Efficacy of Rapamycin as Inducer of Hb F in Primary Erythroid Cultures from Sickle Cell Disease and β-Thalassemia Patients

Interplay between α-thalassemia and β-hemoglobinopathies: Translating genotype-phenotype relationships into therapies

α-Thalassemia represents one of the most important genetic modulators of β-hemoglobinopathies. During this last decade, the ongoing interest in characterizing genotype-phenotype relationships has yielded incredible insights into α-globin gene regulation and its impact on β-hemoglobinopathies. In this review, we provide a holistic update on α-globin gene expression stemming from DNA to RNA to protein, as well as epigenetic mechanisms that can impact gene expression and potentially influence phenotypic outcomes. Here, we highlight defined α-globin targeted strategies and rationalize the use of distinct molecular targets based on the restoration of balanced α/β-like globin chain synthesis. Considering the therapies that either increase β-globin synthesis or reactivate γ-globin gene expression, the modulation of α-globin chains as a disease modifier for β-hemoglobinopathies still remains largely uncharted in clinical studies.

Increased Expression of α-Hemoglobin Stabilizing Protein (AHSP) mRNA in Erythroid Precursor Cells Isolated from β-Thalassemia Patients Treated with Sirolimus (Rapamycin)

Background/Objectives: in β-thalassemia, important clinical complications are caused by the presence of free α-globin chains in the erythroid cells of β-thalassemia patients. These free α-globin chains are present in excess as a result of the lack of β-globin chains to bind with; they tend to aggregate and precipitate, causing deleterious effects and overall cytotoxicity, maturation arrest of the erythroid cells and, ultimately, ineffective erythropoiesis. The chaperone protein α-hemoglobin-stabilizing protein (AHSP) reversibly binds with free α-globin; the resulting AHSP-αHb complex prevents aggregation and precipitation. Sirolimus (rapamycin) has been previously demonstrated to induce expression of fetal hemoglobin and decrease the excess of free α-globin chain in the erythroid cells of β-thalassemia patients. The objective of this study was to verify whether sirolimus is also able to upregulate AHSP expression in erythroid precursor cells (ErPCs) isolated from β-thalassemia patients. Methods: the expression of AHSP genes was analyzed by measuring the AHSP mRNA content by real-time quantitative PCR (RT-qPCR) and the AHSP protein production by Western blotting. Results: AHSP gene expression was found to be higher in ErPCs of β-thalassemia patients in comparison to ErPCs isolated from healthy subjects. In addition, AHSP expression was further induced by treatment of β-thalassemia ErPCs with sirolimus. Finally, AHSP mRNA was expressed at an increased level in ErPCs of sirolimus-treated β-thalassemia patients participating in the NCT03877809 Sirthalaclin clinical trial. Conclusions: this exploratory study suggests that AHSP expression should be considered as an endpoint in clinical trials based on sirolimus.

New Synthetic Isoxazole Derivatives Acting as Potent Inducers of Fetal Hemoglobin in Erythroid Precursor Cells Isolated from β-Thalassemic Patients

Induction of fetal hemoglobin (HbF) is highly beneficial for patients carrying β-thalassemia, and novel HbF inducers are highly needed. Here, we describe a new class of promising HbF inducers characterized by an isoxazole chemical skeleton and obtained through modification of two natural molecules, geldanamycin and radicicol. After preliminary biological assays based on benzidine staining and RT-qPCR conducted on human erythroleukemic K562 cells, we employed erythroid precursors cells (ErPCs) isolated from β-thalassemic patients. ErPCs weretreated with appropriate concentrations of isoxazole derivatives. The accumulation of globin mRNAs was studied by RT-qPCR, and hemoglobin production by HPLC. We demonstrated the high efficacy of isozaxoles in inducing HbF. Most of these derivatives displayed an activity similar to that observed using known HbF inducers, such as hydroxyurea (HU) or rapamycin; some of the analyzed compounds were able to induce HbF with more efficiency than HU. All the compounds were active in reducing the excess of free α-globin in treated ErPCs. All the compounds displayed a lack of genotoxicity. These novel isoxazoles deserve further pre-clinical study aimed at verifying whether they are suitable for the development of therapeutic protocols for β-thalassemia.

