Hydroxyurea for hemoglobin E/β-thalassemia: a systematic review and meta-analysis

A randomized placebo-controlled clinical trial of oral green tea epigallocatechin 3-gallate on erythropoiesis and oxidative stress in transfusion-dependent β-thalassemia patients

β-Thalassemia patients suffer from ineffective erythropoiesis and increased red blood cell (RBC) hemolysis. Blood transfusion, erythropoietic enhancement, and antioxidant supplementation can ameliorate chronic anemia. Green tea extract (GTE) is comprised of catechin derivatives, of which epigallocatechin-3-gallate (EGCG) is the most abundant, presenting free-radical scavenging, iron-chelating, and erythropoiesis-protective effects. The present study aimed to evaluate the effects of GTE tablets on the primary outcome of erythropoiesis and oxidative stress parameters in transfusion-dependent β-thalassemia (TDT) patients. Twenty-seven TDT patients were randomly divided into placebo and GTE tablet (50 and 100 mg EGCG equivalent) groups and assigned to consume the product once daily for 60 days. Blood was collected for analysis of hematological, biochemical, and oxidative stress parameters. Accordingly, consumption of GTE tablets improved blood hemoglobin levels when compared with the placebo; however, there were more responders to the GTE tablets. Interestingly, amounts of nonheme iron in RBC membranes tended to decrease in both GTE tablet groups when compared with the placebo. Importantly, consumption of GTE tablets lowered plasma levels of erythroferrone (p < 0.05) and reduced bilirubin non-significantly and dose-independently. Thus, GTE tablets could improve RBC hemolysis and modulate erythropoiesis regulators in transfusion-dependent thalassemia patients.

A comprehensive study of immune function and immunophenotyping of white blood cells from β-thalassaemia/HbE patients on hydroxyurea supports the safety of the drug

Hydroxyurea (HU) (hydroxycarbamide) is used as a therapeutic option in β-thalassaemia to increase fetal haemoglobin, which results in a reduced requirement for blood transfusion. However, a potential serious adverse effect of HU is neutropenia. Abnormal neutrophil maturation and function in β-thalassaemia/HbE patients are well documented. This raises questions about the effect of the drug with regards to the immune response these patients. This study investigated the effects of HU treatment on both innate and adaptive immunity in a cross-sectional study of 28 β-thalassaemia/HbE patients who had received HU treatment (BE+HU) as compared with 22 β-thalassaemia/HbE patients who had not received HU (BE-HU) and 26 normal subjects. The expression of PU.1 and C/EBPβ, transcription factors, which are associated with neutrophil maturation, was significantly reduced in BE+HU patients as compared with BE-HU patients and normal subjects. Interestingly, C3bR expression on neutrophils and their oxidative burst activity in BE+HU were restored to close to normal levels when compared with BE-HU. There was no observed effect of HU on monocytes, myeloid derived suppressor cells (both granulocytic and monocytic subsets), CD4⁺ T cells, CD8⁺ T cells, complement levels and serum immunoglobulin levels in this study. The full immunophenotyping analysis in this study indicates that HU therapy in β-thalassaemia/HbE patients does not significantly compromise the immune response.

Effects of Hydroxyurea on Skeletal Muscle Energetics and Function in a Mildly Anemic Mouse Model

Hydroxyurea (HU) is a ribonucleotide reductase inhibitor most commonly used as a therapeutic agent in sickle cell disease (SCD) with the aim of reducing the risk of vaso-occlusion and improving oxygen transport to tissues. Previous studies suggest that HU may be even beneficial in mild anemia. However, the corresponding effects on skeletal muscle energetics and function have never been reported in such a mild anemia model. Seventeen mildly anemic HbAA Townes mice were subjected to a standardized rest-stimulation (transcutaneous stimulation)-protocol while muscle energetics using 31Phosphorus magnetic resonance spectroscopy and muscle force production were assessed and recorded. Eight mice were supplemented with hydroxyurea (HU) for 6 weeks while 9 were not (CON). HU mice displayed a higher specific total force production compared to the CON, with 501.35 ± 54.12 N/mm3 and 437.43 ± 57.10 N/mm3 respectively (+14.6%, p &lt; 0.05). Neither the total rate of energy consumption nor the oxidative metabolic rate were significantly different between groups. The present results illustrated a positive effect of a HU chronic supplementation on skeletal muscle function in mice with mild anemia.

