How we treat lower-risk myelodysplastic syndromes

Recent advances in myelodysplastic syndromes: Molecular pathogenesis and its implications for targeted therapies

Myelodysplastic syndromes (MDS) are defined as stem cell disorders caused by various gene abnormalities. Recent analysis using next-generation sequencing has provided great advances in identifying relationships between gene mutations and clinical phenotypes of MDS. Gene mutations affecting RNA splicing machinery, DNA methylation, histone modifications, transcription factors, signal transduction proteins and components of the cohesion complex participate in the pathogenesis and progression of MDS. Mutations in RNA splicing and DNA methylation occur early and are considered “founding mutations”, whereas others that occur later are regarded as “subclonal mutations”. RUNX1 mutations are more likely to subclonal; however, they apparently play a pivotal role in familial MDS. These genetic findings may lead to future therapies for MDS.

Some aspects of allogeneic stem cell transplantation in patients with myelodysplastic syndrome: advances and controversy

Myelodysplastic syndrome (MDS) is a heterogeneous group of myeloid disorders. MDS remains a disease of elderly patients; moreover, the incidence of high risk MDS is proportionally greater in elderly patients, with increased frequency of secondary acute myeloid leukemia, as well as adverse cytogenetic abnormalities. Allogeneic stem cell transplantation is a therapeutic approach with known curative potential for patients with MDS that allows the achievement of long-term disease control. Numerous controversies still exist regarding transplantation in MDS: timing of transplantation, disease status at transplantation and comorbidity, conditioning intensity, pretransplant therapy, and stem cell source. Various transplant modalities of different intensities and alternative donor sources are now in use. Current advances in transplant technology are allowing the consideration of older patients. This should result in a greater number of older patients benefiting from this potentially curative treatment modality. Despite advances in transplantation technology, there is still considerable morbidity and mortality associated with this approach. Nevertheless, with the introduction of reduced-intensity conditioning and thereby reduced early mortality, transplant numbers in MDS patients have significantly increased. Moreover, recent new developments with innovative drugs, including hypomethylating agents, have extended the therapeutic alternatives for MDS patients. Hypomethylating agents allow the delay of allogeneic stem cell transplantation by serving as an effective and well-tolerated means to reduce disease burden.

Feasible outcomes of T cell-replete haploidentical stem cell transplantation with reduced-intensity conditioning in patients with myelodysplastic syndrome

Even with the recent optimization of haploidentical stem cell transplantation (SCT), its role for patients with myelodysplastic syndrome (MDS) or acute myeloid leukemia evolving from MDS (sAML) should be validated. We analyzed the outcomes of consecutive 60 patients with MDS or sAML who received T cell-replete haploidentical SCT after reduced-intensity conditioning with fludarabine, busulfan, and rabbit antithymocyte globuline ± 800 cGy total body irradiation. Patients achieved a rapid neutrophil engraftment after a median of 12 days (range, 8 to 23) and an early immune reconstitution without high incidences of acute graft-versus-host disease (GVHD) II to IV and chronic GVHD (36.7% and 48.3%, respectively). After a median follow-up of 4 years, incidence of relapse and nonrelapse mortality and rate of overall survival and disease-free survival was 34.8%, 23.3%, 46.8%, and 41.9%, respectively. In multivariate analysis, the disease status at peak was a significant predictor for relapse (lower-risk MDS versus higher-risk MDS or sAML; hazard ratio [HR], 5.69; 95% confidence interval [CI], 1.45 to 22.29; P = .013) and disease-free survival (HR, 4.44; 95% CI, 1.14 to 17.34; P = .032). Chronic GVHD was an additional significant predictor for relapse (no versus yes; HR, 2.87; 95% CI, 1.03 to 7.51; P = .043). Our T cell-replete haploidentical SCT may be a feasible option for patients with MDS and sAML without conventional donors.

More is better: combination therapies for myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are a heterogenous collection of clonal hematopoietic malignancies that exist as a subgroup of the myeloid neoplasms as classified by the World Health Organization (WHO). They are characterized by ineffective hematopoiesis, subsequent cytopenias, transformation to acute myeloid leukemia (AML), and poor overall survival. There are currently three FDA-approved medications for MDS; lenalidomide, azacitidine, and decitabine. The role of these agents is to diminish the clinical impact of MDS and delay its progression to AML. However, despite known results with these monotherapies, recent clinical trials with a variety of combinations for MDS have demonstrated promising results. These trials include combinations of hypomethylating agents, histone deacetylase inhibitors, growth factors, and chemotherapy among others. In this paper we review the current literature on combination therapies in MDS, analyze on-going and concluded trials, and suggest future possibilities for combination strategies in MDS.

