Short-term administration of JAK2 inhibitors reduces splenomegaly in mouse models of β-thalassemia intermedia and major

Ferroportin inhibitor vamifeport ameliorates ineffective erythropoiesis in a mouse model of β-thalassemia with blood transfusions

β-thalassemia is an inherited anemia characterized by ineffective erythropoiesis. Blood transfusions are required for survival in transfusion-dependent β-thalassemia and are also occasionally needed in patients with non-transfusion-dependent β-thalassemia. Patients with transfusion-dependent b-thalassemia often have elevated transferrin saturation (TSAT) and non-transferrin-bound iron (NTBI) levels, which can lead to organ iron overload, oxidative stress, and vascular damage. Vamifeport is an oral ferroportin inhibitor that was previously shown to ameliorate anemia, ineffective erythropoiesis, and dysregulated iron homeostasis in the Hbbth3/+ mouse model of β-thalassemia, under non-transfused conditions. Our study aimed to assess the effects of oral vamifeport on iron-related parameters (including plasma NTBI levels) and ineffective erythropoiesis following blood transfusions in Hbbth3/+ mice. A single dose of vamifeport prevented the transient transfusion-mediated NTBI increase in Hbbth3/+ mice. Compared with vehicle treatment, vamifeport significantly increased hemoglobin levels and red blood cell counts in transfused mice. Vamifeport treatment also significantly improved ineffective erythropoiesis in the spleens of Hbbth3/+ mice, with additive effects observed when treatment was combined with repeated transfusions. Vamifeport corrected leukocyte counts and significantly improved iron-related parameters (serum transferrin, TSAT and erythropoietin levels) versus vehicle treatment in Hbbth3/+ mice, irrespective of transfusion status. In summary, vamifeport prevented transfusion-mediated NTBI formation in Hbbth3/+ mice. When given alone or combined with blood transfusions, vamifeport also ameliorated anemia, ineffective erythropoiesis, and dysregulated iron homeostasis. Administering vamifeport together with repeated blood transfusions additively ameliorated anemia and ineffective erythropoiesis in this mouse model, providing preclinical proof-of-concept for the efficacy of combining vamifeport with blood transfusions in β-thalassemia.

Novel potential therapeutics to modify iron metabolism and red cell synthesis in diseases associated with defective erythropoiesis

Under normal conditions, iron metabolism is carefully regulated to sustain normal cellular functions and the production of hemoglobin in erythroid cells. Perturbation to the erythropoiesis-iron metabolism axis can result in iron imbalances and cause anemia or organ toxicity. Various congenital and acquired diseases associated with abnormal red cell production are characterized by aberrant iron absorption. Several recent studies have shown that improvements in red blood cell production also ameliorate iron metabolism and vice versa. Many therapeutics are now under development with the potential to improve a variety of hematologic diseases, from β-thalassemia and iron-refractory iron deficiency anemia to anemia of inflammation and polycythemia vera. This review summarizes selected mechanisms related to red cell production and iron metabolism and describes potential therapeutics and their current uses. We also consider the potential application of the discussed therapeutics on various diseases, alone or in combination. The vast repertoire of drugs under development offers new opportunities to improve the clinical care of patients suffering from congenital or acquired red blood cell disorders with limited or no treatment options.

Computational modeling and in vitro evaluation identified natural product-Z218 as a novel Janus kinase 2 (JAK2) inhibitor to combat β-thalassemia

Aberrant activity of Janus kinase 2 (JAK2) is a known driver of several myeloproliferative disorders, including polycythemia vera, and thalassemia. Several inhibitors have been proposed to inhibit JAK2 activity in order to control the disease progression. Ruxolitinib and fedratinib that targets JAK2 kinase have been approved for use in myeloproliferative neoplasms patients. Experimental structures of JAK2 complexed with ruxolitinib provide insights into critical interactions of ruxolitinib. In this work, using a high-throughput virtual screening followed by experimental validations, we have identified a novel natural product from ZINC database that interacts with JAK2 in a manner similar to ruxolitinib and inhibits the activity of JAK2 kinase. Molecular dynamics simulations and MMPBSA method show binding dynamics and stability of our identified lead compound. Kinase inhibition assays show that our identified lead molecule inhibits JAK2 kinase at a nanomolar range, indicating a plausibility that the identified lead molecule can be further studied as natural product inhibitor of JAK2 kinase.

