Sickle Cell Disease

Emergency department 30-Day emergency department revisits among people with sickle cell disease: Variations in characteristics

People with sickle cell disease (SCD) often have emergency department (ED) revisits. The characteristics of people with SCD with ED revisits were assessed in this study using Medicaid administrative claims data from California and Georgia, representing 2794 and 3641 individuals with SCD, respectively. In both states, those with 6+ primary care provider (PCP) encounters had the highest percentage of ED revisits. In California, those with 6+ hematology encounters had the lowest percentage of individuals with an ED revisit; in Georgia, those with 1-2 hematology encounters. Increasing access to hematologic care may reduce ED revisits among people with SCD.

Reviewing the impact of hydroxyurea on DNA methylation and its potential clinical implications in sickle cell disease

Hydroxyurea (HU) is the most common drug therapy for sickle cell disease (SCD). The clinical benefits of HU derive from its upregulation of fetal hemoglobin (HbF), which reduces aggregation of the mutated sickle hemoglobin protein (HbS) and reduces SCD symptoms and complications. However, some individuals do not respond to HU, or stop responding over time. Unfortunately, current understanding of the mechanism of action of HU is limited, hindering the ability of clinicians to identify those patients who will respond to HU and to optimize treatment for those receiving HU. Given that epigenetic modifications are essential to erythropoiesis and HbF expression, we hypothesize that some effects of HU may be mediated by epigenetic modifications, specifically DNA methylation. However, few studies have investigated this possibility and the effects of HU on DNA methylation remain relatively understudied. In this review, we discuss the evidence linking HU treatment to DNA methylation changes and associated gene expression changes, with an emphasis on studies that were performed in individuals with SCD. Overall, although HU can affect DNA methylation, research on these changes and their clinical effects remains limited. Further study is likely to contribute to our understanding of hematopoiesis and benefit patients suffering from SCD.

Gene therapies on the horizon for sickle cell disease: a clinician's perspective

INTRODUCTION

Sickle cell disease (SCD) is a monogenic disorder that exerts several detrimental health effects on those affected, ultimately resulting in significant morbidity and early mortality. There are millions of individuals globally impacted by this disease. Research in gene therapy has been growing significantly over the past decade, now with two FDA approved products, aiming to find another cure for this complex disease.

AREAS COVERED

This perspective article aims to provide a clinician's insight into the current landscape of gene therapies, exploring the novel approaches, clinical advances, and potential impact on the management and prognosis of SCD. A comprehensive literature search encompassing databases such as PubMed, Web of Science and Google Scholar was employed. The search covered literature published from 1980 to 2024, focusing on SCD and curative therapy.

EXPERT OPINION

After careful evaluation of the risks and benefits associated with the use of gene therapy for affected patients, the need for a cure outweighs the risks associated with treatment in most cases of SCD. With advances in current technologies, gene therapies can increase access to cures for patients with SCD.

Reproductive Health Assessment and Reports of Fertility Counseling in Pediatric and Adolescent Patients with Sickle Cell Disease After Hematopoietic Cell Transplantation

Conditioning regimens for hematopoietic cell transplant (HCT) in patients with sickle cell disease (SCD) place patients at risk for reproductive health issues. The purpose of this study was to assess reproductive health and reports of fertility counseling in patients with SCD who received a transplant. This was a secondary analysis of gonadal hormone production, future infertility risk assessment, and parent-proxy/patient reports of fertility counseling in SCD transplant recipients who are currently pubertal and were enrolled in the Atlanta sites of the Sickle Cell Transplant Evaluation of Long-term and Late Effects Registry (STELLAR) between May 2017 and October 2023. Clinical information was abstracted from medical records and reproductive health survey data from the STELLAR database. Descriptive statistics were reported as median (interquartile range [IQR]) or percentages. There were 20 females and 12 males in the study population. Females were median (IQR) 19.6 (9.4) years old and males 20.8 (11.4) years old at the time of the study. Transplants most commonly occurred in the decade 2010 to 2019 at 10.7 (4.8) years old for females and 11.1 (4.1) years old for males. Most participants received bone marrow stem cells (95.0% females, 100.0% males) from matched sibling donors (90.0% females, 100.0% males). Participants received one of seven HCT conditioning regimens with cyclophosphamide equivalent doses ranging from 3388 to 9706 mg/m2. The majority of females (90.0%) had diminished ovarian reserve with low anti-Mullerian hormone levels, and 61.1% had premature ovarian insufficiency with two follicle-stimulating hormone levels (FSH) ≥40 mIU/mL post-HCT. All males had normal testosterone levels, but 63.6% had elevated FSH levels suggestive of impaired spermatogenesis post-HCT. Parent proxies (for patients <18 years old) and patients ≥18 years old completed surveys 9.0 years (5.2) and 7.9 years (9.3) since HCT in females and males respectively. Twenty-five percent of parent proxies and 45% of patients reported that they had not been informed by a healthcare provider of the risk of infertility post-transplant. There are high rates of gonadal dysfunction post-HCT, but many parent proxies and patients do not recall being told of the risk for future infertility. More effective methods of education are warranted to ensure SCD patients and their families clearly understand the risk for reproductive health issues post-HCT.