Recent developments in myelodysplastic syndromes

Once thought to be rare disorders, the myelodysplastic syndromes (MDS) are now recognized as among the most common hematological neoplasms, probably affecting >30 000 patients per year in the United States. US regulatory approval of azacitidine, decitabine, and lenalidomide between 2004 and 2006 seemed to herald a new era in the development of disease-modifying therapies for MDS, but there have been no further drug approvals for MDS indications in the United States in the last 8 years. The available drugs are not curative, and few of the compounds that are currently in development are likely to be approved in the near future. As a result, MDS diagnoses continue to place a heavy burden on both patients and health care systems. Incomplete understanding of disease pathology, the inherent biological complexity of MDS, and the presence of comorbid conditions and poor performance status in the typical older patient with MDS have been major impediments to development of effective novel therapies. Here we discuss new insights from genomic discoveries that are illuminating MDS pathogenesis, increasing diagnostic accuracy, and refining prognostic assessment, and which will one day contribute to more effective treatments and improved patient outcomes.

Azacitidine for myelodysplastic patients aged > 65 years: a review of clinical efficacy

INTRODUCTION

Therapeutic strategies for elderly patients affected by myelodysplastic syndromes (MDS) are scarce and only few patients have an advantage in performing allogeneic bone marrow transplant.

AREAS COVERED

Primary endpoints for treatment of elderly MDS patients were not curative, but rather allowing to maintain a good quality of life through prolongation of overall survival. In this context, azacitidine showed to improve responses in this subset of patients compared to conventional established regimens, such as intensive or low-dose chemotherapy and best supportive care. Good safety profile of the drug was reported either when it was used inside or outside clinical trials. Improved quality of response was observed when the drug was administered beyond the first response, and it is now usually recommended to continue it at the same dose and schedule in responding patients.

EXPERT OPINION

Evaluation of baseline prognostic factors and comorbidities may help to identify patients who can benefit from the prolonged administration of the drug. Real life data regarding efficacy and safety of azacitidine in MDS elderly patients are required in order to confirm the results of clinical trials.

Use of deferasirox in transfusion-dependent myelodysplastic syndromes with iron overload

SUMMARY 

In myelodysplastic syndromes (MDS), transfusion-dependent anemia has been established as an independent risk factor for decreased survival. Although evidence from prospective studies is still lacking, several guidelines recommend iron-chelating therapy in MDS patients with a longer life expectancy. With the recent introduction of deferasirox, an oral active iron-chelating drug, which has shown dose-dependent efficacy and acceptable tolerability, this therapeutic option has become feasible even in the elderly. Several retrospective and prospective studies showed that in MDS patients deferasirox is effective in reducing iron burden and in maintaining the circulating toxic iron fraction within the normal range. Moreover, in a substantial fraction of patients treated with deferasirox a significant improvement of peripheral cytopenias may occur.

CpG island methylator phenotype of myelodysplastic syndrome identified through genome-wide profiling of DNA methylation and gene expression

The CpG island methylator phenotype (CIMP) is an epigenetic phenomenon and plays an important role in tumourigenesis in various cancers. The identification of aberrant DNA methylation can be exploited for early diagnosis and risk assessment of patients. We identified a CIMP in myelodysplastic syndrome (MDS). Genes were screened for hypermethylation and transcription downregulation through genome-wide DNA methylation profiling and gene expression microarrays. Methylation-specific, real-time, and bisulfite-sequencing polymerase chain reaction were performed to validate selected genes. The hypermethylation of genes as a diagnostic tool for the detection of MDS was evaluated. Kaplan-Meier survival analysis and Cox regression were performed. A draft of an MDS CIMP was established and revised to 6 genes after validation in 20 patients and 20 controls. Further large-scale analysis showed that the majority of 211 MDS patients were hypermethylated in 6 genes. The area under the curve of CIMP was 0·9768 (95% confidence interval 0·9609-0·9928). A combination of 5 or more of the methylated genes showed a specificity of 95% and sensitivity of 91% for the diagnosis of MDS. We found CIMP positivity to be a significantly unfavourable prognostic factor for MDS. These results indicate that the newly established CIMP may improve diagnostic accuracy and prognosis assessment in MDS.

