Meta-analysis on effectiveness of hydroxyurea to treat transfusion-dependent beta-thalassemia

Long-term clinical efficacy and safety of thalidomide in patients with transfusion-dependent β-thalassemia: results from Thal-Thalido study

Regular blood transfusion is the mainstay of treatment in transfusion-dependent β-thalassemia (TDT); however, transfusions culminate in an array of serious complications. Therefore, a single-arm, non-randomized clinical trial was conducted in hydroxyurea refractory TDT patients to explore the long-term safety and efficacy of thalidomide. The primary outcomes for efficacy were rise in hemoglobin (Hb) level and changes in transfusion frequency. Whereas, several clinical and laboratory parameters were assessed for safety of thalidomide. Secondary outcomes included changes in serum ferritin, serum lactate dehydrogenase (LDH), serum uric acid, red blood cell indices, and size of liver and spleen. A total of 532 patients were followed for a period of 30 months. Significant increase in mean Hb level was identified at 6 months (1.4 g/dL, p ≤ 0.001) and 30 months (2 g/dL, p ≤ 0.001) in comparison with baseline. A total of 408 (76.7%) patients responded to thalidomide therapy (excellent responders 25.8%, good responders 31%, and partial responders 19.9%) and attained transfusion independence within 6 months of therapy. A significant decline in mean ferritin, LDH level, liver size, and spleen size was observed. No unfavorable effects were observed on kidney and liver functions. Mild adverse events were reported in 48 (9%) patients and serious adverse events, including cerebral vascular accident and portal vein thrombosis were reported in two patients each. This study concludes that thalidomide is an effective and well-tolerated drug that can improve Hb levels and reduce transfusion burden in hydroxyurea refractory TDT patients.Trial registration: This trial is registered at http://www.clinicaltrial.gov as # NCT03651102.

The Novel Role of the B-Cell Lymphoma/Leukemia 11A (BCL11A) Gene in β-Thalassaemia Treatment

β-thalassaemia is a genetic disorder resulting in a reduction or absence of β-globin gene expression. Due to the high prevalence of β-thalassaemia and the lack of available treatment other than blood transfusion and haematopoietic stem cell (HSC) transplantation, the disease represents a considerable burden to clinical and economic systems. Foetal haemoglobin has an appreciated ameliorating effect in β-haemoglobinopathy, as the γ-globin chain substitutes the β-globin chain reduction by pairing with the excess α-globin chain in β-thalassaemia and reduces sickling in sickle cell disease (SCD). BCL11A is a critical regulator and repressor of foetal haemoglobin. Downregulation of BCL11A in adult erythroblasts and cell lines expressing adult haemoglobin led to a significant increase in foetal haemoglobin levels. Disruption of BCL11A erythroid enhancer resulted in disruption of the BCL11A gene solely in the erythroid lineages and increased γ-globin expression in adult erythroid cells. Autologous haematopoietic stem cell gene therapy represents an attractive treatment option to overcome the immune complications and donor availability associated with allogeneic transplantation. Using genome editing technologies, the disruption of BCL11A to induce γ- globin expression in HSCs has emerged as an alternative approach to treat β-thalassaemia. Targeting the +58 BCL11A erythroid enhancer or BCL11A binding motif at the γ-gene promoter with CRISPR-Cas9 or base editors has successfully disrupted the gene and the binding motif with a subsequent increment in HbF levels. This review outlines the critical role of BCL11A in γ-globin gene silencing and discusses the different genome editing approaches to downregulate BCL11A as a means for ameliorating β-thalassaemia.

A Rational Approach to Drug Repositioning in β-thalassemia: Induction of Fetal Hemoglobin by Established Drugs

Drug repositioning and the relevance of orphan drug designation for β-thalassemia is reviewed. Drug repositioning and similar terms ('drug repurposing', 'drug reprofiling', 'drug redirecting', 'drug rescue', 'drug re-tasking' and/or 'drug rediscovery') have gained great attention, especially in the field or rare diseases (RDs), and represent relevant novel drug development strategies to be considered together with the "off-label" use of pharmaceutical products under clinical trial regimen. The most significant advantage of drug repositioning over traditional drug development is that the repositioned drug has already passed a significant number of short- and long-term toxicity tests, as well as it has already undergone pharmacokinetic and pharmacodynamic (PK/PD) studies. The established safety of repositioned drugs is known to significantly reduce the probability of project failure. Furthermore, development of repurposed drugs can shorten much of the time needed to bring a drug to market. Finally, patent filing of repurposed drugs is expected to catch the attention of pharmaceutical industries interested in the development of therapeutic protocols for RDs. Repurposed molecules that could be proposed as potential drugs for β-thalassemia, will be reported, with some of the most solid examples, including sirolimus (rapamycin) that recently has been tested in a pilot clinical trial.

