Counseling patients with higher-risk MDS regarding survival with azacitidine therapy: are we using realistic estimates?

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.

Measurable (Minimal) Residual Disease in Myelodysplastic Neoplasms (MDS): Current State and Perspectives

Myelodysplastic Neoplasms (MDS) have been traditionally studied through the assessment of blood counts, cytogenetics, and morphology. In recent years, the introduction of molecular assays has improved our ability to diagnose MDS. The role of Measurable (minimal) Residual Disease (MRD) in MDS is evolving, and molecular and flow cytometry techniques have been used in several studies. In this review, we will highlight the evolving concept of MRD in MDS, outline the various techniques utilized, and provide an overview of the studies reporting MRD and the correlation with outcomes.

SOHO State of the Art Updates and Next Questions: An Update on Higher Risk Myelodysplastic Syndromes

Higher-risk myelodysplastic syndromes (HR-MDS) are clonal myeloid neoplasms that cause life-limiting complications from severe cytopenias and leukemic transformation. Efforts to better classify, prognosticate, and assess therapeutic responses in HR-MDS have resulted in publication of new clinical tools in the last several years. Given limited current treatment options and suboptimal outcomes, HR-MDS stands to benefit from the study of investigational agents.Higher-risk myelodysplastic syndromes (HR-MDS) are a heterogenous group of clonal myeloid-lineage malignancies often characterized by high-risk genetic lesions, increased blood transfusion needs, constitutional symptoms, elevated risk of progression to acute myeloid leukemia (AML), and therapeutic need for allogeneic bone marrow transplantation. Use of blast percentage and other morphologic features to define myelodysplastic neoplasm subtypes is rapidly shifting to incorporate genetics, resulting in a subset of former HR-MDS patients now being considered as AML in presence of leukemia-defining genetic alterations. A proliferation of prognostic tools has further focused use of genetic features to drive decision making in clinical management. Recently, criteria to assess response of HR-MDS to therapy were revised to incorporate more clinically meaningful endpoints and better match AML response criteria. Basic science investigations have resulted in improved understanding of the relationship between MDS genetic lesions, bone marrow stromal changes, germline predispositions, and disease phenotype. However, therapeutic advances have been more limited. There has been import of the IDH1 inhibitor ivosidenib, initially approved for AML; the Bcl-2 inhibitor venetoclax and liposomal daunorubicin/cytarabine (CPX-351) are under active investigation as well. Unfortunately, effective treatment of TP53-mutated disease remains elusive, though preliminary evidence suggests improved outcomes with oral decitabine/cedazuridine over parenteral hypomethylating agent monotherapy. Investigational agents with novel mechanisms of action may help expand the repertoire of treatment options for HR-MDS and trials continue to offer a hopeful therapeutic avenue for suitable patients.

A Personalized Risk Model for Azacitidine Outcome in Myelodysplastic Syndrome and Other Myeloid Neoplasms Identified by Machine Learning Model Utilizing Real-World Data

Azacitidine is an approved therapy for higher-risk myelodysplastic syndrome (MDS). However, only 30-40% patients respond to azacitidine, and the responses may take up to six cycles to become evident. Delayed responses and the myelosuppressive effects of azacitidine make it challenging to predict which patients will benefit. This is further compounded by a lack of uniform prognostic tools to identify patients at risk of early treatment failure. Hence, we performed a retrospective analysis of 273 consecutive azacytidine-treated patients. The median overall survival was 16.25 months with only 9% alive at 5 years. By using pre-treatment variables incorporated into a random forest machine learning model, we successfully identified those patients unlikely to benefit from azacytidine upfront (7.99 vs. 22.8 months, p < 0.0001). This model also identified those who required significantly more hospitalizations and transfusion support. Notably, it accurately predicted survival outcomes, outperforming the existing prognostic scoring system. By integrating somatic mutations, we further refined the model and identified three distinct risk groups with significant differences in survival (5.6 vs. 10.5 vs. 43.5 months, p < 0.0001). These real-world findings emphasize the urgent need for personalized prediction tools tailored to hypomethylating agents, reducing unnecessary complications and resource utilization in MDS treatment.

