Transfusion-dependent Β-thalassemia Research Articles

Identification of β-globin gene mutations among transfusion-dependent β-thalassemia patients

Abstract BACKGROUND: β-thalassemias are widely distributed in Mediterranean and Middle Eastern countries, including Iraq. There are more than 400 transfusion-dependent β-thalassemia patients registered in the thalassemia center. β-thalassemia is a significant problem in Karbala as well as other regions of Iraq. The detection of the most frequent mutations is significant to the implementation of an effective preventive program in this area because of the significant burden it places on the local health authorities, patients, and their families. OBJECTIVES: To define the most common mutations and their frequencies among patients with transfusion-dependent β-thalassemia and to evaluate the reverse hybridization strip assay method for the detection of β-thalassemia mutations. PATIENTS, MATERIALS AND METHODS: Sixty transfusion-dependent β-thalassemia patients were recruited from the thalassemia center in Karbala. Blood samples were aspirated from each patient just before blood transfusions for CBC, reticulocyte count, DNA extraction, PCR amplification, and identification of the mutations by reverse hybridization technique using the β-Globin strip assay method. RESULTS: A total of 60 patients with 120 chromosomes were studied, searching for the most common mutations causing β-thalassemia. Among the twelve identified mutations, the six most frequent mutations represented 79.16% of all β-globin defects. These mutations were IVSII-1 (30.83%), IVSI-110 (15.83%), Codon 5 (10.83%), Codon 44 (8.33%), IVSI-1 (6.67%), and IVSI-5 (6.67%). The detection rate of the method used in our population was 96.66%. CONCLUSION: The most frequent mutations encountered were IVSII.1 and IVSI-110, while IVS 2.745 was the least common mutant allele. Reverse hybridization strip assay molecular techniques used in the current study provide an extremely quick, precise, and simple to carry out molecular diagnostic technique for the detection of β-thalassemia mutations.

Clinical Burden and Healthcare Resource Utilization Associated With Managing Transfusion-dependent β-Thalassemia in England

PurposePatients with transfusion-dependent β-thalassemia (TDT) have reduced levels of β-globin, leading to ineffective erythropoiesis and iron overload. Patients with TDT depend on regular red blood cell transfusions (RBCTs) and iron chelation therapy for survival and management of disease- and treatment-related clinical complications. This study describes the clinical and economic burden in patients with TDT in England. MethodsThis longitudinal, retrospective study linked the Clinical Practice Research Datalink (CPRD) database with secondary care data from the Hospital Episode Statistics database to identify patients with a diagnosis of β-thalassemia between July 1, 2008, and June 30, 2018. Included patients had a diagnosis of β-thalassemia prior to the index date, ≥8 RBCTs per year for ≥2 consecutive years, and ≥1 year of follow-up data available from the index date. Each eligible patient was exact matched with up to 5 controls in the CPRD. Proportions of deaths and rates of mortality, acute and chronic complications, and healthcare resource utilization (HCRU) were calculated during the follow-up period. FindingsOf 11,359 identified patients with β-thalassemia, 237 patients with TDT met the eligibility criteria and were matched with 1184 controls. The mean age at the index date was approximately 25 years in the patient and control groups. The proportion of deaths (7.17% vs 1.18%; P < 0.05) and mortality rate (1.19 deaths per 100 person-years vs 0.20 deaths per 100 person-years) were higher among patients with TDT compared to controls. Endocrine complications and bone disorders were the most prevalent complications among patients with TDT (58.23%) and included osteoporosis (29.11%), diabetes mellitus (28.27%), and hypopituitarism (28.27%). Patients with TDT had a mean of 13.62 RBCTs per patient per year (PPPY). HCRU was substantially higher among patients with TDT, wherein patients with TDT had higher rates of prescriptions recorded in primary care (24.09 vs 8.61 PPPY), outpatient visits (16.69 vs 1.31 PPPY), and inpatient hospitalizations (17.41 vs 0.24 PPPY) than controls. Inpatient hospitalizations were primarily <1 day, with 16.62 events PPPY lasting <1 day and 0.79 events PPPY lasting ≥1 day. Patients with TDT aged ≥18 years had increased rates of mortality, clinical complications, and HCRU than those aged <18 years. ImplicationsPatients with TDT in England have higher mortality than matched controls, substantial disease-related clinical complications, and substantial HCRU. High mortality and clinical complications highlight the need for additional innovative therapies for TDT.