Decrease in α-Globin and Increase in the Autophagy-Activating Kinase ULK1 mRNA in Erythroid Precursors from β-Thalassemia Patients Treated with Sirolimus

The β-thalassemias are hereditary monogenic diseases characterized by a low or absent production of adult hemoglobin and excess in the content of α-globin. This excess is cytotoxic for the erythroid cells and responsible for the β-thalassemia-associated ineffective erythropoiesis. Therefore, the decrease in excess α-globin is a relevant clinical effect for these patients and can be realized through the induction of fetal hemoglobin, autophagy, or both. The in vivo effects of sirolimus (rapamycin) and analogs on the induction of fetal hemoglobin (HbF) are of key importance for therapeutic protocols in a variety of hemoglobinopathies, including β-thalassemias. In this research communication, we report data showing that a decrease in autophagy-associated p62 protein, increased expression of ULK-1, and reduction in excess α-globin are occurring in erythroid precursors (ErPCs) stimulated in vitro with low dosages of sirolimus. In addition, increased ULK-1 mRNA content and a decrease in α-globin content were found in ErPCs isolated from β-thalassemia patients recruited for the NCT03877809 clinical trial and treated with 0.5-2 mg/day sirolimus. Our data support the concept that autophagy, ULK1 expression, and α-globin chain reduction should be considered important endpoints in sirolimus-based clinical trials for β-thalassemias.

The Long Scientific Journey of Sirolimus (Rapamycin): From the Soil of Easter Island (Rapa Nui) to Applied Research and Clinical Trials on β-Thalassemia and Other Hemoglobinopathies

In this review article, we present the fascinating story of rapamycin (sirolimus), a drug able to induce γ-globin gene expression and increased production of fetal hemoglobin (HbF) in erythroid cells, including primary erythroid precursor cells (ErPCs) isolated from β-thalassemia patients. For this reason, rapamycin is considered of great interest for the treatment of β-thalassemia. In fact, high levels of HbF are known to be highly beneficial for β-thalassemia patients. The story of rapamycin discovery began in 1964, with METEI, the Medical Expedition to Easter Island (Rapa Nui). During this expedition, samples of the soil from different parts of the island were collected and, from this material, an antibiotic-producing microorganism (Streptomyces hygroscopicus) was identified. Rapamycin was extracted from the mycelium with organic solvents, isolated, and demonstrated to be very active as an anti-bacterial and anti-fungal agent. Later, rapamycin was demonstrated to inhibit the in vitro cell growth of tumor cell lines. More importantly, rapamycin was found to be an immunosuppressive agent applicable to prevent kidney rejection after transplantation. More recently, rapamycin was found to be a potent inducer of HbF both in vitro using ErPCs isolated from β-thalassemia patients, in vivo using experimental mice, and in patients treated with this compound. These studies were the basis for proposing clinical trials on β-thalassemia patients.

Combined approaches for increasing fetal hemoglobin (HbF) and de novo production of adult hemoglobin (HbA) in erythroid cells from β-thalassemia patients: treatment with HbF inducers and CRISPR-Cas9 based genome editing

Genome editing (GE) is one of the most efficient and useful molecular approaches to correct the effects of gene mutations in hereditary monogenetic diseases, including β-thalassemia. CRISPR-Cas9 gene editing has been proposed for effective correction of the β-thalassemia mutation, obtaining high-level "de novo" production of adult hemoglobin (HbA). In addition to the correction of the primary gene mutations causing β-thalassemia, several reports demonstrate that gene editing can be employed to increase fetal hemoglobin (HbF), obtaining important clinical benefits in treated β-thalassemia patients. This important objective can be achieved through CRISPR-Cas9 disruption of genes encoding transcriptional repressors of γ-globin gene expression (such as BCL11A, SOX6, KLF-1) or their binding sites in the HBG promoter, mimicking non-deletional and deletional HPFH mutations. These two approaches (β-globin gene correction and genome editing of the genes encoding repressors of γ-globin gene transcription) can be, at least in theory, combined. However, since multiplex CRISPR-Cas9 gene editing is associated with documented evidence concerning possible genotoxicity, this review is focused on the possibility to combine pharmacologically-mediated HbF induction protocols with the "de novo" production of HbA using CRISPR-Cas9 gene editing.