Revisiting fetal hemoglobin inducers in beta-hemoglobinopathies: a review of natural products, conventional and combinatorial therapies

Beta-hemoglobinopathies exhibit a heterogeneous clinical picture with varying degrees of clinical severity. Pertaining to the limited treatment options available, where blood transfusion still remains the commonest mode of treatment, pharmacological induction of fetal hemoglobin (HbF) has been a lucrative therapeutic intervention. Till now more than 70 different HbF inducers have been identified. The practical usage of many pharmacological drugs has been limited due to safety concerns. Natural compounds, like Resveratrol, Ripamycin and Bergaptene, with limited cytotoxicity and high efficacy have started capturing the attention of researchers. In this review, we have summarized pharmacological drugs and bioactive compounds isolated from natural sources that have been shown to increase HbF significantly. It primarily discusses recently identified synthetic and natural compounds, their mechanism of action, and their suitable screening platforms, including high throughput drug screening technology and biosensors. It also delves into the topic of combinatorial therapy and drug repurposing for HbF induction. Overall, we aim to provide insights into where we stand in HbF induction strategies for treating β-hemoglobinopathies.

Drug Repurposing: Hydroxyurea Therapy Improves the Transfusion-Free Interval in HbE/Beta-Thalassemia-Major Patients with the XmnI Polymorphism

Aims: HbE/β-thalassemia is the most prevalent form of severe β-thalassemia in Asian countries. Hydroxyurea (HU) is the most common drug used for the management of sickle-cell anemia but not thalassemia. In this study, we aimed to assess clinical HU response among the Bengali HbE/β-thalassemia patients with respect to the XmnI γ^Gglobin polymorphism and elucidate the association between this polymorphism and HU response efficacy. Materials and Methods: We enrolled 49 transfusion-dependent patients with HbE/β-thalassemia. Fetal hemoglobin levels were measured using high-performance liquid chromatography and complete blood counts were determined pre- and post-HU therapy. Polymerase chain reaction-restriction fragment length polymorphism analyses were performed for genotyping the XmnI γ^Gglobin polymorphism. Results: A total of 30 (61.22%) patients were found to be responders, whereas the remaining 19 (38.78%) were nonresponders. We found 33 patients with the heterozygous (C/T) and three with the homozygous mutant (T/T) genotype status. We obtained a statistically significant correlation (p < 0.001) between the XmnI polymorphism genotype and transfusion-free interval. Patients with the XmnI polymorphism were found to be good responders for HU therapy and showed increased hemoglobin levels. Conclusions: Our findings indicate that HU is a potential drug candidate for thalassemia management, particularly for HbE/β-thalassemia. These results hold implications in repurposing HU as an effective and efficient therapy for HbE/β-thalassemia.

Long-term safety and efficacy of hydroxyurea in patients with non-transfusion-dependent β-thalassemia: a comprehensive single-center experience

Over the past 20 years, hydroxyurea (HU) has emerged as an effective therapeutic agent in thalassemic patients to improve anemia and decrease the transfusion dependency. We evaluated long-term safety and clinical response to HU in patients with non-transfusion-dependent β-thalassemia (NTDT). In this retrospective study, medical records of 181 patients with NTDT were evaluated during October to December 2020 in Southern Iran. No requirement to blood transfusion was considered as sustained transfusion independence response. All patients were regularly examined and monitored for the occurrence of any adverse event (AE) of HU. The mean duration of HU consumption ± SD was 18.2 ± 4.0 (8-22) years. Overall, 149 patients (82.3%) had sustained transfusion independence response. β-globin gene mutations and XmnI polymorphisms were not significantly associated with clinical response (P > 0.05). Mild and transient AEs were reported in 60 patients (33%) with no requirement to drug interruption. Hydroxyurea with the dose of 8-15 mg/kg can be used as a safe and effective treatment in NTDT patients. It was well tolerated in long term without any serious complication or secondary malignancy. No relationship between XmnI or β-globin gene mutations with HU response was observed in this geographic area of the world.