A Rational Approach to Drug Repositioning in β-thalassemia: Induction of Fetal Hemoglobin by Established Drugs

Drug repositioning and the relevance of orphan drug designation for β-thalassemia is reviewed. Drug repositioning and similar terms ('drug repurposing', 'drug reprofiling', 'drug redirecting', 'drug rescue', 'drug re-tasking' and/or 'drug rediscovery') have gained great attention, especially in the field or rare diseases (RDs), and represent relevant novel drug development strategies to be considered together with the "off-label" use of pharmaceutical products under clinical trial regimen. The most significant advantage of drug repositioning over traditional drug development is that the repositioned drug has already passed a significant number of short- and long-term toxicity tests, as well as it has already undergone pharmacokinetic and pharmacodynamic (PK/PD) studies. The established safety of repositioned drugs is known to significantly reduce the probability of project failure. Furthermore, development of repurposed drugs can shorten much of the time needed to bring a drug to market. Finally, patent filing of repurposed drugs is expected to catch the attention of pharmaceutical industries interested in the development of therapeutic protocols for RDs. Repurposed molecules that could be proposed as potential drugs for β-thalassemia, will be reported, with some of the most solid examples, including sirolimus (rapamycin) that recently has been tested in a pilot clinical trial.

A Rational Approach to Drug Repositioning in β-thalassemia: Induction of Fetal Hemoglobin by Established Drugs

Drug repositioning and the relevance of orphan drug designation for β-thalassemia is reviewed. Drug repositioning and similar terms ('drug repurposing', 'drug reprofiling', 'drug redirecting', 'drug rescue', 'drug re-tasking' and/or 'drug rediscovery') have gained great attention, especially in the field or rare diseases (RDs), and represent relevant novel drug development strategies to be considered together with the "off-label" use of pharmaceutical products under clinical trial regimen. The most significant advantage of drug repositioning over traditional drug development is that the repositioned drug has already passed a significant number of short- and long-term toxicity tests, as well as it has already undergone pharmacokinetic and pharmacodynamic (PK/PD) studies. The established safety of repositioned drugs is known to significantly reduce the probability of project failure. Furthermore, development of repurposed drugs can shorten much of the time needed to bring a drug to market. Finally, patent filing of repurposed drugs is expected to catch the attention of pharmaceutical industries interested in the development of therapeutic protocols for RDs. Repurposed molecules that could be proposed as potential drugs for β-thalassemia, will be reported, with some of the most solid examples, including sirolimus (rapamycin) that recently has been tested in a pilot clinical trial.

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.

Acyclovir induces fetal hemoglobin via downregulation of γ-globin repressors, BCL11A and SOX6 trans-acting factors

Pharmacological reactivation of developmentally silenced fetal hemoglobin (HbF) is an attractive approach to ameliorate the clinical manifestations of β-thalassemia and sickle cell anemia. Hydroxyurea, the only HbF inducer, has obtained regulatory approval. However, hydroxyurea non-responders and associated myelosuppression making its widespread use undesirable. A high level of HbF with safe and effective agents remains an elusive therapeutic goal for this global health burden. This study demonstrated the effect of acyclovir on γ-globin expression and erythropoiesis, associated with increased HbF production. In vitro, human erythroleukemia cells and human CD34⁺ erythroid progenitors, and in vivo β-YAC transgenic mice were used as experimental models. We found that acyclovir significantly induces expression of the γ-globin gene and HbF synthesis in CD34⁺ erythroid progenitors, without affecting terminal erythroid differentiation and erythroid cell proliferation. In contrast to other HbF inducers, no associated cytotoxicity with acyclovir was observed. Further, we reported the effect of acyclovir on γ-globin gene transcriptional regulators including BCL11A, FOP1, KLF1 SOX6, and GATA-1. Significant downregulation of the γ-globin repressors BCL11A and SOX6 was observed at both mRNA and protein levels. Whereas, GATA-1, a master erythroid transcription factor, was upregulated in acyclovir treated human CD34⁺ erythroid culture. Similarly, the HbF inducing effect of acyclovir in β-YAC transgenic mice revealed a good in vitro correlation, with a substantial increase in fetal globin mRNA, and F cells population. These findings collectively suggest acyclovir as an effective HbF inducer and pave the way to evaluate its clinical efficacy in treating β-globin disorders.

