Iron Overload and Chelation Therapy in Non-Transfusion Dependent Thalassemia

Impact of the COVID-19 Pandemic on Iron Overload Assessment by MRI in Patients with Hemoglobinopathies: The E-MIOT Network Experience

BACKGROUND

The E-MIOT (Extension-Myocardial Iron Overload in Thalassemia) project is an Italian Network assuring high-quality quantification of tissue iron overload by magnetic resonance imaging (MRI). We evaluated the impact of the COVID-19 pandemic on E-MIOT services.

METHODS

The activity of the E-MIOT Network MRI centers in the year 2020 was compared with that of 2019. A survey evaluated whether the availability of MRI slots for patients with hemoglobinopathies was reduced and why.

RESULTS

The total number of MRI scans was 656 in 2019 and 350 in 2020, with an overall decline of 46.4% (first MRI: 71.7%, follow-up MRI: 36.9%), a marked decline (86.9%) in the period March-June 2020, and a reduction in the gap between the two years in the period July-September. A new drop (41.4%) was recorded in the period October-December for two centers, due to the general reduction in the total amount of MRIs/day for sanitization procedures. In some centers, patients refused MRI scans for fear of getting COVID. Drops in the MRI services >80% were found for patients coming from a region without an active MRI site.

CONCLUSIONS

The COVID-19 pandemic had a strong negative impact on MRI multi-organ iron quantification, with a worsening in the management of patients with hemoglobinopathies.

Correlation Between Serum Ferritin and Degree of Hepatic Fibrosis on Fibroscan in Thalassemic Patients

Aim and objective This study aimed to examine the relationship between serum ferritin levels and the degree of hepatic fibrosis as detected on Fibroscan in thalassemia patients. Materials and methods This was a single-center and cross-sectional study conducted from April 2021 to December 2022. The sample population comprised 55 beta-thalassemia patients receiving treatment at the National Institute of Blood Diseases and Bone Marrow Transplantation, Karachi, Pakistan. The data was compiled through a series of patient interviews, an examination of medical records and was analyzed to obtain the results. Descriptive statistics were used for several variables, including diagnosis, Fibroscan score, blood group, comorbidity, visceromegaly, consanguinity, serum glutamate pyruvate transaminase (SGPT), viral markers, and C reactive protein (CRP). The correlation analysis was done using Spearman's correlation test. Results There were 55 participants in the study, 40 of whom were male and 15 of whom were female. The mean age of the patients was eight years, while the average age at diagnosis was nine months with a transfusion frequency of every 20 days. Spearman's rho (r = 0.287), and the significant value of (p = 0.033) confirmed a statistically significant positive correlation between serum ferritin levels and hepatic fibrosis. On Fibroscan, 74.5% of patients had F0-F1 stage fibrosis followed by 14.5% of the patients having F2 stage fibrosis. HCV seropositivity was the most prevalent comorbidity among the patients. 80% of patients had serum ferritin levels greater than 1000 ug/mL. Hepatosplenomegaly was present in 43.6% of the patients. 78.2% of patients were born out of consanguineous marriages. Conclusion In conclusion, this study found a statistically significant positive correlation between serum ferritin levels and hepatic fibrosis in beta-thalassemia patients. The study emphasizes the significance of monitoring serum ferritin levels in thalassemia patients to prevent hepatic fibrosis.

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.

Is the Role of Hepcidin and Erythroferrone in the Pathogenesis of Beta Thalassemia the Key to Developing Novel Treatment Strategies?

Thalassemia is a disease of erythrocytes that varies largely on its genetic composition and associated clinical presentation. Though some patients may remain asymptomatic, those with a complicated course may experience severe anemia early in childhood, carrying into adulthood and requiring recurrent blood transfusions as a pillar of symptom management. Due to the consequences of ineffective erythropoiesis and frequent transfusions, patients with severe beta thalassemia may be subsequently susceptible to hemochromatosis. In light of the established role of hepcidin and erythroferrone in the pathogenesis of beta thalassemia, this review aims to discuss current clinical trials and studies in the field while presenting clinical implications of the HAMP gene polymorphisms and novel treatments. Research suggested incorporating erythroferrone and serum hepcidin testing as a part of routine workups for beta thalassemia, as they could be a predictive tool for early iron accumulation. Furthermore, ameliorating low hepcidin and high erythroferrone appeared to be crucial in treating beta thalassemia and its complications due to iron overload. Currently, hepcidin-like compounds, such as minihepcidins, LJPC-401, PTG-300, VIT-2763, and agents that promote hepcidin production by inhibiting TMPRSS6 expression or erythroferrone, were shown to be effective in restoring iron homeostasis in preliminary studies. Moreover, the natural bioactives astragalus polysaccharide and icariin have been recently recognized as hepcidin expression inductors.

