Lenalidomide with or without erythropoietin in transfusion-dependent erythropoiesis-stimulating agent-refractory lower-risk MDS without 5q deletion

Treatment of Anemia in Lower-Risk Myelodysplastic Syndrome

OPINION STATEMENT

A majority of patients with lower-risk myelodysplastic syndrome (MDS) will present with or develop anemia. Anemia in MDS is associated with decreased quality of life and may correlate with decreased progression-free survival and overall survival. In this state of the art review we summarize current risk stratification approaches to identify lower-risk MDS (LR-MDS), the natural history of the disease, and meaningful clinical endpoints. The treatment landscape of LR-MDS with anemia is also rapidly evolving; we review the role of supportive care, erythropoietin stimulating agents, lenalidomide, luspatercept, hypomethylating agents (HMAs), and immunosuppressive therapy (IST) in the management of LR-MDS with anemia. In patients with deletion 5q (del5q) syndrome lenalidomide has both efficacy and durability of response. For patients without del5q who need treatment, the management approach is impacted by serum erythropoietin (EPO) level, SF3B1 mutation status, and ring sideroblast status. Given the data from the Phase III COMMANDS trial, we utilize luspatercept in those with SF3B1 mutation or ring sideroblasts that have an EPO level < 500 U/L; in patients without an SF3B1 mutation or ring sideroblasts there is equipoise between luspatercept and use of an erythropoietin stimulating agent (ESA). For patients who have an EPO level ≥ 500 U/L or have been previously treated there is not a clear standard of care. For those without previous luspatercept exposure it can be considered particularly if there is an SF3B1 mutation or the presence of ring sideroblasts. Other options include HMAs or IST; the Phase III IMERGE trial supports the efficacy of the telomerase inhibitor imetelstat in this setting and this may become a standard option in the future as well.

Role of reactive oxygen species in myelodysplastic syndromes

Reactive oxygen species (ROS) serve as typical metabolic byproducts of aerobic life and play a pivotal role in redox reactions and signal transduction pathways. Contingent upon their concentration, ROS production not only initiates or stimulates tumorigenesis but also causes oxidative stress (OS) and triggers cellular apoptosis. Mounting literature supports the view that ROS are closely interwoven with the pathogenesis of a cluster of diseases, particularly those involving cell proliferation and differentiation, such as myelodysplastic syndromes (MDS) and chronic/acute myeloid leukemia (CML/AML). OS caused by excessive ROS at physiological levels is likely to affect the functions of hematopoietic stem cells, such as cell growth and self-renewal, which may contribute to defective hematopoiesis. We review herein the eminent role of ROS in the hematological niche and their profound influence on the progress of MDS. We also highlight that targeting ROS is a practical and reliable tactic for MDS therapy.

Determinants of lenalidomide response with or without erythropoiesis-stimulating agents in myelodysplastic syndromes: the HOVON89 trial

A randomized phase-II study was performed in low/int-1 risk MDS (IPSS) to study efficacy and safety of lenalidomide without (arm A) or with (arm B) ESA/G-CSF. In arm B, patients without erythroid response (HI-E) after 4 cycles received ESA; G-CSF was added if no HI-E was obtained by cycle 9. HI-E served as primary endpoint. Flow cytometry and next-generation sequencing were performed to identify predictors of response. The final evaluation comprised 184 patients; 84% non-del(5q), 16% isolated del(5q); median follow-up: 70.7 months. In arm A and B, 39 and 41% of patients achieved HI-E; median time-to-HI-E: 3.2 months for both arms, median duration of-HI-E: 9.8 months. HI-E was significantly lower in non-del(5q) vs. del(5q): 32% vs. 80%. The same accounted for transfusion independency-at-week 24 (16% vs. 67%), but similar in both arms. Apart from presence of del(5q), high percentages of bone marrow lymphocytes and progenitor B-cells, a low number of mutations, absence of ring sideroblasts, and SF3B1 mutations predicted HI-E. In conclusion, lenalidomide induced HI-E in patients with non-del(5q) and del(5q) MDS without additional effect of ESA/G-CSF. The identified predictors of response may guide application of lenalidomide in lower-risk MDS in the era of precision medicine. (EudraCT 2008-002195-10).

[Treatment of lower risk myelodysplastic syndromes]

For low-risk myelodysplastic syndromes, the goal of treatment is to correct cytopenias or their consequences. Erythropoiesis-stimulating agents have an important role in the management of anemia. In this chapter, we will detail the response to ESAs, the factors predictive of response to ESAs. However, the search for new therapeutic options for low-risk, ESA-resistant MDS remains necessary as the incidence of AML transformation of the patients is higher. We can retain luspatercept for MDS with excess ring of sideroblasts, lenalidomide, and some molecules currently being tested such as imetelstat or roxedustat. However, the search for new therapeutic options for ESA-resistant low-risk MDS remains necessary. We can use androgenotherapy or TPO agonists in limited access for symptomatic thrombocytopenia.

Classification, risk stratification and response assessment in myelodysplastic syndromes/neoplasms (MDS): A state-of-the-art report on behalf of the International Consortium for MDS (icMDS)

The guidelines for classification, prognostication, and response assessment of myelodysplastic syndromes/neoplasms (MDS) have all recently been updated. In this report on behalf of the International Consortium for MDS (icMDS) we summarize these developments. We first critically examine the updated World Health Organization (WHO) classification and the International Consensus Classification (ICC) of MDS. We then compare traditional and molecularly based risk MDS risk assessment tools. Lastly, we discuss limitations of criteria in measuring therapeutic benefit and highlight how the International Working Group (IWG) 2018 and 2023 response criteria addressed these deficiencies and are endorsed by the icMDS. We also address the importance of patient centered care by discussing the value of quality-of-life assessment. We hope that the reader of this review will have a better understanding of how to classify MDS, predict clinical outcomes and evaluate therapeutic outcomes.

Phase 1 study of JNJ-64619178, a protein arginine methyltransferase 5 inhibitor, in patients with lower-risk myelodysplastic syndromes

Splicing factor (SF) gene mutations are frequent in myelodysplastic syndromes (MDS), and agents that modulate RNA splicing are hypothesized to provide clinical benefit. JNJ-64619178, a protein arginine methyltransferase 5 (PRMT5) inhibitor, was evaluated in patients with lower-risk (LR) MDS in a multi-part, Phase 1, multicenter study. The objectives were to determine a tolerable dose and to characterize safety, pharmacokinetics, pharmacodynamics, and preliminary clinical activity. JNJ-64619178 was administered on a 14 days on/7 days off schedule or every day on a 21-day cycle to patients with International Prognostic Scoring System (IPSS) Low or Intermediate-1 risk MDS who were red blood cell transfusion-dependent. Twenty-four patients were enrolled; 15 (62.5 %) patients had low IPSS risk score, while 18 (75.0 %) had an SF3B1 mutation. Median duration of treatment was 3.45 months (range: 0.03-6.93). No dose limiting toxicities were observed. The 0.5 mg once daily dose was considered better tolerated and chosen for dose expansion. Twenty-three (95.8 %) patients experienced treatment-emergent adverse events (TEAE). The most common TEAEs were neutropenia (15 [62.5 %]) and thrombocytopenia (14 [58.3 %]). JNJ-64619178 pharmacokinetics was dose-dependent. Target engagement as measured by plasma symmetric di-methylarginine was observed across all dose levels; however, variant allele frequency of clonal mutations in bone marrow or blood did not show sustained reductions from baseline. No patient achieved objective response or hematologic improvement per International Working Group 2006 criteria, or transfusion independence. A tolerable dose of JNJ-64619178 was identified in patients with LR MDS. However, no evidence of clinical benefit was observed.

