globally evaluate the epigenetic effects of Aza on MDS bone marrow progenitor cells assessing gene expression (RNA seq), DNA methylation (Illumina 450k) and the histone modifications H3K18ac and H3K9me3 (ChIP seq). Aza induced a general increase in gene expression with 924 significantly upregulated genes but this increase showed no correlation with changes in DNA methylation or H3K18ac, and only a weak association with changes in H3K9me3. Interestingly, we observed activation of transcripts containing 15 endogenous retroviruses (ERVs) confirming previous cell line studies. DNA methylation decreased moderately in 99% of all genes, with a median β-value reduction of 0.018; the most pronounced effects seen in heterochromatin. Aza-induced hypomethylation correlated significantly with change in H3K9me3. The pattern of H3K18ac and H3K9me3 displayed large differences between patients and healthy controls without any consistent pattern induced by Aza. We conclude that the marked induction of gene expression only partly could be explained by epigenetic changes, and propose that activation of ERVs may contribute to the clinical effects of Aza in MDS.

5-Azacytidine specifically inhibits the NIH-3T3 PCD process induced by TNF-alpha and cycloheximide via affecting BCL-XL

DNA methylation plays a crucial role in lots of biological processes and cancer. 5-azacytidine (5-AC), a DNA methylation inhibitor, has been used as a potential chemotherapeutic agent for cancer. In this study, we used 5-AC treatment to investigate whether DNA methylation was involved in regulation of programmed cell death (PCD) in mouse embryo fibroblast NIH-3T3 cells which could undergo PCD after treatment with TNF-α and cycloheximide (CHX). The results showed that the genomic DNA of NIH-3T3 cells was hypermethylated during PCD induced by TNF-α and CHX, and 5-AC might prevent this PCD process. However, treatment with the other three DNA methylation inhibitors, 5-aza-deoxycytidine, 6-thioguanine and RG108, did not interfere with the NIH-3T3 cell PCD process. Additionally, knockdown of DNMT1 did not affect the apoptosis process. The present results and observations indicated that 5-AC specifically inhibited the NIH-3T3 apoptosis process via a genomic DNA methylation-independent pathway. During the TNF-α and CHX-inducing apoptosis process, the PCD related BCL-2 family proteins were significantly down-regulated. Furthermore, after the small interference RNA-mediated knockdown of BCL-XL, one of the BCL-2 family proteins, 5-AC did not inhibit the apoptosis process, suggesting that 5-AC inhibited the PCD process induced by TNF-α and CHX by affecting the anti-apoptotic protein BCL-XL.

Genetic Mutations and Epigenetic Modifications: Driving Cancer and Informing Precision Medicine

Cancer treatment is undergoing a significant revolution from "one-size-fits-all" cytotoxic therapies to tailored approaches that precisely target molecular alterations. Precision strategies for drug development and patient stratification, based on the molecular features of tumors, are the next logical step in a long history of approaches to cancer therapy. In this review, we discuss the history of cancer treatment from generic natural extracts and radical surgical procedures to site-specific and combinatorial treatment regimens, which have incrementally improved patient outcomes. We discuss the related contributions of genetics and epigenetics to cancer progression and the response to targeted therapies and identify challenges and opportunities for the success of precision medicine. The identification of patients who will benefit from targeted therapies is more complex than simply identifying patients whose tumors harbour the targeted aberration, and intratumoral heterogeneity makes it difficult to determine if a precision therapy is successful during treatment. This heterogeneity enables tumors to develop resistance to targeted approaches; therefore, the rational combination of therapeutic agents will limit the threat of acquired resistance to therapeutic success. By incorporating the view of malignant transformation modulated by networks of genetic and epigenetic interactions, molecular strategies will enable precision medicine for effective treatment across cancer subtypes.

Silencing HO-1 sensitizes SKM-1 cells to apoptosis induced by low concentration 5-azacytidine through enhancing p16 demethylation

Heme oxygenase-1 was reported previously as a resistance target on acute myelocytic leukemia (AML). We found that HO-1 was resistant to 5-azacytidine (AZA) treatment of myelodysplastic syndrome (MDS), and explored further the relative mechanisms. Patient bone marrow mononuclear cells (n=48) diagnosed as different levels of MDS were collected. Cell growth was evaluated by MTT assay; cell cycle and apoptosis were detected by flow cytometry; mRNA expression was assessed by real-time PCR, protein expression was analyzed through western blotting. Methylation was assessed by MSP. The survival time, and weight of mice were recorded. HO-1 overexpression was observed in SKM-1 cells after AZA treatment comparing to other cell lines. The HO-1 expression in MDS patients with high-risk was higher than in low-risk patients. After HO-1 was silenced by lentivirus-mediated siRNA, the proliferation of SKM-1 cells was effectively inhibited by low concentration AZA, and the cell cycle was arrested in the G0/G1 phase. Upregulation of p16 and changing of p16-relative cell cycle protein was observed after silencing HO-1 in AZA treated SKM-1 cells. In addition, DNMT1 was downregulated following the decrease of HO-1 expression. In vivo, silencing HO-1 inhibited SKM-1 cell growth induced by AZA in a NOD/SCID mouse model. Silencing HO-1 sensitized SKM-1 cells toward AZA, which may be attributed to the influence of HO-1 on AZA-induced p16 demethylation. HO-1 may be one of the targets that enhance the therapeutic effects of AZA on MDS malignant transformation inspiring new treatment methods for high-risk and very high-risk MDS patients in clinical practice.