An Expert Overview on Therapies in Non-Transfusion-Dependent Thalassemia: Classical to Cutting Edge in Treatment

The thalassemia issue is a growing worldwide health concern that anticipates the number of patients suffering from the disease will soon increase significantly. Patients with β-thalassemia intermedia (β-TI) manifest mild to intermediate levels of anemia, which is a reason for it to be clinically located between thalassemia minor and β-thalassemia major (β-TM). Notably, the determination of the actual rate of β-TI is more complicated than β-TM. The leading cause of this illness could be partial repression of β-globin protein production; accordingly, the rate of β-globin gene repression is different in patients, and the gene repression intensity creates a different clinical status. This review article provides an overview of functional mechanisms, advantages, and disadvantages of the classic to latest new treatments for this group of patients, depending on the disease severity divided into the typical management strategies for patients with β-TI such as fetal hemoglobin (Hb) induction, splenectomy, bone marrow transplantation (BMT), transfusion therapy, and herbal and chemical iron chelators. Recently, novel erythropoiesis-stimulating agents have been added. Novel strategies are subclassified into molecular and cellular interventions. Genome editing is one of the efficient molecular therapies for improving hemoglobinopathies, especially β-TI. It encompasses high-fidelity DNA repair (HDR), base and prime editing, clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 procedure, nuclease-free strategies, and epigenetic modulation. In cellular interventions, we mentioned the approach pattern to improve erythropoiesis impairments in translational models and patients with β-TI that involve activin II receptor traps, Janus-associated kinase 2 (JAK2) inhibitors, and iron metabolism regulation.

Emerging Therapies in β-Thalassemia

Advances in understanding the underlying pathophysiology of β-thalassemia have enabled efforts toward the development of novel therapeutic modalities. These can be classified into three major categories based on their ability to target different features of the underlying disease pathophysiology: correction of the α/β globin chain imbalance, targeting ineffective erythropoiesis, and targeting iron dysregulation. This article provides an overview of these different emerging therapies that are currently in development for β-thalassemia.

Non-Transfusion-Dependent Thalassemia: A Panoramic Review

Non-transfusion-dependent thalassemia (NTDT) has been considered less severe than its transfusion-dependent variants. The most common forms of NTDT include β-thalassemia intermedia, hemoglobin E/beta thalassemia, and hemoglobin H disease. Patients with NTDT develop several clinical complications, despite their regular transfusion independence. Ineffective erythropoiesis, iron overload, and hypercoagulability are pathophysiological factors that lead to morbidities in these patients. Therefore, an early and accurate diagnosis of NTDT is essential to ascertaining early interventions. Currently, several conventional management options are available, with guidelines suggested by the Thalassemia International Federation, and novel therapies are being developed in light of the advancement of the understanding of this disease. This review aimed to increase clinicians’ awareness of NTDT, from its basic medical definition and genetics to its pathophysiology. Specific complications to NTDT were reviewed, along with the risk factors for its development. The indications of different therapeutic options were outlined, and recent advancements were reviewed.

The Roles of Mitophagy and Autophagy in Ineffective Erythropoiesis in β-Thalassemia

β-Thalassemia is one of the most common genetically inherited disorders worldwide, and it is characterized by defective β-globin chain synthesis leading to reduced or absent β-globin chains. The excess α-globin chains are the key factor leading to the death of differentiating erythroblasts in a process termed ineffective erythropoiesis, leading to anemia and associated complications in patients. The mechanism of ineffective erythropoiesis in β-thalassemia is complex and not fully understood. Autophagy is primarily known as a cell recycling mechanism in which old or dysfunctional proteins and organelles are digested to allow recycling of constituent elements. In late stage, erythropoiesis autophagy is involved in the removal of mitochondria as part of terminal differentiation. Several studies have shown that autophagy is increased in earlier erythropoiesis in β-thalassemia erythroblasts, as compared to normal erythroblasts. This review summarizes what is known about the role of autophagy in β-thalassemia erythropoiesis and shows that modulation of autophagy and its interplay with apoptosis may provide a new therapeutic route in the treatment of β-thalassemia. Literature was searched and relevant articles were collected from databases, including PubMed, Scopus, Prospero, Clinicaltrials.gov, Google Scholar, and the Google search engine. Search terms included: β-thalassemia, ineffective erythropoiesis, autophagy, novel treatment, and drugs during the initial search. Relevant titles and abstracts were screened to choose relevant articles. Further, selected full-text articles were retrieved, and then, relevant cross-references were scanned to collect further information for the present review.