Deferiprone has less benefits on gut microbiota and metabolites in high iron-diet induced iron overload thalassemic mice than in iron overload wild-type mice: A preclinical study

AIMS

This study aimed to investigate the changes in gut microbiota in iron-overload thalassemia and the roles of an iron chelator on gut dysbiosis/inflammation, and metabolites, including short-chain fatty acids (SCFAs) and trimethylamine N-oxide (TMAO).

MAIN METHODS

Adult male C57BL/6 mice both wild-type (WT: n = 15) and heterozygous β-thalassemia (BKO: n = 15) were fed on either a normal (ND: n = 5/group) or a high‑iron diet for four months (HFe: n = 10/group). HFe-treated WT and HFe-treated BKO groups were further subdivided into two subgroups and each subgroup given either vehicle (n = 5/subgroup) or deferiprone (n = 5/subgroup) during the last month. Gut microbiota profiles, gut barrier characteristics, levels of proinflammatory cytokines, and plasma SCFAs and TMAO were determined at the end of the study.

KEY FINDINGS

HFe-fed WT mice showed distinct gut microbiota profiles from those of ND-fed WT mice, whereas HFe-fed BKO mice showed slightly different gut microbiota profiles from ND-fed BKO. Gut inflammation and barrier disruption were found only in HFe-fed BKO mice, however, an increase in plasma TMAO levels and decreased levels of SCFAs were observed in both WT and BKO mice with HFe-feeding. Treatment with deferiprone, gut dysbiosis and disturbance of metabolites were attenuated in HFe-fed WT mice, but not in HFe-fed BKO mice. Increased Verrucomicrobia and Ruminococcaceae were associated with the beneficial effects of deferiprone.

SIGNIFICANCE

Iron-overload leads to gut dysbiosis/inflammation and disturbance of metabolites, and deferiprone alleviates those conditions more effectively in WT than in those that are thalassemic.

Iron Chelators in Treatment of Iron Overload

Patients suffering from iron overload can experience serious complications. In such patients, various organs, such as endocrine glands and liver, can be damaged. Although iron is a crucial element for life, iron overload can be potentially toxic for human cells due to its role in generating free radicals. In the past few decades, there has been a major improvement in the survival of patients who suffer from iron overload due to the application of iron chelation therapy in clinical practice. In clinical use, deferoxamine, deferiprone, and deferasirox are the three United States Food and Drug Administration-approved iron chelators. Each of these iron chelators is well known for the treatment of iron overload in various clinical conditions. Based on several up-to-date studies, this study explained iron overload and its clinical symptoms, introduced each of the above-mentioned iron chelators, and evaluated their advantages and disadvantages with an emphasis on combination therapy, which in recent studies seems a promising approach. In numerous clinical conditions, due to the lack of accurate indicators, choosing a standard approach for iron chelation therapy can be difficult; therefore, further studies on the issue are still required. This study aimed to introduce each of these iron chelators, combination therapy, usage doses, specific clinical applications, and their advantages, toxicity, and side effects.

Post-mortem liver and bone marrow iron quantification in haemodialysis patients: A prospective cohort study

Background

Magnetic resonance liver scans indicate that iron overload is common in haemodialysis (HD) patients. However, histological evidence is scarce.

Methods

Liver biopsy and bone marrow aspirate were obtained in the first 24h post mortem from 21 adult HD patients. Biochemical liver iron content (LIC) was quantified by electrothermal atomization atomic absorption spectrophotometry. Tissue iron deposition was graded in the liver and bone marrow using Scheuer and Gale's criteria, respectively.

Findings

Median LIC was 42.5 (22.9-69.7) μmol/g and the majority (n=11; 57%) had mild to moderate liver iron overload (LIC >36 μmol/g). Scheuer grade was 2 (1-3) and 13 (62%) of liver biopsies had increased (> 1) iron deposition. In the bone marrow, median Gale's grade was 3 (3-4) and 9 (45%) patients had increased (>3) iron content.

Contrary to old autopsy studies, done in the pre-erythropoiesis-stimulating agents (ESAs) era, both liver and bone marrow were iron replete and showed a positive correlation (r=0.71, p<0.001).

Ferritin proved to have a good diagnostic accuracy for liver iron overload (0.87 95% CI 0.71-1.00) with an optimal cut-off value of 422 ng/ml. Haemoglobin was negatively associated with both LIC (r= -0.46, p=0.04) and iron content in the bone marrow (p=0.04). Patients with increased LIC had higher resistance to ESAs (p=0.02), yet no association with previous IV iron therapy.