5-azacytidine enhances efficacy of multiple chemotherapy drugs in AML and lung cancer with modulation of CpG methylation

The DNA methyltransferase (DNMT) inhibitory drugs such as 5-azacytidine induce DNA hypomethylation by inhibiting DNA methyltransferases. While clinically effective, DNMT inhibitors are not curative. A combination with cytotoxic drugs might be beneficial, but this is largely unexplored. In the present study, we analyzed potential synergisms between cytotoxic drugs and 5-azacytidine in acute myeloid leukemia (AML) and non-small cell lung cancer (NSCLC) cells. Lung cancer and leukemia cell lines were exposed to low doses of 5-azacytidine with varying doses of cytarabine or etoposide for AML cells (U937 and HL60) as well as cisplatin or gemcitabine for NSCLC cells (A549 and HTB56) for 48 h. Drug interaction and potential synergism was analyzed according to the Chou-Talalay algorithm. Further analyses were based on soft agar colony formation assays, active caspase-3 staining and BrdU incorporation flow cytometry. To identify effects on DNA methylation patterns, we performed genome wide DNA methylation analysis using 450K bead arrays. Azacytidine at low doses was synergistic with cytotoxic drugs in NSCLC and in AML cell lines. Simultaneous exposure to 5-azacytidine with cytotoxic drugs showed strong synergistic activity. In colony formation assays these synergisms were repeatedly verified for 5-azacytidine (25 nM) with low doses of anticancer agents. 5-azacytidine neither affected the cell cycle nor increased apoptosis. 450K methylation bead arrays revealed 1,046 CpG sites in AML and 1,778 CpG sites in NSCLC cells with significant DNA hypomethylation (24-h exposure) to 5-azacytidine combined with the cytotoxic drugs. These CpG-sites were observed in the candidate tumor-suppressor genes MGMT and THRB. Additional incubation time after 24-h treatment led to a 4.1-fold increase of significant hypomethylated CpG-sites in NSCLC cells. These results suggest that the addition of DNA demethylating agents to cytotoxic anticancer drugs exhibits synergistic activity in AML and NSCLC. Dysregulation of an equilibrium of DNA methylation in cancer cells might increase the susceptibility for cytotoxic drugs.

Multitarget effects of quercetin in leukemia

This study proposes to investigate quercetin antitumor efficacy in vitro and in vivo, using the P39 cell line as a model. The experimental design comprised leukemic cells or xenografts of P39 cells, treated in vitro or in vivo, respectively, with quercetin; apoptosis, cell-cycle and autophagy activation were then evaluated. Quercetin caused pronounced apoptosis in P39 leukemia cells, followed by Bcl-2, Bcl-xL, Mcl-1 downregulation, Bax upregulation, and mitochondrial translocation, triggering cytochrome c release and caspases activation. Quercetin also induced the expression of FasL protein. Furthermore, our results demonstrated an antioxidant activity of quercetin. Quercetin treatment resulted in an increased cell arrest in G1 phase of the cell cycle, with pronounced decrease in CDK2, CDK6, cyclin D, cyclin E, and cyclin A proteins, decreased Rb phosphorylation and increased p21 and p27 expression. Quercetin induced autophagosome formation in the P39 cell line. Autophagy inhibition induced by quercetin with chloroquine triggered apoptosis but did not alter quercetin modulation in the G1 phase. P39 cell treatment with a combination of quercetin and selective inhibitors of ERK1/2 and/or JNK (PD184352 or SP600125, respectively), significantly decreased cells in G1 phase, this treatment, however, did not change the apoptotic cell number. Furthermore, in vivo administration of quercetin significantly reduced tumor volume in P39 xenografts and confirmed in vitro results regarding apoptosis, autophagy, and cell-cycle arrest. The antitumor activity of quercetin both in vitro and in vivo revealed in this study, point to quercetin as an attractive antitumor agent for hematologic malignancies.

Isocitrate dehydrogenase 1 (IDH1) mutation in breast adenocarcinoma is associated with elevated levels of serum and urine 2-hydroxyglutarate

Mutations in the IDH1 and IDH2 (isocitrate dehydrogenase) genes have been discovered across a range of solid-organ and hematologic malignancies, including acute myeloid leukemia, glioma, chondrosarcoma, and cholangiocarcinoma. An intriguing aspect of IDH-mutant tumors is the aberrant production and accumulation of the oncometabolite 2-hydroxyglutarate (2-HG), which may play a pivotal oncogenic role in these malignancies. We describe the first reported case of an IDH1 p.R132L mutation in a patient with hormone receptor-positive (HR+) breast adenocarcinoma. This patient was initially treated for locally advanced disease, but then suffered a relapse and metastasis, at which point an IDH1-R132 mutation was discovered in an affected lymph node. The mutation was subsequently found in the primary tumor tissue and all metastatic sites, but not in an uninvolved lymph node. In addition, the patient's serum and urine displayed marked elevations in the concentration of 2-HG, significantly higher than that measured in six other patients with metastatic HR+ breast carcinoma whose tumors were found to harbor wild-type IDH1. In summary, IDH1 mutations may impact a rare subgroup of patients with breast adenocarcinoma. This may suggest future avenues for disease monitoring through noninvasive measurement of 2-HG, as well as for the development and study of targeted therapies against the aberrant IDH1 enzyme.

