Luspatercept for the treatment of congenital sideroblastic anemia: Two case reports

Congenital sideroblastic anemia (CSA) is a group of disorders caused by different genetic mutations that result in low iron utilization and ineffective erythropoiesis. Current treatments are limited, and some patients do not respond to vitamin B6 therapy. Luspatercept is a novel erythropoietic maturation agent approved for adult β-thalassemia and Myelodysplastic syndromes with ring sideroblasts (MDS-RS) associated with ineffective erythropoiesis. Here we report 2 patients with CSA due to mutations in ALAS2 and SLC25A38 genes who became unresponsive after a period of treatment with vitamin B6 and iron chelators but achieved transfusion independence and a markedly reduced spleen after combination with luspatercept.

Phase to phase: Navigating drug combinations with hypomethylating agents in higher-risk MDS trials for optimal outcomes

Recent developments in high-risk Myelodysplastic Neoplasms (HR MDS) treatment are confronted with challenges in study design due to evolving drug combinations with Hypomethylating Agents (HMAs). The shift from the International Prognostic Scoring System (IPSS) to its molecular revision (IPSS-M) has notably influenced research and clinical practice. Introducing concepts like the MDS/AML overlap complicate classifications and including chronic myelomonocytic leukemia (CMML) in MDS studies introduces another layer of complexity. The International Consortium for MDS emphasizes aligning HR MDS criteria with the 2022 ELN criteria for AML. Differences in advancements between AML and MDS treatments and hematological toxicity in HR MDS underline the importance of detailed trial designs. Effective therapeutic strategies require accurate reporting of adverse events, highlighting the need for clarity in criteria like the Common Terminology Criteria for Adverse Events (CTCAE). We provide an overview on negative clinical trials in HR MDS, analyze possible reasons and explore possibilities to optimize future clinical trials in this challenging patient population.

[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.

Treatment of refractory or relapsed myelodysplastic neoplasms with luspatercept: a multicenter Chinese study

Few effective therapies are available to treat patients with relapsed/refractory myelodysplastic neoplasms (MDS). Luspatercept was shown to display good efficacy in a phase 3 clinical trial for lower-risk MDS (LR-MDS) patients, yet real-world data are limited, especially in China. Therefore, data from patients diagnosed as having MDS with low blasts and SF3B1 mutation (MDS-SF3B1) and MDS with SF3B1 mutation and thrombocytosis were retrospectively analyzed. Of the 23 enrolled patients, 17 (73.9%) were males (median age 67 years: range 29 to 80 years). Previously, a total of 22 (95.7%) patients had received recombinant human erythropoietin (rhEPO), 9 (39.1%) roxadustat, 7 (30.4%) lenalidomide and 3 (13.0%) hypomethylating agents (HMA). The median treatment time was 22.9 weeks (9.0-32.4). At week 12, 60.9% (14/23) of the patients achieved a hematologic improvement-erythroid (HI-E) response. Red blood cell transfusion independence (RBC-TI) for ≥ 8 weeks was found in 57.1% (8/14) of transfusion-dependent patients. The median hemoglobin concentration was 84 g/L, and patients had significantly higher hemoglobin concentrations after 12 weeks of treatment (P < 0.001). It is noteworthy that responders had a greater reduction in serum ferritin (P = 0.021). Those with serum EPO < 500 IU/L at baseline tended to have a higher HI-E rate (P = 0.081), but only patients in non-transfusion and low transfusion burden (LTB) subgroups had statistical differences (P = 0.024). The most commonly occurring adverse events were blood bilirubin increase (17.4%), fatigue (13.0%) and dizziness (13.0%). Luspatercept was effective and tolerated well in refractory LR-MDS-SF3B1 patients. In particular, baseline non-transfusion and LTB patients exhibited a greater response rate to treatment.