In silico multiscale drug design to discover key structural features of potential JAK2 inhibitors

Background: JAK2 inhibitors have been proposed as a new therapeutic option for thalassemia therapy. The objective of this study was to discover the key structural features for improving 2-aminopyrimidine derivatives as potential JAK2 inhibitors. Materials & methods: Quantitative structure-activity relationship (QSAR) approaches (hologram QSAR and comparative molecular similarity indices analysis), molecular dynamics simulations, binding energy calculations and pharmacokinetic predictions were employed. Results: Reliable QSAR models, binding mode and binding interactions of JAK2 inhibitors were obtained and these obtained results were used as the key information for rational design of highly potent JAK2 inhibitors. Conclusion: The concept of new potential JAK2 inhibitors integrated from the obtained results was proved, producing two newly designed compounds, D01 and D02, with potential for use as JAK2 inhibitors.

Improving Ineffective Erythropoiesis in Thalassemia: A Hope on the Horizon

Beta-thalassemia is an inherited hemoglobinopathy characterized by the impaired synthesis of beta-globin chains of hemoglobin leading to chronic hemolytic anemia. The mainstay of treatment for most patients remains regular blood transfusions and iron chelation. This conventional therapy has many limitations and challenges. Allogeneic hematopoietic stem cell transplant (HSCT) is the only available curative treatment but the availability of a suitable donor, financial constraints, and a need for specialist physicians can be limiting factors. Gene therapy is an upcoming curative therapeutic modality. An increased understanding of the underlying pathophysiology and molecular mechanisms of thalassemia has paved the way for novel pharmacological agents targeting ineffective erythropoiesis. These drugs act by decreasing transfusion requirements and hence decrease transfusion-related complications. The present review intends to provide an insight into the recent advances in pharmacological agents targeting ineffective erythropoiesis. Literature was searched and relevant articles evaluating newer drugs in thalassemia were collected from databases, including Pubmed, Scopus, Prospero, Clinicaltrials.gov, Google Scholar, and the Google search engine. We used the following keywords: thalassemia, novel, treatment, drugs, and ineffective erythropoiesis during the initial search. Relevant titles and abstracts were screened to choose relevant articles. Further, the full-text articles were retrieved and relevant cross-references were scanned to collect information for the present review.

2021 update on clinical trials in β-thalassemia

The treatment landscape for patients with β-thalassemia is witnessing a swift evolution, yet several unmet needs continue to persist. Patients with transfusion-dependent β-thalassemia (TDT) primarily rely on regular transfusion and iron chelation therapy, which can be associated with considerable treatment burden and cost. Patients with non-transfusion-dependent β-thalassemia (NTDT) are also at risk of significant morbidity due to the underlying anemia and iron overload, but treatment options in this patient subgroup are limited. In this review, we provide updates on clinical trials of novel therapies targeting the underlying pathology in β-thalassemia, including the α/non-α-globin chain imbalance, ineffective erythropoiesis, and iron dysregulation.

The Role of Iron in Benign and Malignant Hematopoiesis

Significance: Iron is an essential element required for sustaining a normal healthy life. However, an excess amount of iron in the bloodstream and tissue generates toxic hydroxyl radicals through Fenton reactions. Henceforth, a balance in iron concentration is extremely important to maintain cellular homeostasis in both normal hematopoiesis and erythropoiesis. Iron deficiency or iron overload can impact hematopoiesis and is associated with many hematological diseases. Recent Advances: The mechanisms of action of key iron regulators such as erythroferrone and the discovery of new drugs, such as ACE-536/luspatercept, are of potential interest to treat hematological disorders, such as β-thalassemia. New therapies targeting inflammation-induced ineffective erythropoiesis are also in progress. Furthermore, emerging evidences support differential interactions between iron and its cellular antioxidant responses of hematopoietic and neighboring stromal cells. Both iron and its systemic regulator, such as hepcidin, play a significant role in regulating erythropoiesis. Critical Issues: Significant pre-clinical studies are on the way and new drugs targeting iron metabolism have been recently approved or are undergoing clinical trials to treat pathological conditions with impaired erythropoiesis such as myelodysplastic syndromes or β-thalassemia. Future Directions: Future studies should explore how iron regulates hematopoiesis in both benign and malignant conditions. Antioxid. Redox Signal. 35, 415-432.