Optimizing outcomes with azacitidine: recommendations from Canadian centres of excellence

Myelodysplastic syndromes (mdss) constitute a heterogeneous group of malignant hematologic disorders characterized by marrow dysplasia, ineffective hematopoiesis, peripheral blood cytopenias, and pronounced risk of progression to acute myeloid leukemia. Azacitidine has emerged as an important treatment option and is recommended by the Canadian Consortium on Evidence-Based Care in mds as a first-line therapy for intermediate-2 and high-risk patients not eligible for allogeneic stem cell transplant; however, practical guidance on how to manage patients through treatment is limited. This best practice guideline provides recommendations by a panel of experts from Canadian centres of excellence on the selection and clinical management of mds patients with azacitidine. Familiarity with the referral process, treatment protocols, dose scheduling, treatment expectations, response monitoring, management of treatment breaks and adverse events, and multidisciplinary strategies for patient support will improve the opportunity for optimizing treatment outcomes with azacitidine.

DNA methylation and apoptosis resistance in cancer cells

Apoptosis is a cell death programme primordial to cellular homeostasis efficiency. This normal cell suicide program is the result of the activation of a cascade of events in response to death stimuli. Apoptosis occurs in normal cells to maintain a balance between cell proliferation and cell death. A deregulation of this balance due to modifications in the apoptosic pathway leads to different human diseases including cancers. Apoptosis resistance is one of the most important hallmarks of cancer and some new therapeutical strategies focus on inducing cell death in cancer cells. Nevertheless, cancer cells are resistant to treatment inducing cell death because of different mechanisms, such as DNA mutations in gene coding for pro-apoptotic proteins, increased expression of anti-apoptotic proteins and/or pro-survival signals, or pro-apoptic gene silencing mediated by DNA hypermethylation. In this context, aberrant DNA methylation patterns, hypermethylation and hypomethylation of gene coding for proteins implicated in apoptotic pathways are possible causes of cancer cell resistance. This review highlights the role of DNA methylation of apoptosis-related genes in cancer cell resistance.

3-D DNA methylation phenotypes correlate with cytotoxicity levels in prostate and liver cancer cell models

Background

The spatial organization of the genome is being evaluated as a novel indicator of toxicity in conjunction with drug-induced global DNA hypomethylation and concurrent chromatin reorganization. 3D quantitative DNA methylation imaging (3D-qDMI) was applied as a cell-by-cell high-throughput approach to investigate this matter by assessing genome topology through represented immunofluorescent nuclear distribution patterns of 5-methylcytosine (MeC) and global DNA (4,6-diamidino-2-phenylindole = DAPI) in labeled nuclei.

Methods

Differential progression of global DNA hypomethylation was studied by comparatively dosing zebularine (ZEB) and 5-azacytidine (AZA). Treated and untreated (control) human prostate and liver cancer cells were subjected to confocal scanning microscopy and dedicated 3D image analysis for the following features: differential nuclear MeC/DAPI load and codistribution patterns, cell similarity based on these patterns, and corresponding differences in the topology of low-intensity MeC (LIM) and low in intensity DAPI (LID) sites.

Results

Both agents generated a high fraction of similar MeC phenotypes across applied concentrations. ZEB exerted similar effects at 10–100-fold higher drug concentrations than its AZA analogue: concentration-dependent progression of global cytosine demethylation, validated by measuring differential MeC levels in repeat sequences using MethyLight, and the concurrent increase in nuclear LIM densities correlated with cellular growth reduction and cytotoxicity.

Conclusions

3D-qDMI demonstrated the capability of quantitating dose-dependent drug-induced spatial progression of DNA demethylation in cell nuclei, independent from interphase cell-cycle stages and in conjunction with cytotoxicity. The results support the notion of DNA methylation topology being considered as a potential indicator of causal impacts on chromatin distribution with a conceivable application in epigenetic drug toxicology.

The effects of 5-azacytidine on the function and number of regulatory T cells and T-effectors in myelodysplastic syndrome

Expansion of regulatory T cells occurs in high-risk myelodysplastic syndrome and correlates with a poor prognosis. DNA methyltransferase inhibitors, particularly 5-azacytidine, have been shown to increase the survival of patients with high-risk myelodysplastic syndrome. It is not entirely clear whether this improvement in patients' survival is related to the effects of DNA methyltransferase inhibitors on the immune system and/or the direct effect of these drugs on the dysplastic clone. In this study we investigated the effect of 5-azacytidine on the function and proliferation capability of regulatory T cells and T-helper cells. The number and function of CD4(+) T-cell subsets in 68 patients with intermediate-2/high-risk myelodysplastic syndrome were serially assessed at diagnosis and following treatment. The in-vitro effects of 5-azacytidine on CD4(+) T-cell subsets isolated from both healthy donors and patients with myelodysplastic syndrome were also investigated. The number of peripheral blood regulatory T cells was significantly higher in myelodysplastic syndrome patients than in healthy donors and responders to treatment (P=0.01). The absolute numbers of T-helper 1 and T-helper 2, but not T-helper 17, cells were significantly reduced following 12 months of treatment (P=0.03, P=0.03). The in vitro addition of 5-azacytidine to CD4(+) T cells reduced the proliferative capacity of regulatory T cells (P=0.03). In addition, the 5-azacytidine-treated regulatory T cells had reduced suppressive function and produced larger amounts of interleukin-17. The FOXP3 expression in 5-azacyti-dine-treated T-effectors was also increased. Interestingly, these FOXP3(+)/interleukin-17(+) cells originated mainly from effector T cells rather than regulatory T cells. Our data suggest that 5-azacytidine has profound effects on CD4(+) T cells, which correlate with disease status after treatment. Furthermore, despite the demethylation of the FOXP3 promoter and increased FOXP3 expression following 5-azacytidine treatment, these phenotypic regulatory T cell-like cells lack the regulatory function and cytokine profile of regulatory T cells. These findings are important in correlating the clinically relevant immunomodulatory effects of 5-azacytidine.