Effects of Sirolimus Treatment on Fetal Hemoglobin Production and Response to SARS-CoV-2 Vaccination: A Case Report Study

The β-thalassemias are a group of monogenic hereditary hematological disorders caused by deletions and/or mutations of the β-globin gene, leading to low or absent production of adult hemoglobin (HbA). For β-thalassemia, sirolimus has been under clinical consideration in two trials (NCT03877809 and NCT04247750). A reduced immune response to anti-SARS-CoV-2 vaccination has been reported in organ recipient patients treated with the immunosuppressant sirolimus. Therefore, there was some concern regarding the fact that monotherapy with sirolimus would reduce the antibody response after SARS-CoV-2 vaccination. In the representative clinical case reported in this study, sirolimus treatment induced the expected increase of fetal hemoglobin (HbF) but did not prevent the production of anti-SARS-CoV-2 IgG after vaccination with mRNA-1273 (Moderna). In our opinion, this case report should stimulate further studies on β-thalassemia patients under sirolimus monotherapy in order to confirm the safety (or even the positive effects) of sirolimus with respect to the humoral response to anti-SARS-CoV-2 vaccination. In addition, considering the extensive use of sirolimus for the treatment of other human pathologies (for instance, in organ transplantation, systemic lupus erythematosus, autoimmune cytopenia, and lymphangioleiomyomatosis), this case report study might be of general interest, as large numbers of patients are currently under sirolimus treatment.

A deep dive into future therapies for microcytic anemias and clinical considerations

INTRODUCTION

Microcytic anemias (MA) have frequent or rare etiologies. New discoveries in understanding and treatment of microcytic anemias need to be reviewed.

AREAS COVERED

Microcytic anemias with a focus on most frequent causes and on monogenic diseases that are relevant for understanding biocellular mechanisms of MA. All treatments excepting gene therapy, with a focus on recent advances. Pubmed search with references selected by expert opinion.

EXPERT OPINION

As the genetic and cellular background of dyserythropoiesis will continue to be clarified, collaboration with bioengineering of treatments acting specifically at the protein domain level will continue to provide new therapies in haematology as well as oncology and neurology.

Effects of Sirolimus treatment on patients with β-Thalassemia: Lymphocyte immunophenotype and biological activity of memory CD4+ and CD8+ T cells

Inhibitors of the mammalian target of rapamycin (mTOR) have been proposed to improve vaccine responses, especially in the elderly. Accordingly, testing mTOR inhibitors (such as Sirolimus) and other geroprotective drugs might be considered a key strategy to improve overall health resilience of aged populations. In this respect, Sirolimus (also known as rapamycin) is of great interest, in consideration of the fact that it is extensively used in routine therapy and in clinical studies for the treatment of several diseases. Recently, Sirolimus has been considered in laboratory and clinical studies aimed to find novel protocols for the therapy of hemoglobinopathies (e.g. β-Thalassemia). The objective of the present study was to analyse the activity of CD4⁺ and CD8⁺ T cells in β-Thalassemia patients treated with Sirolimus, taking advantages from the availability of cellular samples of the NCT03877809 clinical trial. The approach was to verify IFN-γ releases following stimulation of peripheral blood mononuclear cells (PBMCs) to stimulatory CEF and CEFTA peptide pools, stimulatory for CD4⁺ and CD8⁺ T cells, respectively. The main results of the present study are that treatment of β-Thalassemia patients with Sirolimus has a positive impact on the biological activity and number of memory CD4⁺ and CD8⁺ T cells releasing IFN-γ following stimulation with antigenic stimuli present in immunological memory. These data are to our knowledge novel and in our opinion of interest, in consideration of the fact that β-Thalassemia patients are considered prone to immune deficiency.

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.

Expression of γ-globin genes in β-thalassemia patients treated with sirolimus: results from a pilot clinical trial (Sirthalaclin)

Introduction:

β-thalassemia is caused by autosomal mutations in the β-globin gene, which induce the absence or low-level synthesis of β-globin in erythroid cells. It is widely accepted that a high production of fetal hemoglobin (HbF) is beneficial for patients with β-thalassemia. Sirolimus, also known as rapamycin, is a lipophilic macrolide isolated from a strain of Streptomyces hygroscopicus that serves as a strong HbF inducer in vitro and in vivo. In this study, we report biochemical, molecular, and clinical results of a sirolimus-based NCT03877809 clinical trial (a personalized medicine approach for β-thalassemia transfusion-dependent patients: testing sirolimus in a first pilot clinical trial, Sirthalaclin).