Interpretation

In the majority of HD patients there was iron accumulation in both the liver and bone marrow that associated with anaemia severity and resistance to ESAs, suggesting a blocking mechanism of iron's utilization.

Funding

None.

Activation of STAT and SMAD Signaling Induces Hepcidin Re-Expression as a Therapeutic Target for β-Thalassemia Patients

Iron homeostasis is regulated by hepcidin, a hepatic hormone that controls dietary iron absorption and plasma iron concentration. Hepcidin binds to the only known iron export protein, ferroportin (FPN), which regulates its expression. The major factors that implicate hepcidin regulation include iron stores, hypoxia, inflammation, and erythropoiesis. When erythropoietic activity is suppressed, hepcidin expression is hampered, leading to deficiency, thus causing an iron overload in iron-loading anemia, such as β-thalassemia. Iron overload is the principal cause of mortality and morbidity in β-thalassemia patients with or without blood transfusion dependence. In the case of thalassemia major, the primary cause of iron overload is blood transfusion. In contrast, iron overload is attributed to hepcidin deficiency and hyperabsorption of dietary iron in non-transfusion thalassemia. Beta-thalassemia patients showed marked hepcidin suppression, anemia, iron overload, and ineffective erythropoiesis (IE). Recent molecular research has prompted the discovery of new diagnostic markers and therapeutic targets for several diseases, including β-thalassemia. In this review, signal transducers and activators of transcription (STAT) and SMAD (structurally similar to the small mothers against decapentaplegic in Drosophila) pathways and their effects on hepcidin expression have been discussed as a therapeutic target for β-thalassemia patients. Therefore, re-expression of hepcidin could be a therapeutic target in the management of thalassemia patients. Data from 65 relevant published experimental articles on hepcidin and β-thalassemia between January 2016 and May 2021 were retrieved by using PubMed and Google Scholar search engines. Published articles in any language other than English, review articles, books, or book chapters were excluded.

Impaired bone marrow microenvironment and stem cells in transfusion-dependent beta-thalassemia

Beta-thalassemia (BT) is a hereditary disease caused by abnormal hemoglobin synthesis with consequent ineffective erythropoiesis. Patients with thalassemia major are dependent on long-term blood transfusions with associated long-term complications such as iron overload (IO). This excess iron can result in tissue damage, impaired organ function, and increased morbidity. Growing evidence has demonstrated that IO contributes to impairment of the bone marrow (BM) microenvironment that largely impacts the function of BM mesenchymal stem cells, hematopoietic stem cells, and endothelial cells. In this article, we review recent progress in the understanding of iron metabolism and the perniciousness induced by IO. We highlight the importance of understanding the cross-talk between BM stem cells and the BM microenvironment, particularly the pathological effect of IO on BM stem cells and BT-associated complications. We also provide an update on recent novel therapies to cure transfusion-dependent beta-thalassemia and iron overload-induced complications for their future clinical application.

Oral ferroportin inhibitor vamifeport for improving iron homeostasis and erythropoiesis in β-thalassemia: current evidence and future clinical development

INTRODUCTION

In β-thalassemia, imbalanced globin synthesis causes reduced red blood cell survival and ineffective erythropoiesis. Suppressed hepcidin levels increase ferroportin-mediated iron transport in enterocytes, causing increased iron absorption and potentially iron overload. Low hepcidin also stimulates ferroportin-mediated iron release from macrophages, increasing transferrin saturation (TSAT), potentially forming non-transferrin-bound iron, which can be toxic. Modulating the hepcidin-ferroportin axis is an attractive strategy to improve ineffective erythropoiesis and limit the potential tissue damage resulting from iron overload. There are no oral β-thalassemia treatments that consistently ameliorate anemia and prevent iron overload.

AREAS COVERED

The preclinical and clinical development of vamifeport (VIT-2763), a novel ferroportin inhibitor, was reviewed. PubMed, EMBASE and ClinicalTrials.gov were searched using the search term 'VIT-2763'.

EXPERT OPINION

Vamifeport is the first oral ferroportin inhibitor in clinical development. In healthy volunteers, vamifeport had comparable safety to placebo, was well tolerated and rapidly decreased iron levels and reduced TSAT, consistent with observations in preclinical models. Data from ongoing/planned Phase II studies are critical to define its potential in β-thalassemia and other conditions associated with iron overabsorption and/or ineffective erythropoiesis. If vamifeport potentially increases hemoglobin and reduces iron-related parameters, it could be a suitable treatment for non-transfusion-dependent and transfusion-dependent β-thalassemia.