Evaluation of the outcomes of newly diagnosed patients with high-risk myelodysplastic syndrome according to the initial therapeutical strategies chosen in usual clinical practice

Myelodysplastic syndromes (MDS) are a heterogeneous group of diseases without a care standard and show variability in treatment outcomes. This Spanish, observational, prospective study ERASME (CEL-SMD-2012-01) assessed the evolution of newly diagnosed and treatment-naïve high-risk MDS patients (according to IPPS-R). 204 patients were included: median age 73.0 years, 54.4% males, 69.6% 0-1 ECOG, and 94.6% with comorbidities. Active treatment was the most common strategy (52.0%) vs. stem cell transplantation (25.5%) and supportive care/watchful-waiting (22.5%). Overall (median) event-free survival was 7.9 months (9.1, 8.3, and 5.3); progression-free survival: 10.1 months (12.9, 12.8, and 4.3); and overall survival: 13.8 months (15.4, 14.9; 8.4), respectively, with significant differences among groups. Adverse events (AEs) of ≥3 grade were reported in 72.6% of patients; serious AEs reported in 60.6%. 33.1% of patients died due to AEs. Three patients developed second primary malignant neoplasms (median: 8.2 months). Our study showed better outcomes in patients receiving active therapy early after diagnosis.

Contingent Synergistic Interactions between Non-Coding RNAs and DNA-Modifying Enzymes in Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic stem cell disorders with maturation and differentiation defects exhibiting morphological dysplasia in one or more hematopoietic cell lineages. They are associated with peripheral blood cytopenias and by increased risk for progression into acute myelogenous leukemia. Among their multifactorial pathogenesis, age-related epigenetic instability and the error-rate DNA methylation maintenance have been recognized as critical factors for both the initial steps of their pathogenesis and for disease progression. Although lower-risk MDS is associated with an inflammatory bone marrow microenvironment, higher-risk disease is delineated by immunosuppression and clonal expansion. "Epigenetics" is a multidimensional level of gene regulation that determines the specific gene networks expressed in tissues under physiological conditions and guides appropriate chromatin rearrangements upon influence of environmental stimulation. Regulation of this level consists of biochemical modifications in amino acid residues of the histone proteins' N-terminal tails and their concomitant effects on chromatin structure, DNA methylation patterns in CpG dinucleotides and the tissue-specific non-coding RNAs repertoire, which are directed against various gene targets. The role of epigenetic modifications is widely recognized as pivotal both in gene expression control and differential molecular response to drug therapies in humans. Insights to the potential of synergistic cooperations of epigenetic mechanisms provide new avenues for treatment development to comfort human diseases with a known epigenetic shift, such as MDS. Hypomethylating agents (HMAs), such as epigenetic modulating drugs, have been widely used in the past years as first line treatment for elderly higher-risk MDS patients; however, just half of them respond to therapy and are benefited. Rational outcome predictors following epigenetic therapy in MDS and biomarkers associated with disease relapse are of high importance to improve our efforts in developing patient-tailored clinical approaches.

Hypomethylating agents for the treatment of myelodysplastic syndromes and acute myeloid leukemia: Past discoveries and future directions

Azacitidine and decitabine are hypomethylating agents that have dose-dependent epigenetic and cytotoxic effects and are widely used in the treatment of myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). In this review, we discuss the path to regulatory approval of azacitidine and decitabine, highlighting the substantial efforts that have been made to optimize the dosing schedule and administration of these drugs, including the development of new, oral formulations of both agents. We also review novel combination strategies that are being investigated in ongoing clinical trials for patients with MDS and AML, as well as efforts to expand the current indications of these agents.

Transposable elements and Piwi‑interacting RNAs in hemato‑oncology with a focus on myelodysplastic syndrome (Review)

Our current understanding of hematopoietic stem cell differentiation and the abnormalities that lead to leukemogenesis originates from the accumulation of knowledge regarding protein‑coding genes. However, the possible impact of transposable element (TE) mobilization and the expression of P‑element‑induced WImpy testis‑interacting RNAs (piRNAs) on leukemogenesis has been beyond the scope of scientific interest to date. The expression profiles of these molecules and their importance for human health have only been characterized recently due to the rapid progress of high‑throughput sequencing technology development. In the present review, current knowledge on the expression profile and function of TEs and piRNAs was summarized, with specific focus on their reported involvement in leukemogenesis and pathogenesis of myelodysplastic syndrome.