Methods:

Accumulation of γ-globin mRNA was analyzed using reverse-transcription quantitative polymerase chain reaction (PCR), while the hemoglobin pattern was analyzed using high-performance liquid chromatography (HPLC). The immunophenotype was analyzed using a fluorescence-activated cell sorter (FACS), with antibodies against CD3, CD4, CD8, CD14, CD19, CD25 (for analysis of peripheral blood mononuclear cells), or CD71 and CD235a (for analysis of in vitro cultured erythroid precursors).

Results:

The results were obtained in eight patients with the β⁺/β⁺ and β⁺/β⁰ genotypes, who were treated with a starting dosage of 1 mg/day sirolimus for 24–48 weeks. The first finding of this study was that the expression of γ-globin mRNA increased in the blood and erythroid precursor cells isolated from β-thalassemia patients treated with low-dose sirolimus. This trial also led to the important finding that sirolimus influences erythropoiesis and reduces biochemical markers associated with ineffective erythropoiesis (excess free α-globin chains, bilirubin, soluble transferrin receptor, and ferritin). A decrease in the transfusion demand index was observed in most (7/8) of the patients. The drug was well tolerated, with minor effects on the immunophenotype, and an only side effect of frequently occurring stomatitis.

Conclusion:

The data obtained indicate that low doses of sirolimus modify hematopoiesis and induce increased expression of γ-globin genes in a subset of patients with β-thalassemia. Further clinical trials are warranted, possibly including testing of the drug in patients with less severe forms of the disease and exploring combination therapies.

Salubrinal induces fetal hemoglobin expression via the stress-signaling pathway in human sickle erythroid progenitors and sickle cell disease mice

Sickle cell disease (SCD) is an inherited blood disorder caused by a mutation in the HBB gene leading to hemoglobin S production and polymerization under hypoxia conditions leading to vaso-occlusion, chronic hemolysis, and progressive organ damage. This disease affects ~100,000 people in the United States and millions worldwide. An effective therapy for SCD is fetal hemoglobin (HbF) induction by pharmacologic agents such as hydroxyurea, the only Food and Drug Administration-approved drug for this purpose. Therefore, the goal of our study was to determine whether salubrinal (SAL), a selective protein phosphatase 1 inhibitor, induces HbF expression through the stress-signaling pathway by activation of p-eIF2α and ATF4 trans-activation in the γ-globin gene promoter. Sickle erythroid progenitors treated with 24μM SAL increased F-cells levels 1.4-fold (p = 0.021) and produced an 80% decrease in reactive oxygen species. Western blot analysis showed SAL enhanced HbF protein by 1.6-fold (p = 0.0441), along with dose-dependent increases of p-eIF2α and ATF4 levels. Subsequent treatment of SCD mice by a single intraperitoneal injection of SAL (5mg/kg) produced peak plasma concentrations at 6 hours. Chronic treatments of SCD mice with SAL mediated a 2.3-fold increase in F-cells (p = 0.0013) and decreased sickle erythrocytes supporting in vivo HbF induction.

Possible effects of sirolimus treatment on the long‑term efficacy of COVID‑19 vaccination in patients with β‑thalassemia: A theoretical perspective

The pandemic caused by the severe acute respiratory syndrome coronavirus (SARS‑CoV‑2), responsible for coronavirus disease 2019 (COVID‑19) has posed a major challenge for global health. In order to successfully combat SARS‑CoV‑2, the development of effective COVID‑19 vaccines is crucial. In this context, recent studies have highlighted a high COVID‑19 mortality rate in patients affected by β‑thalassemia, probably due to their co‑existent immune deficiencies. In addition to a role in the severity of SARS‑CoV‑2 infection and in the mortality rate of COVID‑19‑infected patients with thalassemia, immunosuppression is expected to deeply affect the effectivity of anti‑COVID‑19 vaccines. In the context of the interplay between thalassemia‑associated immunosuppression and the effectiveness of COVID‑19 vaccines, the employment of immunomodulatory molecules is hypothesized. For instance, short‑term treatment with mammalian target of rapamycin inhibitors (such as everolimus and sirolimus) has been found to improve responses to influenza vaccination in adults, with benefits possibly persisting for a year following treatment. Recently, sirolimus has been considered for the therapy of hemoglobinopathies (including β‑thalassemia). Sirolimus induces the expression of fetal hemoglobin (and this may contribute to the amelioration of the clinical parameters of patients with β‑thalassemia) and induces autophagy (thereby reducing the excessive levels of α‑globin). It may also finally contribute to the mobilization of erythroid cells from the bone marrow (thereby reducing anemia). In the present study, the authors present the hypothesis that sirolimus treatment, in addition to its beneficial effects on erythroid‑related parameters, may play a crucial role in sustaining the effects of COVID‑19 vaccination in patients with β‑thalassemia. This hypothesis is based on several publications demonstrating the effects of sirolimus treatment on the immune system.