Mortality, Clinical Complications, and Healthcare Resource Utilization Associated with Managing Transfusion-Dependent β-Thalassemia and Sickle Cell Disease with Recurrent Vaso-occlusive Crises in Italy.

To examine the clinical burden and healthcare resource utilization (HCRU) among patients with transfusion-dependent β-thalassemia (TDT) and patients with sickle cell disease (SCD) with recurrent vaso-occlusive crises (VOCs) in Italy. Eligible patients were identified from an administrative claims database from 1 January 2010 and 1 February 2019. Patients with TDT had ≥ 1 iron chelation treatment, ≥ 8 red blood cell transfusions (RBCTs) during any 12-month period, and ≥ 12 months of available data pre- and post-index (i.e., first RBCT claim). Patients with SCD with recurrent VOCs had ≥ 2 VOCs/year in ≥ 2 consecutive years and ≥ 12 months of available data pre- and post-index (second VOC claim in the second of 2 consecutive years). Patients were propensity score matched to five controls by age, sex, geographic area, and index year. Clinical and HCRU outcomes were evaluated post-index. In total, 214 patients with TDT and 111 patients with SCD with recurrent VOCs were matched to 1070 and 555 controls, respectively. Both patient groups had substantially higher mortality rates than controls (TDT: 4.8 versus 0.8 deaths per 100 person-years; SCD: 1.6 versus 0.4 deaths per 100 person-years). Clinical complications were prevalent in both patient groups. Compared with controls, both patient groups had significantly higher mean rates of all-cause hospitalizations (TDT: 1.4 versus 0.1; SCD: 2.0 versus 0.1) and outpatient services (TDT: 21.9 versus 1.6; SCD: 6.2 versus 1.0) per patient per year (all: p < 0.05). Management of TDT and SCD in Italy is associated with significant clinical and health system burden, highlighting the need for new treatments that eliminate RBCTs and VOCs.

Association of age to nutritional status and muscle mass in children with transfusion-dependent β-thalassemia: a cross-sectional study.

Transfusion-dependent β-thalassemia (TDT) is a hereditary blood disorder that often leads to complications affecting growth, nutritional status, and muscle mass in children. This study aims to investigate the associations between age, nutritional status, and muscle mass in children with TDT, providing insights into the progressive impact of age on these parameters. One hundred twenty-two children with TDT from March 2023 to March 2024 were enrolled in this cross-sectional study. Their nutritional status was assessed using the 2006-2007 World Health Organization (WHO) Growth Charts, and their muscle mass was measured using bioelectrical impedance analysis (BIA). Data related to age, gender, weight, height, fat-free mass (FFM), skeletal muscle mass (SMM), and soft lean mass (SLM) of children were collected for comparative analysis from the hospital record room. Furthermore, Spearman's rank correlation coefficients and regression analyses were utilized to investigate the associations between age and both nutritional status and muscle mass. The results of this study revealed negative correlations between age and wasting (r = -0.26, p < 0.001), stunting (r = -0.28, p < 0.001), FFM (r = -0.3, p < 0.001), SMM (r = -0.23, p < 0.01), and SLM (r = -0.36, p < 0.001). The regression analysis indicated that age was an independent predictor of wasting, stunting, and reduced muscle mass in these children (all p < 0.001). Our study observed a trend of worsening stunting, wasting, and muscle loss in children with TDT as they age. These findings highlight the importance of monitoring both nutritional and muscular health in TDT patients. Early detection and comprehensive nutritional management may improve outcomes in this population.