Real world practices of luspatercept at an academic medical center

Introduction: Luspatercept is approved for patients with very low-to intermediate-risk myelodysplastic syndrome (MDS). Dosing is based on pre-dose hemoglobin levels and transfusion requirements. This study aims to evaluate if a site with a pharmacist prospectively reviewing luspatercept doses achieves dose optimization, compared to a site that does not have a pharmacist prospectively reviewing doses. Methods: We performed a retrospective chart review involving patients age ≥18 years or older with MDS at a major academic medical center main campus, which does not have a pharmacist prospectively review luspatercept doses, and a satellite campus infusion center, which has a pharmacist prospectively reviewing doses. Patients included received at least one dose of luspatercept between January 1, 2017 through August 31, 2022. The primary endpoint is the percentage of off-label luspatercept doses not consistent with prescribing information (PI) recommended dose adjustments. Results: The study included 17 patients. Of the 162 doses evaluated, 37 (23%) were off-label. Off-label dosing at the main campus was more common than at a satellite location (29.6% vs. 2.4%; p < 0.003). More patients achieved transfusion independence at the satellite compared to the main campus (83.3% vs. 27.3% p < 0.39). Conclusions: There was a higher percentage of off-label dosing at a center without a pharmacist's prospective review vs. a center with a pharmacist's prospective review. On-label dose optimization may lead to a higher percentage of patients achieving transfusion independence. Enhancements in the current ordering and review process can be improved with the involvement of a pharmacist's prospective involvement at both centers.

SOHO State of the Art Updates and Next Questions: Novel Therapeutic Strategies in Development for Myelofibrosis

Development of myelofibrosis (MF) therapeutics has reached fruition as the transformative impact of JAK2 inhibitors in the MPN landscape is complemented/expanded by a profusion of novel monotherapies and rational combinations in the frontline and second line settings. Agents in advanced clinical development span various mechanisms of action (eg, epigenetic or apoptotic regulation), may address urgent unmet clinical needs (cytopenias), increase the depth/duration of spleen and symptom responses elicited by ruxolitinib, improve other aspects of the disease besides splenomegaly/constitutional symptoms (eg, resistance to ruxolitinib, bone marrow fibrosis or disease course), provide personalized strategies, and extend overall survival (OS). Ruxolitinib had a dramatic impact on the quality of life and OS of MF patients. Recently, pacritinib received regulatory approval for severely thrombocytopenic MF patients. Momelotinib is advantageously poised among JAK inhibitors given its differentiated mode of action (suppression of hepcidin expression). Momelotinib demonstrated significant improvements in anemia measures, spleen responses, and MF-associated symptoms in MF patients with anemia; and will likely receive regulatory approval in 2023. An array of other novel agents combined with ruxolitinib, such as pelabresib, navitoclax, parsaclisib, or as monotherapies (navtemadlin) are evaluated in pivotal phase 3 trials. Imetelstat (telomerase inhibitor) is currently evaluated in the second line setting; OS was set as the primary endpoint, marking an unprecedented goal in MF trials, wherein SVR35 and TSS50 at 24 weeks have been typical endpoints heretofore. Transfusion independence may be considered another clinically meaningful endpoint in MF trials given its correlation with OS. Overall, therapeutics are at the cusp of an exponential expansion and advancements that will likely lead to the golden era in treatment of MF.

Therapeutic perspective for children and young adults living with thalassemia and sickle cell disease

Hemoglobinopathies, including thalassemias and sickle cell disease, are the most common monogenic diseases worldwide, with estimated annual births of more than 330,000 affected infants. Hemoglobin disorders account for about 3.4% of deaths in children under 5 years of age. The distribution of these diseases is historically linked to current or previously malaria-endemic regions; however, immigration has led to a worldwide distribution of these diseases, making them a global health problem. During the last decade, new treatment approaches and novel therapies have been proposed, some of which have the potential to change the natural history of these disorders. Indeed, the first erythroid maturation agent, luspatercept, and gene therapy have been approved for beta-thalassemia adult patients. For sickle cell disease, molecules targeting vaso-occlusion and hemoglobin S polymerization include crizanlizumab, which has been approved for patients ≥ 16 years, voxelotor approved for patients ≥ 12 years, and L-glutamine for patients older than 5 years.    Conclusion: We herein present the most recent advances and future perspectives in thalassemia and sickle cell disease treatment, including new drugs, gene therapy, and gene editing, and the current clinical trial status in the pediatric populations. What is Known: • Red blood cell transfusions, iron chelation therapy and hematopoietic stem cell transplantation have been the mainstay of treatment of thalassemia patients for decades. • For sickle cell disease, until 2005, treatment strategies were mostly the same as those for thalassemia, with the option of simple transfusion or exchange transfusion. In 2007, hydroxyurea was approved for patients ≥ 2 years old. What is New: • In 2019, gene therapy with betibeglogene autotemcel (LentiGlobin BB305) was approved for TDT patients ≥ 12 years old non β0/β0 without matched sibling donor. • Starting from 2017 several new drugs, such as L-glutamine (approved only by FDA), crizanlizumab (approved by FDA and EMA for patients ≥ 16 years), and lastly voxelotor (approved by FDA and EMA for patients ≥ 12 years old).