Innovative Treatments for Rare Anemias

Rare anemias (RA) are mostly hereditary disorders with low prevalence and a broad spectrum of clinical severity, affecting different stages of erythropoiesis or red blood cell components. RA often remains underdiagnosed or misdiagnosed, and treatment options have been limited to supportive care for many years. During the last decades, the elucidation of the molecular mechanisms underlying several RA paved the way for developing new treatments. Innovative treatments other than supportive care and allogeneic bone marrow transplantation are currently in clinical trials for β-thalassemias, sickle cell disease (SCD), and congenital hemolytic anemias. Recently, luspatercept, an activin receptor ligand trap targeting ineffective erythropoiesis, has been approved as the first pharmacological treatment for transfusion-dependent β-thalassemia. L-glutamine, voxelotor, and crizanlizumab are new drugs approved SCD, targeting different steps of the complex pathophysiological mechanism. Gene therapy represents an innovative and encouraging strategy currently under evaluation in several RA and recently approved for β-thalassemia. Moreover, the advent of gene-editing technologies represents an additional option, mainly focused on correcting the defective gene or editing the expression of genes that regulate fetal hemoglobin synthesis. In this review, we aim to update the status of innovative treatments and the ongoing trials and discuss RA treatments’ future directions. Interestingly, several molecules that showed promising results for treating one of these disorders are now under evaluation in the others. In the near future, the management of RA will probably consist of polypharmacotherapy tailored to patients’ characteristics.

Novel therapies in β-thalassaemia

Beta-thalassaemia is one of the most significant haemoglobinopathies worldwide resulting in the synthesis of little or no β-globin chains. Without treatment, β-thalassaemia major is lethal within the first decade of life due to the complex pathophysiology, which leads to wide clinical manifestations. Current clinical management for these patients depends on repeated transfusions followed by iron-chelating therapy. Several novel approaches to correct the resulting α/β-globin chain imbalance, treat ineffective erythropoiesis and improve iron overload are currently being developed. Up to now, the only curative treatment for β-thalassemia is haematopoietic stem-cell transplantation, but this is a risky and costly procedure. Gene therapy, gene editing and base editing are emerging as a powerful approach to treat this disease. In β-thalassaemia, gene therapy involves the insertion of a vector containing the normal β-globin or γ-globin gene into haematopoietic stem cells to permanently produce normal red blood cells. Gene editing and base editing involves the use of zinc finger nucleases, transcription activator-like nucleases and clustered regularly interspaced short palindromic repeats/Cas9 to either correct the causative mutation or else insert a single nucleotide variant that will increase foetal haemoglobin. In this review, we will examine the current management strategies used to treat β-thalassaemia and focus on the novel therapies targeting ineffective erythropoiesis, improving iron overload and correction of the globin chain imbalance.

Drug safety in thalassemia: lessons from the present and directions for the future

Introduction: Beta-thalassemia is an autosomal recessive hereditary anemia characterized by reduced or absent β-globin chain synthesis, affecting about 60,000 people peryear. Management for β-thalassemia major includes regular blood transfusions followed by iron chelating therapy and drug targeting ineffective erythropoiesis.Areas covered: The safety of licensed drugs for the management of β-thalassemia is reviewed, using evidence from clinical trials and observational research. Such drugs include the iron chelators and the erythrocyte maturation agent luspatercept. The safety of emerging treatment, such as hydroxyurea and thalidomide is also reviewed.Expert opinion: Beta-thalassemia is arare disease, and is not surprising that there are limited studies investigating the safety of drugs used in this disease. Indeed, although observational studies are the main source of drug safety information in areal-world setting, only eleven studies were identified for iron-chelators and none of these estimated the risk of agiven safety outcome. Future work should aim to better leverage existing sources of real-world datato investigate drug safety in thalassemia.