Initial transfusion intensity predicts survival in myelodysplastic syndrome

We evaluated 52 patients with myelodysplastic syndrome (MDS) who had received at least one red blood cell (RBC) transfusion. In the 4-week period following the first transfusion, 24 patients (group 1) required no transfusion, while 28 (group 2) required transfusion of two or more units of RBCs. Survival was greater in group 1 (440 weeks vs. 167 weeks, p < 0.01), even when only international prognostic scoring system (IPSS) low and intermediate-1 risk patients were analyzed (median overall survival 491 vs. 170 weeks, p < 0.05), independent of age, IPSS and progression to acute myeloid leukemia (AML). The intensity of transfusion required in the first few weeks after the first transfusion predicts disease severity and correlates with survival.

Iron overload and chelation therapy in myelodysplastic syndromes

Iron overload remains a concern in MDS patients especially those requiring recurrent blood transfusions. The consequence of iron overload may be more relevant in patients with low and intermediate-1 risk MDS who may survive long enough to experience such manifestations. It is a matter of debate whether this overload has time to yield organ damage, but it is quite evident that cellular damage and DNA genotoxic effect are induced. Iron overload may play a critical role in exacerbating pre-existing morbidity or even unmask silent ones. Under these circumstances, iron chelation therapy could play an integral role in the management of these patients. This review entails an in depth analysis of iron overload in MDS patients; its pathophysiology, effect on survival, associated risks and diagnostic options. It also discusses management options in relation to chelation therapy used in MDS patients and the impact it has on survival, hematologic response and organ function.

How we treat higher-risk myelodysplastic syndromes

Higher-risk myelodysplastic syndromes (MDS) are defined by patients who fall into higher-risk group categories in the original or revised International Prognostic Scoring System. Survival for these patients is dismal, and treatment should be initiated rapidly. Standard therapies include the hypomethylating agents azacitidine and decitabine, which should be administered for a minimum of 6 cycles, and continued for as long as a patient is responding. Once a drug fails in one of these patients, further treatment options are limited, median survival is <6 months, and consideration should be given to clinical trials. Higher-risk eligible patients should be offered consultation to discuss hematopoietic stem cell transplantation close to the time of diagnosis, depending on patient goals of therapy, with consideration given to proceeding to transplantation soon after an optimal donor is located. In the interim period before transplantation, hypomethylating agent therapy, induction chemotherapy, or enrollment in a clinical trial should be considered to prevent disease progression, although the optimal pretransplantation therapy is unknown.

Prognostic models in myelodysplastic syndromes

Establishing the prognosis for patients with myelodysplastic syndromes (MDS) is a key element of their care. It helps patients understand the severity of their disease and set expectations for their future. For physicians, an accurate estimate of prognosis drives decisions about the timing and choice of therapeutic options to consider. The International Prognostic Scoring System (IPSS) has been the standard tool for MDS risk stratification since it was released in 1997. It has been used to describe patients in pivotal clinical trials and is a key element of practice guidelines. Subsequent changes to the classification scheme for MDS and an underestimation of risk in some patients from the low and intermediate-1 categories have led to the development of several newer prognostic models. The most recent is the revised IPSS (IPSS-R), which addresses several of the perceived deficiencies of its predecessor. Despite their utility, none of the available prognostic systems incorporates disease-related molecular abnormalities such as somatic mutations. These lesions are present in the nearly all cases and many have been shown to improve upon existing prognostic models. However, the interpretation of somatic mutations can be challenging and it is not yet clear how best to combine them with clinical predictors of outcome. Here I review several prognostic scoring systems developed after the IPSS and describe the emerging use of molecular markers to refine risk stratification in the MDS patient population.

Acquired myelodysplasia or myelodysplastic syndrome: clearing the fog

Myelodysplastic syndromes (MDS) are clonal myeloid disorders characterized by progressive peripheral blood cytopenias associated with ineffective myelopoiesis. They are typically considered neoplasms because of frequent genetic aberrations and patient-limited survival with progression to acute myeloid leukemia (AML) or death related to the consequences of bone marrow failure including infection, hemorrhage, and iron overload. A progression to AML has always been recognized among the myeloproliferative disorders (MPD) but occurs only rarely among those with essential thrombocythemia (ET). Yet, the World Health Organization (WHO) has chosen to apply the designation myeloproliferative neoplasms (MPN), for all MPD but has not similarly recommended that all MDS become the myelodysplastic neoplasms (MDN). This apparent dichotomy may reflect the extremely diverse nature of MDS. Moreover, the term MDS is occasionally inappropriately applied to hematologic disorders associated with acquired morphologic myelodysplastic features which may rather represent potentially reversible hematological responses to immune-mediated factors, nutritional deficiency states, and disordered myelopoietic responses to various pharmaceutical, herbal, or other potentially myelotoxic compounds. We emphasize the clinical settings, and the histopathologic features, of such AMD that should trigger a search for a reversible underlying condition that may be nonneoplastic and not MDS.