Mechanisms of Action of Hypomethylating Agents: Endogenous Retroelements at the Epicenter

Abnormal DNA methylation patterns are thought to drive the pathobiology of high-risk myelodysplastic syndromes (HR-MDS) and acute myeloid leukemia (AML). Sixteen years after their initial approval, the hypomethylating agents (HMAs), 5-azacytidine (AZA) and 5-aza-2′-deoxycytidine, remain the mainstay of treatment for HR-MDS and AML. However, a connection of the hypomethylating or additional effects of HMAs with clinical responses remains yet to be shown, and the mode of action of HMAs remains obscure. Given the relatively short-lived responses and the inevitable development of resistance in HMAs, a thorough understanding of the antineoplastic mechanisms employed by HMAs holds critical importance. Recent data in cancer cell lines demonstrate that reactivation of endogenous retroelements (EREs) and induction of a cell-intrinsic antiviral response triggered by RNA neotranscripts may underlie the antitumor activity of HMAs. However, data on primary CD34⁺ cells derived from patients with HR-MDS failed to confirm a link between HMA-mediated ERE modulation and clinical response. Though difficult to reconcile the apparent discrepancy, it is possible that HMAs mediate their effects in more advanced levels of differentiation where cells become responsive to interferon, whereas, inter-individual variations in the process of RNA editing and, in particular, in the ADAR1/OAS/RNase L pathway may also confound the associations of clinical response with the induction of viral mimicry. Further ex vivo studies along with clinical correlations in well-annotated patient cohorts are warranted to decipher the role of ERE derepression in the antineoplastic mechanisms of HMAs.

Oral cedazuridine/decitabine for MDS and CMML: a phase 2 pharmacokinetic/pharmacodynamic randomized crossover study

This phase 2 study was designed to compare systemic decitabine exposure, demethylation activity, and safety in the first 2 cycles with cedazuridine 100 mg/decitabine 35 mg vs standard decitabine 20 mg/m2 IV. Adults with International Prognostic Scoring System intermediate-1/2- or high-risk myelodysplastic syndromes (MDS) or chronic myelomonocytic leukemia (CMML) were randomized 1:1 to receive oral cedazuridine/decitabine or IV decitabine in cycle 1, followed by crossover to the other treatment in cycle 2. All patients received oral cedazuridine/decitabine in subsequent cycles. Cedazuridine and decitabine were given initially as separate capsules in a dose-confirmation stage and then as a single fixed-dose combination (FDC) tablet. Primary end points: mean decitabine systemic exposure (geometric least-squares mean [LSM]) of oral/IV 5-day area under curve from time 0 to last measurable concentration (AUClast), percentage long interspersed nuclear element 1 (LINE-1) DNA demethylation for oral cedazuridine/decitabine vs IV decitabine, and clinical response. Eighty patients were randomized and treated. Oral/IV ratios of geometric LSM 5-day AUClast (80% confidence interval) were 93.5% (82.1-106.5) and 97.6% (80.5-118.3) for the dose-confirmation and FDC stages, respectively. Differences in mean %LINE-1 demethylation between oral and IV were ≤1%. Clinical responses were observed in 48 patients (60%), including 17 (21%) with complete response. The most common grade ≥3 adverse events regardless of causality were neutropenia (46%), thrombocytopenia (38%), and febrile neutropenia (29%). Oral cedazuridine/decitabine (100/35 mg) produced similar systemic decitabine exposure, DNA demethylation, and safety vs decitabine 20 mg/m2 IV in the first 2 cycles, with similar efficacy. This study is registered at www.clinicaltrials.gov as #NCT02103478.

Navigating Myelodysplastic and Myelodysplastic/Myeloproliferative Overlap Syndromes

Myelodysplastic syndromes (MDS) and MDS/myeloproliferative neoplasms (MPNs) are clonal diseases that differ in morphologic diagnostic criteria but share some common disease phenotypes that include cytopenias, propensity to acute myeloid leukemia evolution, and a substantially shortened patient survival. MDS/MPNs share many clinical and molecular features with MDS, including frequent mutations involving epigenetic modifier and/or spliceosome genes. Although the current 2016 World Health Organization classification incorporates some genetic features in its diagnostic criteria for MDS and MDS/MPNs, recent accumulation of data has underscored the importance of the mutation profiles on both disease classification and prognosis. Machine-learning algorithms have identified distinct molecular genetic signatures that help refine prognosis and notable associations of these genetic signatures with morphologic and clinical features. Combined geno-clinical models that incorporate mutation data seem to surpass the current prognostic schemes. Future MDS classification and prognostication schema will be based on the portfolio of genetic aberrations and traditional features, such as blast count and clinical factors. Arriving at these systems will require studies on large patient cohorts that incorporate advanced computational analysis. The current treatment algorithm in MDS is based on patient risk as derived from existing prognostic and disease classes. Luspatercept is newly approved for patients with MDS and ring sideroblasts who are transfusion dependent after erythropoietic-stimulating agent failure. Other agents that address red blood cell transfusion dependence in patients with lower-risk MDS and the failure of hypomethylating agents in higher-risk disease are in advanced testing. Finally, a plethora of novel targeted agents and immune checkpoint inhibitors are being evaluated in combination with a hypomethylating agent backbone to augment the depth and duration of response and, we hope, improve overall survival.