Beta Thalassemia: New Therapeutic Options Beyond Transfusion and Iron Chelation

Hemoglobinopathies are among the most common monogenic diseases worldwide. Approximately 1–5% of the global population are carriers for a genetic thalassemia mutation. The thalassemias are characterized by autosomal recessive inherited defects in the production of hemoglobin. They are highly prevalent in the Mediterranean, Middle East, Indian subcontinent, and East and Southeast Asia. Due to recent migrations, however, the thalassemias are now becoming more common in Europe and North America, making this disease a global health concern. Currently available conventional therapies in thalassemia have many challenges and limitations. A better understanding of the pathophysiology of β-thalassemia in addition to key developments in optimizing transfusion programs and iron-chelation therapy has led to an increase in the life span of thalassemia patients and paved the way for new therapeutic strategies. These can be classified into three categories based on their efforts to address different features of the underlying pathophysiology of β-thalassemia: correction of the globin chain imbalance, addressing ineffective erythropoiesis, and improving iron overload. In this review, we provide an overview of the novel therapeutic approaches that are currently in development for β-thalassemia.

Heparanase Level and Procoagulant Activity Are Increased in Thalassemia and Attenuated by Janus Kinase 2 Inhibition

Patients with thalassemia exhibit an increased risk of thrombotic events that is augmented after splenectomy. Heparanase protein enhances cancer progression, angiogenesis, and inflammation; it also activates the coagulation system through direct interaction with tissue factor (TF). Additionally, erythropoietin, which is elevated in anemic patients, up-regulates heparanase expression via the Janus kinase 2 (JAK-2) pathway. This study aimed was to explore the heparanase profile in thalassemia. Coagulation factors were analyzed via immunostaining, enzyme-linked immunosorbent assay, and heparanase procoagulant activity assay. In spleen specimens of thalassemia major patients, a higher level of heparanase staining was observed compared with control spleens resected after trauma (P < 0.001). Higher heparanase levels, heparanase and TF procoagulant activity, and erythropoietin levels were found in the plasma of 67 thalassemia major patients compared with 29 control subjects. No difference was found in pediatric patients (23 of 67) compared with adults or splenectomized versus nonsplenectomized patients. Higher levels of heparanase, TF, TF pathway inhibitor, and TF pathway inhibitor-2 were observed in liver, spleen, heart, and kidney tissues of thalassemia intermedia mice (Hbb^th3/+). These protein levels significantly reduced when mice were treated with the JAK-2 inhibitor ruxolitinib (P < 0.0001). In summary, heparanase levels are elevated in thalassemia, which may contribute to thrombotic phenomena in these patients. Inhibition of heparanase or the JAK-2 pathway may reduce thrombotic risk in thalassemia.

Oxidation and erythropoiesis

PURPOSE OF REVIEW

Erythropoiesis is a complex multistep process going from committed erythroid progenitors to mature red cells. Although recent advances allow the characterization of some components of erythropoiesis, much still remains to be investigated particularly on stress erythropoiesis. This review summarizes recent progresses made to understand the impact of oxidative stress on normal and pathologic erythropoiesis.

RECENT FINDINGS

During erythroid maturation, reactive oxygen species might function as second messenger through either transient oxidation of cysteine residues on signaling targets or modulation of intracellular signaling pathways. Thus, in erythropoiesis, efficient cytoprotective systems are required to limit possible reactive oxygen species-related toxic effects especially in stress erythropoiesis characterized by severe oxidation such as β-thalassemia. In addition, prolonged or severe oxidative stress impairs autophagy, which might contribute to the block of erythroid maturation in stress erythropoiesis. Understanding the functional role of cytoprotective systems such as peroxiredoxin-2 or classical molecular chaperones such as the heat shock proteins will contribute to develop innovative therapeutic strategies for ineffective erythropoiesis.

SUMMARY

We provide an update on cytoprotective mechanisms against oxidation in normal and stress erythropoiesis. We discuss the role of oxidative sensors involved in modulation of intracellular signaling during erythroid maturation process in normal and stress erythropoiesis.

