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

A Novel Combination Therapy of Erythropoietin and Thrombopoietin to Treat Erythropoietin-Resistance anemia

PURPOSE

Treatment with recombinant human erythropoietin (rHuEPO) may correct anemia in patients with chronic kidney disease. However, up to 10% of these patients exhibit EPO resistance or hyporesponsiveness, which may be caused by the depletion of erythroid progenitor cells. Thrombopoietin (TPO) stimulates the self-renewal of stem cells and promotes the growth of early erythroid progenitor cells. The objective of this study was to determine whether the combination of recombinant human TPO (rHuTPO) and rHuEPO could correct the depletion of erythroid precursor cells to treat EPO-resistant anemia.

METHODS

To test our hypothesis, pharmacokinetic (PK) and pharmacodynamic (PD) studies of rHuEPO and rHuTPO were performed in healthy rats. Rats received rHuEPO or rHuTPO alone or in combination. Plasma concentrations of rHuTPO and rHuEPO were measured. PD responses, including erythropoietic and thrombopoietic responses, were assessed in peripheral blood.

RESULTS

On one hand, the results demonstrated the synergistic effect of the combination of rHuEPO and rHuTPO on erythropoiesis. Compared with rHuEPO monotherapy, the combination therapies further stimulated the production of red blood cells and hemoglobin. On the other hand, rHuEPO inhibited the platelet production induced by rHuTPO and mitigate the risk of blood clots. Furthermore, we successfully developed a mechanism-based PD model to simultaneously characterize the responses of the two molecules.

CONCLUSIONS

Overall, our study indicated that a combination therapy of rHuTPO and rHuEPO could be used to treat EPO-resistant anemia and provided a quantitative basis for further optimizing the combination therapy for clinical use.

Impact of iron overload by transfusion on survival and leukemia transformation of myelodysplastic syndromes in a single center of China

INTRODUCTION

Myelodysplastic syndromes (MDS) are a heterogeneous group of diseases which are prone to progress into acute myeloid leukemia (AML). Iron overload (IOL) caused by transfusion occurred in most MDS patients. But how IOL influences MDS progression has not been clarified yet.

METHODS

Herein, we collected clinical data from 143 MDS patients to investigate the impacts of IOL on patients survival and AML transformation.

RESULTS

We found that median survival time, 3-year survival rate, leukemia-free survival (LFS) time were significantly shorter in patients with IOL than those with non-iron overload (NIOL) (P = 0.040; P = 0.044; P = 0.037). Besides, IOL was more likely to be found in higher-risk subgroups (assessed by IPSS and WPSS) of MDS patients which also promoted 2-year AML transformation. Furthermore, the serum ferritin (SF) was significantly correlated with the overall survival (OS) of MDS patients (r = -0.311, P < 0.05). The concentrations of both intracellular iron and reactive oxygen species (ROS) in CD34⁺ cells of bone marrow were higher in the IOL group than the NIOL group, respectively (P = 0.0426; P = 0.0185). Moreover, ROS level was closely correlated with the percentage of bone marrow blasts (r = 0.7200, P = 0.0370). Collectively, IOL threatened the survival of MDS patients and promoted AML transformation.

CONCLUSION

Elevated intracellular iron and ROS in CD34⁺ cells of bone marrow could accelerate the abnormal proliferation of blasts.

Targeting low-risk myelodysplastic syndrome with novel therapeutic strategies

Myelodysplastic syndrome (MDS) is a group of hematopoietic disorders with limited treatment options. Anemia is a common symptom in MDS, and although erythropoiesis-stimulating agents such as erythropoietin, lenalidomide, and luspatercept are available to treat anemia, many MDS patients do not respond to these first-line therapies. Therefore, alternative drug development strategies are needed to improve therapeutic efficacy. Splicing modulators to correct splicing-related defects have shown promising results in clinical trials. Targeting differentiation of early erythroid progenitors to increase the erythroid output in MDS is another novel approach, which has shown encouraging results at the pre-clinical stage. Together, these therapeutic strategies provide new avenues to target MDS symptoms untreatable previously.