Outdoor Air Pollution and Pediatric Respiratory Disease

Outdoor air pollution is ubiquitous, and no safe level of exposure has been identified for the most common air pollutants such as ozone and particle pollution. Children are uniquely more susceptible to the harms of outdoor air pollution, which can cause and exacerbate respiratory disease. Although challenging to identify the effects of outdoor air pollution on individual patients, understanding the basics of outdoor air pollution is essential for pediatric respiratory health care providers. This review covers basic information regarding outdoor air pollution, unique considerations for children, mechanisms for increased susceptibility, and association with incident and exacerbation of respiratory disease in children.

Screening for sickle cell disease: focus on newborn investigations

Drepanocytosis is a genetic disease relevant for its epidemiological, clinical and socio-economic aspects. In our country the prevalence is highly uneven with peaks in former malaria areas, but migration flows in recent years have led to significant changes. In this document we review the screening programs currently existing in Italy with particular emphasis on newborn screening, which in other countries around the world, including within Europe, is at most universal and mandatory. The essential laboratory issues are reviewed, from sampling aspects (cord blood or peripheral), to the analytical (analytical methods dedicated to neonatal screening and adult carrier detection) and post analytical (reporting, informative) ones. An economic analysis based on data collected in the province of Modena is also proposed, clearly showing that neonatal screening is also beneficial from an economic point of view.

Multicenter, phase 1 study of etavopivat (FT-4202) treatment for up to 12 weeks in patients with sickle cell disease

ABSTRACT

Etavopivat is an investigational, once daily, oral, selective erythrocyte pyruvate kinase (PKR) activator. A multicenter, randomized, placebo-controlled, double-blind, 3-part, phase 1 study was conducted to characterize the safety and clinical activity of etavopivat. Thirty-six patients with sickle cell disease (SCD) were enrolled into 4 cohorts: 1 single-dose, 2 multiple ascending doses, and 1 open-label (OL). In the OL cohort, 15 patients (median age 33.0 years [range, 17-55]) received 400 mg etavopivat once daily for 12 weeks; 14 patients completed treatment. Consistent with the mechanism of PKR activation, increases in adenosine triphosphate and decreases in 2,3-diphosphoglycerate were observed and sustained over 12 weeks' treatment. This translated clinically to an increase in hemoglobin (Hb; mean maximal increase 1.6 g/dL [range, 0.8-2.8]), with >1 g/dL increase in 11 (73%) patients during treatment. In addition, the oxygen tension at which Hb is 50% saturated was reduced (P = .0007) with a concomitant shift in point of sickling (P = .0034) to lower oxygen tension in oxygen-gradient ektacytometry. Hemolysis markers (absolute reticulocyte count, indirect bilirubin, and lactate dehydrogenase) decreased from baseline, along with matrix metalloproteinase-9 and erythropoietin. In the OL cohort, adverse events (AEs) were mostly grade 1/2, consistent with underlying SCD; 5 patients had serious AEs. Vaso-occlusive pain episode was the most common treatment-emergent AE (n = 7) in the OL cohort. In this, to our knowledge, the first study of etavopivat in SCD, 400 mg once daily for 12 weeks was well tolerated, resulting in rapid and sustained increases in Hb, improved red blood cell physiology, and decreased hemolysis. This trial was registered at www.ClinicalTrials.gov as #NCT03815695.