Effects of azacitidine on matrix metalloproteinase-9 in acute myeloid leukemia and myelodysplasia

Matrix metalloprotease-9 (MMP9) plays a critical role in acute myeloid leukemia (AML) by increasing the invasive properties of malignant myeloblasts. The role of this enzyme in high-risk myelodysplastic diseases (MDS) and the effect of azacitidine on its expression in MDS and AML have not been studied in detail. In this work, we have analyzed the effect of different concentrations of azacitidine in two well-established, MDS-derived, acute myeloid leukemic cell lines: MOLM-13 and SKM-1. We have demonstrated that 1 μmol/L azacitidine decreases MMP9 DNA methylation levels and that this is correlated with a significant increase in messenger RNA expression in both cell lines. Surprisingly, changes in protein levels were minor. This paradoxic effect is explained by the drug-dependent induction of apoptosis that reduces the amount of active secreting cells. A balance between induced expression and apoptosis was established at an azacitidine concentration of 0.2 μmol/L in MOLM-13 cells. This dose significantly increased the invasive capacity of viable cells, as measured in the Matrigel assay. To evaluate the clinical relevance of this observation, we have examined the effect of azacitidine on MMP9 expression in bone marrow from five patients with MDS, with the finding that this drug significantly increased MMP9 protein levels in all analyzed patients after six cycles of treatment. Based on these results, we conclude that azacitidine increases MMP9 expression and may enhance invasiveness in vitro. Because all five patients relapsed, these findings might explain, at least partially, the clinical failure of the drug and the progression to a more aggressive disease.

Concomitant inhibition of DNA methyltransferase and BCL-2 protein function synergistically induce mitochondrial apoptosis in acute myelogenous leukemia cells

DNA methylation and BLC-2 are potential therapeutic targets in acute myeloid leukemia (AML). We investigated pharmacologic interaction between the DNA methyltransferase inhibitor 5-azacytidine (5-AZA) and the BCL-2 inhibitor ABT-737. Increased BCL-2 expression determined by reverse phase protein analysis was associated with poor survival in AML patients with unfavorable cytogenetics (n = 195). We found that 5-AZA, which itself has modest apoptotic activity, acts synergistically with ABT-737 to induce apoptosis. The 5-AZA/ABT-737 combination enhanced mitochondrial outer membrane permeabilization, as evidenced by effective conformational activation of BAX and ∆ψ(m) loss. Although absence of p53 limited apoptotic activities of 5-AZA and ABT-737 as single agents, the combination synergistically induced apoptosis independent of p53 expression. 5-AZA down-regulated MCL-1, known to mediate resistance to ABT-737, in a p53-independent manner. The 5-AZA/ABT-737 combination synergistically induced apoptosis in AML cells in seven of eight patients. 5-AZA significantly reduced MCL-1 levels in two of three samples examined. Our data provide a molecular rationale for this combination strategy in AML therapy.

Epigenomics of leukemia: from mechanisms to therapeutic applications

Leukemogenesis is a multistep process in which successive transformational events enhance the ability of a clonal population arising from hematopoietic progenitor cells to proliferate, differentiate and survive. Clinically and pathologically, leukemia is subdivided into four main categories: chronic lymphocytic leukemia, chronic myeloid leukemia, acute lymphocytic leukemia and acute myeloid leukemia. Leukemia has been previously considered only as a genetic disease. However, in recent years, significant advances have been made in the elucidation of the leukemogenesis-associated processes. Thus, we have come to understand that epigenetic alterations including DNA methylation, histone modifications and miRNA are involved in the permanent changes of gene expression controlling the leukemia phenotype. In this article, we will focus on the epigenetic defects associated with leukemia and their implications as biomarkers for diagnostic, prognostic and therapeutic applications.

Genomic DNA methylation changes in response to folic acid supplementation in a population-based intervention study among women of reproductive age

Folate is a source of one-carbons necessary for DNA methylation, a critical epigenetic modification necessary for genomic structure and function. The use of supplemental folic acid is widespread however; the potential influence on DNA methylation is unclear. We measured global DNA methylation using DNA extracted from samples from a population-based, double-blind randomized trial of folic acid supplementation (100, 400, 4000 µg per day) taken for 6 months; including a 3 month post-supplementation sample. We observed no changes in global DNA methylation in response to up to 4,000 µg/day for 6 months supplementation in DNA extracted from uncoagulated blood (approximates circulating blood). However, when DNA methylation was determined in coagulated samples from the same individuals at the same time, significant time, dose, and MTHFR genotype-dependent changes were observed. The baseline level of DNA methylation was the same for uncoagulated and coagulated samples; marked differences between sample types were observed only after intervention. In DNA from coagulated blood, DNA methylation decreased (−14%; P<0.001) after 1 month of supplementation and 3 months after supplement withdrawal, methylation decreased an additional 23% (P<0.001) with significant variation among individuals (max+17%; min-94%). Decreases in methylation of ≥25% (vs. <25%) after discontinuation of supplementation were strongly associated with genotype: MTHFR CC vs. TT (adjusted odds ratio [aOR] 12.9, 95%CI 6.4, 26.0). The unexpected difference in DNA methylation between DNA extracted from coagulated and uncoagulated samples in response to folic acid supplementation is an important finding for evaluating use of folic acid and investigating the potential effects of folic acid supplementation on coagulation.