Nuclear Inositides and Inositide-Dependent Signaling Pathways in Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are a heterogeneous group of hematological malignancies characterized by peripheral blood cytopenia and abnormal myeloproliferation, as well as a variable risk of evolution into acute myeloid leukemia (AML). The nucleus is a highly organized organelle with several distinct domains where nuclear inositides localize to mediate essential cellular events. Nuclear inositides play a critical role in the modulation of erythropoiesis or myelopoiesis. Here, we briefly review the nuclear structure, the localization of inositides and their metabolic enzymes in subnuclear compartments, and the molecular aspects of nuclear inositides in MDS.

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.

Development of two complementary LC–HRMS methods for analyzing sotatercept in dried blood spots for doping controls

Aim: sotatercept is a therapeutic Fc-fusion protein with erythropoiesis-stimulating activity. Due to a potential abuse of the drug by athletes in professional sports, a sensitive detection method is required. In sports drug testing, alternative matrices such as dried blood spots (DBS) are gaining increasing attention as they can provide several advantages over conventional matrices. Materials & methods: Herein, two complementary LC–high-resolution mass spectrometry (HRMS) detection methods for sotatercept from DBS, an initial testing procedure (ITP) and a confirmation procedure (CP) were developed and validated for the first time. Both methods comprise an ultrasonication-assisted extraction, affinity enrichment, proteolytic digestion and HRMS detection. Results & conclusion: For the multianalyte ITP, artificial samples fortified with sotatercept, luspatercept and bimagrumab, and authentic specimens containing bimagrumab were successfully analyzed as proof-of-concept. The validated detection methods for sotatercept are fit for purpose and the ITP was shown to be suitable for the detection of novel IgG-based pharmaceuticals in doping control DBS samples.

Therapeutic discovery for marrow failure with MDS predisposition using pluripotent stem cells

Monosomy 7 or deletion of 7q (del(7q)) are common clonal cytogenetic abnormalities associated with high grade myelodysplastic syndrome (MDS) arising in inherited and acquired bone marrow failure. Current non-transplant approaches to treat marrow failure may be complicated by stimulation of clonal outgrowth. To study the biological consequences of del(7q) within the context of a failing marrow, we generated induced pluripotent stem cells (iPSCs) derived from patients with Shwachman Diamond Syndrome (SDS), a bone marrow failure disorder with MDS predisposition, and genomically engineered a 7q deletion. The TGFβ pathway was the top differentially regulated pathway in transcriptomic analysis of SDS versus SDSdel(7q) iPSCs. SMAD2 phosphorylation was increased in SDS relative to wild type cells consistent with hyperactivation of the TGFbeta pathway in SDS. Phospho-SMAD2 levels were reduced following 7q deletion in SDS cells and increased upon restoration of 7q diploidy. Inhibition of the TGFbeta pathway rescued hematopoiesis in SDS-iPSCs and in bone marrow hematopoietic cells from SDS patients while it had no impact on the SDSdel(7q) cells. These results identified a potential targetable vulnerability to improve hematopoiesis in an MDS-predisposition syndrome, and highlight the importance of the germline context of somatic alterations to inform precision medicine approaches to therapy.

Transforming growth factor (TGF)-β pathway as a therapeutic target in lower risk myelodysplastic syndromes

The transforming growth factor (TGF)-β superfamily comprises more than 30 soluble growth factors that play a central role in erythropoiesis and are part of a tightly regulated myelosuppressive negative feedback loop under physiologic conditions. TGF-β receptor activation and phosphorylation trigger a regulatory circuit of activating and inhibitory SMAD proteins and increased activation of the TGF-β signaling pathway either by a loss of negative feedback or constitutive activation has been associated with the myelosuppression and ineffective erythropoiesis in myelodysplastic syndromes (MDS). Anemia is the predominant cause of morbidity and quality of life impairment in patients with lower-risk (LR)-MDS, and there are very limited therapy options for these patients after failure of erythropoiesis stimulating agents (ESAs). Targeting the aberrant TGF-ß signaling pathway has therefore been investigated as a promising therapeutic approach to resolve the ineffective erythropoiesis in LR-MDS. In this article, we provide a brief overview of the TGF-β signaling cascade in hematopoiesis under physiologic conditions and its role in MDS pathogenesis. We also review preclinical and clinical data for the activin receptor type IIA ligand traps sotatercept and luspatercept that have recently shown promising results in overcoming the myelosuppressive effects of TGF-β signaling alterations to improve hematopoiesis in transfusion-dependent, non-del(5q) LR-MDS patients. Additional potential targets within the TGF-β pathway have also been identified in preclinical experiments and may provide further therapeutic options. Finally, combining different TGF-β pathway inhibitors or using them in combination with ESAs or the immunomodulator lenalidomide might have synergistic effects as well.