Oxidation Impacts the Intracellular Signaling Machinery in Hematological Disorders

The dynamic coordination between kinases and phosphatases is crucial for cell homeostasis, in response to different stresses. The functional connection between oxidation and the intracellular signaling machinery still remains to be investigated. In the last decade, several studies have highlighted the role of reactive oxygen species (ROS) as modulators directly targeting kinases, phosphatases, and downstream modulators, or indirectly acting on cysteine residues on kinases/phosphatases resulting in protein conformational changes with modulation of intracellular signaling pathway(s). Translational studies have revealed the important link between oxidation and signal transduction pathways in hematological disorders. The intricate nature of intracellular signal transduction mechanisms, based on the generation of complex networks of different types of signaling proteins, revealed the novel and important role of phosphatases together with kinases in disease mechanisms. Thus, therapeutic approaches to abnormal signal transduction pathways should consider either inhibition of overactivated/accumulated kinases or homeostatic signaling resetting through the activation of phosphatases. This review discusses the progress in the knowledge of the interplay between oxidation and cell signaling, involving phosphatase/kinase systems in models of globally distributed hematological disorders.

Beta Thalassemia: Monitoring and New Treatment Approaches

Beta thalassemias are a significant global health problem. Globin chain imbalance leads to a complex physiologic cascade of hemolytic anemia, ineffective erythropoiesis, and iron overload. Management of the broad spectrum of phenotypes requires the careful use of red blood transfusions, supportive care, monitoring, and management of iron overload. In this article, the authors discuss recommendations for monitoring of individuals with thalassemia, as well as ongoing preclinical and clinical trials of therapies targeting different aspects of thalassemia pathophysiology.

Iron metabolism under conditions of ineffective erythropoiesis in β-thalassemia

β-Thalassemia (BT) is an inherited genetic disorder that is characterized by ineffective erythropoiesis (IE), leading to anemia and abnormal iron metabolism. IE is an abnormal expansion of the number of erythroid progenitor cells with unproductive synthesis of enucleated erythrocytes, leading to anemia and hypoxia. Anemic patients affected by BT suffer from iron overload, even in the absence of chronic blood transfusion, suggesting the presence of ≥1 erythroid factor with the ability to modulate iron metabolism and dietary iron absorption. Recent studies suggest that decreased erythroid cell differentiation and survival also contribute to IE, aggravating the anemia in BT. Furthermore, hypoxia can also affect and increase iron absorption. Understanding the relationship between iron metabolism and IE could provide important insights into the BT condition and help to develop novel treatments. In fact, genetic or pharmacological manipulations of iron metabolism or erythroid cell differentiation and survival have been shown to improve IE, iron overload, and anemia in animal models of BT. Based on those findings, new therapeutic approaches and drugs have been proposed; clinical trials are underway that have the potential to improve erythrocyte production, as well as to reduce the iron overload and organ toxicity in BT and in other disorders characterized by IE.

Transferrin receptor 2 is a potential novel therapeutic target for β-thalassemia: evidence from a murine model

β-thalassemias are genetic disorders characterized by anemia, ineffective erythropoiesis, and iron overload. Current treatment of severe cases is based on blood transfusion and iron chelation or allogeneic bone marrow (BM) transplantation. Novel approaches are explored for nontransfusion-dependent patients (thalassemia intermedia) who develop anemia and iron overload. Here, we investigated the erythropoietin (EPO) receptor partner, transferrin receptor 2 (TFR2), as a novel potential therapeutic target. We generated a murine model of thalassemia intermedia specifically lacking BM Tfr2: because their erythroid cells are more susceptible to EPO stimulation, mice show improved erythropoiesis and red blood cell morphology as well as partial correction of anemia and iron overload. The beneficial effects become attenuated over time, possibly due to insufficient iron availability to sustain the enhanced erythropoiesis. Germ line deletion of Tfr2, including haploinsufficiency, had a similar effect in the thalassemic model. Because targeting TFR2 enhances EPO-mediated effects exclusively in cells expressing both receptors, this approach may have advantages over erythropoiesis-stimulating agents in the treatment of other anemias.