Azacitidine in patients with acute myeloid leukemia medically unfit for or resistant to chemotherapy: a multicenter phase I/II study

The safety and efficacy of azacitidine (5-day schedule) were assessed in a multicenter study in 40 patients (median age 72 years) with acute myeloid leukemia (AML) medically unfit for (n = 20) or resistant to chemotherapy (n = 20) from April to October 2008. Median marrow blasts were 42%. After a median follow-up of 13 months, response (complete remission [CR]/partial remission [PR]/hematologic improvement [HI]) was 50% and 10% in newly diagnosed and relapsed/refractory patients, respectively (p = 0.008). Median time-to-response was 2.5 months with a median duration of 5.9 months. Median survival was not reached for responders versus 3.8 months for 15 (38%) patients with stable disease (p < 0.045). High-risk cytogenetics was associated with inferior survival (p = 0.05). Lower marrow blasts on day 15 of cycle 1, irrespective of pretreatment count, predicted subsequent response (p = 0.01). Azacitidine is active and well tolerated in elderly patients with newly diagnosed AML.

Impact of the hypomethylating agent 5-azacytidine on dendritic cells function

Recent evidence suggested that 5-azacytidine (5-aza) can impact important immune functions via epigenetic modifications, making it an attractive candidate for pharmacologic manipulation of the immune system. The aim of this work was to study the effects of 5-aza on human dendritic cells (DC) generated from peripheral blood monocytes, and to test the type of immune response induced in patients treated with 5-aza. On the phenotypic level, CD40 and CD86 expression was significantly increased on mature DC exposed to 5-aza (5-aza-DC), compared with control untreated DC. Mature control DC and mature 5-aza-DC secreted comparable amounts of interleukin (IL)-6, IL-12p70, IL-23, and tumor necrosis factor-α. However, mature 5-aza-DC secreted significantly lower levels of IL-10 and IL-27 compared to mature control DC (p = 0.04 and p = 0.005, respectively). In the peripheral blood of 14 patients (7 males and 7 females; age range, 53-81 years) with advanced myeloid malignancies (8 acute myeloid leukemia and 6 myelodysplastic syndrome) treated with 5-aza, there was a significant decrease of IL-4-secreting CD4(+) T cells (p = 0.001), and a significant increase of IL-17A- and IL-21-secreting CD4(+) T cells (p = 0.003 and p = 0.01, respectively, compared to 5 healthy donors) suggesting a Th17 response pattern in the blood of patients receiving 5-aza. In all, these data suggest potentially novel mechanisms of action of epigenetic therapies, such as 5-aza, which may have broader implications for immunotherapeutic strategies.

The DNA methyltransferase inhibitors zebularine and decitabine induce mitochondria-mediated apoptosis and DNA damage in p53 mutant leukemic T cells

DNA methyltransferase (DNMT)-inhibiting nucleoside analogs reactivate the expression of tumor suppressor genes and apoptosis-related genes silenced by methylation, thus favoring the induction of apoptosis in tumor cells. Moreover, induction of DNA damage seems to contribute to their antitumor effect. However, the apoptotic signaling pathway induced by these demethylating drugs is not well understood. Here, we have investigated the induction of apoptosis by two nucleoside DNMT inhibitors, decitabine and zebularine, in leukemic T cells. Both inhibitors induced caspase-dependent apoptosis in Jurkat, CEM-6 and MOLT-4 leukemia T cell lines, all with mutant p53, whereas resting and activated normal T lymphocytes were highly resistant to these demethylating agents. Although decitabine and zebularine showed different ability to induce apoptosis and cell cycle arrest among the three cell lines, they similarly activated the intrinsic apoptotic pathway by inducing mitochondrial alterations such as Bak activation, loss of transmembrane potential and generation of reactive oxygen species (ROS). Accordingly, Bcl-2- and Bcl-x(L) -overexpressing Jurkat cells, as well as caspase-9-deficient Jurkat cells, were resistant to apoptosis induced by decitabine and zebularine. Interestingly, ROS production seemed to be necessary for the induction of apoptosis. Apoptotic events, such as Bak and caspase activation, started as soon as 20 hr after treatment with either decitabine or zebularine. In addition, progression of apoptosis triggered by both DNMT inhibitors was paralleled by the induction of DNA damage. Our results suggest that the mitochondrial apoptotic pathway activated by decitabine and zebularine in p53 mutant leukemic T cells depends mainly on the induction of DNA damage.

Mutations in epigenetic modifiers in myeloid malignancies and the prospect of novel epigenetic-targeted therapy

In the recent years, the discovery of a series of mutations in patients with myeloid malignancies has provided insight into the pathogenesis of myelodysplastic syndromes (MDSs), myeloproliferative neoplasms (MPNs), and acute myeloid leukemia (AML). Among these alterations have been mutations in genes, such as IDH1/2, TET2, DNMT3A, and EZH2, which appear to affect DNA and/or histone lysine methylation. Large clinical correlative studies are beginning to decipher the clinical importance, prevalence, and potential prognostic significance of these mutations. Additionally, burgeoning insight into the role of epigenetics in the pathogenesis of myeloid malignancies has prompted increased interest in development of novel therapies which target DNA and histone posttranslational modifications. DNA demethylating agents have been demonstrated to be clinically active in a subset of patients with MDS and AML and are used extensively. However, newer, more specific agents which alter DNA and histone modification are under preclinical study and development and are likely to expand our therapeutic options for these diseases in the near future. Here, we review the current understanding of the clinical importance of these newly discovered mutations in AML and MDS patients. We also discuss exciting developments in DNA methyltransferase inhibitor strategies and the prospect of novel histone lysine methyltransferase inhibitors.