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.

Improved benefit of continuing luspatercept therapy: sub-analysis of patients with lower-risk MDS in the MEDALIST study

Red blood cell transfusion independence (RBC-TI) is an important goal in treating lower-risk myelodysplastic syndromes with ring sideroblasts. In the phase 3 MEDALIST study, RBC-TI of ≥ 8 weeks was achieved by significantly more luspatercept- versus placebo-treated patients in the first 24 weeks of treatment. In this post hoc analysis, we evaluated RBC transfusion units and visits based on patients' baseline transfusion burden level and the clinical benefit of luspatercept treatment beyond week 25 in initial luspatercept nonresponders (patients who did not achieve RBC-TI ≥ 8 weeks by week 25) but continued luspatercept up to 144 weeks. RBC transfusion burden, erythroid response, serum ferritin levels, and hemoglobin levels relative to baseline were evaluated. Through week 25, fewer RBC transfusion units and visits were observed in luspatercept-treated patients versus placebo, regardless of baseline transfusion burden. This continued through 144 weeks of luspatercept treatment, particularly in patients with low baseline transfusion burden. Sixty-eight patients were initial nonresponders at week 25 but continued treatment; most (81%) received the maximum dose of luspatercept (1.75 mg/kg). Sixteen percent achieved RBC-TI for ≥ 8 weeks during weeks 25-48, 26% had reduced RBC transfusion burden, 10% achieved an erythroid response, 44% had reduced serum ferritin, and hemoglobin levels increased an average of 1.3 g/dL from baseline. These data have implications for clinical practice, as transfusion units and visits are less in luspatercept-treated patients through week 25 regardless of baseline transfusion burden, and continuing luspatercept beyond week 25 can potentially provide additional clinical benefits for initial nonresponders. Trial registration: NCT02631070.

Detection of activin receptor type IIA and IIB-Fc fusion proteins by automated capillary immunoassay

Activin receptor type IIA and type IIB fusion protein have been designed to sequester circulating molecules of the TGF-β superfamily and inactivate their actions. Members of this superfamily have been reported as essential regulators of erythropoiesis by triggering the formation of activated ternary complexes containing different combinations of type I and type II receptors which can limit RBC production by accelerating erythroid differentiation and inhibiting erythroid progenitor expansion. The recent approval of Luspatercept for the treatment of anemia associated to transfusion-dependent MDS and Beta-thalassemia in afflicted patients means that it can now pose a real threat of being abuse in sport for its ability to stimulate erythropoiesis. Several methods for the detection of these molecules in blood have been proposed for the purpose of sport antidoping control. Here we propose the detection of the ActRIIA-Fc and ActRIIB-Fc fusion proteins by automated capillary Western immunoassay (Simple Western). The use of these immunoassays for the detection of protein targets has become widespread in the recent years. The work presented here demonstrates that this methodology enables a versatile, rapid, and sensitive detection of activin ligand traps in blood samples, either plasma, serum or DBS. Preliminary results indicate that detection in urine samples is also possible. The option to use different antibodies allows the possibility to use this method as an initial testing procedure as well as a confirmation procedure. Finally, results coming from an administration study confirm that the method is suitable for routine analysis.

Luspatercept (RAP-536) modulates oxidative stress without affecting mutation burden in myelodysplastic syndromes

In low-risk myelodysplastic syndrome (LR-MDS), erythropoietin (EPO) is widely used for the treatment of chronic anemia. However, initial response to EPO has time-limited effects. Luspatercept reduces red blood cell transfusion dependence in LR-MDS patients. Here, we investigated the molecular action of luspatercept (RAP-536) in an in vitro model of erythroid differentiation of MDS, and also in a in vivo PDX murine model with primary samples of MDS patients carrying or not SF3B1 mutation. In our in vitro model, RAP-536 promotes erythroid proliferation by increasing the number of cycling cells without any impact on apoptosis rates. RAP-536 promoted late erythroid precursor maturation while decreasing intracellular reactive oxygen species level. RNA sequencing of erythroid progenitors obtained under RAP-536 treatment showed an enrichment of genes implicated in positive regulation of response to oxidative stress and erythroid differentiation. In our PDX model, RAP-536 induces a higher hemoglobin level. RAP-536 did not modify variant allele frequencies in vitro and did not have any effect against leukemic burden in our PDX model. These results suggest that RAP-536 promotes in vivo and in vitro erythroid cell differentiation by decreasing ROS level without any remarkable impact on iron homeostasis and on mutated allele burden.