Correcting β-thalassemia by combined therapies that restrict iron and modulate erythropoietin activity

β-Thalassemia intermedia is a disorder characterized by ineffective erythropoiesis (IE), anemia, splenomegaly, and systemic iron overload. Novel approaches are being explored based on the modulation of pathways that reduce iron absorption (ie, using hepcidin activators like Tmprss6-antisense oligonucleotides [ASOs]) or increase erythropoiesis (by erythropoietin [EPO] administration or modulating the ability of transferrin receptor 2 [Tfr2] to control red blood cell [RBC] synthesis). Targeting Tmprss6 messenger RNA by Tmprss6-ASO was proven to be effective in improving IE and splenomegaly by inducing iron restriction. However, we postulated that combinatorial strategies might be superior to single therapies. Here, we combined Tmprss6-ASO with EPO administration or removal of a single Tfr2 allele in the bone marrow of animals affected by β-thalassemia intermedia (Hbbth3/+). EPO administration alone or removal of a single Tfr2 allele increased hemoglobin levels and RBCs. However, EPO or Tfr2 single-allele deletion alone, respectively, exacerbated or did not improve splenomegaly in β-thalassemic mice. To overcome this issue, we postulated that some level of iron restriction (by targeting Tmprss6) would improve splenomegaly while preserving the beneficial effects on RBC production mediated by EPO or Tfr2 deletion. While administration of Tmprss6-ASO alone improved the anemia, the combination of Tmprss6-ASO + EPO or Tmprss6-ASO + Tfr2 single-allele deletion produced significantly higher hemoglobin levels and reduced splenomegaly. In conclusion, our results clearly indicate that these combinatorial approaches are superior to single treatments in ameliorating IE and anemia in β-thalassemia and could provide guidance to translate some of these approaches into viable therapies.

The Interplay between Drivers of Erythropoiesis and Iron Homeostasis in Rare Hereditary Anemias: Tipping the Balance

Rare hereditary anemias (RHA) represent a group of disorders characterized by either impaired production of erythrocytes or decreased survival (i.e., hemolysis). In RHA, the regulation of iron metabolism and erythropoiesis is often disturbed, leading to iron overload or worsening of chronic anemia due to unavailability of iron for erythropoiesis. Whereas iron overload generally is a well-recognized complication in patients requiring regular blood transfusions, it is also a significant problem in a large proportion of patients with RHA that are not transfusion dependent. This indicates that RHA share disease-specific defects in erythroid development that are linked to intrinsic defects in iron metabolism. In this review, we discuss the key regulators involved in the interplay between iron and erythropoiesis and their importance in the spectrum of RHA.

The Oral Ferroportin Inhibitor VIT-2763 Improves Erythropoiesis without Interfering with Iron Chelation Therapy in a Mouse Model of β-Thalassemia

In β-thalassemia, ineffective erythropoiesis leads to anemia and systemic iron overload. The management of iron overload by chelation therapy is a standard of care. However, iron chelation does not improve the ineffective erythropoiesis. We recently showed that the oral ferroportin inhibitor VIT-2763 ameliorates anemia and erythropoiesis in the Hbb^th3/+ mouse model of β-thalassemia. In this study, we investigated whether concurrent use of the iron chelator deferasirox (DFX) and the ferroportin inhibitor VIT-2763 causes any pharmacodynamic interactions in the Hbb^th3/+ mouse model of β-thalassemia. Mice were treated with VIT-2763 or DFX alone or with the combination of both drugs once daily for three weeks. VIT-2763 alone or in combination with DFX improved anemia and erythropoiesis. VIT-2763 alone decreased serum iron and transferrin saturation (TSAT) but was not able to reduce the liver iron concentration. While DFX alone had no effect on TSAT and erythropoiesis, it significantly reduced the liver iron concentration alone and in the presence of VIT-2763. Our results clearly show that VIT-2763 does not interfere with the iron chelation efficacy of DFX. Furthermore, VIT-2763 retains its beneficial effects on improving ineffective erythropoiesis when combined with DFX in the Hbb^th3/+ mouse model. In conclusion, co-administration of the oral ferroportin inhibitor VIT-2763 and the iron chelator DFX is feasible and might offer an opportunity to improve both ineffective erythropoiesis and iron overload in β-thalassemia.