Impact of met-haemoglobin and oxidative stress on endothelial function in patients with transfusion dependent β-thalassemia

Transfusion dependent β-thalassemia is a genetic blood disorder characterized by chronic anaemia. Blood transfusion is lifesaving but comes at a cost. Iron overload emerges as a prime culprit as a free radicals damage endothelial cells. Chronic anaemia further disrupts oxygen delivery, exacerbating the oxidative stress. Increased levels of met-haemoglobin and malondialdehyde compromise endothelial function. This research sheds light on the impact of met-haemoglobin and oxidative stress on endothelial function in 50 patients with transfusion dependent β-thalassemia major compared to 50 healthy individuals as control. Blood samples were collected & subjected to CBC, biochemical analysis including creatinine, ferritin, CRP, LDH, and HCV antibodies. Oxidative stress was assessed using met-haemoglobin & malondialdehyde. Endothelial dysfunction was evaluated by endothelial activation and stress index (EASIX). EASIX, met-haemoglobin and malondialdehyde were significantly increased in patients (1.44 ± 0.75, 2.07 ± 0.2, 4.8 ± 0.63; respectively) compared to the control (0.52 ± 0.24,0.88 ± 0.34,0.8 ± 0.34; respectively). Significant strong positive correlation was found between EASIX and met-haemoglobin, malondialdehyde, serum ferritin and CRP (P = 0.00, r = 0.904, P = 0.00, r = 0.948, P = 0.00, r = 0.772, P = 0.00, r = 0.971; respectively. Met-haemoglobin as well as EASIX should be routinely estimated to assess endothelial function especially before the decision of splenectomy. Antioxidant drugs should be supplemented.

Gene therapy in transfusion-dependent non-β0/β0 genotype β-thalassemia: first real-world experience of beti-cel

AbstractGene addition and editing strategies for transfusion-dependent β-thalassemia have gained momentum as potentially curative treatment options, with studies showcasing their efficacy and safety. We report, to our knowledge, the first real-world application of betibeglogene autotemcel (beti-cel; Zynteglo) during its period of active license in Europe from January 2020 to March 2022 for patients aged ≥12 years without a β0/β0 genotype and without a HLA-matched sibling donor, before beti-cel marketing authorization was withdrawn by its holder because of nonsafety reasons. Among 15 screened patients, 4 opted out for fertility and safety concerns, 2 were excluded because of marked hepatic siderosis, and 1 had apheresis collection failure. Eight patients received beti-cel after busulfan myeloablative conditioning, all achieving transfusion independence within 8 to 59 days, with posttreatment hemoglobin levels ranging from 11.3 to 19.3 g/dL. No deaths occurred, but acute toxicity mirrored busulfan’s known effects. Posttreatment platelet management faced challenges because of HLA-antibodies in 3 patients. Monitoring up to month 24 revealed pituitary-gonadal endocrine dysfunction in all 3 female and in 2 of 5 male patients. Additionally, we observed unexpected posttreatment sequelae: 1 patient developed polycythemia that could not be explained by known genetic or acquired mechanisms, 1 patient developed posttreatment depression and anxiety prohibiting her from returning to work, and 1 patient developed fatigue severely compromising both quality of life and work capacity. This real-world experience corroborates beti-cel’s efficacy and safety and provides information on adverse events observed during real-world use of the therapy.

Ovarian Insufficiency in Adolescent Females with Transfusion-Dependent β-Thalassemia: Pituitary versus Ovarian Iron Overload