Getting personal with myelodysplastic syndromes: is now the right time?

INTRODUCTION

Commonly used scoring systems rely on blood counts, histological and cytological examination of bone marrow and peripheral blood as well as cytogenetic assessments to estimate prognosis of patients with myelodysplastic syndromes (MDS) and guide therapy decisions. Next-generation sequencing (NGS) has identified recurrent genetic abnormalities in up to 90% of patients with MDS and may provide important information regarding the pathogenesis of the disease, diagnostic and prognostic evaluation, and therapy selection. Areas covered: Herein, the authors review the role of NGS in diagnosis, treatment, and prognosis of MDS at various disease stages, and discuss advantages and caveats of incorporating molecular genetics in routine management of MDS. While a vast majority of patients harbor recurrent mutations implicated in MDS pathogenesis, similar mutations can be detected in otherwise healthy individuals with other hematologic malignancies. Besides establishing a diagnosis, NGS may be used to monitor minimal residual disease following treatment. Expert opinion: As more targeted therapies become available, assessment of genetic mutations will become central to individualized therapy selection and may improve diagnostic accuracy and further guide management for each patient. However, multiple challenges remain before NGS can be incorporated into routine clinical practice.

The role of TGFβ in hematopoiesis and myeloid disorders

The role of transforming growth factor-β (TGFβ) signaling in embryological development and tissue homeostasis has been thoroughly characterized. Its canonical downstream cascade is well known, even though its true complexity and other non-canonical pathways are still being explored. TGFβ signaling has been described as an important pathway involved in carcinogenesis and cancer progression. In the hematopoietic compartment, the TGFβ pathway is an important regulator of proliferation and differentiation of different cell types and has been implicated in the pathogenesis of a diverse variety of bone marrow disorders. Due to its importance in hematological diseases, novel inhibitors of this pathway are being developed against a number of hematopoietic disorders, including myelodysplastic syndromes (MDS). In this review, we provide an overview of the TGFβ pathway, focusing on its role in hematopoiesis and impact on myeloid disorders. We will discuss therapeutic interventions with promising results against MDS.

Treatment of MDS

The heterogeneous nature of myelodysplastic syndromes (MDS) demands a complex and personalized variety of therapeutic approaches. Among them, allogeneic hematopoietic stem cell transplantation remains the only potentially curative option and is accessible to only a small number of fit patients. For the majority of patients with MDS, treatment strategies are nonintensive and risk-adapted (by the revised version of the International Prognostic Scoring System), ranging from iron chelation and growth factors to lenalidomide and hypomethylating agents. These approaches are noncurative and aimed instead at improving cytopenias and quality of life and delaying disease progression. These limitations underpin the need for more translational research-based clinical trials in well-defined subgroups of patients with MDS. Indeed, much progress has been made over the past decade in understanding the complex molecular mechanisms underlying MDS. Unfortunately, this has not yet translated into approval of novel treatment options. There is a particularly urgent medical need in patients failing current first-line therapies, such as with erythropoiesis-stimulating or hypomethylating agents. Nevertheless, actual developments are expected to pave the way for exciting novel therapeutic opportunities. This review provides an overview of the current therapeutic landscape in MDS focusing on recent advances in clinical and translational research.