Elevating fetal hemoglobin: recently discovered regulators and mechanisms

ABSTRACT

It has been known for over half a century that throughout ontogeny, humans produce different forms of hemoglobin, a tetramer of α- and β-like hemoglobin chains. The switch from fetal to adult hemoglobin occurs around the time of birth when erythropoiesis shifts from the fetal liver to the bone marrow. Naturally, diseases caused by defective adult β-globin genes, such as sickle cell disease and β-thalassemia, manifest themselves as the production of fetal hemoglobin fades. Reversal of this developmental switch has been a major goal to treat these diseases and has been a driving force to understand its underlying molecular biology. Several review articles have illustrated the long and at times arduous paths that led to the discovery of the first transcriptional regulators involved in this process. Here, we survey recent developments spurred by the discovery of CRISPR tools that enabled for the first time high-throughput genetic screens for new molecules that impact the fetal-to-adult hemoglobin switch. Numerous opportunities for therapeutic intervention have thus come to light, offering hope for effective pharmacologic intervention for patients for whom gene therapy is out of reach.

Hydroxyurea in the sickle cell disease modern era

INTRODUCTION

Sickle cell disease is an inherited disorder characterized by hemoglobin S polymerization leading to vaso-occlusion and hemolytic anemia. These result in a variety of pathological events, causing both acute and chronic complications. Millions around the world are affected by sickle cell disease with predominance in sub-Saharan Africa. Hydroxyurea was the first drug approved for use in sickle cell disease to reduce the occurrence of painful crises and blood transfusions in patients with frequent, moderate to severe painful crises.

AREAS COVERED

With the development of new therapeutics, the role of hydroxyurea is evolving. This narrative review aims to provide clinical data, safety information, and supplementary evidence for the role of hydroxyurea in the current era of sickle cell disease. A comprehensive literature search of databases, including PubMed and Cochrane Library, was conducted from 1963 to 2024.

EXPERT OPINION

Even though new medications have been approved for sickle cell disease, hydroxyurea remains the gold standard. Hydroxyurea is not only a disease modifier but it has additional clinical benefits, it is affordable, and its longevity has prompted expanded research in areas such as underutilization and pharmacogenomics. As the treatment landscape evolves, hydroxyurea's long-standing record of efficacy and safety continues to support its role as a key agent in disease management.

Iron metabolism in sickle cell disease patients undergoing chronic red blood cell exchange: A delicate homeostasis in balance

Sickle cell disease (SCD) is an inherited haemoglobinopathy associated with significant morbidity and mortality. Automated red blood cell exchange (aRCE) plays a key role in managing SCD, eliciting both therapeutic and prophylactic effects. The ideal post-apheresis Ht target for chronic aRCE treatment is not yet unanimously recognized, as well as iron homeostasis can be different among patients. Ross et al. reported their experience on the chronic management of SCD patients undergoing aRCE with a final post-exchange Ht higher than the value commonly adopted, analysing red blood cell transfusion requirements and iron-related outcomes in the study population. Commentary on: Ross et al. Automated red blood cell exchange with a post-procedure haematocrit targeted at 34% in the chronic management of sickle cell disease. Br J Haematol 2024 (Online ahead of print). doi: 10.1111/bjh.19674.

Knowledge, attitudes, and practices of primary healthcare practitioners in low- and middle-income countries: a scoping review on genetics

Individualised treatment, including genetic services, calls for an increased role of primary healthcare practitioners (pHCPs) in diagnosing and caring for individuals with genetic conditions. PHCPs' genetics knowledge and practices must be current to ensure adequate care. A scoping review was conducted to explore peer-reviewed articles on the knowledge, attitudes, and practices (KAPs) of pHCPs concerning genetics, genetic testing, and genetic services. English-language human genetics/genomics articles published between January 1990 and April 2022 in low- and middle-income countries (LMICs) were included. Twenty-eight articles from 16 LMICs in five World Health Organisation (WHO)-defined regions met the inclusion criteria and showed a steady increase in publications, with varied contributions by region. The Eastern Mediterranean Region (EMR) contributed the most articles (n = 8), while the Western Pacific Region (WPR) had the least (n = 2). Brazil published the most articles (n = 6), while ten countries contributed one article each. Fifteen articles included knowledge, 19 included attitudes towards genetics, and eight included genetic practices. The findings indicate that pHCPs in LMICs lack knowledge of genetics and its applications despite their positive outlook towards genetic services. Barriers such as limited resources, financial constraints, and cultural or religious beliefs hinder access to genetic services. Enhancing pHCPs' genetics education is vital for improving care for those affected by genetic conditions. The scarcity of literature in LMICs emphasises the need for research on educational interventions to improve patient outcomes and family support.