Why do we not have more drugs approved for MDS? A critical viewpoint on novel drug development in MDS

Approval of new agents to treat higher risk (HR) myelodysplastic syndrome (MDS) has stalled since the approval of DNA methyltransferase inhibitors (DNMTi). In addition, the options for patients with lower risk (LR) MDS who have high transfusion needs and do not harbor ring sideroblasts or 5q- syndrome are limited. Here, we review the current treatment landscape in MDS and identify areas of unmet need, such as treatment after failure of erythropoiesis-stimulating agents or DNMTis, TP53-mutated disease, and MDS with potentially targetable mutations. We discuss how our understanding of MDS pathogenesis can inform therapy development, including treating HR-MDS similarly to AML and pursuing therapies to address splicing factor mutations and dysregulated inflammation. We then bring a critical lens to current methodology of MDS studies and propose solutions to improve the efficiency and yield of these clinical trials, including using the most meaningful response metrics and expanding enrollment.

Management of Patients with Lower-Risk Myelodysplastic Neoplasms (MDS)

Myelodysplastic neoplasms (MDS) are a heterogenous group of clonal hematologic disorders characterized by morphologic dysplasia, ineffective hematopoiesis, and cytopenia. In the past year, the classification of MDS has been updated in the 5th edition of the World Health Organization (WHO) Classification of Haematolymphoid Tumours and the International Consensus Classification (ICC) of Myeloid Neoplasms and Acute Leukemia with incorporation of morphologic, clinical, and genomic data. Furthermore, the more comprehensive International Prognostic Scoring System-Molecular (IPSS-M) allows for improved risk stratification and prognostication. These three developments allow for more tailored therapeutic decision-making in view of the expanding treatment options in MDS. For patients with lower risk MDS, treatment is aimed at improving cytopenias, usually anemia. The recent approval of luspatercept and decitabine/cedazuridine have added on to the current armamentarium of erythropoietic stimulating agents and lenalidomide (for MDS with isolated deletion 5q). Several newer agents are being evaluated in phase 3 clinical trials for this group of patients, such as imetelstat and oral azacitidine. This review provides a summary of the classification systems, the prognostic scores and clinical management of patients with lower risk MDS.

Evolution of Therapeutic Benefit Measurement Criteria in Myelodysplastic Syndromes/Neoplasms

ABSTRACT

Myelodysplastic syndromes/neoplasms (MDS) are heterogeneous, clonal myeloid neoplasms characterized by ineffective hematopoiesis, progressive cytopenias, and an increased risk of progression to acute myeloid leukemia. The diversity in disease severity, morphology, and genetic landscape challenges not only novel drug development but also therapeutic response assessment. The MDS International Working Group (IWG) response criteria were first published in the year 2000 focusing on measures of blast burden reduction and hematologic recovery. Despite revision of the IWG criteria in 2006, correlation between IWG-defined responses and patient-focused outcomes, including long-term benefits, remains limited and has potentially contributed to failures of several phase III clinical trials. Several IWG 2006 criteria also lacked clear definitions leading to problems in practical applications and interobserver and intraobserver consistency of response reporting. Although the 2018 revision addressed lower-risk MDS, the most recent update in 2023 redefined responses for higher-risk MDS and has set out to provide clear definitions to enhance consistency while focusing on clinically meaningful outcomes and patient-centered responses. In this review, we analyze the evolution of the MDS response criteria, limitations, and areas of improvement.

Current Therapeutic Landscape in Lower Risk Myelodysplastic Syndromes

OPINION STATEMENT

Lower risk myelodysplastic syndromes are typically characterized by an indolent disease course with a relatively low risk of transformation into acute myeloid leukemia. These patients are classically identified using the revised International Prognostic Scoring System and most likely its molecular version in the near future which may change the paradigm of treatment. The overall goals of care are symptomatic control to reduce transfusion requirements and improve quality of life. Symptomatic anemia is the most common indication to initiate disease-specific therapies after the optimization of supportive measures. Currently, erythropoiesis-stimulating agents remain the standard upfront therapy for anemia, and patients with del(5q) cytogenetic changes can benefit from lenalidomide monotherapy. Other therapeutic options after failure of upfront treatment include luspatercept, hypomethylating agents, and immunosuppressive therapies after taking into account of individualized disease features. Allogeneic hematopoietic stem cell transplant is the only potentially curative option and is usually reserved for medically fit patients with severe symptomatic cytopenias who failed all standard options and/or the disease is progressing toward higher risk categories. Fortunately, novel investigational therapies are rapidly emerging by targeting different biological processes contributing to MDS pathogenesis, and eligible patients should be managed in clinical trials if available.

The Genetic Landscape of Myelodysplastic Neoplasm Progression to Acute Myeloid Leukemia

Myelodysplastic neoplasm (MDS) represents a heterogeneous group of myeloid disorders that originate from the hematopoietic stem and progenitor cells that lead to the development of clonal hematopoiesis. MDS was characterized by an increased risk of transformation into acute myeloid leukemia (AML). In recent years, with the aid of next-generation sequencing (NGS), an increasing number of molecular aberrations were discovered, such as recurrent mutations in FLT3, NPM1, DNMT3A, TP53, NRAS, and RUNX1 genes. During MDS progression to leukemia, the order of gene mutation acquisition is not random and is important when considering the prognostic impact. Moreover, the co-occurrence of certain gene mutations is not random; some of the combinations of gene mutations seem to have a high frequency (ASXL1 and U2AF1), while the co-occurrence of mutations in splicing factor genes is rarely observed. Recent progress in the understanding of molecular events has led to MDS transformation into AML and unraveling the genetic signature has paved the way for developing novel targeted and personalized treatments. This article reviews the genetic abnormalities that increase the risk of MDS transformation to AML, and the impact of genetic changes on evolution. Selected therapies for MDS and MDS progression to AML are also discussed.

Vitamin B5 and succinyl-CoA improve ineffective erythropoiesis in SF3B1-mutated myelodysplasia

Patients with myelodysplastic syndrome and ring sideroblasts (MDS-RS) present with symptomatic anemia due to ineffective erythropoiesis that impedes their quality of life and increases morbidity. More than 80% of patients with MDS-RS harbor splicing factor 3B subunit 1 (SF3B1) mutations, the founder aberration driving MDS-RS disease. Here, we report how mis-splicing of coenzyme A synthase (COASY), induced by mutations in SF3B1, affects heme biosynthesis and erythropoiesis. Our data revealed that COASY was up-regulated during normal erythroid differentiation, and its silencing prevented the formation of erythroid colonies, impeded erythroid differentiation, and precluded heme accumulation. In patients with MDS-RS, loss of protein due to COASY mis-splicing led to depletion of both CoA and succinyl-CoA. Supplementation with COASY substrate (vitamin B5) rescued CoA and succinyl-CoA concentrations in SF3B1mut cells and mended erythropoiesis differentiation defects in MDS-RS primary patient cells. Our findings reveal a key role of the COASY pathway in erythroid maturation and identify upstream and downstream metabolites of COASY as a potential treatment for anemia in patients with MDS-RS.