Clinical effectiveness and safety of erythropoietin-stimulating agents for the treatment of low- and intermediate-1-risk myelodysplastic syndrome: a systematic literature review

Many patients with lower-risk myelodysplastic syndrome (MDS) experience anaemia, which has negative consequences. Erythropoiesis-stimulating agents (ESAs) and their biosimilars are used to treat anaemia in MDS and, currently, epoetin alfa and darbepoetin alfa are commonly used and recommended by clinical guidelines. To better understand the evidence available on the use of ESAs for anaemia in lower-risk MDS, we conducted a systematic literature review to identify randomized and nonrandomized prospective studies reporting on clinical efficacy/effectiveness, patient-reported quality of life (QoL), and safety. We extended our review to include retrospective studies for darbepoetin alfa specifically and to ascertain the feasibility of completing an indirect network meta-analysis comparing epoetin and darbepoetin alfa. Overall, 53 articles reporting on 35 studies were included. The studies indicated a clinical benefit of ESAs, with benefits observed across key clinical outcomes. ESAs showed consistent improvement in erythroid response rates (ESA-naïve, 45-73%; previous ESA exposure, 25-75%) and duration of response. Comparative studies demonstrated similar progression to acute myeloid leukaemia and several showed improved overall survival and QoL. Limited safety concerns were identified. This analysis confirmed ESA therapy should be the foremost first-line treatment of anaemia in most patients with lower-risk MDS who lack the 5q deletion.

Iron overload impairs normal hematopoietic stem and progenitor cells through reactive oxygen species and shortens survival in myelodysplastic syndrome mice

There is increasing clinical evidence to suggest a suppressive effect on hematopoiesis in myelodysplastic syndrome patients with iron overload. However, how iron overload influences hematopoiesis in myelodysplastic syndrome (MDS) remains unknown. Here, the RUNX1S291fs-transduced bone marrow mononuclear cells were yielded and transplanted into lethally irradiated recipient mice together with radioprotective bone marrow cells to generate MDS mice. Eight weeks post transplantation, the recipient mice received an intraperitoneal injection of 0.2 mL iron dextran at a concentration of 25 mg/mL once every other day for a total of 8 times to establish an iron overload model. In the present study, we show that iron overload impairs the frequency and colony-forming capacity of normal hematopoietic stem and progenitor cells, especially in erythroid, in MDS mice, which is due, at least in part, to growth differentiation factor 11-induced reactive oxygen species, shortening survival of MDS mice. Given that we are the first to construct an iron overload model in MDS mice, we hope this model will be helpful for further exploring the influence and mechanism of iron overload on MDS.

Anemia in the Elderly

Anemia affects a substantial fraction of the elderly population, representing a public health problem that is predicted to further increase in coming years because of the demographic drive. Being typically mild, it is falsely perceived as a minor problem, particularly in the elderly with multimorbidity, so that it often remains unrecognized and untreated. Indeed, mounting evidence indicates that anemia in the elderly (AE) is independently associated with disability and other major negative outcomes, including mortality. AE is generally multifactorial, but initial studies suggested that etiology remains unexplained in near one-third of cases. This proportion is consistently declining due to recent advances highlighting the role of several conditions including clonal hematopoiesis, "inflammaging," correctable androgen deficiency in men, and under-recognized iron deficiency. Starting from a real-world case vignette illustrating a paradigmatic example of anemia in an elderly patient with multimorbidity, we review the main clinical and pathophysiological aspect of AE, giving some practical insights into how to manage similar cases.