Current therapy of myelodysplastic syndromes

After being a neglected and poorly-understood disorder for many years, there has been a recent explosion of data regarding the complex pathogenesis of myelodysplastic syndromes (MDS). On the therapeutic front, the approval of azacitidine, decitabine, and lenalidomide in the last decade was a major breakthrough. Nonetheless, the responses to these agents are limited and most patients progress within 2 years. Allogeneic stem cell transplantation remains the only potentially curative therapy, but it is associated with significant toxicity and limited efficacy. Lack or loss of response after standard therapies is associated with dismal outcomes. Many unanswered questions remain regarding the optimal use of current therapies including patient selection, response prediction, therapy sequencing and combinations, and management of resistance. It is hoped that the improved understanding of the underpinnings of the complex mechanisms of pathogenesis will be translated into novel therapeutic approaches and better prognostic/predictive tools that would facilitate accurate risk-adaptive therapy.

A randomized controlled trial of romiplostim in patients with low- or intermediate-risk myelodysplastic syndrome receiving decitabine

Patients with myelodysplastic syndrome (MDS) receiving hypomethylating agents commonly develop thrombocytopenia. This double-blind study evaluated the efficacy and safety of romiplostim, a peptibody protein that increases platelets, in patients with MDS receiving decitabine. Patients received romiplostim 750 μg (n = 15) or placebo (n = 14) and decitabine. Median platelet counts at the beginning of each decitabine cycle trended lower in placebo-treated than in romiplostim-treated patients. Bleeding events occurred in 43% of placebo-treated and 27% of romiplostim-treated patients, and platelet transfusions were administered to 57% of placebo-treated and 47% of romiplostim-treated patients. Overall clinical therapeutic response was achieved by 21% of placebo-treated and 33% of romiplostim-treated patients. Treatment was generally well tolerated. Progression to acute myeloid leukemia (AML) occurred in one patient per group. Adding romiplostim to decitabine treatment is well tolerated and may be beneficial, as indicated by trends toward higher platelet counts at the beginning of each treatment cycle and lower platelet transfusion rates and percentages of patients with bleeding events.

Key clinical observations after 5-azacytidine and decitabine treatment of myelodysplastic syndromes suggest practical solutions for better outcomes

Clinical experience with 5-azacytidine and decitabine treatment of myelodysplastic syndromes (MDS), complemented by biological and pharmacological studies, has revealed compelling mechanism of action differences compared with traditional myeloid cancer treatment mainstays such as cytarabine. For example, 5-azacytidine and decitabine produce remissions and better overall survival in MDS with high-risk chromosome abnormalities at a surprisingly high rate, consistent with experimental observations that noncytotoxic DNA methyltransferase depletion by 5-azacytidine/decitabine can trigger cell cycle exit independently of p53, thus circumventing a basis for resistance to apoptosis-based DNA-damaging therapy. That responses cut across the chaotic genomic landscape of MDS highlights common threads in disease, such as high expression in myeloblasts of differentiation-driving transcription factors yet paradoxical epigenetic suppression of proliferation-terminating late-differentiation genes. Less toxic regimens (lower dosages but more frequent administration) of 5-azacytidine/decitabine have been more successful, underscoring the importance of preserving functionally normal stem cells, which are rendered more precious by attrition from age, previous cytotoxic treatments, and the disease process and are needed to relieve cytopenias, the cause of morbidity and mortality. Also emphasized is that there can be no therapeutic benefit, regardless of mutation or cytogenetic subtype, if DNA methyltransferase is not depleted by sufficient overlap between intracellular drug half-lives and S-phase entries of malignant cells. Improved understanding of mechanism-of-action differences demands new approaches, from historic (but not scientific) more-is-better and one-size-fits-all empiricism to pharmacodynamic-based designs and combinations directed not solely at suppressing malignant clones, but at improving therapeutic indices.