Efficacy and safety of iron chelator for transfusion-dependent patients with myelodysplastic syndrome: a meta-analysis

To systematically evaluate the efficacy and safety of iron chelators for transfusion-dependent patients with MDS. Thirteen cohort studies with 12,990 patients diagnosed with MDS were included in this study. According to m eta-analysis results transfusion-dependent MDS patients with secondary iron overload had a longer (HR = 0.52, 95%CI = 0.43-0.62, P < 0.001). Further subgroup analysis revealed a longer LFS (HR = 0.84, 95%CI = 0.76-0.93, P = 0.001) in MDS patients receiving iron chelators than in MDS patients not receiving iron chelators (HR = 0.52, 95%CI = 0.43-0.62, P < 0.001) and in patients with lower-risk MDS (HR = 0.50, 95%CI = 0.43-0.59, P < 0.001). Subgroup analysis of DFX showed that compared with patients not treated with iron chelators, the group receiving DFX monotherapy had significantly increased OS (HR = 0.43, 95%CI = 0.27-0.69, P < 0.001). In terms of tolerance, meta-analysis of binary variables in CAEs indicated that the occurrence of CAEs was significantly reduced by ICT (RR = 0.64, 95%CI = 0.57-0.71, P < 0.001).

Thalassemias: An Overview

Thalassemia syndromes are among the most serious and common genetic conditions. They are indigenous in a wide but specific geographical area. However, through migration they are spreading across regions not previously affected. Thalassemias are caused by mutations in the α (HBA1/HBA2) and β globin (HBB) genes and are usually inherited in an autosomal recessive manner. The corresponding proteins form the adult hemoglobin molecule (HbA) which is a heterotetramer of two α and two β globin chains. Thalassemia-causing mutations lead to an imbalanced globin chain production and consecutively to impaired erythropoiesis. The severity of the disease is largely determined by the degree of chain imbalance. In the worst case, survival is dependent on regular blood transfusions, which in turn cause transfusional iron overload and secondary multi-organ damage due to iron toxicity. A vigorous monitoring and treatment regime is required, even for the milder syndromes. Thalassemias are a major public health issue in many populations which many health authorities fail to address. Even though comprehensive care has resulted in long-term survival and good quality of life, poor access to essential components of management results in complications which increase the cost of treatment and lead to poor outcomes. These requirements are not recognized by measures such as the Global Burden of Disease project, which ranks thalassemia very low in terms of disability-adjusted life years (DALYs), and fails to consider that it ranks highly in the one to four-year-old age group, making it an important contributor to under-5 mortality. Thalassemia does not fulfil the criteria to be accepted as a target disease for neonatal screening. Nevertheless, depending on the screening methodology, severe cases of thalassemia will be detected in most neonatal screening programs for sickle cell disease. This is very valuable because: (1) it helps to prepare the affected families for having a sick child and (2) it is an important measure of secondary prevention.

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.

Bone marrow stromal cells from β-thalassemia patients have impaired hematopoietic supportive capacity

BACKGROUND. The human bone marrow (BM) niche contains a population of mesenchymal stromal cells (MSCs) that provide physical support and regulate hematopoietic stem cell (HSC) homeostasis. β-Thalassemia (BT) is a hereditary disorder characterized by altered hemoglobin beta-chain synthesis amenable to allogeneic HSC transplantation and HSC gene therapy. Iron overload (IO) is a common complication in BT patients affecting several organs. However, data on the BM stromal compartment are scarce.

METHODS. MSCs were isolated and characterized from BM aspirates of healthy donors (HDs) and BT patients. The state of IO was assessed and correlated with the presence of primitive MSCs in vitro and in vivo. Hematopoietic supportive capacity of MSCs was evaluated by transwell migration assay and 2D coculture of MSCs with human CD34⁺ HSCs. In vivo, the ability of MSCs to facilitate HSC engraftment was tested in a xenogenic transplant model, whereas the capacity to sustain human hematopoiesis was evaluated in humanized ossicle models.

RESULTS. We report that, despite iron chelation, BT BM contains high levels of iron and ferritin, indicative of iron accumulation in the BM niche. We found a pauperization of the most primitive MSC pool caused by increased ROS production in vitro which impaired MSC stemness properties. We confirmed a reduced frequency of primitive MSCs in vivo in BT patients. We also discovered a weakened antioxidative response and diminished expression of BM niche–associated genes in BT-MSCs. This caused a functional impairment in MSC hematopoietic supportive capacity in vitro and in cotransplantation models. In addition, BT-MSCs failed to form a proper BM niche in humanized ossicle models.

CONCLUSION. Our results suggest an impairment in the mesenchymal compartment of BT BM niche and highlight the need for novel strategies to target the niche to reduce IO and oxidative stress before transplantation.

FUNDING. This work was supported by the SR-TIGET Core grant from Fondazione Telethon and by Ricerca Corrente.

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.