Efficacy and safety of oral hydroxyurea in transfusion-dependent β-thalassaemia: a protocol for randomised double-blind controlled clinical trial

INTRODUCTION

Despite being one of the first diseases to be genetically characterised, β-thalassaemia remains a disorder without a cure in a majority of patients. Most patients with β-thalassaemia receive only supportive treatment and therefore have a poor quality of life and shorter life spans. Hydroxyurea, which has shown to induce fetal haemoglobin synthesis in human erythroid cells, is currently recommended for the treatment of sickle cell disease. However, its clinical usefulness in transfusion-dependent β-thalassaemia is unclear. Here, we present a protocol for a randomised double-blind controlled clinical trial to evaluate the efficacy and safety of oral hydroxyurea in transfusion-dependent β-thalassaemia.

METHODS AND ANALYSIS

This single-centre randomised double-blind placebo-controlled clinical trial is conducted at the Thalassaemia Centre of Colombo North Teaching Hospital, Ragama, Sri Lanka. Adult and adolescent patients with haematologically and genetically confirmed transfusion-dependent β-thalassaemia are enrolled and randomised into the intervention or control group. The intervention group receives oral hydroxyurea 10-20 mg/kg daily for 6 months, while the control group receives a placebo which is identical in size, shape and colour to hydroxyurea without its active ingredient. Transfused blood volume, pretransfusion haemoglobin level, fetal haemoglobin percentage and adverse effects of treatment are monitored during treatment and 6 months post-treatment. Cessation or reduction of blood transfusions during the treatment period will be the primary outcome measure. The statistical analysis will be based on intention to treat.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Ethics Committee of Faculty of Medicine, University of Kelaniya (P/116/05/2018) and the trial is approved by the National Medicinal Regulatory Authority of Sri Lanka. Results of the trial will be disseminated in scientific publications in reputed journals.

TRIAL REGISTRATION NUMBER

SLCTR/2018/024; Pre-results.

Effects of hydroxyurea on CNV induction in the mouse germline

Copy number variants (CNVs) are important in genome variation and genetic disease, with new mutations arising frequently in the germline and somatic cells. Replication stress caused by aphidicolin and hydroxyurea (HU) is a potent inducer of de novo CNVs in cultured mammalian cells. HU is used extensively for long-term management of sickle cell disease. Here, we examined the effects of HU treatment on germline CNVs in vivo in male mice to explore whether replication stress can act as a CNV mutagen in germline mitotic divisions as in cultured cells and whether this would support a concern for increased CNV mutations in offspring of men treated with HU. Several trials of HU administration were performed by oral gavage and subcutaneous pump, with CNVs characterized in C57BL/6 x C3H/HeJ hybrid mouse offspring by microarray and mate-pair sequencing. HU had a short half-life of ~14 min and a narrow dose window over which studies could be performed while maintaining fertility. Tissue histopathology and reticulocyte micronucleus assays verified that doses had a substantial tissue and genetic toxicity. CNVs were readily detected in offspring that originated in both paternal and maternal mouse strains, as de novo and inherited events. However, HU did not increase CNV formation above baseline levels. These results reveal a high rate of CNV mutagenesis in the mouse germline but do not support the hypothesis that HU would increase CNV formation during mammalian spermatogenesis, perhaps due to highly toxic effects on sperm development or experimental variables related to HU pharmacology in mice. Environ. Mol. Mutagen. 59:698-714, 2018. © 2018 Wiley Periodicals, Inc.