Emerging treatment options for patients with high-risk myelodysplastic syndrome

Myelodysplastic syndromes (MDS) are clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis with peripheral blood cytopenias, dysplastic cell morphology, and a variable risk of progression to acute myeloid leukemia (AML). The hypomethylating agents (HMA) azacitidine and decitabine have been used for over a decade in MDS treatment and lead to a modest survival benefit. However, response rates are only around 40% and responses are mostly transient. For HMA-refractory patients the prognosis is poor and there are no therapies approved by the United States Food and Drug Administration.

Combinations of HMAs, especially along with immune checkpoint inhibitors, have shown promising signals in both the frontline and HMA-refractory setting. Several other novel agents including orally available and longer acting HMAs, the BCL-2 inhibitor venetoclax, oral agents targeting driver mutations (IDH1/2, FLT3), immunotherapies, and new options for intensive chemotherapy have been studied with variable success and will be reviewed herein. Except for the minority of patients with targetable driver mutations, HMAs – likely as part of combination therapies – will remain the backbone of frontline MDS treatment. However, the wider use of genetic testing may enable a more targeted and individualized therapy of MDS patients.

Estimated glomerular filtration rate independently predicts outcome of azacitidine therapy in higher-risk Myelodysplastic syndromes. Results from 536 patients of the Hellenic National Registry of Myelodysplastic and Hypoplastic syndromes

Higher-risk Myelodysplastic syndromes (MDS) patients undergoing treatment with 5-azacytidine (AZA) are typically elderly with several comorbidities. However, the effect of comorbidities on the effectiveness and safety of AZA in real-world settings remains unclear. We analyzed data from 536 AZA-treated patients with higher-risk MDS, Myelodysplastic/Myeloproliferative neoplasms and low blast count Acute Myeloid Leukemia enrolled to the Hellenic National Registry of Myelodysplastic and Hypoplastic Syndromes. Multivariate analysis adjusted also for the International Prognostic Scoring System (IPSS), its revised version (IPSS-R) and the French Prognostic Scoring System (FPSS), demonstrated independent associations of overall and leukemia-free survival with estimated glomerular filtration rate (eGFR) <45 mL min^-1 /1.73 m² (P = .039, P = .023, respectively), ECOG performance status <2 (P = .015, P = .006), and presence of peripheral blood blasts (P = .008, P = .034), while secondary MDS also correlated with significantly shorter leukemia-free survival (P = .039). Addition of eGFR <45 mL min^-1 /1.73 m² , in IPSS-R and FPSS increased the predictive power of both models. Only FPSS ≤2 and eGFR <45 mL min^-1 /1.73 m² predicted worse response to AZA in multivariate analysis, whereas eGFR <45 mL min^-1 /1.73 m² correlated significantly with death from hemorrhage (P = .003) and cardiovascular complications (P = .006). In conclusion, in the second largest real-world series of AZA-treated MDS patients, we show that an eGFR <45 mL min^-1 /1.73 m² is an independent predictor of worse response and survival. This higher cut-off, instead of the commonly used serum creatinine >2 mg/dL, can be utilized as a more precise indicator of renal comorbidity during AZA therapy. Incorporation of eGFR in the prognostic assessment of AZA-treated MDS patients may prove useful not only in routine practice, but also for the appropriate patient stratification in clinical trials with AZA combinations.

Following in the footsteps of acute myeloid leukemia: are we witnessing the start of a therapeutic revolution for higher-risk myelodysplastic syndromes?

For most patients with higher-risk myelodysplastic syndromes (HR-MDS) the hypomethylating agents (HMA) azacitidine and decitabine remain the mainstay of therapy. However, the prognosis mostly remains poor and aside from allogeneic hematopoietic stem cell transplantation no curative treatment options exist. Unlike acute myeloid leukemia, which has seen a dramatic expansion of available therapies recently, no new agents have been approved for MDS in the United States since 2006. However, various novel HMAs, HMA in combination with venetoclax, immune checkpoint inhibitors, and targeted therapies for genetically defined patient subgroups such as APR-246 or IDH inhibitors, have shown promising results in early stages of clinical testing. Furthermore, the wider availability of genetic testing is going to allow for a more individualized treatment of MDS patients. Herein, we review the current treatment approach for HR-MDS and discuss recent therapeutic advances and the implications of genetic testing on management of HR-MDS.