Introduction: Females with transfusion-dependent β-thalassemia (TDT) display menstrual irregularities and subfertility at certain points in their lives, even if well-chelated, representing a significant physical and psychological burden. Little is known about the effects of pituitary and ovarian iron contents on ovarian reserve and function. Hence, this study aimed to assess ovarian reserve and pituitary-gonadal axis function in adolescent females with TDT and correlate them with pituitary and ovarian volume, pituitary iron load, and serum ferritin. Methods: Fifty adolescent females with TDT were compared to 50 age-matched healthy females. Age of diagnosis of TDT, transfusion index, type of chelation therapy, age at menarche, and Tanner breast stage were assessed. Serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), anti-Müllerian hormone (AMH), and ferritin were measured. Magnetic resonance imaging (MRI) pituitary iron content R2* and T2* were measured, and 3-D transabdominal ovarian ultrasound performed. Results: The mean age of the studied females with TDT was 14.54 ± 2.24 years. Ovarian insufficiency was found in 20 of them (40%). Compared to controls, adolescent females with TDT had significantly delayed age of menarche, AMH, FSH, LH, antral follicle count (AFC), and ovarian volume. Upon comparing those with ovarian insufficiency and those without, adolescents with TDT having ovarian insufficiency had significantly higher serum ferritin and pituitary MRI-R2* than those without insufficiency. Multivariate-logistic regression showed that pituitary MRI-R2* was the most significant independent variable associated with ovarian insufficiency among adolescent females with TDT. Conclusion: Adolescent females with TDT have decreased ovarian reserve, AFC, and gonadotropins that are correlated with serum ferritin, pituitary iron load, and ovarian volume. Hence, regular ovarian reserve assessment should be implemented as a part of endocrinological follow-up of females with TDT advising procedures to preserve fertility to those who are likely to have ovarian insufficiency.

Hb SKMC and an unprecedented γδβ-thalassemia: first report from Iraq

ABSTRACT Background Thalassemias are genetic disorders of globin chain synthesis. In Iraq, β-thalassemia is more prevalent than α-thalassemia. This study identifies two unpredicted globin gene mutations, a rare α-globin gene mutation (Hb SKMC) and a novel γδβ-thalassemia deletion. Methods Over 2 years, the Genetics unit at PAR hospital in Erbil, northern Iraq processed 137 β-thalassemia and 97 α-thalassemia genetic testing requests. Three symptomatic thalassemia cases with unreported genotypes were identified. Proband-1α and proband-2α had Hb H disease, while proband-1β had severe transfusion-dependent β-thalassemia (TDT). Molecular studies included multiplex PCR, reverse hybridization, multiplex ligation-dependent probe amplification (MLPA), and globin gene sequencing. Results The α-thalassemia probands exhibited moderate microcytic hypochromic anemia with irregular transfusions and splenomegaly. Hb H disease was confirmed by positive Hb H tests and high-performance liquid chromatography (HPLC). Molecular analysis revealed heterozygous –MED deletion in proband-1α and α2Poly-A2 mutation in proband-2α. Sequencing identified the Hb SKMC (HBA1:c.283_300+3dup) mutation in both probands. The β-thalassemia proband showed anemia and regular transfusions. Molecular studies detected the IVS1.110 G>A mutation and a novel γδβ-thalassemia deletion in compound heterozygous form. The maternal sample showed the IVS1.110 G>A mutation, and MLPA confirmed the γδβ-thalassemia deletion in the paternal sample. Conclusion These findings highlight the genetic diversity of thalassemias in the region and emphasize the importance of advanced molecular diagnostics in detecting rare mutations.

Therapeutic Gene Editing for Hemoglobinopathies.

In the last ten years, a consistent number of clinical studies have evaluated different gene approaches for the treatment of patients with sickle cell disease (SCD) and transfusion-dependent β-thalassemia (TDT). Initial studies of gene therapy for hemoglobinopathies involved the use of lentiviral vectors to add functional copies of the gene encoding β-globin in defective CD34 cells; more recently, gene editing techniques have been used involving either CRISPR-Cas9, transcription activation-like effector protein nuclease, zinc finger nuclease, and base editing to either induce fetal hemoglobin production at therapeutic levels or to genetically repair the underlying molecular defect causing the disease. Here, we review recent gene editing studies that have started the development of a new era in the treatment of hemoglobinopathies and, in general, monoallelic hereditary diseases.