Management of patients with lower-risk myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a heterogeneous group of hematopoietic stem cell disorders characterized by ineffective hematopoiesis with abnormal blood cell development (dysplasia) leading to cytopenias and an increased risk for progression to acute myeloid leukemia (AML). Patients with MDS can generally be classified as lower- (LR-MDS) or higher-risk (HR-MDS). As treatment goals for patients with LR-MDS and those with HR-MDS differ significantly, appropriate diagnosis, classification, and follow-up are critical for correct disease management. In this review, we focus on the diagnosis, prognosis, and treatment options, as well as the prediction of the disease course and monitoring of treatment response in patients with LR-MDS. We discuss how next-generation sequencing, increasing knowledge on mechanisms of MDS pathogenesis, and novel therapies may change the current treatment landscape in LR-MDS and why structured assessments of responses, toxicities, and patient-reported outcomes should be incorporated into routine clinical practice.

Lower-risk myelodysplastic syndromes: Current treatment options for anemia

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematological disorders. Treatment options are classified and defined by prognostic risk based on the International Prognostic Scoring System (IPSS) and, more recently, the revised IPSS (IPSS-R). The treatment goal for lower-risk MDS is to correct cytopenias or their consequences, with the goal of maintaining or improving quality of life. Erythropoiesis-stimulating agents (ESAs) play an important role in treating anemia. Individuals with MDS who have a 5q deletion are particularly sensitive to treatment with lenalidomide; however, this comprises the minority of patients with MDS. Luspatercept was recently approved in the United States and the European Union for the treatment of ESA-refractory MDS with ring sideroblasts. Research into new treatment options, especially after ESA failure, is needed. In this review, we will focus on the current therapeutic options for MDS-related anemia.

Past, present and future in low-risk myelodysplastic syndrome

Myelodysplastic syndromes (MDS) is a heterogeneous group of disorders characterized by increased risk of acute myeloid leukemia transformation and cytopenia. The prognosis of MDS patients can be evaluated with various scoring systems, the most commonly used are IPSS (International Prognostic Scoring System), revised-IPSS, and WPSS (WHO classification-based prognostic scoring system). MDS treatment is decided according to the risk classification. The goal of treatment in low-risk MDS is to improve cytopenia, reduce transfusion needs, improve quality of life, prolong overall survival, and maybe reduce the risk of progression to leukemia. In the near future, combining both genomics-based, ex vivo functional based and molecular stratification analysis will lead the way to a personalized and targeted approach.

Isolated duodenal ischemia of unknown etiology: a case report

Background

Acute abdomen is among the most common presentations observed in clinical practice. The present study describes a patient with isolated duodenal ischemia as an extremely rare etiology of acute abdomen.

Case presentation

A 79-year-old male with acute abdominal pain, nausea, and vomiting presented to the emergency department of our hospital. He was diagnosed with myelodysplastic syndrome 7 years ago, for which he took thalidomide and erythropoietin as the main medications. The prominent findings of the physical examination were hypotension, tachycardia, fever, mild hypoxemia, and epigastric and right upper quadrant tenderness of the abdomen. Except for mildly increased creatinine and lipase, other laboratory findings were in concordance with myelodysplastic syndrome. Due to the patient’s oliguria, the computed tomography (CT) scan was performed without contrast, which, together with the ultrasonography, raised the clinical impression of acute pancreatitis. The patient’s hypotension was refractive to supportive treatment, resulting in progressive deterioration of the clinical condition. A later contrast-enhanced CT scan suggested microvascular ischemia of the duodenum. An emergent Whipple’s procedure was planned initially, which was later switched to a damage control surgery due to the patient’s cardiac arrest during the surgery. Despite all the supportive therapy provided at the intensive care unit, the patient expired of a cardiac arrest which occurred two hours after the termination of the surgery.

Conclusions

The high rate of mortality in duodenal necrosis necessitates emergent diagnosis and proper management. When other common etiologies are ruled out, clinicians should consider duodenal pathology as a potential cause of acute abdomen.

Myelodysplastic Syndromes in the Postgenomic Era and Future Perspectives for Precision Medicine

Simple Summary

With demographic ageing, improved cancer survivorship and increased diagnostic sensitivity, incident cases of patients with Myelodysplastic Syndromes (MDS) are continuously rising, leading to a relevant impact on health care resources. Disease heterogeneity and various comorbidities are challenges for the management of the generally elderly patients. Therefore, experienced physicians and multidisciplinary teams should be involved in the establishment of the correct diagnosis, risk-assessment and personalized treatment plan. Next-generation sequencing allows for early detection of clonal hematopoiesis and monitoring of clonal evolution, but also poses new challenges for its appropriate use. At present, allogeneic hematopoietic stem cell transplantation remains the only curative treatment option for a minority of fit MDS patients. All others receive palliative treatment and will eventually progress, having an unmet need for novel therapies. Targeting compounds are in prospect for precision medicine, however, abrogation of clonal evolution to acute myeloid leukemia remains actually out of reach.

Abstract

Myelodysplastic syndromes (MDS) represent a heterogeneous group of clonal disorders caused by sequential accumulation of somatic driver mutations in hematopoietic stem and progenitor cells (HSPCs). MDS is characterized by ineffective hematopoiesis with cytopenia, dysplasia, inflammation, and a variable risk of transformation into secondary acute myeloid leukemia. The advent of next-generation sequencing has revolutionized our understanding of the genetic basis of the disease. Nevertheless, the biology of clonal evolution remains poorly understood, and the stochastic genetic drift with sequential accumulation of genetic hits in HSPCs is individual, highly dynamic and hardly predictable. These continuously moving genetic targets pose substantial challenges for the implementation of precision medicine, which aims to maximize efficacy with minimal toxicity of treatments. In the current postgenomic era, allogeneic hematopoietic stem cell transplantation remains the only curative option for younger and fit MDS patients. For all unfit patients, regeneration of HSPCs stays out of reach and all available therapies remain palliative, which will eventually lead to refractoriness and progression. In this review, we summarize the recent advances in our understanding of MDS pathophysiology and its impact on diagnosis, risk-assessment and disease monitoring. Moreover, we present ongoing clinical trials with targeting compounds and highlight future perspectives for precision medicine.

Development of luspatercept to treat ineffective erythropoiesis

Luspatercept (Reblozyl) was recently approved for treating patients with transfusion-dependent lower-risk myelodysplastic syndrome (MDS) with ring sideroblasts (RS) and/or SF3B1 mutation who were not eligible for erythropoiesis-stimulating agents (ESAs) or patients for whom those agents failed. Luspatercept acts as an activin receptor type IIB fusion protein ligand trap that targets the altered transforming growth factor beta pathway in MDS, which is associated with impaired terminal erythroid maturation. Treatment with luspatercept results in decreased SMAD signaling, which enables erythroid maturation by means of late-stage erythroblast differentiation and thus improves anemia. ESAs, the current standard first-line therapeutic option for anemic lower-risk patients with MDS, also improve red cell parameters mainly by expanding proliferation of early erythroid progenitor cells. However, erythropoietin (EPO) and its receptor (EPO-R) are also required for survival of late-stage definitive erythroid cells, and they play an essential role in promoting proliferation, survival, and appropriate timing of terminal maturation of primitive erythroid precursors. Thus, luspatercept joins the mechanism of ESAs in promoting erythroid maturation. Especially in the subgroup of MDS patients with RS, luspatercept showed high clinical activity for the treatment of anemia in the phase 2 (PACE-MDS) trial and subsequently in the phase 3 (MEDALIST) trial, which resulted in approval by both the US Food and Drug Administration and the European Medicines Agency in April 2020. Additional studies are needed to better understand the mechanism of action and pharmacodynamics of this novel agent in MDS.