Discovery of Novel Fetal Hemoglobin Inducers through Small Chemical Library Screening

The screening of chemical libraries based on cellular biosensors is a useful approach to identify new hits for novel therapeutic targets involved in rare genetic pathologies, such as β-thalassemia and sickle cell disease. In particular, pharmacologically mediated stimulation of human γ-globin gene expression, and increase of fetal hemoglobin (HbF) production, have been suggested as potential therapeutic strategies for these hemoglobinopathies. In this article, we screened a small chemical library, constituted of 150 compounds, using the cellular biosensor K562.GR, carrying enhanced green fluorescence protein (EGFP) and red fluorescence protein (RFP) genes under the control of the human γ-globin and β-globin gene promoters, respectively. Then the identified compounds were analyzed as HbF inducers on primary cell cultures, obtained from β-thalassemia patients, confirming their activity as HbF inducers, and suggesting these molecules as lead compounds for further chemical and biological investigations.

Thalidomide for the Treatment of Thrombocytopenia and Hypersplenism in Patients With Cirrhosis or Thalassemia

Hypersplenism and thrombocytopenia are common complications of liver cirrhosis or thalassemia, but current treatment strategies are limited. This study aimed to evaluate the efficacy and safety of thalidomide in the treatment of hypersplenism and thrombocytopenia in patients with liver cirrhosis or thalassemia. A total of 31 patients with hepatic cirrhosis (n=19) or thalassemia (n=12) diagnosed with hypersplenism and thrombocytopenia (platelet count [PLT] <100×10⁹/L) were included in this prospective cohort study between January 2015 and May 2017. Patients were treated with thalidomide (150-200 mg/d) plus conventional therapy. Spleen length, PLT, leukocyte count (WBC), absolute neutrophil count (ANC), and hemoglobin level (Hb) were measured at baseline, 3, 6, and 12 months. Any adverse events were noted. All of the 31 patients were showed a progressive increase PLT during the 12-month follow-up, and similar results were obtained when subgroup analyses were performed based on the primary disease (cirrhosis or thalassemia). WBC, ANC, and Hb also increased progressively during the 12-month follow-up. Spleen length decreased progressively during the follow-up. No serious adverse events occurred. Thalidomide is a potential treatment for thrombocytopenia caused by hypersplenism in patients with cirrhosis or thalassemia.

Profiling of hydroxyurea-treated β-thalassemia/ serum proteome through nano-LC-ESI-MS/ MS in combination with microsol-isoelectric focusing

Advancements in proteomic tools offer a comprehensive solution to studying the complexity of diseases at molecular level. This study focusses on the clinical proteomic profiling of pre- and post-hydroxyurea (HU)-treated β-thalassemia patients in parallel with healthy individuals to better understand the role of HU in the treatment of β-thalassemia. The strategy encompasses sequential high-resolution protein fractionation using MicroSol-isoelectric focusing (ZOOM- IEF) followed by one-dimensional SDS-PAGE before nano-RP-LC-MS/ MS analysis of tryptic peptides. Protein identification was performed through Mascot search using NCBInr and SwissProt databases. Several different proteins were observed in pool serum samples of each of the three study groups. Approximately, 1250 proteins exclusive to each group were identified, and after removing the redundant and low sequence coverage proteins, the number was reduced to 576 (201 in healthy, 187 in HU-untreated and 188 in HU-treated group). Uniquely identified proteins in the HU-treated group regulate the focal adhesion, ECM-receptor interaction, PI3K-Akt signaling, Rap1 signaling, cAMP signaling, platelet activation, and Ca²⁺ signaling pathways in the HU-treated group. The proteomic profile presented here will add to the current state of understanding of molecular mechanisms involved in hydroxyurea treatment of β-thalassemia.

Pharmacoproteomics Profiling of Plasma From β-Thalassemia Patients in Response to Hydroxyurea Treatment

β-Thalassemia is a genetic disorder caused by defects in the β-globin gene resulting in the absence or reduced synthesis of adult hemoglobin (HbA). Hydroxyurea is an effective drug to increase fetal γ-globin (HbF) expression, replacing the missing adult β-globin. The mechanism of HbF induction by hydroxyurea and improvement in clinical symptoms are still poorly understood. In the present study we performed comparative analysis of plasma proteome in pre- and post-hydroxyurea-treated β-thalassemia major transfusion-dependent children (n = 10, mean age = 3.2 years) as well as responders versus nonresponders to hydroxyurea treatment. Plasma was collected before and after 6 months of hydroxyurea treatment, with patients subcategorized on the basis of their response to hydroxyurea. Among 400 identified proteins using a label-free quantitative proteomics approach, 28 proteins were found to be significantly different in pre- versus post-hydroxyurea-treated groups, with transferrin receptor protein-1 being most downregulated and hemopexin and haptoglobin the most upregulated proteins after treatment. In responder versus nonresponder comparison, 26 proteins were found to be differentially expressed, with carbonic anhydrase 1, hemoglobin subunit γ-1, and peroxiredoxin-2 showing the significant changes. The mechanism of hydroxyurea treatment in β-thalassemia patients appears to be complex, requiring a large sample size and a longer period of treatment to reveal its details.