Bone mineral density in a cohort of transfusion-dependent β-thalassemia (TDT) patients

Background and objective: β-Thalassemia is a common inherited disease in this region. A considerable number of transfusion-dependent β-thalassemia (TDT) patients suffer bone problems. The objective of this study was to evaluate bone mineral density in TDT patients using dual-energy X-ray absorptiometry (DEXA) scan. Methods: In this study, 53 TDT patients aged ≥10 years, together with 25 normal healthy individuals were enrolled. Their bone status was assessed using DEXA scan at lumber spine (L1-L4) and femoral neck. The effect of physical, biochemical, and hormonal characteristics on the bone mineral density (BMD) parameters were evaluated. BMD-Z score was used to assess the magnitude of bone disease. Results: The mean age of the patients was 21.3±7.8 years with male to female ratio 1.4:1. The values BMD parameters were significantly lower in the patients compared to the normal group. The mean values of BMD Z-core among the patients at lumber spine and femoral neck were -2.95±1.07 and -1.51±1.02 respectively. Among the patients, osteoporosis was detected in 69.8% and 13.2% in lumber spine and femoral neck respectively. None of the normal individuals had osteoporosis. Patients’ age. body mass index (BMI) and parathyroid hormone level had a significant association with BMD Z-score (P &lt;0.05). Conclusion: Osteoporosis and osteopenia are extremely prevalent among our TDT patients. DEXA scan is an effective, non-invasive, and relatively inexpensive procedure for assessing bone status.

Regulatory Assessment of Casgevy for the Treatment of Transfusion-Dependent β-Thalassemia and Sickle Cell Disease with Recurrent Vaso-Occlusive Crises.

Sickle cell disease (SCD) and transfusion-dependent β-thalassemia (TDT) are hereditary haemoglobinopathies characterized by a reduction in functional β-globin chains. Both conditions cause tiredness and increase susceptibility to infection, which can lead organ failure, significantly reducing life expectancy and typically requiring those affected to undergo regular erythrocyte transfusion. Recently, a novel therapeutic treatment for SCD and TDT was approved by the UK regulatory body (Medicines and Healthcare products Regulatory Agency; MHRA). Exagamglogene autotemcel (Casgevy) is the first licensed therapy globally to utilize CRIPSR/Cas9 technology and induces an increase in expression of γ-globin chains to compensate for the reduction in functional β-globin. Casgevy represents a first-in-class therapeutic, and numerous considerations were made by the MHRA throughout its assessment of the medicine. These include, but are not limited to, the risk of tumorigenicity and off-target editing, a limited cohort size, the validity of proposed dosing and the conduction of only single-arm studies. The MHRA's analyses of the data to support the proposed indications are presented and discussed throughout this manuscript. Overall, the sponsors claims were considered well supported by their data, and Casgevy was licensed for the treatment of TDT or SCD in patients 12 years of age and older for whom hematopoietic stem cell (HSC) transplantation is appropriate, but a human leukocyte antigen-matched related HSC donor is not available.

Clinical burden and healthcare resource utilization associated with managing transfusion-dependent β-thalassemia in France

Objective To describe the clinical burden and healthcare resource utilization associated with managing transfusion-dependent β-thalassemia (TDT) in France. Methods We used the French National Health Data System (système national des données de santé) to identify eligible patients from January 1, 2012, to March 1, 2019. Inclusion criteria were a diagnosis of β-thalassemia, ≥8 red blood cell (RBC) transfusion episodes per year in ≥2 consecutive years following the diagnosis, and ≥1 year of follow-up data. Patients were excluded if medical records showed evidence of sickle cell disease, α-thalassemia, hereditary persistence of fetal hemoglobin, or hematopoietic stem cell transplant. Clinical complications, mortality, treatment use, and healthcare resource utilization were evaluated. Results Overall, 331 eligible patients with TDT were identified. Mean age was 26.1 (standard deviation [SD]: 18.0) years, and 50.5% were male. Common clinical complications were endocrine (26.0%), hepatobiliary (22.7%), and cardiopulmonary (18.7%). Fifteen (4.5%) patients died during follow-up, with a mortality rate of 1.16 deaths per 100 person-years (mean age of death: 52.5 years [SD: 22]). Patients had a mean of 13.5 (SD: 5.2) RBC transfusion episodes and 11.2 (SD: 5.3) iron chelation therapy treatments per year. Healthcare resource utilization was substantial, with a mean of 14.8 inpatient hospitalizations (including 13.8 mean inpatient day cases) and 16.9 outpatient prescriptions per patient per year. Conclusions Patients with TDT in France experience significant clinical complications, elevated mortality, and substantial healthcare resource utilization driven by frequent RBC transfusion episodes and inpatient hospitalizations. These results reinforce the need for disease-modifying therapies for this patient population.