Current Therapy of the Patients with MDS: Walking towards Personalized Therapy

Myelodysplastic syndromes (MDS) are characterized by ineffective hematopoiesis, dysplasia and peripheral cytopenias. Nowadays, MDS therapy is selected based on risk. The goals of therapy are different in low-risk and high-risk patients. In low-risk MDS, the goal is to decrease transfusion needs and to increase the quality of life. Currently, available drugs for newly diagnosed low-risk MDS include growth factor support, lenalidomide and immunosuppressive therapy. Additionally, luspatercept has recently been added to treat patients with MDS with ring sideroblasts, who are not candidates or have lost the response to erythropoiesis-stimulating agents. Treatment of high-risk patients is aimed to improve survival. To date, the only currently approved treatments are hypomethylating agents and allogeneic stem cell transplantation. However, the future for MDS patients is promising. In recent years, we are witnessing the emergence of multiple treatment combinations based on hypomethylating agents (pevonedistat, magrolimab, eprenetapopt, venetoclax) that have proven to be effective in MDS, even those with high-risk factors. Furthermore, the approval in the US of an oral hypomethylating agent opens the door to exclusively oral combinations for these patients and their consequent impact on the quality of life of these patients. Relapsed and refractory patients remain an unmet clinical need. We need more drugs and clinical trials for this profile of patients who have a dismal prognosis.

Clinical effectiveness of DNA methyltransferase inhibitors and lenalidomide in older patients with refractory anemia with ring sideroblasts: a population-based study in the United States

Existing studies regarding the role of DNA methyltransferase inhibitors (DNMTi) and lenalidomide in refractory anemia with ring sideroblasts (RARS) are limited. Using the surveillance, epidemiology, and end results-medicare database, we assembled a population-based cohort of older adults diagnosed with non-del(5q) lower-risk myelodysplastic syndromes during 2007-2015. Of 2167 patients, 30% had RARS. About 16% of RARS and non- ring sideroblasts (RS) patients received DNMTi. RARS patients were more likely to receive lenalidomide (11.1% vs. 7.1%, p < 0.01). Among patients who were transfusion-dependent at treatment initiation, 55.6% of those treated with DNMTi only and 42.5% treated with lenalidomide only achieved red blood cell transfusion independence (RBC-TI) for a median duration of 21 and 12 weeks, respectively. RS status did not impact rate of RBC-TI. RARS patients had a significantly better survival, and the median survival of RARS patients varied by treatment group. In this population-based study of older RARS patients, DNMTi and lenalidomide were clinically active.

Precision medicine in myeloid malignancies

Myeloid malignancies have always been at the forefront of an improved understanding of the molecular pathogenesis of cancer. In accordance, over the last years, basic research focusing on the aberrations underlying malignant transformation of myeloid cells has provided the basis for precision medicine approaches and subsequently has led to the development of powerful therapeutic strategies. In this review article, we will recapitulate what has happened since in the 1980s the use of all-trans retinoic acid (ATRA), as a first targeted cancer therapy, has changed one of the deadliest leukemia subtypes, acute promyelocytic leukemia (APL), into one that can be cured without classical chemotherapy today. Similarly, imatinib, the first molecularly designed cancer therapy, has revolutionized the management of chronic myeloid leukemia (CML). Thus, targeted treatment approaches have become the paradigm for myeloid malignancy, but many questions still remain unanswered, especially how identical mutations can be associated with different phenotypes. This might be linked to the impact of the cell of origin, gene-gene interactions, or the tumor microenvironment including the immune system. Continuous research in the field of myeloid neoplasia has started to unravel the molecular pathways that are not only crucial for initial treatment response, but also resistance of leukemia cells under therapy. Ongoing studies focusing on leukemia cell vulnerabilities do already point to novel (targetable) "Achilles heels" that can further improve myeloid cancer therapy.

Risk-Adapted, Individualized Treatment Strategies of Myelodysplastic Syndromes (MDS) and Chronic Myelomonocytic Leukemia (CMML)

Myelodysplastic syndrome (MDS) and chronic myelomonocytic leukemia (CMML) are two distinct blood cancers with a variable clinical symptom burden and risk of progression to acute myeloid leukemia. Management decisions should be guided by individual patient and disease characteristics and based on validated risk stratification tools. While supportive care with red blood cell transfusions, erythropoiesis-stimulating agents, and iron chelation remains the mainstay of therapy for lower-risk (LR)-MDS patients, luspatercept has recently been approved for transfusion-dependent anemic LR-MDS patients ending a decade without any new drug approvals for MDS. For higher-risk patients, allogeneic hematopoietic cell transplant (allo-HCT) remains the only curative therapy for both MDS and CMML but most patients are not eligible for allo-HCT. For those patients, the hypomethylating agents (HMA) azacitidine and decitabine remain standard of care with azacitidine being the only agent that has shown an overall survival benefit in randomized trials. Although early results from novel molecularly driven agents such as IDH1/2 inhibitors, venetoclax, magrolimab, and APR-246 for MDS as well as tagraxofusp, tipifarnib, and lenzilumab for CMML appear encouraging, confirmatory randomized trials must be completed to fully assess their safety and efficacy prior to routine clinical use. Herein, we review the current management of MDS and CMML and conclude with a critical appraisal of novel therapies and general trends in this field.

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.

Myelodysplastic syndromes with ring sideroblasts (MDS-RS) and MDS/myeloproliferative neoplasm with RS and thrombocytosis (MDS/MPN-RS-T) - "2021 update on diagnosis, risk-stratification, and management"

DISEASE OVERVIEW

Ring sideroblasts (RS) are erythroid precursors with abnormal perinuclear mitochondrial iron accumulation. Two myeloid neoplasms defined by the presence of RS, include myelodysplastic syndromes with RS (MDS-RS) and MDS/myeloproliferative neoplasm with RS and thrombocytosis (MDS/MPN-RS-T).

DIAGNOSIS

MDS-RS is a lower risk MDS, with single or multilineage dysplasia (MDS-RS-SLD/MLD), <5% bone marrow (BM) blasts, <1% peripheral blood blasts and ≥15% BM RS (≥5% in the presence of SF3B1 mutations). MDS/MPN-RS-T, now a formal entity in the MDS/MPN overlap syndromes, has diagnostic features of MDS-RS-SLD, along with a platelet count ≥450 × 10⁹ /L and large atypical megakaryocytes.

MUTATIONS AND KARYOTYPE

Mutations in SF3B1 are seen in ≥80% of patients with MDS-RS-SLD and MDS/MPN-RS-T, and strongly correlate with the presence of BM RS; MDS/MPN-RS-T patients also demonstrate JAK2V617F (50%), DNMT3A, TET2 and ASXL1 mutations. Cytogenetic abnormalities are uncommon in both.