Luspatercept, a two-edged sword in beta-thalassemia-associated paravertebral extramedullary hematopoietic masses (EHMs)

Paravertebral extramedullary hematopoietic masses (EHMs) account for up to 15% of extramedullary pseudotumors in beta-thalassemia (BT) and are most likely related to compensatory hematopoiesis. In most cases, pseudotumors are incidentally detected, as the majority of patients are asymptomatic. Since June 2020, luspatercept is approved for the treatment of patients with BT who require regular red blood cell transfusions. Data addressing the safety and efficacy of luspatercept in patients with BT-associated EHMs are pending. To date (May 2022), paravertebral EHMs were observed in two asymptomatic patients out of currently 43 adult patients with BT registered at the Adult Hemoglobinopathy Outpatient Unit of the University Hospital Essen, Germany. In one of them, a paravertebral EHM was diagnosed for more than 10 years prior to referral. Throughout observation time, treatment with luspatercept was associated with a clinically significant reduction in transfusion burden while allowing to maintain a baseline hemoglobin concentration of ≥10 g/dl aiming to suppress endogenous (ineffective) erythropoiesis associated with BT. Considering the rarity of paravertebral EHMs in BT, luspatercept might potentially represent a novel therapeutic option for these often-serious disease-associated complications. However, appropriate follow-up investigations are recommended to detect (early) treatment failures secondary to an undesired luspatercept-associated erythroid expansion.

Detection of erythropoiesis stimulating agent Luspatercept after administration to healthy volunteers for antidoping purposes

Luspatercept (Reblozyl®) is a newly approved anti-anemic drug prohibited by the World Anti-Doping Agency. It promotes erythropoiesis by limiting apoptosis of immature erythroblasts and the risk of misuse by athletes for doping is high. Proposed detection methods have been published recently but only evaluated in vitro. The objective of this study was to perform the first administration of luspatercept in healthy volunteers for antidoping purpose and to evaluate the detectability in serum, dried capillary blood spots (DBS, collected using TASSO M20 device), and urine. Indirect detection was also evaluated by analyzing hematological parameters for the Athlete Biological Passport. Four volunteers (two males, two females) received one subtherapeutic dose of luspatercept (0.25 mg/kg) followed 3 weeks after by a second dose. Samples were collected from before administration until 7 weeks after the second dose. After immunopurification, electrophoretic separation SDS-/SAR-/IEF- polyacrylamide gel electrophoresis (PAGE), and immunodetection, luspatercept was detected at high levels in serum until the end of the collection, sign of a very slow elimination and similarly detected unchanged at lower levels in urine from 2 days after the first administration until 7 weeks postadministration. DBS showed also the same long window of detection. Luspatercept effects were however of limited amplitude on hematological markers, and only two subjects presented atypical points outside the physiological limits during the study. The direct detection method was very efficient, and change of electrophoretic method and detection antibody can be used for confirmation of suspicious samples.

SOHO State of the Art Updates and Next Questions: Novel Therapies in Development for Myelofibrosis

Myeloproliferative neoplasms research has entered a dynamic and exciting era as we witness exponential growth of novel agents in advanced/early phase clinical trials for myelofibrosis (MF). Building on the success and pivotal role of ruxolitinib, many novel agents, spanning a wide range of mechanisms/targets (epigenetic regulation, apoptotic/intracellular signaling pathways, telomerase, bone marrow fibrosis) are in clinical development; several are studied in registrational trials and hold great potential to expand the therapeutic arsenal/shift the treatment paradigm if regulatory approval is granted. Insight into MF pathogenesis and its molecular underpinnings, preclinical studies demonstrating synergism of ruxolitinib with investigational agents, urgent unmet clinical needs (cytopenias, loss of response to JAK inhibitors); and progressive disease fueled the rapid rise of innovative therapeutics. New strategies include pairing ruxolitinib with erythroid maturation agents to manage anemia (luspatercept), designing rational combinations with ruxolitinib to boost responses in both the frontline and suboptimal response settings (pelabresib, navitoclax, parsaclisib), treatment with non-JAK inhibitor monotherapy in the second-line setting (navtemadlin, imetelstat), novel JAK inhibitors tailored to subgroups with challenging unmet needs (momelotinib and pacritinib for anemia and thrombocytopenia, respectively); and agents potentially enhancing longevity (imetelstat). Beyond typical endpoints evaluated in MF clinical trials (spleen volume reduction ≥ 35%, total symptom score reduction ≥ 50%) thus far, emerging endpoints include overall survival, progression-free survival, transfusion independence, anemia benefits, bone marrow fibrosis and driver mutation allele burden reduction. Novel biomarkers and additional clinical features are being sought to assess new agents and tailor emerging therapies to appropriate patients. New strategies are needed to optimize the design of clinical trials comparing novel combinations to standard agent monotherapy.

