New strategies to target iron metabolism for the treatment of beta thalassemia

Loss of miR-144/451 alleviates β-thalassemia by stimulating ULK1-mediated autophagy of free α-globin

Most cells can eliminate unstable or misfolded proteins through quality control mechanisms. In the inherited red blood cell disorder β-thalassemia, mutations in the β-globin gene (HBB) lead to a reduction in the corresponding protein and the accumulation of cytotoxic free α-globin, which causes maturation arrest and apoptosis of erythroid precursors and reductions in the lifespan of circulating red blood cells. We showed previously that excess α-globin is eliminated by Unc-51-like autophagy activating kinase 1 (ULK1)-dependent autophagy and that stimulating this pathway by systemic mammalian target of rapamycin complex 1 (mTORC1) inhibition alleviates β-thalassemia pathologies. We show here that disrupting the bicistronic microRNA gene miR-144/451 alleviates β-thalassemia by reducing mTORC1 activity and stimulating ULK1-mediated autophagy of free α-globin through 2 mechanisms. Loss of miR-451 upregulated its target messenger RNA, Cab39, which encodes a cofactor for LKB1, a serine-threonine kinase that phosphorylates and activates the central metabolic sensor adenosine monophosphate-activated protein kinase (AMPK). The resultant enhancement of LKB1 activity stimulated AMPK and its downstream effects, including repression of mTORC1 and direct activation of ULK1. In addition, loss of miR-144/451 inhibited the expression of erythroblast transferrin receptor 1, causing intracellular iron restriction, which has been shown to inhibit mTORC1, reduce free α-globin precipitates, and improve hematological indices in β-thalassemia. The beneficial effects of miR-144/451 loss in β-thalassemia were inhibited by the disruption of Cab39 or Ulk1 genes. Together, our findings link the severity of β-thalassemia to a highly expressed erythroid microRNA locus and a fundamental, metabolically regulated protein quality control pathway that is amenable to therapeutic manipulation.

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.

Thalassemia and Nanotheragnostics: Advanced Approaches for Diagnosis and Treatment

Thalassemia is a monogenic autosomal recessive disorder caused by mutations, which lead to abnormal or reduced production of hemoglobin. Ineffective erythropoiesis, hemolysis, hepcidin suppression, and iron overload are common manifestations that vary according to genotypes and dictate, which diagnosis and therapeutic modalities, including transfusion therapy, iron chelation therapy, HbF induction, gene therapy, and editing, are performed. These conventional therapeutic methods have proven to be effective, yet have several disadvantages, specifically iron toxicity, associated with them; therefore, there are demands for advanced therapeutic methods. Nanotechnology-based applications, such as the use of nanoparticles and nanomedicines for theragnostic purposes have emerged that are simple, convenient, and cost-effective methods. The therapeutic potential of various nanoparticles has been explored by developing artificial hemoglobin, nano-based iron chelating agents, and nanocarriers for globin gene editing by CRISPR/Cas9. Au, Ag, carbon, graphene, silicon, porous nanoparticles, dendrimers, hydrogels, quantum dots, etc., have been used in electrochemical biosensors development for diagnosis of thalassemia, quantification of hemoglobin in these patients, and analysis of conventional iron chelating agents. This review summarizes the potential of nanotechnology in the development of various theragnostic approaches to determine thalassemia-causing gene mutations using various nano-based biosensors along with the employment of efficacious nano-based therapeutic procedures, in contrast to conventional therapies.

A farewell to phlebotomy-use of placenta-derived drugs Laennec and Porcine for improving hereditary hemochromatosis without phlebotomy: a case report

BACKGROUND

Human hepcidin, produced by hepatocytes, regulates intestinal iron absorption, iron recycling by macrophages, and iron release from hepatic storage. Recent studies indicate that hepcidin deficiency is the underlying cause of the most known form of hereditary hemochromatosis.

CASE PRESENTATION

A 44-year-old Asian man who developed type 2 diabetes mellitus had elevated serum ferritin levels (10,191 ng/mL). Liver biopsy revealed remarkable iron deposition in the hepatocytes and relatively advanced fibrosis (F3). Chromosomal analysis confirmed the presence of transferrin receptor type 2 mutations (c.1100T>G, c.2008_9delAC, hereditary hemochromatosis type 3 analyzed by Kawabata). The patient received intravenous infusions of Laennec (672 mg/day, three times/week) or oral administration with Porcine (3.87 g/day) for 84 months as an alternative to repeated phlebotomy. At the end of the treatment period, serum ferritin level decreased to 428.4 ng/mL (below the baseline level of 536.8 ng/mL). Hemoglobin A1c levels also improved after treatment with the same or lower dose of insulin (8.8% before versus 6.8% after). Plural liver biopsies revealed remarkable improvements in the grade of iron deposition and fibrosis (F3 before versus F1 after) of the liver tissue.