RISK STRATIFICATION

Most patients with MDS-RS-SLD are stratified into lower risk groups by the revised-IPSS. Disease outcome in MDS/MPN-RS-T is better than that of MDS-RS-SLD, but worse than that of essential thrombocythemia (MPN). Both diseases are associated with a low risk of leukemic transformation.

TREATMENT

Anemia and iron overload are complications seen in both and are managed similar to lower risk MDS and MPN. Luspatercept, a first-in-class erythroid maturation agent is now approved for the management of anemia in patients with MDS-RS and MDS/MPN-RS-T. Aspirin therapy is reasonable in MDS/MPN-RS-T, especially in the presence of JAK2V617F, but the value of platelet-lowering drugs remains to be defined.

Luspatercept in the treatment of lower-risk myelodysplastic syndromes

Transforming growth factor beta (TGF-β) signaling pathway is key to hematopoiesis regulation. Increased activation of this pathway contributes to ineffective terminal erythroid differentiation in myelodysplastic syndromes (MDS). Luspatercept is a novel fusion protein that traps TGF-β ligands preventing them from binding to Type II TGF-β receptors, thereby decreasing phosphorylated SMAD2/3 resulting in the downstream effect of promoting erythropoiesis. Seminal clinical trials using luspatercept, PACE-MD and MEDALIST, demonstrated impressive efficacy in the treatment of transfusion-dependent anemia in intermediate risk or lower MDS had led to the US FDA approval for this indication. This review summarizes luspatercept mechanisms of action, efficacy/safety data supporting its use and ongoing clinical trials in MDS.

Clinical Management of Anemia in Patients with Myelodysplastic Syndromes: An Update on Emerging Therapeutic Options

For the majority of patients with lower-risk myelodysplastic syndrome (LR-MDS), one of the primary clinical goals is to alleviate the symptoms associated with the resultant cytopenias and to minimize the transfusion burden. While supportive red blood cell (RBC) transfusions and erythropoiesis-stimulating agents (ESAs) may lead to clinical improvement, frequent transfusions are often complicated by iron overload and decreased quality of life; furthermore, most patients either do not respond to ESAs or will eventually develop resistance. As such, there is a great need for further therapeutic options in the management of anemia related to MDS. Several additional therapeutics are now available in select patients with LR-MDS and symptomatic anemia including luspatercept, lenalidomide, and immunosuppressive therapy. Furthermore, several novel agents are currently in development to address this area of clinical need such as imetelstat and roxadustat. In this article, we review the currently available therapeutic options for symptomatic anemia in LR-MDS as well as review the therapeutic agents in development.

Lenalidomide-Epoetin Alfa Versus Lenalidomide Monotherapy in Myelodysplastic Syndromes Refractory to Recombinant Erythropoietin

PURPOSE

Impaired response to erythropoietin underlies ineffective erythropoiesis and anemia in myelodysplastic syndromes (MDS). We investigated whether treatment with lenalidomide (LEN), which augments erythropoietin receptor signaling in vitro, can restore and improve hemoglobin response to epoetin (EPO) alfa in patients with lower-risk, non-del(5q) MDS who have anemia that is refractory to or have low probability of benefit from treatment with recombinant erythropoietin.

METHODS

In a phase III, US intergroup trial, we randomly assigned patients to receive either LEN and EPO alfa or LEN alone following stratification by serum erythropoietin concentration and prior erythropoietin treatment.

RESULTS

A total of 195 evaluable patients were randomly assigned: 99 patients to the LEN-EPO alfa cohort and 96 to LEN alone. After four cycles of treatment, the primary end point of major erythroid response (MER) was significantly higher (28.3%) with the combination compared with LEN alone (11.5%) (P = .004). Among 136 patients who completed 16 weeks of study treatment, 38.9% and 15.6% achieved MER, respectively (P = .004). Additionally, minor erythroid response was achieved in 18.2% and 20.8% of patients, for an overall erythroid response rate of 46.5% versus 32.3%. Among LEN nonresponders, 38 crossed over to the addition of EPO alfa with 10 patients (26.3%) achieving a MER. Responses to the combined treatment were highly durable with a median MER duration of 23.8 months compared with 13 months with LEN alone.

CONCLUSION

LEN restores sensitivity to recombinant erythropoietin in growth factor-insensitive, lower-risk, non-del(5q) MDS, to yield a significantly higher rate and duration of MER compared with LEN alone (funded by the National Cancer Institute; E2905 ClinicalTrials.gov identifier: NCT02048813).

Current and emerging strategies for management of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are characterized by ineffective hematopoiesis with varying degrees of dysplasia and peripheral cytopenias. MDS are driven by structural chromosomal alterations and somatic mutations in neoplastic myeloid cells, which are supported by a tumorigenic and a proinflammatory marrow microenvironment. Current treatment strategies for lower-risk MDS focus on improving quality of life and cytopenias, while prolonging survival and delaying disease progression is the focus for higher-risk MDS. Several promising drugs are in the horizon, including the hypoxia-inducible factor stabilizer roxadustat, telomerase inhibitor imetelstat, oral hypomethylating agents (CC-486), TP53 modulators (APR-246 and ALRN-6924), and the anti-CD47 antibody magrolimab. Targeted therapies approved for acute myeloid leukemia treatment, such as isocitrate dehdyrogenase inhibitors and venetoclax, are also being studied for use in MDS. In this review, we provide a brief overview of pathogenesis and current treatment strategies in MDS followed by a discussion of newer agents that are under clinical investigation.

Therapy for lower-risk MDS

Lower-risk myelodysplastic syndromes (MDS) are characterized by the presence of dysplasia, low bone marrow blast percentage, low number and depth of cytopenia(s), and relatively good-risk karyotpic and molecular abnormalities. A score of ≤3.5 on the Revised International Prognostic Scoring System classifies patients as lower-risk MDS. Information from a mutational profile of the MDS at time of diagnosis (and over serial time points) can be reassuring for predicted behavior of lower-risk MDS compared with one expected to progress more rapidly (higher-risk MDS). Supportive care continues to be the crux of treatment, although the options to reduce transfusion needs have improved in 2020. Erythropoiesis stimulating agents, lenalidomide, and luspatercept address the most frequent (and symptomatic) cytopenia (anemia) and are started only when patients are transfusion dependent. Patients can derive long-term benefits (years) from these approaches but will often progress to higher-risk MDS. Interestingly, some patients with lower-risk MDS can present with an isolated thrombocytopenia for which thrombopoietin receptor analogs such as romiplostim and eltrombopag are options (as long as blast counts are low). The presence of pancytopenia and or intensifying and unremitting clinical symptoms are often treated with hypomethylating agents or (anti-thymocyte globulin if hypocellular MDS is of concern). Targeted therapies are emerging for small subsets of MDS patients with specific somatic mutations (ie, TP53, IDH1/2, FLT3), although currently, there are no approved, mutation-directed medications to treat MDS.