Assaying pharmacodynamic endpoints with targeted therapy: flavopiridol and 17AAG induced dephosphorylation of histone H1.5 in acute myeloid leukemia

Histone H1 is commonly used to assay kinase activity in vitro. As many promising targeted therapies affect kinase activity of specific enzymes involved in cancer transformation, H1 phosphorylation can serve as potential pharmacodynamic marker for drug activity within the cell. In this study we utilized a phosphoproteomic workflow to characterize histone H1 phosphorylation changes associated with two targeted therapies in the Kasumi-1 acute myeloid leukemia cell line. The phosphoproteomic workflow was first validated with standard casein phosphoproteins and then applied to the direct analysis of histone H1 from Kasumi-1 nuclear lysates. Ten H1 phosphorylation sites were identified on the H1 variants, H1.2, H1.3, H1.4, H1.5 and H1.x. LC MS profiling of intact H1s demonstrated global dephosphorylation of H1.5 associated with therapy by the cyclin-dependent kinase inhibitor, flavopiridol and the Heat Shock Protein 90 inhibitor, 17-(Allylamino)-17-demethoxygeldanamycin. In contrast, independent treatments with a nucleotide analog, proteosome inhibitor and histone deacetylase inhibitor did not exhibit decreased H1.5 phosphorylation. The data presented herein demonstrate that potential of histones to assess the cellular response of reagents that have direct and indirect effects on kinase activity that alters histone phosphorylation. As such, this approach may be a highly informative marker for response to targeted therapies influencing histone phosphorylation.

Continued azacitidine therapy beyond time of first response improves quality of response in patients with higher-risk myelodysplastic syndromes

BACKGROUND

In the AZA-001 trial, azacitidine (75 mg/m(2) /d subcutaneously for Days 1-7 of every 28-day cycle) demonstrated improved survival compared with conventional care regimens in patients with International Prognostic Scoring System-defined intermediate-2- or high-risk myelodysplastic syndrome and World Health Organization-defined acute myeloid leukemia with 20% to 30% bone marrow blasts.

METHODS

This secondary analysis of the AZA-001 phase 3 study evaluated the time to first response and the potential benefit of continued azacitidine treatment beyond first response in responders.

RESULTS

Overall, 91 of 179 patients achieved a response to azacitidine; responding patients received a median of 14 treatment cycles (range, 2-30). Median time to first response was 2 cycles (range, 1-16). Although 91% of first responses occurred by 6 cycles, continued azacitidine improved response category in 48% of patients. Best response was achieved by 92% of responders by 12 cycles. Median time from first response to best response was 3.5 cycles (95% confidence interval [CI], 3.0-6.0) in 30 patients who ultimately achieved a complete response, and 3.0 cycles (95% CI, 1.0-3.0) in 21 patients who achieved a partial response.

CONCLUSIONS

Continued azacitidine therapy in responders was associated with a quantitative increase in response to a higher response category in 48% of patients, and therefore may enhance clinical benefit in patients with higher-risk MDS.

Analysis of genome-wide methylation and gene expression induced by 5-aza-2'-deoxycytidine identifies BCL2L10 as a frequent methylation target in acute myeloid leukemia

Epigenetic changes play a role in the pathogenesis of myeloid malignancies, and hypomethylating agents have shown efficacy in these diseases. We studied the apoptotic effect, genome-wide methylation, and gene expression profiles in HL60 cells following 5-aza-2'-deoxycytidine (decitabine; DAC) treatment, using microarray technologies. Decitabine treatment resulted in a decrease in global DNA methylation, corresponding to 4876 probeset IDs with significantly reduced methylation levels, while the expression of 2583 IDs was modified. The integrated analysis identified 160 genes demethylated and up-regulated by decitabine, mainly including development and differentiation pathway genes. Gene targets of Polycomb group protein regulation were overrepresented in this group. Apoptosis was induced by decitabine, and apoptosis-specific PCR arrays more precisely indicated decitabine-induced up-regulation of 13 apoptosis-related genes, in particular DAP-kinase 1 and BCL2L10. Correspondingly, in primary patient samples, BCL2L10 was hypermethylated in 45% of AML, 43% of therapy-related myeloid neoplasms, 12% of MDS, and in none of the controls. In conclusion, decitabine induces global demethylation and gene expression, in particular of Polycomb target genes involved in development and differentiation pathways. The apoptotic gene BCL2L10 is a frequent target for aberrant promoter methylation in patients with acute leukemia, de novo and therapy-related.