CONCLUSION

The discovery of hepcidin and its role in iron metabolism could lead to novel therapies for hereditary hemochromatosis. Laennec (parenteral) and Porcine (oral), which act as hepcidin inducers, actually improved iron overload in this hereditary hemochromatosis patient, without utilizing sequential phlebotomy. This suggests the possibility of not only improving the prognosis of hereditary hemochromatosis (types 1, 2, and 3) but also ameliorating complications, such as type 2 diabetes, liver fibrosis, and hypogonadism. Laennec and Porcine can completely replace continuous venesection in patients with venesection and may improve other iron-overloading disorders caused by hepcidin deficiency.

Molecular genetics of β-thalassemia: A narrative review

ABSTRACT

β-thalassemia is a hereditary hematological disease caused by over 350 mutations in the β-globin gene (HBB). Identifying the genetic variants affecting fetal hemoglobin (HbF) production combined with the α-globin genotype provides some prediction of disease severity for β-thalassemia. However, the generation of an additive composite genetic risk score predicts prognosis, and guide management requires a larger panel of genetic modifiers yet to be discovered.Presently, using data from prior clinical trials guides the design of further research and academic studies based on gene augmentation, while fundamental insights into globin switching and new technology developments have inspired the investigation of novel gene therapy approaches.Genetic studies have successfully characterized the causal variants and pathways involved in HbF regulation, providing novel therapeutic targets for HbF reactivation. In addition to these HBB mutation-independent strategies involving HbF synthesis de-repression, the expanding genome editing toolkit provides increased accuracy to HBB mutation-specific strategies encompassing adult hemoglobin restoration for personalized treatment of hemoglobinopathies. Allogeneic hematopoietic stem cell transplantation was, until very recently, the curative option available for patients with transfusion-dependent β-thalassemia. Gene therapy currently represents a novel therapeutic promise after many years of extensive preclinical research to optimize gene transfer protocols.We summarize the current state of developments in the molecular genetics of β-thalassemia over the last decade, including the mechanisms associated with ineffective erythropoiesis, which have also provided valid therapeutic targets, some of which have been shown as a proof-of-concept.

Luspatercept for β-thalassemia: beyond red blood cell transfusions

INTRODUCTION

Red blood cell transfusions and iron chelation therapy are the cornerstone of treatment for β-thalassemia, with allogeneic hematopoietic stem cell transplantation and gene therapy offering further disease-management options for eligible patients. With up to 90% of severe cases of β-thalassemia occurring in resource-constrained countries, and estimates indicating that 22,500 deaths occur annually as a direct consequence of undertransfusion, provision of adequate treatment remains a major issue.

AREAS COVERED

In this review, we provide an overview of luspatercept, a first-in-class erythroid maturation agent, and present the available clinical data related to the treatment of β-thalassemia.

EXPERT OPINION

The recent approval of luspatercept offers a new, long-term therapeutic option for adult patients with transfusion-dependent β-thalassemia to reduce red blood cell transfusion burden, anemia, and iron overload.

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.

Oral ferroportin inhibitor VIT-2763: First-in-human, phase 1 study in healthy volunteers

Restriction of iron availability by ferroportin inhibition is a novel approach to treating non‐transfusion‐dependent thalassemia (β‐thalassemia intermedia). This first‐in‐human, Phase I study (https://www.clinicaltrialsregister.eu; EudraCT no. 2017‐003395‐31) assessed the safety, tolerability, pharmacokinetics and pharmacodynamics of single‐ and multiple‐ascending doses (SAD and MAD) of the oral ferroportin inhibitor, VIT‐2763, in healthy volunteers. Participants received VIT‐2763 5/15/60/120/240 mg or placebo in the SAD phase and VIT‐2763 60/120 mg once daily, VIT‐2763 60/120 mg twice daily, or placebo for 7 days in the MAD phase. Seventy‐two participants completed treatment. VIT‐2763 was well tolerated and demonstrated a similar safety profile to the placebo. There were no serious or severe adverse events, or discontinuations due to adverse events. VIT‐2763 absorption was relatively fast, with detectable levels 15 to 30 minutes post‐dose. Following multiple dosing there was no apparent change in absorption and accumulation was minimal. Mean elimination half‐life was 1.9 to 5.3 hours following single dosing, and 2.1 to 3.8 hours on Day 1 and 2.6 to 5.3 hours on Day 7, following repeated dosing. There was a temporary decrease in mean serum iron levels with VIT‐2763 single doses ≥60 mg and all multiple doses; mean calculated transferrin saturation (only assessed following multiple dosing) also temporarily decreased. A shift in mean serum hepcidin peaks followed administration of all iron‐lowering doses of VIT‐2763. This effect was less pronounced after 7 days of multiple dosing (aside from with 120 mg once daily). These results support the initiation of clinical studies in patients with non‐transfusion‐dependent thalassemia and documented iron overload due to ineffective erythropoiesis.