Patient stratification in myelodysplastic syndromes: how a puzzle may become a map

Heterogeneity is the disease-defining epithet of myelodysplastic syndromes (MDS), a clonal disorder of hematopoietic stem and progenitor cells. During the last decade, significant progress has been made to better understand the diversity of clinical, molecular, cellular, and immunological factors that are bound to the prognosis and outcomes of patients with MDS. Despite the rapid generation of all of this biological information, how to implement it has fallen short. Redefining clinical tools to use this new information remains a challenge. The holistic integration of novel, high-impact individual risk parameters such as patient-reported outcomes or mutational and immunological data into conventional risk stratification systems may further refine patient subgroups, improve predictive power for survival, and provide a next-generation classification and prognosis system for patients with MDS. Dichotomic treatment strategies in patients with MDS according to their patient and disease profiles highlight the importance of precise risk stratification, which may be complemented by the definition of granular cohorts of patients with myeloid neoplasms and a druggable target (ie, IDH1/2 mutations) across conventional blast thresholds.

No clear survival benefit of azacitidine for lower-risk myelodysplastic syndromes: A retrospective study of Nagasaki

The efficacy of azacitidine (AZA) on survival of lower risk (LR) - myelodysplastic syndromes (MDS) is controversial. To address this issue, we retrospectively evaluated the long-term survival benefit of AZA for patients with LR-MDS defined by International Prognostic Scoring System (IPSS). Using data from 489 patients with LR-MDS in Nagasaki, hematologic responses according to International Working Group 2006 and overall survival (OS) were compared among patients that received best supportive care (BSC), immunosuppressive therapy (IST), erythropoiesis-stimulating agents (ESA), and AZA. Patients treated with AZA showed complete remission (CR) rate at 11.3%, marrow CR at 1.9%, and any hematologic improvement at 34.0%, with transfusion independence (TI) of red blood cells in 27.3% of patients. and platelet in 20% of patients, respectively. Median OS for patients received IST, ESA, BSC, and AZA (not reached, 91 months, 58 months, and 29 months, respectively) differed significantly (P < .001). Infection-related severe adverse events were observed in more than 20% of patients treated with AZA. Multivariate analysis showed age, sex, IPSS score at diagnosis, and transfusion dependence were significant for OS, but AZA treatment was not, which maintained even response to AZA, and IPSS risk status at AZA administration was added as factors. We could not find significant survival benefit of AZA treatment for LR-MDS patients.

Myelodysplastic syndromes: 2021 update on diagnosis, risk stratification and management

DISEASE OVERVIEW

The myelodysplastic syndromes (MDS) are a very heterogeneous group of myeloid disorders characterized by peripheral blood cytopenias and increased risk of transformation to acute myelogenous leukemia (AML). Myelodysplastic syndromes occur more frequently in older males and in individuals with prior exposure to cytotoxic therapy.

DIAGNOSIS

Diagnosis of MDS is based on morphological evidence of dysplasia upon visual examination of a bone marrow aspirate and biopsy. Information obtained from additional studies such as karyotype, flow cytometry and molecular genetics is usually complementary and may help refine diagnosis.

RISK-STRATIFICATION

Prognosis of patients with MDS can be calculated using a number of scoring systems. In general, all these scoring systems include analysis of peripheral cytopenias, percentage of blasts in the bone marrow and cytogenetic characteristics. The most commonly accepted system is the Revised International Prognostic Scoring System (IPSS-R). Somatic mutations can help define prognosis and therapy.

RISK-ADAPTED THERAPY

Therapy is selected based on risk, transfusion needs, percent of bone marrow blasts, cytogenetic and mutational profiles, comorbidities, potential for allogeneic stem cell transplantation (alloSCT) and prior exposure to hypomethylating agents (HMA). Goals of therapy are different in lower-risk patients than in higher-risk individuals and in those with HMA failure. In lower-risk MDS, the goal is to decrease transfusion needs and transformation to higher risk disease or AML, as well as to improve survival. In higher-risk disease, the goal is to prolong survival. In 2020, we witnessed an explosion of new agents and investigational approaches. Current available therapies include growth factor support, lenalidomide, HMAs, intensive chemotherapy and alloSCT. Novel therapeutics approved in 2020 are luspatercept and the oral HMA ASTX727. At the present time, there are no approved interventions for patients with progressive or refractory disease particularly after HMA-based therapy. Options include participation in a clinical trial, cytarabine-based therapy or alloSCT.

Myelo-deception: Luspatercept & TGF-Beta ligand traps in myeloid diseases & anemia

Myelodysplastic syndromes (MDS) encompass a clinically heterogenous group of diseases defined by a clonal bone marrow failure state. Patients with lower-risk MDS primarily suffer from the consequences of anemia, with a subset having increased risks of bleeding and infection. There are few good therapeutic options for this patient population, as patients are dependent on cytokine support to improve hematopoiesis. Our review will discuss luspatercept, a transforming growth factor (TGF)-Beta ligand trap, the first new Food & Drug Administration (FDA)-approved treatment in MDS in over a decade. We will explore the different TGF-Beta ligand traps that have been developed for a number of diseases, with a focus on myeloid malignancies.

A variant erythroferrone disrupts iron homeostasis in SF3B1-mutated myelodysplastic syndrome

Myelodysplastic syndromes (MDS) with ring sideroblasts are hematopoietic stem cell disorders with erythroid dysplasia and mutations in the SF3B1 splicing factor gene. Patients with MDS with SF3B1 mutations often accumulate excessive tissue iron, even in the absence of transfusions, but the mechanisms that are responsible for their parenchymal iron overload are unknown. Body iron content, tissue distribution, and the supply of iron for erythropoiesis are controlled by the hormone hepcidin, which is regulated by erythroblasts through secretion of the erythroid hormone erythroferrone (ERFE). Here, we identified an alternative ERFE transcript in patients with MDS with the SF3B1 mutation. Induction of this ERFE transcript in primary SF3B1-mutated bone marrow erythroblasts generated a variant protein that maintained the capacity to suppress hepcidin transcription. Plasma concentrations of ERFE were higher in patients with MDS with an SF3B1 gene mutation than in patients with SF3B1 wild-type MDS. Thus, hepcidin suppression by a variant ERFE is likely responsible for the increased iron loading in patients with SF3B1-mutated MDS, suggesting that ERFE could be targeted to prevent iron-mediated toxicity. The expression of the variant ERFE transcript that was restricted to SF3B1-mutated erythroblasts decreased in lenalidomide-responsive anemic patients, identifying variant ERFE as a specific biomarker of clonal erythropoiesis.

Myelodysplastic syndromes: moving towards personalized management

The myelodysplastic syndromes (MDS) share their origin in the hematopoietic stem cell but have otherwise very heterogeneous biological and genetic characteristics. Clinical features are dominated by cytopenia and a substantial risk for progression to acute myeloid leukemia. According to the World Health Organization, MDS is defined by cytopenia, bone marrow dysplasia and certain karyotypic abnormalities. The understanding of disease pathogenesis has undergone major development with the implementation of next-generation sequencing and a closer integration of morphology, cytogenetics and molecular genetics is currently paving the way for improved classification and prognostication. True precision medicine is still in the future for MDS and the development of novel therapeutic compounds with a propensity to markedly change patients' outcome lags behind that for many other blood cancers. Treatment of higher-risk MDS is dominated by monotherapy with hypomethylating agents but novel combinations are currently being evaluated in clinical trials. Agents that stimulate erythropoiesis continue to be first-line treatment for the anemia of lower-risk MDS but luspatercept has shown promise as second-line therapy for sideroblastic MDS and lenalidomide is an established second-line treatment for del(5q) lower-risk MDS. The only potentially curative option for MDS is hematopoietic stem cell transplantation, until recently associated with a relatively high risk of transplant-related mortality and relapse. However, recent studies show increased cure rates due to better tools to target the malignant clone with less toxicity. This review provides a comprehensive overview of the current status of the clinical evaluation, biology and therapeutic interventions for this spectrum of disorders.