Treatment of Erythroid Precursor Cells from β-Thalassemia Patients with Cinchona Alkaloids: Induction of Fetal Hemoglobin Production

β-thalassemias are among the most common inherited hemoglobinopathies worldwide and are the result of autosomal mutations in the gene encoding β-globin, causing an absence or low-level production of adult hemoglobin (HbA). Induction of fetal hemoglobin (HbF) is considered to be of key importance for the development of therapeutic protocols for β-thalassemia and novel HbF inducers need to be proposed for pre-clinical development. The main purpose on this study was to analyze Cinchona alkaloids (cinchonidine, quinidine and cinchonine) as natural HbF-inducing agents in human erythroid cells. The analytical methods employed were Reverse Transcription quantitative real-time PCR (RT-qPCR) (for quantification of γ-globin mRNA) and High Performance Liquid Chromatography (HPLC) (for analysis of the hemoglobin pattern). After an initial analysis using the K562 cell line as an experimental model system, showing induction of hemoglobin and γ-globin mRNA, we verified whether the two more active compounds, cinchonidine and quinidine, were able to induce HbF in erythroid progenitor cells isolated from β-thalassemia patients. The data obtained demonstrate that cinchonidine and quinidine are potent inducers of γ-globin mRNA and HbF in erythroid progenitor cells isolated from nine β-thalassemia patients. In addition, both compounds were found to synergize with the HbF inducer sirolimus for maximal production of HbF. The data obtained strongly indicate that these compounds deserve consideration in the development of pre-clinical approaches for therapeutic protocols of β-thalassemia.

β-Thalassemia: evolving treatment options beyond transfusion and iron chelation

After years of reliance on transfusion alone to address anemia and suppress ineffective erythropoiesis in β-thalassemia, many new therapies are now in development. Luspatercept, a transforming growth factor-β inhibitor, has demonstrated efficacy in reducing ineffective erythropoiesis, improving anemia, and possibly reducing iron loading. However, many patients do not respond to luspatercept, so additional therapeutics are needed. Several medications in development aim to induce hemoglobin F (HbF): sirolimus, benserazide, and IMR-687 (a phosphodiesterase 9 inhibitor). Another group of agents seeks to ameliorate ineffective erythropoiesis and improve anemia by targeting abnormal iron metabolism in thalassemia: apotransferrin, VIT-2763 (a ferroportin inhibitor), PTG-300 (a hepcidin mimetic), and an erythroferrone antibody in early development. Mitapivat, a pyruvate kinase activator, represents a unique mechanism to mitigate ineffective erythropoiesis. Genetically modified autologous hematopoietic stem cell transplantation offers the potential for lifelong transfusion independence. Through a gene addition approach, lentiviral vectors have been used to introduce a β-globin gene into autologous hematopoietic stem cells. One such product, betibeglogene autotemcel (beti-cel), has reached phase 3 trials with promising results. In addition, 2 gene editing techniques (CRISPR-Cas9 and zinc-finger nucleases) are under investigation as a means to silence BCL11A to induce HbF with agents designated CTX001 and ST-400, respectively. Results from the many clinical trials for these agents will yield results in the next few years, which may end the era of relying on transfusion alone as the mainstay of thalassemia therapy.

Hemoglobin F (HbF) inducers; History, Structure and Efficacies

Inherited beta-thalassemia is a major disease caused by irregular production of hemoglobin through reducing beta-globin chains. It has been observed that increasing fetal hemoglobin (HbF) production improves symptoms in the patients. Therefore, an increase in the level of HbF has been an operative approach for treating patients with beta-thalassemia. This review represents compounds with biological activities and pharmacological properties that can promote the HBF level and therefore used in the β-thalassemia patients' therapy. Various natural products with different mechanisms of action can be helpful in this medication cure. Clinical trials were efficient in improving the signs of patients. Association of in vivo, and in vitro studies of HbF induction and γ-globin mRNA growth displays that in vitro experiments could be an indicator of the in vivo response. The current study shows that; (a) HbF inducers can be grouped in several classes based on their chemical structures and mechanism of actions; b) According to several clinical trials, well-known drugs such as hydroxyurea and decitabine are useful HbF inducers; (c) The cellular biosensor K562 carrying genes under the control of the human γ-globin and β-globin gene promoters were applied during the researches; d) New natural products and lead compounds were found based on various studies as HbF inducers.