Abnormal red blood cell morphological changes in thalassaemia associated with iron overload and oxidative stress

AIMS

Iron overload is a major factor contributing to the overall pathology of thalassaemia, which is primarily mediated by ineffective erythropoiesis and shorter mature red blood cell (RBC) survival. Iron accumulation in RBCs generates reactive oxygen species (ROS) that cause cellular damage such as lipid peroxidation and RBC membrane deformation. Abnormal RBCs in patients with thalassaemia are commonly known as microcytic hypochromic anaemia with poikilocytosis. However, iron and ROS accumulation in RBCs as related to RBC morphological changes in patients with thalassaemia has not been reported.

METHODS

Twenty-one patients with thalassaemia, including HbH, HbH with Hb Constant Spring and β-thalassaemia/HbE (splenectomy and non-splenectomy) genotypes, and five normal subjects were recruited. RBC morphology was analysed by light and scanning electron microscopy. Systemic and RBC iron status and oxidative stress were examined.

RESULTS

Decreased normocytes were observed in the samples of patients with thalassaemia, with RBC morphological abnormality being related to the type of disease (α-thalassaemia or β-thalassaemia) and splenic status. Target cells and crenated cells were mainly found in splenectomised patients with β-thalassaemia/HbE, while target cells and teardrop cells were found in non-splenectomised patients. Patients with thalassaemia had high levels of serum ferritin, red cell ferritin and ROS in RBCs compared with normal subjects (p<0.05). Negative correlations between the amount of normocytes and serum ferritin (r_s=-0.518, p=0.011), red cell ferritin (r_s=-0.467, p=0.025) or ROS in RBCs (r_s=-0.672, p<0.001) were observed.

CONCLUSIONS

Iron overload and its consequent intracellular oxidative stress in RBCs were associated with reduce normocytes in patients with thalassaemia.

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.

The effect of quercetin on iron overload and inflammation in β-thalassemia major patients: A double-blind randomized clinical trial

OBJECTIVES

The aim of this study was to determine whether quercetin can reduce iron overload and inflammation in thalassemic patients.

METHODS

Eighty four patients were recruited to this study and randomly assigned to two groups: 42 patients received a 500 mg/day quercetin tablet and 42 others took a 500 mg/day starch placebo for 12 weeks. Demographic, anthropometric and biochemical evaluation were performed.

RESULTS

ANCOVA analysis revealed that compared to the control group, quercetin could reduce high sensitivity C-reactive protein (hs-CRP) (P = 0.046), iron (p = 0.036), ferritin (p = 0.043), and transferrin saturation (TS) (p = 0.008) and increase transferrin (p = 0.045) significantly, but it had no significant effect on total iron binding capacity (TIBC) (p = 0.734) and tumor necrosis factor α (TNF-α) (p = 0.310).

CONCLUSIONS

Quercetin could ameliorate the iron status in thalassemia major, but its effect on inflammation is indistinctive.

The effect of vitamin D pathway genes and deferasirox pharmacogenetics on liver iron in thalassaemia major patients

Monitoring and treating iron overload is crucial in transfusion-dependent thalassaemia patients. Liver stiffness measurement by transient elastography and T2* magnetic resonance imaging represent non-invasive ways to evaluate the adequacy of the iron chelation treatment. We explored the role of single nucleotide polymorphisms involved in vitamin D metabolism, transport and activity, and in deferasirox metabolism on liver iron burden parameters. One-hundred and five beta-thalassaemia patients, treated with deferasirox, have been enrolled. Drug plasma C_trough and AUC were measured by a HPLC-UV method. Allelic discrimination was performed by real-time PCR. Age, UGT1A1-364 CT/TT and CYP27B1 -1260 GT/TT positively predicted liver stiffness values. Deferasirox dose and serum ferritin negatively predicted T2* data, whereas age and CYP2D6 1457 GG genotype positively influenced these values. The discoveries of this research may be useful for personalized medicine and the proposed method could be applied in patients with hereditary hemochromatosis and myelodysplastic syndromes.

Hepcidin agonists as therapeutic tools

Hepcidin agonists are a new class of compounds that regulate blood iron levels, limit iron absorption, and could improve the treatment of hemochromatosis, β-thalassemia, polycythemia vera, and other disorders in which disrupted iron homeostasis causes or contributes to disease. Hepcidin agonists also have the potential to prevent severe complications of siderophilic infections in patients with iron overload or chronic liver disease. This review highlights the preclinical studies that support the development of hepcidin agonists for the treatment of these disorders.