Hypomethylating agent (HMA) therapy use and survival in older adults with Refractory Anemia with Excess Blasts (RAEB) in the United States (USA): a large propensity score-matched population-based study†

Hypomethylating agents (HMA) showed overall survival (OS) benefits in patients with higher-risk myelodysplastic syndromes (HR-MDS) in clinical trials. We conducted a retrospective cohort study of Surveillance, Epidemiology, and End Results (SEER)-Medicare data of patients ≥66 years diagnosed with refractory anemia with excess blasts (RAEB), a proxy for HR-MDS, in 01/2001-04/2004 (pre-period) or 01/2006-12/2011 (post-period). Association between post-period diagnosis and OS was examined using propensity scores (PS)-matched samples. Among 1876 RAEB patients, median OS was 9 months and 30.8% received HMAs (3.6% in pre-period; 43.0% in post-period) with no association between post-period diagnosis and OS. In the top PS quartile, post-period diagnosis was associated with a 74% lower risk of death (Hazard ratio [HR] = 0.26, 95%-CI: 0.10-0.69, p = 0.007), while outcomes were worse in the lowest PS quartile (HR = 2.80, 95%-CI: 1.06-7.36, p = 0.037). HMA lead to a 3-month OS benefit for patients most likely to receive HMA but not for unselected RAEB cohort.

Hypomethylating agent based combinations in higher risk myelodysplastic syndrome

For over a decade the hypomethylating agents (HMA) azacitidine and decitabine have been the mainstay of therapy for myelodysplastic syndrome (MDS). There is a critical need to improve frontline therapy, given that only up to half of high-risk MDS patients will respond to HMA therapy, and responses are short-lived. Currently, a key strategy has been to combine HMAs with other novel agents to improve patient outcomes. While synergy of agents is the goal of combination therapy, combinations often come at the cost of increased side effects that are often intolerable in this vulnerable population. The purpose of this review is to critically examine clinically relevant HMA combinations and discuss the future of MDS management.

Therapeutic strategies in low and high-risk MDS: What does the future have to offer?

Myelodysplastic syndromes (MDS) are a heterogeneous group of myeloid disorders characterized by cytopenias and increased risk of acute leukemia transformation. Prognosis of MDS patients can be assessed by various scoring systems, the most common being the International Prognostic Scoring System (IPSS) now refined by the revised version (IPSS-R). Genomic information at baseline, that is currently not included in clinical prognostic scores, will, in the future, help us to stratify patients with various prognoses. Therapy of MDS is based on risk stratification. The aim of therapy in low-risk MDS is to improve anemia or thrombocytopenia, decrease transfusion needs, improve quality of life, attempt to prolong overall survival, and reduce the risk of progression. In higher-risk MDS, the goal of therapy is to prolong survival and reduce the risk of transformation into acute leukemia. Only a few drugs are currently available for treatment, but more drugs are now under clinical investigation, in line with new, recently discovered molecular and immunological pathways. This review describes potential new drugs for low and high-risk MDS. The increasing knowledge of immunological and signalling pathways in MDS will assist us in identifying targeted patient-oriented treatments. In the near future, initial molecular stratification will lead the way to a personalized approach and targeted therapy.

Epigenetic therapies in acute myeloid leukemia: the role of hypomethylating agents, histone deacetylase inhibitors and the combination of hypomethylating agents with histone deacetylase inhibitors

Epigenetic regulation includes changes of DNA methylation and modifications of histone proteins and is essential for normal physiologic functions, especially for controlling gene expression. Epigenetic dysregulation plays a key role in disease pathogenesis and progression of some malignancies, including acute myeloid leukemia (AML). Epigenetic therapies, including hypomethylating agents (HMAs) and histone deacetylase (HDAC) inhibitors, were developed to reprogram the epigenetic abnormalities in AML. However, the molecular mechanisms and therapeutic effects of the two agents alone or their combination remain unknown. An overview of these epigenetic therapies is given here. A literature search was conducted through PubMed database, looking for important biological or clinical studies related to the epigenetic regimens in the treatment of AML until October 15th, 2019. Various types of articles, including original research and reviews, were assessed, identified, and eventually summarized as a collection of data pertaining the mechanisms and clinical effects of HMAs and HDAC inhibitors in AML patients. We provided here an overview of the current understanding of the mechanisms and clinical therapeutic effects involved in the treatment with HMAs and HDAC inhibitors alone, the combination of epigenetic therapies with intensive chemotherapy, and the combination of both types of epigenetic therapies. Relevant clinical trials were also discussed. Generally speaking, the large number of studies and their varied outcomes demonstrate that effects of epigenetic therapies are heterogeneous, and that HMAs combination regimens probably contribute to significant response rates. However, more research is needed to explore therapeutic effects of HDAC inhibitors and various combinations of HMAs and HDAC inhibitors.