Myelodysplastic syndromes: a review of therapeutic progress over the past 10 years

INTRODUCTION

Myelodysplastic syndromes (MDS) represent a range of bone marrow disorders, with patients affected by cytopenias and risk of progression to AML. There are limited therapeutic options available for patients, including hypomethylating agents (azacitidine/decitabine), growth factor support, lenalidomide, and allogeneic stem cell transplant.

AREAS COVERED

This review provides an overview of the progress made over the past decade for emerging therapies for lower- and higher-risk MDS (MDS-HR). We also cover advances in prognostication, supportive care, and use of allogeneic SCT in MDS.

EXPERT OPINION

While there have been no FDA-approved therapies for MDS in the past decade, we anticipate the approval of luspatercept based on results from the MEDALIST trial for patients with lower-risk MDS (MDS-LR) and ringed sideroblasts who have failed or are ineligible for erythropoiesis stimulating agents (ESAs). With growing knowledge of the biologic and molecular mechanisms underlying MDS, it is anticipated that new therapies will be approved in the coming years.

Management of cancer-associated anemia with erythropoiesis-stimulating agents: ASCO/ASH clinical practice guideline update

PURPOSE

To update the American Society of Clinical Oncology (ASCO)/American Society of Hematology (ASH) recommendations for use of erythropoiesis-stimulating agents (ESAs) in patients with cancer.

METHODS

PubMed and the Cochrane Library were searched for randomized controlled trials (RCTs) and meta-analyses of RCTs in patients with cancer published from January 31, 2010, through May 14, 2018. For biosimilar ESAs, the literature search was expanded to include meta-analyses and RCTs in patients with cancer or chronic kidney disease and cohort studies in patients with cancer due to limited RCT evidence in the cancer setting. ASCO and ASH convened an Expert Panel to review the evidence and revise previous recommendations as needed.

RESULTS

The primary literature review included 15 meta-analyses of RCTs and two RCTs. A growing body of evidence suggests that adding iron to treatment with an ESA may improve hematopoietic response and reduce the likelihood of RBC transfusion. The biosimilar literature review suggested that biosimilars of epoetin alfa have similar efficacy and safety to reference products, although evidence in cancer remains limited.

RECOMMENDATIONS

ESAs (including biosimilars) may be offered to patients with chemotherapy-associated anemia whose cancer treatment is not curative in intent and whose hemoglobin has declined to < 10 g/dL. RBC transfusion is also an option. With the exception of selected patients with myelodysplastic syndromes, ESAs should not be offered to most patients with nonchemotherapy-associated anemia. During ESA treatment, hemoglobin may be increased to the lowest concentration needed to avoid transfusions. Iron replacement may be used to improve hemoglobin response and reduce RBC transfusions for patients receiving ESA with or without iron deficiency. Additional information is available at www.asco.org/supportive-care-guidelines and www.hematology.org/guidelines.

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.

Targeting Aberrant Splicing in Myelodysplastic Syndromes: Biologic Rationale and Clinical Opportunity

Myelodysplastic syndromes are enriched for somatic mutations in the pre-mRNA splicing apparatus, with recurrent acquired mutations most commonly occurring in SF3B1, SRSF2, U2AF1, and ZRSR2. These mutations appear to be early events in the pathogenesis of disease, and, given their frequency and central role in leukemogenesis, are of interest as potential therapeutic targets. Clinical trials are exploring targets that directly affect the spliceosome (splicing modulators or protein arginine methyltransferase 5 inhibitors) or that exploit possible vulnerabilities created by alternative splicing (inhibiting ATR). Future research is needed to explore novel targets and therapeutic combinations and understand how these mutations lead to clonal dominance.

Evolving therapies for lower-risk myelodysplastic syndromes

The development in the therapeutic landscape of myelodysplastic syndromes (MDS) has substantially lagged behind other hematologic malignancies with no new drug approvals for MDS for 13 years since the approval of decitabine in the United States in 2006. While therapeutic concepts for MDS patients continue to be primarily defined by clinical-pathologic risk stratification tools such as the International Prognostic Scoring System (IPSS) and its revised version IPSS-R, our understanding of the genetic landscape and the molecular pathogenesis of MDS has greatly evolved over the last decade. It is expected that the therapeutic approach to MDS patients will become increasingly individualized based on prognostic and predictive genetic features and other biomarkers. Herein, we review the current treatment of lower-risk MDS patients and discuss promising agents in advanced clinical testing for the treatment of symptomatic anemia in lower-risk MDS patients such as luspatercept and imetelstat. Lastly, we review the clinical development of new agents and the implications of the wider availability of mutational analysis for the management of individual MDS patients.

Achievement of red blood cell transfusion independence in red blood cell transfusion-dependent patients with lower-risk non-del(5q) myelodysplastic syndromes correlates with serum erythropoietin levels

In the randomized, phase 3, MDS-005 study (NCT01029262), lenalidomide-induced red blood cell transfusion independence (RBC-TI) in 27% of transfusion-dependent patients with lower-risk non-del(5q) myelodysplastic syndromes (MDS) ineligible for or refractory to erythropoiesis-stimulating agents. To determine the influence of erythropoietin (EPO) level on response, 155 patients treated with lenalidomide in MDS-005 were categorized into four groups by baseline EPO level. The EPO >500 mU/mL group had higher RBC transfusion burden and the lowest proportion of patients with ring sideroblasts ≥15% versus lower EPO groups. Achievement of RBC-TI ≥8 weeks inversely correlated with EPO level, ranging from 42.5 to 15.5%. EPO level did not affect erythroid hematologic improvement response (36.2-44.4%). This analysis suggests patients with lower EPO levels experience the strongest benefit from lenalidomide. Although meaningful improvements were observed in some patients with EPO level >500 mU/mL, new treatments are needed for this population.

Phospho-PTM proteomic discovery of novel EPO- modulated kinases and phosphatases, including PTPN18 as a positive regulator of EPOR/JAK2 Signaling