Library-Assisted Evolution in Eukaryotic Cells Yield Adenine Base Editors with Enhanced Editing Specificity

The current-generation adenine base editor (ABE) ABE8e, which has evolved from the prokaryotic evolution system, exhibits high efficiency in mediating A-to-G conversion and is presumed to be promising for gene therapy. However, its much wider editing window and substantially higher off-target editing activity restricted its applications in precise base editing for therapeutic use. This study uses a library-assisted protein evolution approach using eukaryotic cells to generate ABE variants with improved specificity and reduced off-target editing while maintaining high activity in human cells. The study generated an expanded set of ABEs with efficient editing activities and chose four evolved variants that offered either similar or modestly higher efficiency within a narrower editing window of protospacer position ≈4-7 compared to that of ABE8e in human cells, which would enable minimized bystander editing. Moreover, these variants resulted in reduced off-target editing events when delivered as plasmid or mRNA into human cells. Finally, these variants can install both disease-suppressing mutations and disease-correcting mutations efficiently with minimal undesired bystander editing making them promising approaches for specific therapeutic edits. In summary, the work establishes a mutant-library-assisted protein evolution method in eukaryotic cells and generates alternative ABE variants as efficient tools for precise human genome editing.

Haemoglobinopathies and other rare anemias in Spain: ten years of a nationwide registry (REHem-AR)

REHem-AR was created in 2013. The progressive implementation of neonatal screening for haemoglobinopathies in Spanish autonomous communities where the registry had not been implemented, as well as the addition of new centres during this period, has considerably increased the sample of patients covered. In this study, we update our previous publication in this area, after a follow-up of more than 5 years. An observational, descriptive, multicentre and ambispective study of adult and paediatric patients with haemoglobinopathies and rare anaemias registered in REHem was performed. The data are from a cross-sectional analysis performed on 1 June, 2023. The study population comprised 1,756 patients, of whom 1,317 had SCD, 214 had thalassaemia and 224 were diagnosed with another condition. Slightly more than one third of SCD patients (37%) were diagnosed based on neonatal bloodspot screening, and the mean age at diagnosis was 2.5 years; 71% of thalassaemia patients were diagnosed based on the presence of anaemia. Vaso-occlusive crisis and acute chest syndrome continue to be the most frequent complications in SCD. HSCT was performed in 83 patients with SCD and in 50 patients with thalassaemia. Since the previous publication, REHem-AR has grown in size by more than 500 cases. SCD and TM are less frequent in Spain than in other European countries, although the data show that rare anaemias are frequent within rare diseases. REHem-AR constitutes an important structure for following the natural history of rare anaemias and enables us to calculate investment needs for current and future treatments.

The many faces of sickle cell disease in children: complications in the appendicular skeleton

Sickle cell disease (SCD) is a hereditary red cell disorder with clinical manifestations secondary to sickling or crescent-shaped distortion of the red blood cells. Musculoskeletal complications of SCD are often the main causes for acute and chronic morbidities in children with manifestations including osteomyelitis, osteoporosis and osteonecrosis. This article aims to familiarise the paediatric radiologist with appendicular skeletal complications of SCD in the paediatric population and their imaging appearance.

Shift in emergency department utilization by frequent attendees with sickle cell disease during the COVID-19 pandemic: A multicentre cohort study

While the coronavirus disease-2019 (COVID-19) might have increased acute episodes in people living with sickle cell disease (SCD), it may also have changed their reliance on emergency department (ED) services. We assessed the impact of the COVID-19 pandemic and lockdowns on ED visits in adult SCD people followed in five French reference centres, with a special focus on 'high users' (≥10 visits in 2019). We analysed the rate of ED visits from 1 January 2015 to 31 December 2021, using a self-controlled case series. Among 1530 people (17 829 ED visits), we observed a significant reduction in ED visits during and after lockdowns, but the effect vanished over time. Compared to pre-pandemic, incidence rate ratios for ED visits were 0.59 [95% CI 0.52-0.67] for the first lockdown, 0.66 [95% CI 0.58-0.75] for the second and 0.85 [95% CI 0.73-0.99] for the third. High users (4% of people but 33.7% of visits) mainly drove the reductions after the first lockdown. COVID-19 lockdowns were associated with reduced ED visits. While most people returned to their baseline utilization by April 2021, high users had a lasting decrease in ED visits. Understanding the factors driving the drop in ED utilization among high users might inform clinical practice and health policy.