HYPOMETHYLATING AGENTS IN TREATMENT OF MYELODYSPLASTIC SYNDROME

Thelkey to the successful treatment of myelodysplastic syndrome is the careful characterization and diagnosis of the disease, which includes clinical, cytogenetic, biological and molecular investigation of individual patients. Today therapeutic approaches to the treatment of such patients are differentiated and depend, first of all, on the subtype of the disease, age, general condition of the patients and the possibility of allogeneic hematopoietic cell transplantation. For young patients, the best option is transplantation, whereas in older patients, the standard of therapy is the use of hypomethylating agents (azacitidine, decitabine). These drugs promote hematologic improvement, elimination of transfusion dependence and prolongation of the duration of both general and leukemia free survival in elderly patients with concomitant pathology. Despite the fact that therapy with hypomethylating drugs is widely used and has good results, many respondents are losing their response within 1–2 years. Reasons for the development of resistance to this type of treatment are still unclear, and the insensitivity to drugs is associated with very poor prognosis in patients with all subtypes of myelodysplastic syndrome. Such data and the presence of numerous genetic and epigenetic mechanisms for the development of this pathology have prompted the use of combinations of drugs with different application points and are relevant in terms of research. In the literature review, the results of clinical studies on the use of hypomethylating agents in patients with MDS of low and high risk, as in monotherapy and combined schemes are presented. The nearest prospect of treatment of myelodysplastic syndrome is the creation of new treatment regimens based on a combination of drugs of different pathogenetic direction for the elimination of the dysplastic clone in order to achieve not only long-term remissions, but also lengthening the duration of overall survival, especially for patients with high risk myelodysplastic syndrome.

The bone-marrow niche in MDS and MGUS: implications for AML and MM

Several haematological malignancies, including multiple myeloma (MM) and acute myeloid leukaemia (AML), have well-defined precursor states that precede the development of overt cancer. MM is almost always preceded by monoclonal gammopathy of undetermined significance (MGUS), and at least a quarter of all patients with myelodysplastic syndromes (MDS) have disease that evolves into AML. In turn, MDS are frequently anteceded by clonal haematopoiesis of indeterminate potential (CHIP). The acquisition of additional genetic and epigenetic alterations over time clearly influences the increasingly unstable and aggressive behaviour of neoplastic haematopoietic clones; however, perturbations in the bone-marrow microenvironment are increasingly recognized to have key roles in initiating and supporting oncogenesis. In this Review, we focus on the concept that the haematopoietic neoplasia-microenvironment relationship is an intimate rapport between two partners, provide an overview of the evidence supporting a role for the bone-marrow niche in promoting neoplasia, and discuss the potential for niche-specific therapeutic targets.

Diagnosis, management and response criteria of iron overload in myelodysplastic syndromes (MDS): updated recommendations of the Austrian MDS platform

INTRODUCTION

Despite the availability of effective iron chelators, transfusion-related morbidity is still a challenge in chronically transfused patients with myelodysplastic syndromes (MDS). In these patients, transfusion-induced iron overload may lead to organ dysfunction or even organ failure. In addition, iron overload is associated with reduced overall survival in MDS. Areas covered: During the past 10 years, various guidelines for the management of MDS patients with iron overload have been proposed. In the present article, we provide our updated recommendations for the diagnosis, prevention and therapy of iron overload in MDS. In addition, we propose refined treatment response criteria. As in 2006 and 2007, recommendations were discussed and formulated by participants of our Austrian MDS platform in a series of meetings in 2016 and 2017. Expert commentary: Our updated recommendations should support early recognition of iron overload, optimal patient management and the measurement of clinical responses to chelation treatment in daily practice.

The aryl hydrocarbon receptor in the crossroad of signalling networks with therapeutic value

The aryl hydrocarbon receptor (AhR) is well-known for its major contributions to the cellular responses against environmental toxins and carcinogens. Notably, AhR has also emerged as a key transcription factor controlling many physiological processes including cell proliferation and apoptosis, differentiation, adhesion and migration, pluripotency and stemness. These novel functions have broadened our understanding of the signalling pathways and molecular intermediates interacting with AhR under both homeostatic and pathological conditions. Recent discoveries link AhR with the function of essential organs such as liver, skin and gonads, and with complex organismal structures including the immune and cardiovascular systems. The identification of potential endogenous ligands able to regulate AhR activity, opens the possibility of designing ad hoc molecules with pharmacological and/or therapeutic value to treat human diseases in which AhR may have a causal role. Integration of experimental data from in vitro and in vivo studies with "omic" analyses of human patients affected with cancer, immune diseases, inflammation or neurological disorders will likely contribute to validate the clinical relevance of AhR and the possible benefits of modulating its activity by pharmacologically-driven strategies. In this review, we will highlight signalling pathways involved in human diseases that could be targetable by AhR modulators and discuss the feasibility of using such molecules in therapy. The pros and cons of AhR-aimed approaches will be also mentioned.