Appropriateness of the EQ-5D-5L in capturing health-related quality of life in individuals with transfusion-dependent β-thalassemia: a mixed methods study

BackgroundIndividuals with transfusion-dependent β-thalassemia (TDT) experience symptoms and functional impacts that reduce their health-related quality of life. However, EQ-5D-derived health utility index scores in TDT often indicate good HRQoL, suggesting the EQ-5D may not adequately capture the impact of TDT. This study explored the disease and treatment burden of TDT and examined the appropriateness of the EQ-5D-5L descriptive system (DS) in measuring HRQoL in TDT.MethodsAdults with TDT in the United Kingdom, United States, and France completed a background questionnaire and EQ-5D-5L DS, followed by 60-minute semi-structured interviews on symptoms and HRQoL impacts of TDT (concept elicitation) and appropriateness of EQ-5D-5L DS (cognitive debrief). Transcribed interviews were analyzed using thematic and content analyses. The relationship between TDT symptoms and impacts were summarized in a conceptual model. EQ-5D-5L DS was mapped to concepts identified in the qualitative data to assess its capture of HRQoL concepts. Participants’ EQ-5D-5L DS scores were compared to their qualitative descriptions for each dimension to assess their concordance.ResultsThirty participants in the United States (n = 14 [46.7%]), United Kingdom. (n = 12 [40.0%]), and France (n = 4 [13.3%]) completed the study (73.3% female; mean age = 28.4 years [standard deviation (SD) = 5.1]; mean annual red blood cell transfusion [RBCT] frequency = 18.4 [SD = 7.6]). Participants reported TDT symptoms and impacts on HRQoL, all fluctuating across the RBCT cycle. EQ-5D-5L DS did not fully capture 11 of 16 (68.8%) HRQoL concepts reported. Most participants (n = 20/27 [74.1%]) reported that EQ-5D-5L DS did not capture important aspects of living with TDT, and 42.9% (n = 12/28) reported negative/neutral overall impressions of EQ-5D-5L DS. The highest degree of discordance between participants’ qualitative data and EQ-5D-5L DS dimension scores was observed with mobility (42.3%) and self-care (34.6%), where the qualitative descriptions relating to these dimensions were worse than their quantitative scores.ConclusionCurrent findings suggest that EQ-5D-5L DS lacks content validity and the derived health utility index score may not fully represent the burden of disease in TDT.

Casgevy: Innovative Medicinal Products Require Innovative Approaches to Regulatory Assessment.

Casgevy (exa-cel) is an autologous cellular therapy modified ex vivo by a CRISPR-Cas9-mediated gene-editing technology. For Casgevy to be granted the indication in transfusion-dependent β-thalassemia, one single-arm trial was submitted which was not amenable to conventional statistical analysis of 'effect of cause'. Therefore, an analysis was conducted on the basis of 'cause of effect' making use of the scheme described by Toulmin coupled to an analysis of causal inference. Based on the current data within the submitted study: subjects with transfusion-dependent β-thalassemia no longer needed a red blood cell transfusion with a 93-percent probability if and only if administered Casgevy; PNS = 93%. It is acknowledged that unknown elements of safety may yet be revealed by long-term follow-up of recipients of Casgevy. Its durability of efficacy is, at present, also an unknown that may also be ascertained by long-term follow-up of recipients. The limitations of a causal analysis are related to assumptions of the proposed causal structure which may not capture the complexity of the real world. Overall, the claim that Casgevy is indicated to treat people with transfusion-dependent β-thalassemia is considered to be supported by the results of the submitted study; the benefit-risk evaluation of Casgevy is found to be positive.

The CRISPR-Cas System and Clinical Applications of CRISPR-Based Gene Editing in Hematology with a Focus on Inherited Germline Predisposition to Hematologic Malignancies.