Base Editors-Mediated Gene Therapy in Hematopoietic Stem Cells for Hematologic Diseases

Base editors, developed from the CRISPR/Cas system, consist of components such as deaminase and Cas variants. Since their emergence in 2016, the precision, efficiency, and safety of base editors have been gradually optimized. The feasibility of using base editors in gene therapy has been demonstrated in several disease models. Compared with the CRISPR/Cas system, base editors have shown great potential in hematopoietic stem cells (HSCs) and HSC-based gene therapy, because they do not generate double-stranded breaks (DSBs) while achieving the precise realization of single-base substitutions. This precise editing mechanism allows for the permanent correction of genetic defects directly at their source within HSCs, thus promising a lasting therapeutic effect. Recent advances in base editors are expected to significantly increase the number of clinical trials for HSC-based gene therapies. In this review, we summarize the development and recent progress of DNA base editors, discuss their applications in HSC gene therapy, and highlight the prospects and challenges of future clinical stem cell therapies.

The clinical spectrum of HbSC sickle cell disease-not a benign condition

Sickle cell disease (SCD) includes a group of heterogenous disorders that result in significant morbidities. HbSS is the most common type of SCD and HbSC is the second most common type of SCD. The prevalence of HbSC disease in the United States and United Kingdom is ~1 in 7174 births and 1 in 6174 births respectively. Despite its frequency, however, HbSC disease has been insufficiently studied and was historically categorized as a more 'mild' form of SCD. We conducted this study of HbSC disease as part of the NHLBI funded Sickle Cell Disease Implementation Consortium (SCDIC). The SCDIC registry included 2282 individuals with SCD, ages 15-45 years of whom 502 (22%) had HbSC disease. Compared with people with sickle cell anaemia (SCA), the study found that people with HbSC disease had a higher frequency of splenomegaly (n (%) = 169 (33.7) vs. 392 (22.1)) and retinopathy (n (%) = 116 (23.1) vs. 189 (10.6)). A Many people with HbSC also had avascular necrosis (n (%) = 112 (22.3)), pulmonary embolism (n (%) = 43 (8.6)) and acute chest syndrome (n (%) = 228 (45.4)) demonstrating significant disease severity. HbSC disease is more clinically severe than was previously recognized and deserves additional evaluation and targeted treatments.

Sickle Cell Health Awareness, Perspectives, and Experiences (SHAPE) survey: Perspectives of adolescent and adult patients, caregivers, and healthcare professionals on the burden of sickle cell disease

OBJECTIVES

Sickle cell disease (SCD) is an inherited disorder that causes lifelong complications, substantially impacting the physical and emotional well-being of patients and their caregivers. Studies investigating the effects of SCD on quality of life (QOL) are often limited to individual countries, lack SCD-specific QOL questionnaires, and exclude the caregiver experience. The SHAPE survey aimed to broaden the understanding of the global burden of SCD on patients and their caregivers and to capture the viewpoint of healthcare providers (HCPs).

METHODS

A total of 919 patients, 207 caregivers, and 219 HCPs from 10, 9, and 8 countries, respectively, answered a series of closed-ended questions about their experiences with SCD.

RESULTS

The symptoms most frequently reported by patients were fatigue/tiredness (84%) and pain/vaso-occlusive crises (71%). Patients' fatigue/tiredness had one of the greatest impacts on both patients' and caregivers' QOL. On average, patients and caregivers reported missing 7.5 days and 5.0 days per month, respectively, of school or work. HCPs reported a need for effective tools to treat fatigue/tiredness and a desire for more support to educate patients on long-term SCD-related health risks.

CONCLUSIONS

The multifaceted challenges identified using the SHAPE survey highlight the global need to improve both patient and caregiver QOL.