Epigenetic Changes as a Target in Aging Haematopoietic Stem Cells and Age-Related Malignancies

Aging is associated with multiple molecular and functional changes in haematopoietic cells. Most notably, the self-renewal and differentiation potential of hematopoietic stem cells (HSCs) are compromised, resulting in myeloid skewing, reduced output of red blood cells and decreased generation of immune cells. These changes result in anaemia, increased susceptibility for infections and higher prevalence of haematopoietic malignancies. In HSCs, age-associated global epigenetic changes have been identified. These epigenetic alterations in aged HSCs can occur randomly (epigenetic drift) or are the result of somatic mutations in genes encoding for epigenetic proteins. Mutations in loci that encode epigenetic modifiers occur frequently in patients with haematological malignancies, but also in healthy elderly individuals at risk to develop these. It may be possible to pharmacologically intervene in the aberrant epigenetic program of derailed HSCs to enforce normal haematopoiesis or treat age-related haematopoietic diseases. Over the past decade our molecular understanding of epigenetic regulation has rapidly increased and drugs targeting epigenetic modifications are increasingly part of treatment protocols. The reversibility of epigenetic modifications renders these targets for novel therapeutics. In this review we provide an overview of epigenetic changes that occur in aging HSCs and age-related malignancies and discuss related epigenetic drugs.

Epigenetic therapy combinations in acute myeloid leukemia: what are the options?

Epigenetics refers to the regulation of gene expression mainly by changes in DNA methylation and modifications of histone proteins without altering the actual DNA sequence. While epigenetic modifications are essential for normal cell differentiation, several driver mutations in leukemic pathogenesis have been identified in genes that affect epigenetic processes, such as DNA methylation and histone acetylation. Several therapeutic options to target epigenetic alterations in acute myeloid leukemia (AML) have been successfully tested in preclinical studies and various drugs have already been approved for use in clinical practice. Among these already approved therapeutics are hypomethylating agents (azacitidine and decitabine) and isocitrate dehydrogenase inhibitors (ivosidenib, enasidenib). Other agents such as bromodomain-containing epigenetic reader proteins and histone methylation (e.g. DOT1L) inhibitors are currently in advanced clinical testing. As several epigenetic therapies have only limited efficacy when used as single agents, combination therapies that target AML pathogenesis at different levels and exploit synergistic mechanisms are also in clinical trials. Combinations of either epigenetic therapies with conventional chemotherapy, different forms of epigenetic therapies, or epigenetic therapies with immunotherapy are showing promising early results. In this review we summarize the underlying pathophysiology and rationale for epigenetically-based combination therapies, review current preclinical and clinical data and discuss the future directions of epigenetic therapy combinations in AML.

Immunosuppressive therapy in myelodysplastic syndromes: a borrowed therapy in search of the right place

INTRODUCTION

Myelodysplastic syndromes (MDS) encompass a heterogenous collection of clonal hematopoietic stem cell disorders defined by dysregulated hematopoiesis, peripheral cytopenias, and a risk of leukemic progression. Increasing data support the role of innate and adaptive immune pathways in the pathogenesis and disease course of MDS. The role of immunosuppressive therapy has an established role in the treatment of other hematologic diseases, such as aplastic anemia whose pathogenesis is postulated to reflect that of MDS with regards to many aspects of immune activation. Areas covered: This paper discusses the current understanding of immune dysregulation as it pertains to MDS, the clinical experience with immunosuppressive therapy in the management of MDS, as well as future prospects which will likely improve therapeutic options and outcomes for patients with MDS. Expert commentary: Though limited by paucity of high quality data, immunomodulatory and immunosuppressive therapies for the treatment of MDS have shown meaningful clinical activity in selected patients. Continued clarification of the immune pathways that are dysregulated in MDS and establishing predictors for clinical benefit of immunosuppressive therapy are vital to improve the use and outcomes with these therapies.