Clustered regularly interspaced short palindromic repeats (CRISPR)-based gene editing has begun to transform the treatment landscape of genetic diseases. The history of the discovery of CRISPR/CRISPR-associated (Cas) proteins/single-guide RNA (sgRNA)-based gene editing since the first report of repetitive sequences of unknown significance in 1987 is fascinating, highly instructive, and inspiring for future advances in medicine. The recent approval of CRISPR-Cas9-based gene therapy to treat patients with severe sickle cell anemia and transfusion-dependent β-thalassemia has renewed hope for treating other hematologic diseases, including patients with a germline predisposition to hematologic malignancies, who would benefit greatly from the development of CRISPR-inspired gene therapies. The purpose of this paper is three-fold: first, a chronological description of the history of CRISPR-Cas9-sgRNA-based gene editing; second, a brief description of the current state of clinical research in hematologic diseases, including selected applications in treating hematologic diseases with CRISPR-based gene therapy, preceded by a brief description of the current tools being used in clinical genome editing; and third, a presentation of the current progress in gene therapies in inherited hematologic diseases and bone marrow failure syndromes, to hopefully stimulate efforts towards developing these therapies for patients with inherited bone marrow failure syndromes and other inherited conditions with a germline predisposition to hematologic malignancies.

Association between Epicardial Adipose Tissue and Atrial Fibrillation in Patients with Transfusion-Dependent β-Thalassemia.

Background: Modern treatments for transfusion-dependent β-thalassemia (TDβT) have allowed patients to reach high life expectancy with no iron overload. Despite survival improvement, atrial fibrillation (AF) has emerged as a relevant issue. AF pathophysiology and characteristics in TDβT are different than in the general population. Epicardial adipose tissue (EAT) may play a role but its relationship with AF in patients with TDβT has not been explored. Methods: A monocentric, cross-sectional study, enrolling consecutive patients with TDβT. Epicardial adipose tissue (EAT) was evaluated at magnetic resonance. Characteristics of patients with and without history of AF were investigated. Factors independently associated with AF prevalence were analyzed. Results: A total of 116 patients were enrolled. All patients were treated with regular chelation therapy. The prevalence of AF was 29.3% (34/116). Cardiac T2* and liver iron concentration were no different between patients with and without AF. EAT thickness was significantly higher in patients with AF at left atrium, right atrium and right ventricle (5.0 vs. 4.0 mm, p < 0.01, 4.4 vs. 4.0, p = 0.02 and 5.0 vs. 4.3, p = 0.04). Patients with AF presented with older age, (53 vs. 49 years, p < 0.01), more hypothyroidism (44.1 vs. 20.7%, p = 0.01), pulmonary hypertension (23.5 vs. 2.4% p < 0.01), splenectomy (88.2 vs. 64.6%, p = 0.01), higher right and left atrial volume (61 vs. 40 and 74 vs. 43 mL, both p < 0.01). At multivariable analysis, hypothyroidism, left atrial volume and left atrial EAT were independently associated with AF (odds ratio 9.95, 1.09 and 1.91, respectively). Conclusions: In a contemporary cohort of patients with TDβT, treated with regular chelation therapy, prevalence of AF was unrelated to iron overload. EAT was independently associated with AF.

Iron chelation therapy for children with transfusion-dependent β-thalassemia: How young is too young?

In this review, we provide a summary of evidence on iron overload in young children with transfusion-dependent β-thalassemia (TDT) and explore the ideal timing for intervention. Key data from clinical trials and observational studies of the three available iron chelators deferoxamine, deferiprone, and deferasirox are also evaluated for inclusion of subsets of young children, especially those less than 6years of age. Evidence on the efficacy and safety of iron chelation therapy for children ≥2years of age with transfusional iron overload is widely available. New data exploring the risks and benefits of early-start iron chelation in younger patients with minimal iron overload are also emerging.