Psychological trauma and post-traumatic growth in parents of children with sickle cell disease

Sickle cell disease (SCD) is a hereditary blood condition characterized by abnormal hemoglobin, leading to chronic hemolysis and vaso-occlusive complications. Caregivers of children with SCD often experience significant distress, akin to post-traumatic stress disorder (PTSD). This study aimed to measure the degree of trauma and post-traumatic growth among parents (caregivers) of children with SCD in the Kingdom of Saudi Arabia. A total of 294 primary caregivers were recruited for this study, through direct phone calls and online outreach using contact information obtained from their primary treating physician in Maternity and Children Hospitals and the Hereditary Blood Diseases Center in Al-Ahsa. Inclusion criteria required caregivers not to be receiving professional mental health care and to have a child with SCD below the age of 18. Results indicate that caregiver gender significantly affected IESR scores, with mothers reporting higher scores than fathers. Family income had a significant effect on IESR as well. In terms of education level, higher-educated caregivers were less likely to experience severe trauma. Significant differences emerged between online and phone interview participants, with online respondents reporting higher post-traumatic growth and higher trauma levels. This study represents a crucial step in understanding the challenges faced by caregivers of children with SCD in Al-Ahsa, Saudi Arabia. However, the study has limitations, including a substantial portion of the sample being from a single clinic and a cross-sectional design.

An Examination of John Henryism in Adults Living with Sickle Cell Disease

BACKGROUND

John Henryism (JH) is a behavioral predisposition for high-effort coping with adversity. JH has been associated with hypertension in Black Americans with low socioeconomic status (SES) and is also found to be associated with psychological well-being. Sickle cell disease (SCD), a rare genetic disease largely affecting Black Americans in the United States, presents as a chronic condition that may benefit from a deeper understanding of the impact of JH on overall health.

PURPOSE

This study examined the association between high and low JH and diastolic blood pressure, systolic blood pressure, hypertension prevalence, and sleep function. We relied on the biopsychosocial transaction model to adjust for relevant clinical and sociodemographic variables.

METHODS

This was a cross-sectional secondary analysis of 274 adults with SCD living in the United States and recruited between 2014 and 2020. Study visits consisted of physical examinations, medical history, demographic, and psychosocial questionnaires. Adjusted linear regressions estimated associations between high and low JH and diastolic and systolic blood pressure as well as self-reported sleep function. Multivariable logistic regression was used to examine associations with hypertension prevalence.

RESULTS

High JH was significantly associated with lower diastolic blood pressure (β =  - 2.98; 95% confidence interval =  - 5.92, - 0.04) but higher sleep dysfunction (β = 2.76; 95% confidence interval = 1.45, 4.07).

CONCLUSIONS

Overall, we found positive psychological coping resources associated with high JH, with the exception of sleep.

TRIAL REGISTRATION

CLINICALTRIALS

gov Identifier: NCT02156102.

Association of elevated tricuspid regurgitation velocity with cerebrovascular and kidney disease in children with sickle cell disease

BACKGROUND

Tricuspid regurgitation velocity (TRV), measured by echocardiography, is a surrogate marker for pulmonary hypertension. Limited pediatric studies have considered the association between TRV and surrogate markers of end-organ disease.

METHODS

We conducted a cross-sectional study that evaluated the prevalence of elevated TRV ≥2.5 m/s and its associations with renal and cerebrovascular outcomes in children with sickle cell disease (SCD) 1-21 years of age in two large sickle cell cohorts, the University of Alabama at Birmingham (UAB) sickle cell cohort, and the Sickle Cell Clinical Research and Intervention Program (SCCRIP) cohort at St. Jude Children's Research Hospital. We hypothesized that patients with SCD and elevated TRV would have higher odds of having either persistent albuminuria or cerebrovascular disease.

RESULTS

We identified 166 children from the UAB cohort (mean age: 13.49 ± 4.47 years) and 325 children from the SCCRIP cohort (mean age: 13.41 ± 3.99 years) with echocardiograms. The prevalence of an elevated TRV was 21% in both UAB and SCCRIP cohorts. Elevated TRV was significantly associated with cerebrovascular disease (odds ratio [OR] 1.88, 95% confidence interval [CI]: 1.12-3.15; p = .017) and persistent albuminuria (OR 1.81, 95% CI: 1.07-3.06; p = .028) after adjusting for age, sex, treatment, and site.

CONCLUSION

This cross-sectional, multicenter study identifies associations between surrogate markers of pulmonary hypertension with kidney disease and cerebrovascular disease. A prospective study should be performed to evaluate the longitudinal outcomes for patients with multiple surrogate markers of end-organ disease.