SOHO State of the Art Updates and Next Questions: Identifying and Treating "Progression" in Myelofibrosis

Over the last decade, the Janus kinase (JAK) 1/2 inhibitor ruxolitinib has become widely established as the cornerstone of pharmacologic therapy for most patients with myelofibrosis (MF), providing dramatic and durable benefits in terms of splenomegaly and symptoms, and prolonging survival. Ruxolitinib does not address all aspects of the disease, however; notably cytopenias, and its ability to modify the underlying biology of the disease remains in question. Furthermore, patients eventually lose response to ruxolitinib. Multiple groups have reported the median overall survival of MF patients after ruxolitinib discontinuation to be 13 to 14 months. While consensus criteria only recognize splenic and blast progression as "progressive disease" in patients with MF, disease progression can occur in a variety of ways. Besides increasing splenomegaly and progression to accelerated phase/leukemic transformation, patients may develop worsening disease-related symptoms, cytopenias, progressive leukocytosis, extramedullary hematopoiesis, etc. As in the frontline setting, treatment needs to be tailored to the clinical needs of the patient. Current treatment options for patients with MF who fail ruxolitinib remain unsatisfactory, and this continues to represent an area of major unmet medical need. The regulatory approval of fedratinib has introduced an important option in the postruxolitinib setting. Fortunately, a plethora of novel agents, both new JAK inhibitors and drugs from other classes, eg, bromodomain and extraterminal (BET), murine double minute 2 (MDM2) and telomerase inhibitors, activin receptor ligand traps, BH3-mimetics and more, are poised to greatly expand the therapeutic armamentarium for patients with MF if successful in pivotal trials.

Luspatercept: A Gigantic Step in the Treatment of Transfusion-Dependent β-Thalassemia Patients-a Quick Review

INTRODUCTION

Some studies have indicated that the use of luspatercept may be a novel and efficient treatment for β-thalassemia patients. In this article, we aimed to review the current evidence related to luspatercept prescription and its clinical effectiveness in patients with β-thalassemia.

METHODS

PubMed, Web of Science, Scopus, Trip and CENTRAL were searched up to June 2020. The inclusion criteria were English-language articles that studied the effects of luspatercept on improving anemia severity in patients with β-thalassemia in a clinical setting.

RESULTS

The search strategy yielded 273 potentially relevant articles. After searching the databases, scanning of titles, abstracts and full texts for relevancy was performed to identify suitable articles. A total of 77 articles were confirmed for full text analysis. The estimated number of patients needed to treat (NNT) for luspatercept treatment, using data derived from conducted clinical trials, according to a reduction in transfusion need of ≥ 33% or ≥ 50 from baseline, during week 13-24/week 37-48/any 12- and 24-week intervals as outcomes, was 3-5 in patients with β-thalassemia.

CONCLUSION

Based on the conducted studies, the effectiveness of luspatercept on transfusion burden and hemoglobin levels was outstanding in β-thalassemia patients. Further large and well-designed clinical studies are needed to identify any unforeseen complications subsequent to use of luspatercept, particularly when used with other treatments with potentially serious adverse effects such as anti-osteoporotic and iron chelator agents.

[Thalassemia in Japan]

Thalassemia is caused by a reduced production of one globin chain due to a quantitative imbalance between the α-globin and non-α-globin chains that make up the hemoglobin. It is classified into α- and β-thalassemia and characterized by microcytosis with polycythemia, and a Mentzer index of ≤13 aids in the diagnosis. In the genetic analysis of α-thalassemia, the Southeast Asian type was found to be the most common genetic subtype among Japanese and non-Japanese without a substantial difference. Conversely, the genetic analysis of β-thalassemia revealed differences in the types and frequencies of mutations between Japanese individuals and foreigners living in Japan, with Japanese-specific mutations such as -31 A→G (TATA box). Acquired α-thalassemia exists in exceptional cases, and cases of myelodysplastic syndrome with acquired Hemoglobin H disease have been reported as α-thalassemia myelodysplastic syndrome. Recent trials using a novel therapeutic agent, luspatercept, for transfusion-dependent β-thalassemia revealed that luspatercept safely and significantly reduces the transfusion volume.