Advances in Sickle Cell Disease Treatments

Sickle Cell Disease (SCD) is an inherited disorder of red blood cells that is caused by a single mutation in the β -globin gene. The disease, which afflicts millions of patients worldwide mainly in low income countries, is characterized by high morbidity, mortality and low life expectancy. The new pharmacological and non-pharmacological strategies for SCD is urgent in order to promote treatments able to reduce patient's suffering and improve their quality of life. Since the FDA approval of HU in 1998, there have been few advances in discovering new drugs; however, in the last three years voxelotor, crizanlizumab, and glutamine have been approved as new therapeutic alternatives. In addition, new promising compounds have been described to treat the main SCD symptoms. Herein, focusing on drug discovery, we discuss new strategies to treat SCD that have been carried out in the last ten years to discover new, safe, and effective treatments. Moreover, non-pharmacological approaches, including red blood cell exchange, gene therapy and hematopoietic stem cell transplantation will be presented.

Association of FOXO3 polymorphism (rs3800231) and clinical subphenotypes of beta thalassemic individuals

INTRODUCTION

Studies have shown that the loss of the FOXO3 transcriptional function is involved in the pathophysiology of some chronic erythroid disorders, including beta-thalassemia (β-thal). Therefore, the single nucleotide polymorphism (SNP) rs3800231 (35-2764A > G) could contribute to alterations in its transcriptional activity, acting as a modifier of β-thal phenotypic manifestations.

OBJECTIVE AND METHOD

In order to better understand the genotypic and/or allelic distributions among β-thal patients, we evaluated 83 β-thal heterozygous and 20 homozygous, compared to 117 individuals without hemoglobinopathies (control group). Additionally, we verified any influence of the FOXO3 polymorphism on clinical manifestations among β-thal homozygotes.

RESULTS

We obtained higher frequencies of the wild-type homozygous (AA) and the wild-type allele (A) in the β-thal group (p < 0.0001 and p = 0.00014, respectively). The most common clinical manifestations found among β-thal homozygotes were iron overload (90%), splenomegaly (65%) and bone complications (35%), e.g., osteopenia/osteoporosis. We observed that close to 80% of the patients presenting such manifestations had the genotype AA. However, we did not find any significant involvement of the FOXO3 polymorphism in clinical manifestation occurrences.

CONCLUSION

Thus, we concluded that the SNP rs3800231 did not play a significant role as a modifier of the clinical manifestations observed in the β-thal homozygotes studied.

Impact of iron overload on bone remodeling in thalassemia

INTRODUCTION

Iron overload, a state with excessive iron storage in the body, is a common complication in thalassemia patients which leads to multiple organ dysfunctions including the bone. Iron overload-induced bone disease is one of the most common and severe complications of thalassemia including osteoporosis. Currently, osteoporosis is still frequently found in thalassemia even with widely available iron chelation therapy.

STUDY SELECTION

Relevant publications published before December 2019 in PubMed database were reviewed. Both pre-clinical studies and clinical trials were obtained using iron overload, thalassemia, osteoporosis, osteoblast, and osteoclast as keywords.

RESULTS

Increased ROS production is a hallmark of iron overload-induced impaired bone remodeling. At the cellular level, oxidative stress affects bone remodeling by both osteoblast inhibition and osteoclast activation via many signaling pathways. In thalassemia patients, it has been shown that bone resorption was increased while bone formation was concurrently reduced.

CONCLUSION

In this review, reports on the cellular mechanisms of iron overload-associated bone remodeling are comprehensively summarized and presented to provide current understanding this pathological condition. Moreover, current treatments and potential interventions for attenuating bone remodeling in iron overload are also summarized to pave ways for the future discoveries of novel agents that alleviate this condition.