Involvement of the immune system in idiosyncratic drug reactions

There is strong evidence that most idiosyncratic drug reactions (IDRs) are immune-mediated and are caused by reactive metabolites of a drug rather than by the drug itself. Several hypotheses have been proposed by which a drug could induce an immune response. The major hypotheses are the hapten hypothesis and the danger hypothesis; however, the characteristics and spectrum of IDRs are different with different drugs, and this likely reflects mechanistic differences; therefore, no one hypothesis is likely to explain all IDRs. Some IDRs appear to involve epigenetic effects, direct activation of antigen-presenting cells, or disturbing the normal balance of the immune system. It has been suggested that many cases of idiosyncratic liver injury are not immune-mediated, and other mechanisms such as mitochondrial injury may be involved. It is essential that any hypothesis be consistent with the clinical characteristics of the IDR. Although the characteristics of most idiosyncratic liver injury do not suggest that mitochondria are the major target, it is quite possible that milder mitochondrial injury could stimulate an immune-mediated reaction. The observation that IDRs can vary widely among different drugs and different patients is most easily explained by an immune mechanism in which the target of the immune response is different.

Maintenance treatment with azacytidine for patients with high-risk myelodysplastic syndromes (MDS) or acute myeloid leukaemia following MDS in complete remission after induction chemotherapy

This prospective Phase II study is the first to assess the feasibility and efficacy of maintenance 5-azacytidine for older patients with high-risk myelodysplastic syndrome (MDS), chronic myelomonocytic leukaemia and MDS-acute myeloid leukaemia syndromes in complete remission (CR) after induction chemotherapy. Sixty patients were enrolled and treated by standard induction chemotherapy. Patients that reached CR started maintenance therapy with subcutaneous azacytidine, 5/28 d until relapse. Promoter-methylation status of CDKN2B (P15 ink4b), CDH1 and HIC1 was examined pre-induction, in CR and 6, 12 and 24 months post CR. Twenty-four (40%) patients achieved CR after induction chemotherapy and 23 started maintenance treatment with azacytidine. Median CR duration was 13.5 months, >24 months in 17% of the patients, and 18-30.5 months in the four patients with trisomy 8. CR duration was not associated with CDKN2B methylation status or karyotype. Median overall survival was 20 months. Hypermethylation of CDH1 was significantly associated with low CR rate, early relapse, and short overall survival (P = 0.003). 5-azacytidine treatment, at a dose of 60 mg/m(2) was well tolerated. Grade III-IV thrombocytopenia and neutropenia occurred after 9.5 and 30% of the cycles, respectively, while haemoglobin levels increased during treatment. 5-azacytidine treatment is safe, feasible and may be of benefit in a subset of patients.

Azacitidine: a review of its use in higher-risk myelodysplastic syndromes/acute myeloid leukaemia

Azacitidine (Vidaza) is a pyrimidine nucleoside analogue of cytidine. Subcutaneous azacitidine was recently approved in the EU for the treatment of adults who are not eligible for haematopoietic stem cell transplantation and who have intermediate-2-risk or high-risk myelodysplastic syndromes (MDS) [according to International Prognostic Scoring System (IPSS) criteria], chronic myelomonocytic leukaemia (CMML) with 10-29% marrow blasts without myeloproliferative disorder, or acute myeloid leukaemia (AML) with 20-30% blasts and multilineage dysplasia (according to the WHO classification). Subcutaneous azacitidine is the only drug shown to significantly prolong survival in patients with higher-risk MDS or WHO-defined AML, compared with conventional care (i.e. best supportive care, low-dose cytarabine or intensive chemotherapy). In addition, azacitidine is associated with a lower risk of AML progression and higher rates of complete remission, partial remission, haematological improvement and red blood cell (RBC) transfusion independence. Azacitidine has an acceptable tolerability profile; peripheral cytopenias are the most commonly occurring adverse event. Thus, azacitidine is a valuable option for the first-line treatment of patients with higher-risk MDS/AML.

Epigenetics and cancer treatment

In addition to the genetic alterations, observed in cancer cells, are mitotically heritable changes in gene expression not encoded by the DNA sequences, which are referred to as epigenetic changes. DNA methylation is among the most studied epigenetic mechanisms together with various histone modifications involved in chromatin remodeling. As opposed to genetic lesions, the epigenetic changes are potentially reversible by a number of small molecules, known as epi-drugs. This review will focus on the biological mechanisms underlying the epigenetic silencing of tumor suppressor genes observed in cancer cells, and the targeted molecular strategies that have been investigated to reverse these aberrations. In particular, we will focus on DNA methyltransferases (DNMTs) and histone deacetylases (HDACs) as epigenetic targets for cancer treatment. A synergistic effect of a combined use of DNMT and HDAC inhibitors has been observed. Moreover, epi-drugs sensitize multiple different cancer cells to a large variety of other treatment strategies. In particular, we have focused on the ability of DNMT and HDAC inhibitors to restore the estrogen receptor alpha (ERalpha) activity in breast cancer. Finally, we will discuss the potential of DNA methylation changes as biomarkers to be used in diverse areas of cancer treatment, especially for predicting response to treatment with DNMT and HDAC inhibitors.