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.

Luspatercept to treat β-thalassemia

Recently, after years of research often characterized by disappointments and frustrations, finally a new drug impacting on pathological human erythropoiesis has been developed and approved. This drug, luspatercept-aamt (Reblozyl), proved to be effective in both malignant and nonmalignant disease characterized by ineffective erythropoiesis with consequent life-threatening severe anemia. Moreover, for the first time, a medication demonstrated efficacy and effectiveness in β-thalassemia where no other drug, including recombinant human erythropoietin, showed effectiveness in improving anemia. Despite recent impressive advances in understanding human normal and abnormal erythropoiesis, there are few new drugs and limited pharma research focusing on ineffective erythropoiesis. This review will discuss recent advances in understanding normal and pathological erythropoiesis that represent the background to discuss pharmacology, toxicology, efficacy, safety and effectiveness of this new drug for the treatment of human β-thalassemia.

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.

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.

Management of Myelofibrosis-Related Cytopenias

PURPOSE OF REVIEW

Cytopenias, particularly anemia, are frequently encountered in patients with myelofibrosis. Management of cytopenias in myelofibrosis can be very challenging because current therapeutic interventions are only of modest efficacy and ruxolitinib, the only approved drug for myelofibrosis, is myelosuppressive. Yet, dose optimization of ruxolitinib is important for its survival benefit in patients with advanced disease. We sought to summarize the data on treatments for cytopenias available at present and review promising agents in development and emerging strategies.

RECENT FINDINGS

The activin receptor ligand traps hold considerable promise for the treatment of anemia and could represent an attractive combination strategy with ruxolitinib. Low-dose thalidomide, which could offset both anemia and thrombocytopenia caused by ruxolitinib, represents another potential partner for ruxolitinib. The anti-fibrotic agent PRM-151 produced sustained improvements in cytopenias in some patients, and further data on this drug are eagerly awaited. Finally, several preclinical leads with translational potential are worthy of clinical investigation as strategies to halt/reverse bone marrow fibrosis and thereby improve cytopenias. Cytopenias remain a significant hurdle in myelofibrosis management, but several novel investigational agents hold considerable promise for the future.

Activin Receptor II Ligand Traps and Their Therapeutic Potential in Myelodysplastic Syndromes with Ring Sideroblasts

Distinct subtypes of lower risk myelodysplastic syndromes display ring sideroblasts in the bone marrow, i. e., erythroid progenitors characterized by excessive iron deposited in the mitochondria. This morphological feature is frequently associated with somatic mutations in components of the splicing machinery that constitutes the underlying molecular principle of the disease. Conventional treatment regimen with erythropoiesis-stimulating agents often fails to induce sustained erythroid improvement in these patients that harbor defects in late-stage erythroblasts downstream of erythropoietin action. In the present review, we will discuss activin receptor ligand traps as novel therapeutic strategies particularly for sideroblastic subgroups of myelodysplastic syndromes that were recently shown to alleviate anemia by specifically inhibiting aberrant TGF-β signaling and thereby promoting erythroid differentiation.

Increasing the effectiveness of hematopoiesis in myelodysplastic syndromes: erythropoiesis-stimulating agents and transforming growth factor-β superfamily inhibitors

Patients with lower-risk myelodysplastic syndromes (MDS) are mainly affected by chronic anemia and fatigue. Treatment strategies aim to improve anemia and quality of life, as well as iron overload due to red blood cell transfusion support. To promote proliferation and differentiation of erythropoiesis, erythropoiesis-stimulating agents (ESAs) such as erythropoietin (EPO) and mimetics are applied as first-line therapy in a large fraction of lower-risk MDS patients. In general, ESAs yield favorable responses in about half of the patients, although responses are often short-lived. In fact, many ESA-refractory patients harbor defects in late-stage erythropoiesis downstream of EPO action. Novel transforming growth factor (TGF)-β superfamily inhibitors sotatercept and luspatercept represent a promising approach to alleviate anemia by stimulating erythroid differentiation.