Recent Progress in Gene Therapy and Other Targeted Therapeutic Approaches for Beta Thalassemia

Beta-thalassemia is a genetic disorder characterized by the impaired synthesis of the betaglobin chain of adult hemoglobin. The disorder has a complex pathophysiology that affects multiple organ systems. The main complications of beta thalassemia are ineffective erythropoiesis, chronic hemolytic anemia and hemosiderosis-induced organ dysfunction. Regular blood transfusions are the main therapy for beta thalassemia major; however, this treatment can cause cardiac and hepatic hemosiderosis - the most common cause of death in these patients. This review focuses on unique future therapeutic interventions for thalassemia that reverse splenomegaly, reduce transfusion frequency, decrease iron toxicity in organs, and correct chronic anemia. The targeted effective protocols include hemoglobin fetal inducers, ineffective erythropoiesis correctors, antioxidants, vitamins, and natural products. Resveratrol is a new herbal therapeutic approach which serves as fetal Hb inducer in beta thalassemia. Hematopoietic stem cell transplantation (HSCT) is the only curative therapy for beta thalassemia major and is preferred over iron chelation and blood transfusion for ensuring long life in these patients. Meanwhile, several molecular therapies, such as ActRIIB/IgG1 Fc recombinant protein, have emerged to address complications of beta thalassemia or the adverse effects of current drugs. Regarding gene correction strategies, a phase III trial called HGB-207 (Northstar-2; NCT02906202) is evaluating the efficacy and safety of autologous cell transplantation with LentiGlobin. Advanced gene-editing approaches aim to cut DNA at a targeted site and convert HbF to HbA during infancy, such as the suppression of BCL11A (B cell lymphoma 11A), HPFH (hereditary persistence of fetal hemoglobin) and zinc-finger nucleases. Gene therapy is progressing rapidly, with multiple clinical trials being conducted in many countries and the promise of commercial products to be available in the near future.

The autophagy-activating kinase ULK1 mediates clearance of free α-globin in β-thalassemia

In β-thalassemia, accumulated free α-globin forms intracellular precipitates that impair erythroid cell maturation and viability. Protein quality control systems mitigate β-thalassemia pathophysiology by degrading toxic free α-globin, although the associated mechanisms are poorly understood. We show that loss of the autophagy-activating Unc-51-like kinase 1 (Ulk1) gene in β-thalassemic mice reduces autophagic clearance of α-globin in red blood cell precursors and exacerbates disease phenotypes, whereas inactivation of the canonical autophagy-related 5 (Atg5) gene has relatively minor effects. Systemic treatment with the mTORC1 inhibitor rapamycin reduces α-globin precipitates and lessens pathologies in β-thalassemic mice via an ULK1-dependent pathway. Similarly, rapamycin reduces free α-globin accumulation in erythroblasts derived from CD34⁺ cells of β-thalassemic individuals. Our findings define a drug-regulatable pathway for ameliorating β-thalassemia.

Oxidative Stress in β-Thalassemia

Cell oxidative status, which represents the balance between oxidants and antioxidants, is involved in normal functions. Under pathological conditions, there is a shift toward the oxidants, leading to oxidative stress, which is cytotoxic, causing oxidation of cellular components that result in cell death and organ damage. Thalassemia is a hereditary hemolytic anemia caused by mutations in globin genes that cause reduced or complete absence of specific globin chains (commonly, α or β). Although oxidative stress is not the primary etiology of thalassemia, it mediates several of its pathologies. The main causes of oxidative stress in thalassemia are the degradation of the unstable hemoglobin and iron overload-both stimulate the production of excess free radicals. The symptoms aggravated by oxidative stress include increased hemolysis, ineffective erythropoiesis and functional failure of vital organs such as the heart and liver. The oxidative status of each patient is affected by multiple internal and external factors, including genetic makeup, health conditions, nutrition, physical activity, age, and the environment (e.g., air pollution, radiation). In addition, oxidative stress is influenced by the clinical manifestations of the disease (unpaired globin chains, iron overload, anemia, etc.). Application of personalized (theranostics) medicine principles, including diagnostic tests for selecting targeted therapy, is therefore important for optimal treatment of the oxidative stress of these patients. We summarize the role of oxidative stress and the current and potential antioxidative therapeutics in β-thalassemia and describe some methodologies, mostly cellular, that might be helpful for application of a theranostics approach to therapy.