The formation of erythroid progenitor cells depends sharply upon erythropoietin (EPO), its cell surface receptor (erythropoietin receptor, EPOR), and Janus kinase 2 (JAK2). Clinically, recombinant human EPO (rhEPO) additionally is an important anti-anemia agent for chronic kidney disease (CKD), myelodysplastic syndrome (MDS) and chemotherapy, but induces hypertension, and can exert certain pro-tumorigenic effects. Cellular signals transduced by EPOR/JAK2 complexes, and the nature of EPO-modulated signal transduction factors, therefore are of significant interest. By employing phospho-tyrosine post-translational modification (p-Y PTM) proteomics and human EPO- dependent UT7epo cells, we have identified 22 novel kinases and phosphatases as novel EPO targets, together with their specific sites of p-Y modification. New kinases modified due to EPO include membrane palmitoylated protein 1 (MPP1) and guanylate kinase 1 (GUK1) guanylate kinases, together with the cytoskeleton remodeling kinases, pseudopodium enriched atypical kinase 1 (PEAK1) and AP2 associated kinase 1 (AAK1). Novel EPO- modified phosphatases include protein tyrosine phosphatase receptor type A (PTPRA), phosphohistidine phosphatase 1 (PHPT1), tensin 2 (TENC1), ubiquitin associated and SH3 domain containing B (UBASH3B) and protein tyrosine phosphatase non-receptor type 18 (PTPN18). Based on PTPN18's high expression in hematopoietic progenitors, its novel connection to JAK kinase signaling, and a unique EPO- regulated PTPN18-pY389 motif which is modulated by JAK2 inhibitors, PTPN18's actions in UT7epo cells were investigated. Upon ectopic expression, wt-PTPN18 promoted EPO dose-dependent cell proliferation, and survival. Mechanistically, PTPN18 sustained the EPO- induced activation of not only mitogen-activated protein kinases 1 and 3 (ERK1/2), AKT serine/threonine kinase 1-3 (AKT), and signal transducer and activator of transcription 5A and 5B (STAT5), but also JAK2. Each effect further proved to depend upon PTPN18's EPO- modulated (p)Y389 site. In analyses of the EPOR and the associated adaptor protein RHEX (regulator of hemoglobinization and erythroid cell expansion), wt-PTPN18 increased high molecular weight EPOR forms, while sharply inhibiting the EPO-induced phosphorylation of RHEX-pY141. Each effect likewise depended upon PTPN18-Y389. PTPN18 thus promotes signals for EPO-dependent hematopoietic cell growth, and may represent a new druggable target for myeloproliferative neoplasms.

Treatment of Acquired Sideroblastic Anemias

Sideroblastic anemias are a heterogeneous group of disorders unified by the presence of abnormal erythroid precursors with perinuclear mitochondrial iron deposition in the bone marrow. Based on etiology, they are classified into clonal and nonclonal. Clonal sideroblastic anemias refer to myeloid neoplasms with ring sideroblasts (RS) and frequently have somatic perturbations in the SF3B1 gene. Anemia is a major cause of morbidity in patients, and restoration of effective erythropoiesis is a major treatment goal. Morbidity includes transfusion and disease-related complications. This article focuses on treatment of acquired sideroblastic anemias and highlights areas of future investigation.

Luspatercept in Patients with Lower-Risk Myelodysplastic Syndromes

BACKGROUND

Patients with anemia and lower-risk myelodysplastic syndromes in whom erythropoiesis-stimulating agent therapy is not effective generally become dependent on red-cell transfusions. Luspatercept, a recombinant fusion protein that binds transforming growth factor β superfamily ligands to reduce SMAD2 and SMAD3 signaling, showed promising results in a phase 2 study.

METHODS

In a double-blind, placebo-controlled, phase 3 trial, we randomly assigned patients with very-low-risk, low-risk, or intermediate-risk myelodysplastic syndromes (defined according to the Revised International Prognostic Scoring System) with ring sideroblasts who had been receiving regular red-cell transfusions to receive either luspatercept (at a dose of 1.0 up to 1.75 mg per kilogram of body weight) or placebo, administered subcutaneously every 3 weeks. The primary end point was transfusion independence for 8 weeks or longer during weeks 1 through 24, and the key secondary end point was transfusion independence for 12 weeks or longer, assessed during both weeks 1 through 24 and weeks 1 through 48.

RESULTS

Of the 229 patients enrolled, 153 were randomly assigned to receive luspatercept and 76 to receive placebo; the baseline characteristics of the patients were balanced. Transfusion independence for 8 weeks or longer was observed in 38% of the patients in the luspatercept group, as compared with 13% of those in the placebo group (P<0.001). A higher percentage of patients in the luspatercept group than in the placebo group met the key secondary end point (28% vs. 8% for weeks 1 through 24, and 33% vs. 12% for weeks 1 through 48; P<0.001 for both comparisons). The most common luspatercept-associated adverse events (of any grade) included fatigue, diarrhea, asthenia, nausea, and dizziness. The incidence of adverse events decreased over time.

CONCLUSIONS

Luspatercept reduced the severity of anemia in patients with lower-risk myelodysplastic syndromes with ring sideroblasts who had been receiving regular red-cell transfusions and who had disease that was refractory to or unlikely to respond to erythropoiesis-stimulating agents or who had discontinued such agents owing to an adverse event. (Funded by Celgene and Acceleron Pharma; MEDALIST ClinicalTrials.gov number, NCT02631070; EudraCT number, 2015-003454-41.).

Treatment of Anemia in Transfusion-Dependent and Non-Transfusion-Dependent Lower-Risk MDS: Current and Emerging Strategies

Myelodysplastic syndromes (MDS) are a heterogeneous group of bone marrow disorders with a highly diverse clinical course. For lower-risk MDS patients, therapeutic objectives aim to correct chronic anemia and improve/maintain health-related quality of life (HRQoL). However, disease burden is often insufficiently recognized, and although some patients do not respond/lose response to standard treatment, many are treated late. This is the case for non-transfusion-dependent patients with symptomatic anemia, in whom delayed treatment initiation may lead to unnecessary morbidity. Current active treatment options for lower-risk MDS are limited. Standard care for lower-risk 5q deletion [del(5q)] MDS patients with anemia remains supportive, consisting of red blood cell (RBC) transfusions, iron chelation therapy, and treatment with erythropoiesis-stimulating agents (ESAs) in the case of low serum erythropoietin levels. Response rates to ESAs range from 15% to 63%, whereas 56% to 67% of patients with del(5q) MDS achieve RBC transfusion independence with lenalidomide. Treatment options for patients’ refractory to ESAs and/or lenalidomide, however, are limited. Frequent transfusions are associated with profound clinical, HRQoL, and economic consequences for transfusion-dependent patients. This review focuses on the multiple unmet clinical needs that exist in the treatment of anemia associated with lower-risk MDS and the current and future treatment options that may improve disease management and patient outcomes.

The prognostic value of serum erythropoietin in patients with lower-risk myelodysplastic syndromes: a review of the literature and expert opinion

Myelodysplastic syndromes (MDS) are hematopoietic stem cell malignancies associated with an erythroid maturation defect, resulting in anemia. Treatments for MDS include erythropoiesis-stimulating agents (ESAs). The identification of prognostic markers is important to help predict response and improve outcomes. Various scoring systems have been developed to help predict response to ESAs. Despite limitations in its assessment, serum erythropoietin (sEPO) level is an important predictor of hematologic response to ESAs in patients with lower-risk MDS. Numerous studies have reported significantly lower sEPO levels among responders versus non-responders. Furthermore, treatment response is significantly more likely among those with sEPO levels below versus those above various cutoffs. Other prognostic indicators for response to ESAs include lower transfusion requirement, fewer bone marrow blasts, higher hemoglobin, lower serum ferritin, lower-risk MDS, and more normal cytogenetics. Studies of other MDS therapies (e.g., lenalidomide and luspatercept) have also reported that lower sEPO levels are indicative of hematologic response. In addition, lower sEPO levels (up to 500 IU/L) have been included in treatment algorithms for patients with lower-risk MDS to define whether ESAs are indicated. Lower sEPO levels are predictive of hematologic response—particularly to ESAs. Further, clinical trials should use sEPO thresholds to ensure more homogeneous cohorts.