Sickle Cell Disease and Gut Health: The Influence of Intestinal Parasites and the Microbiome on Angolan Children

Parasitic infections are a common problem in developing countries and can intensify morbidity in patients with sickle cell disease (SCD), increasing the severity of anemia and the need for transfusions. It has been demonstrated that both helminths and protozoa can affect gut microbiome composition. On the other hand, the presence of specific bacterial communities can also influence parasite establishment. Considering this, our aim was to associate the presence of intestinal parasites with the results of hematological analyses and microbiome composition evaluations in a population of Angolan children with and without SCD. A total of 113 stool samples were collected, and gut microbiome analysis was performed using 16S sequencing and real-time PCR to detect eight different intestinal parasites. In our population, more than half of children (55%) had at least one parasitic infection, and of these, 43% were co-infected. Giardia intestinalis and Ascaris lumbricoides were more frequently found in children from the rural area of Bengo. Moreover, SCD children with ascariasis exhibited higher values of leukocytes and neutrophils, whereas the total hemoglobin levels were lower. In regards to the gut microbiome, the presence of intestinal parasites lowered the prevalence of some beneficial bacteria, namely: Lactobacillus, Bifidobacterium, Cuneatibacter, Bacteroides uniformis, Roseburia, and Shuttleworthia. This study presents the prevalence of several intestinal parasites in a high-risk transmission area with scarce information and opens new perspectives for understanding the interaction between parasites, the microbiome, and SCD.

Impacts of oxidative stress and anti-oxidants on the development, pathogenesis, and therapy of sickle cell disease: A comprehensive review

Sickle cell disease (SCD) is the most severe monogenic hemoglobinopathy caused by a single genetic mutation that leads to repeated polymerization and depolymerization of hemoglobin resulting in intravascular hemolysis, cell adhesion, vascular occlusion, and ischemia-reperfusion injury. Hemolysis causes oxidative damage indirectly by generating reactive oxygen species through various pathophysiological mechanisms, which include hemoglobin autoxidation, endothelial nitric oxide synthase uncoupling, reduced nitric oxide bioavailability, and elevated levels of asymmetric dimethylarginine. Red blood cells have a built-in anti-oxidant system that includes enzymes like sodium dismutase, catalase, and glutathione peroxidase, along with free radical scavenging molecules, such as vitamin C, vitamin E, and glutathione, which help them to fight oxidative damage. However, these anti-oxidants may not be sufficient to prevent the effects of oxidative stress in SCD patients. Therefore, in line with a recent FDA request that the focus to be placed on the development of innovative therapies for SCD that address the root cause of the disease, there is a need for therapies that target oxidative stress and restore redox balance in SCD patients. This review summarizes the current state of knowledge regarding the role of oxidative stress in SCD and the potential benefits of anti-oxidant therapies. It also discusses the challenges and limitations of these therapies and suggests future directions for research and development.

Mass spectrometry for metabolomics analysis: Applications in neonatal and cancer screening

Chemical analysis by analytical instrumentation has played a major role in disease diagnosis, which is a necessary step for disease treatment. While the treatment process often targets specific organs or compounds, the diagnostic step can occur through various means, including physical or chemical examination. Chemically, the genome may be evaluated to give information about potential genetic outcomes, the transcriptome to provide information about expression actively occurring, the proteome to offer insight on functions causing metabolite expression, or the metabolome to provide a picture of both past and ongoing physiological function in the body. Mass spectrometry (MS) has been elevated among other analytical instrumentation because it can be used to evaluate all four biological machineries of the body. In addition, MS provides enhanced sensitivity, selectivity, versatility, and speed for rapid turnaround time, qualities that are important for instance in clinical procedures involving the diagnosis of a pediatric patient in intensive care or a cancer patient undergoing surgery. In this review, we provide a summary of the use of MS to evaluate biomarkers for newborn screening and cancer diagnosis. As many reviews have recently appeared focusing on MS methods and instrumentation for metabolite analysis, we sought to describe the biological basis for many metabolomic and additional omics biomarkers used in newborn screening and how tandem MS methods have recently been applied, in comparison to traditional methods. Similar comparison is done for cancer screening, with emphasis on emerging MS approaches that allow biological fluids, tissues, and breath to be analyzed for the presence of diagnostic metabolites yielding insight for treatment options based on the understanding of prior and current physiological functions of the body.