Current challenges in the management of patients with sickle cell disease - A report of the Italian experience

Sickle cell disease (SCD) is an inherited red blood cell disorder caused by a structural abnormality of hemoglobin called sickle hemoglobin (HbS). Clinical manifestations of SCD are mainly characterized by chronic hemolysis and acute vaso-occlusive crisis, which are responsible for severe acute and chronic organ damage. SCD is widespread in sub-Saharan Africa, in the Middle East, Indian subcontinent, and some Mediterranean regions. With voluntary population migrations, people harboring the HbS gene have spread globally. In 2006, the World Health Organization recognized hemoglobinopathies, including SCD, as a global public health problem and urged national health systems worldwide to design and establish programs for the prevention and management of SCD. Herein we describe the historical experience of the network of hemoglobinopathy centers and their approach to SCD in Italy, a country where hemoglobinopathies have a high prevalence and where SCD, associated with different genotypes including ß-thalassemia, is present in the native population.

Autophagy as a pharmacological target in hematopoiesis and hematological disorders

Autophagy is involved in many cellular processes, including cell homeostasis, cell death/survival balance and differentiation. Autophagy is essential for hematopoietic stem cell survival, quiescence, activation and differentiation. The deregulation of this process is associated with numerous hematological disorders and pathologies, including cancers. Thus, the use of autophagy modulators to induce or inhibit autophagy emerges as a potential therapeutic approach for treating these diseases and could be particularly interesting for differentiation therapy of leukemia cells. This review presents therapeutic strategies and pharmacological agents in the context of hematological disorders. The pros and cons of autophagy modulators in therapy will also be discussed.

Pathophysiology and treatment of patients with beta-thalassemia - an update

Thalassemia (thal) is an autosomal recessive, hereditary, chronic hemolytic anemia due to a partial or complete deficiency in the synthesis of α-globin chains (α-thal) or β-globin chains (β-thal) that compose the major adult hemoglobin (α ₂β _2). It is caused by one or more mutations in the corresponding genes. The unpaired globin chains are unstable; they precipitate intracellularly, resulting in hemolysis, premature destruction of red blood cell [RBC] precursors in the bone marrow, and a short life-span of mature RBCs in the circulation. The state of anemia is treated by frequent RBC transfusions. This therapy results in the accumulation of iron (iron overload), a condition that is exacerbated by the breakdown products of hemoglobin (heme and iron) and the increased iron uptake for the chronic accelerated, but ineffective, RBC production. Iron catalyzes the generation of reactive oxygen species, which in excess are toxic, causing damage to vital organs such as the heart and liver and the endocrine system. Herein, we review recent findings regarding the pathophysiology underlying the major symptoms of β-thal and potential therapeutic modalities for the amelioration of its complications, as well as new modalities that may provide a cure for the disease.

2017 Clinical trials update in new treatments of β-thalassemia

The underlying basis of β-thalassemia pathology is the diminished β-globin synthesis leading to α-globin accumulation and premature apoptotic destruction of erythroblasts, causing oxidative stress-induced ineffective erythropoiesis, bone marrow hyperplasia, splenomegaly, and increased intestinal iron absorption with progressive iron overload. Better understanding of the molecular mechanisms underlying this disease led to the recognition of new targets with potential therapeutic utility. Agents such as JAK2 inhibitors and TGF-β ligand traps that reduce the ineffective erythropoiesis process are already being tested in clinical trials with promising results. Other agents that aim to reduce oxidative stress (activators of Foxo3, HRI-eIF2aP, Prx2, Hsp70, and PK anti-oxidant systems and inhibitors of HO-1) and to decrease iron overload (hepcidin agonists, erythroferrone inhibitors and exogenous transferrin) are also under experimental investigation. Significant progress has also been made in the area of allogeneic hematopoietic stem cell transplantation with several ongoing clinical trials examining new condition regimens as well as different donor selection and stem cell source options. Gene therapy has reached a critical point and phase 1 clinical trials have recently been launched to examine the effectiveness and especially long term safety. Epigenetic manipulation and genomic editing of the γ- or β-globin gene are novel and promising experimental gene therapy approaches for β-thalassemia giving hope for cure for this chronic disease. This review outlines the key points of the molecular mechanisms underlying β-thalassemia in relation to the development of new therapies and an update is given both at the pre-clinical and clinical level. Am. J. Hematol. 91:1135-1145, 2016. © 2016 Wiley Periodicals, Inc.