Reduction of phosphoinositide-phospholipase C beta1 methylation predicts the responsiveness to azacitidine in high-risk MDS

Lipid signaling pathways are involved in cell growth, differentiation, and apoptosis, and could have a role in the progression of myelodysplastic syndromes (MDS) into acute myeloid leukemia (AML). Indeed, recent studies showed that phosphoinositide-phospholipase (PI-PL)Cbeta1 mono-allelic deletion correlates with a higher risk of AML evolution. Also, a single patient treated with azacitidine, a DNA methyltransferase inhibitor currently used in MDS, displayed a direct correlation between PI-PLCbeta1 gene expression and drug responsiveness. Consequently, we hypothesized that PI-PLCbeta1 could be a target for demethylating therapy. First, we analyzed the structure of PI-PLCbeta1 gene promoter, then quantified the degree of PI-PLCbeta1 promoter methylation and gene expression in MDS patients at baseline and during azacitidine administration. Indeed, PI-PLCbeta1 mRNA increased in responder patients, along with a reduction of PI-PLCbeta1 promoter methylation. Also, the molecular response correlated to and anticipated the clinical outcome, thus suggesting that PI-PLCbeta1 gene reactivation could predict azacitidine responsiveness. Our results demonstrate not only that PI-PLCbeta1 promoter is hypermethylated in high-risk MDS patients, but also that the amount of PI-PLCbeta1 mRNA could predict the clinical response to azacitidine, therefore indicating a promising new therapeutic approach.

Efficacy of a 3-day, low-dose treatment with 5-azacytidine followed by donor lymphocyte infusions in older patients with acute myeloid leukemia or chronic myelomonocytic leukemia relapsed after allografting

We have piloted a low-dose schedule of 5-azacytidine followed by donor lymphocyte infusions (DLIs) in patients with relapse of AML or chronic myelomonocytic leukemia (CMMoL) after allografting. Of the 26 patients (median age 62 years, range 28-75) with relapsed AML (n=24) or CMMoL (n=2), 11 (42%) had poor-risk cytogenetics. Twenty-three patients had received fludarabine-based reduced-toxicity conditioning regimens, and three had received conventional myeloablative conditioning. Patients received 5-azacytidine s.c., at a total daily dose of 100 mg, on days 1-3, to be followed by DLI on day 10, with the next course of treatment to be started on day 22. A total of 60 courses of 5-azacytidine were administered, with a median of 2 courses (range: 1-10). In 44 courses, 5-azacytidine was followed by DLI, and thus 19/26 (73%) patients received at least one course of this combined treatment. Clinically relevant neutropenic infections not associated with progressive disease developed in four patients, one of them succumbing to sepsis. Only two patients developed de novo acute GvHD after the combination of 5-azacytidine and DLI. Overall, 66% of the patients benefited from this treatment, with continued CRs achieved in 4 (16%) patients, lasting a median of 525 days (range: 450+ to 820+), and a 50% rate of temporary disease control with stable mixed chimerism (median duration 72 days). The median survival from the start of 5-azacytidine treatment was 136 days (range: 23 to 873+), with an estimated 2-year survival probability of 16%. In conclusion, this non-intensive outpatient regimen of 5-azacytidine followed by DLI is feasible, with a very low aGVHD rate. Objective responses, including continuous complete donor chimerism, occurred also in patients with poor-risk cytogenetics.

Idiosyncratic drug-induced agranulocytosis: possible mechanisms and management

The incidence of drug-induced neutropenia has not changed in the western hemisphere over the last 30 years. Yet, the drug panorama has changed considerably. This implies that host factors may play an intriguing role for this idiosyncratic reaction. The knowledge as to mechanisms for the reaction has advanced with emerging understanding of neutropoiesis and immune regulation. Nonetheless, it is still remarkably difficult to pinpoint why and how a drug causes this unexpected, severe adverse event in a patient. Patient characteristics, e.g. genetics, appear to be keys for better understanding, predictions and prevention. Am. J. Hematol. 2009. (c) 2009 Wiley-Liss, Inc.

Efficacy of azacitidine compared with that of conventional care regimens in the treatment of higher-risk myelodysplastic syndromes: a randomised, open-label, phase III study

BACKGROUND

Drug treatments for patients with high-risk myelodysplastic syndromes provide no survival advantage. In this trial, we aimed to assess the effect of azacitidine on overall survival compared with the three commonest conventional care regimens.

METHODS

In a phase III, international, multicentre, controlled, parallel-group, open-label trial, patients with higher-risk myelodysplastic syndromes were randomly assigned one-to-one to receive azacitidine (75 mg/m(2) per day for 7 days every 28 days) or conventional care (best supportive care, low-dose cytarabine, or intensive chemotherapy as selected by investigators before randomisation). Patients were stratified by French-American-British and international prognostic scoring system classifications; randomisation was done with a block size of four. The primary endpoint was overall survival. Efficacy analyses were by intention to treat for all patients assigned to receive treatment. This study is registered with ClinicalTrials.gov, number NCT00071799.

FINDINGS

Between Feb 13, 2004, and Aug 7, 2006, 358 patients were randomly assigned to receive azacitidine (n=179) or conventional care regimens (n=179). Four patients in the azacitidine and 14 in the conventional care groups received no study drugs but were included in the intention-to-treat efficacy analysis. After a median follow-up of 21.1 months (IQR 15.1-26.9), median overall survival was 24.5 months (9.9-not reached) for the azacitidine group versus 15.0 months (5.6-24.1) for the conventional care group (hazard ratio 0.58; 95% CI 0.43-0.77; stratified log-rank p=0.0001). At last follow-up, 82 patients in the azacitidine group had died compared with 113 in the conventional care group. At 2 years, on the basis of Kaplan-Meier estimates, 50.8% (95% CI 42.1-58.8) of patients in the azacitidine group were alive compared with 26.2% (18.7-34.3) in the conventional care group (p<0.0001). Peripheral cytopenias were the most common grade 3-4 adverse events for all treatments.

INTERPRETATION

Treatment with azacitidine increases overall survival in patients with higher-risk myelodysplastic syndromes relative to conventional care.