Modified lentiviral globin gene therapy for pediatric β0/β0 transfusion-dependent β-thalassemia: A single-center, single-arm pilot trial

β0/β0 thalassemia is the most severe type of transfusion-dependent β-thalassemia (TDT) and is still a challenge facing lentiviral gene therapy. Here, we report the interim analysis of a single-center, single-arm pilot trial (NCT05015920) evaluating the safety and efficacy of a β-globin expression-optimized and insulator-engineered lentivirus-modified cell product (BD211) in β0/β0 TDT. Two female children were enrolled, infused with BD211, and followed up for an average of 25.5months. Engraftment of genetically modified hematopoietic stem and progenitor cells was successful and sustained in both patients. No unexpected safety issues occurred during conditioning or after infusion. Both patients achieved transfusion independence for over 22months. The treatment extended the lifespan of red blood cells by over 42days. Single-cell DNA/RNA-sequencing analysis of the dynamic changes of gene-modified cells, transgene expression, and oncogene activation showed no notable adverse effects. Optimized lentiviral gene therapy may safely and effectively treat all β-thalassemia.

CRISPR-Based Gene Therapies: From Preclinical to Clinical Treatments.

In recent years, clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) protein have emerged as a revolutionary gene editing tool to treat inherited disorders affecting different organ systems, such as blood and muscles. Both hematological and neuromuscular genetic disorders benefit from genome editing approaches but face different challenges in their clinical translation. The ability of CRISPR/Cas9 technologies to modify hematopoietic stem cells ex vivo has greatly accelerated the development of genetic therapies for blood disorders. In the last decade, many clinical trials were initiated and are now delivering encouraging results. The recent FDA approval of Casgevy, the first CRISPR/Cas9-based drug for severe sickle cell disease and transfusion-dependent β-thalassemia, represents a significant milestone in the field and highlights the great potential of this technology. Similar preclinical efforts are currently expanding CRISPR therapies to other hematologic disorders such as primary immunodeficiencies. In the neuromuscular field, the versatility of CRISPR/Cas9 has been instrumental for the generation of new cellular and animal models of Duchenne muscular dystrophy (DMD), offering innovative platforms to speed up preclinical development of therapeutic solutions. Several corrective interventions have been proposed to genetically restore dystrophin production using the CRISPR toolbox and have demonstrated promising results in different DMD animal models. Although these advances represent a significant step forward to the clinical translation of CRISPR/Cas9 therapies to DMD, there are still many hurdles to overcome, such as in vivo delivery methods associated with high viral vector doses, together with safety and immunological concerns. Collectively, the results obtained in the hematological and neuromuscular fields emphasize the transformative impact of CRISPR/Cas9 for patients affected by these debilitating conditions. As each field suffers from different and specific challenges, the clinical translation of CRISPR therapies may progress differentially depending on the genetic disorder. Ongoing investigations and clinical trials will address risks and limitations of these therapies, including long-term efficacy, potential genotoxicity, and adverse immune reactions. This review provides insights into the diverse applications of CRISPR-based technologies in both preclinical and clinical settings for monogenic blood disorders and muscular dystrophy and compare advances in both fields while highlighting current trends, difficulties, and challenges to overcome.

β-Thalassemia gene editing therapy: Advancements and difficulties.

β-Thalassemia is the world's number 1 single-gene genetic disorder and is characterized by suppressed or impaired production of β-pearl protein chains. This results in intramedullary destruction and premature lysis of red blood cells in peripheral blood. Among them, patients with transfusion-dependent β-thalassemia face the problem of long-term transfusion and iron chelation therapy, which leads to clinical complications and great economic stress. As gene editing technology improves, we are seeing the dawn of a cure for the disease, with its reduction of ineffective erythropoiesis and effective prolongation of survival in critically ill patients. Here, we provide an overview of β-thalassemia distribution and pathophysiology. In addition, we focus on gene therapy and gene editing advances. Nucleic acid endonuclease tools currently available for gene editing fall into 3 categories: zinc finger nucleases, transcription activator-like effector nucleases, and regularly interspaced short palindromic repeats (CRISPR-Cas9) nucleases. This paper reviews the exploratory applications and exploration of emerging therapeutic tools based on 3 classes of nucleic acid endonucleases in the treatment of β-thalassemia diseases.