Gene therapy in pediatrics - Clinical studies and approved drugs (as of 2023)

Gene therapy in pediatrics represents a cutting-edge therapeutic strategy for treating a range of genetic disorders that manifest in childhood. Gene therapy involves the modification or correction of a mutated gene or the introduction of a functional gene into a patient's cells. In general, it is implemented through two main modalities namely ex vivo gene therapy and in vivo gene therapy. Currently, a noteworthy array of gene therapy products has received valid market authorization, with several others in various stages of the approval process. Additionally, a multitude of clinical trials are actively underway, underscoring the dynamic progress within this field. Pediatric genetic disorders in the fields of hematology, oncology, vision and hearing loss, immunodeficiencies, neurological, and metabolic disorders are areas for gene therapy interventions. This review provides a comprehensive overview of the evolution and current progress of gene therapy-based treatments in the clinic for pediatric patients. It navigates the historical milestones of gene therapies, currently approved gene therapy products by the U.S. Food and Drug Administration (FDA) and/or European Medicines Agency (EMA) for children, and the promising future for genetic disorders. By providing a thorough compilation of approved gene therapy drugs and published results of completed or ongoing clinical trials, this review serves as a guide for pediatric clinicians to get a quick overview of the situation of clinical studies and approved gene therapy products as of 2023.

Assessing and Evaluating HbS Concentration in Asymptomatic Sickle Cell Patients and Patients With Sickle Cell Crisis Through High-Performance Liquid Chromatography (HPLC) in a Tertiary Hospital in Central India

Background Sickle cell disease (SCD) is a significant health concern, particularly due to the variability in disease severity and frequency of crisis episodes among patients. Accurate assessment of HbS concentrations is crucial for understanding the disease's progression and severity. This study aimed to assess and evaluate HbS concentrations in sickle cell patients and those experiencing sickle cell crisis using high-performance liquid chromatography (HPLC). The objectives included screening individuals for SCD, diagnosing the disease using Hb electrophoresis, estimating HbS concentration via HPLC, and comparing HbS concentration values between sickle cell patients and those in crisis. Methods An analytical study design was employed at Jawaharlal Nehru Medical College, Sawangi, Wardha, Maharashtra, involving 80 participants diagnosed with SCD. Data collection included clinical assessments, routine sickling tests, Hb electrophoresis, and HPLC for HbS concentration measurement. Descriptive and inferential statistics were utilized for data analysis, including chi-square tests, Mann-Whitney U tests, and regression analyses. Results Significant differences in HbS concentrations were observed between different patient groups. Individuals with the SS pattern exhibited higher HbS levels than those with the AS pattern (p = 0.001). Non-crisis patients had significantly higher mean HbS concentrations than crisis patients (p = 0.001). A moderate positive correlation (0.476, p = 0.001) was found between HbS concentrations and clinical outcomes. No significant differences in HbS concentrations were noted based on sex or age group. Longitudinal analysis revealed a significant increase in HbS levels over time (p = 0.001). Conclusion The study underscores the importance of HbS concentration measurement in understanding the severity and progression of SCD. HPLC proves to be a valuable tool in accurately estimating HbS levels, aiding in better clinical management of the disease.

Role of gene therapy in sickle cell disease

BACKGROUND

Gene therapy is an emerging treatment for sickle cell disease that works by replacing a defective gene with a healthy gene, allowing the body to produce normal red blood cells. This form of treatment has shown promising results in clinical trials, and is a promising alternative to traditional treatments. Gene therapy involves introducing a healthy gene into the body to replace a defective gene. The new gene can be delivered using a viral vector, which is a modified virus that carries the gene. The vector, carrying the healthy gene, is injected into the bloodstream. The healthy gene then enters the patient's cells and begins to produce normal hemoglobin, the protein in red blood cells that carries oxygen throughout the body.

METHODOLOGY

We conducted an all-language literature search on Medline, Cochrane, Embase, and Google Scholar until December 2022. The following search strings and Medical Subject Heading (MeSH) terms were used: "Sickle Cell," "Gene Therapy" and "Stem Cell Transplantation". We explored the literature on Sickle Cell Disease for its epidemiology, etiopathogenesis, the role of various treatment modalities and the risk-benefit ratio of gene therapy over conventional stem cell transplant.

RESULTS

Gene therapy can reduce or eliminate painful episodes, prevent organ damage, and raise the quality of life for those living with the disease. Additionally, gene therapy may reduce the need for blood transfusions and other traditional treatments. Gene therapy has the potential to improve the lives of those living with sickle cell disease, as well as reduce the burden of the disease on society.

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.

The Application of Clinical and Molecular Diagnostic Techniques to Identify a Rare Haemoglobin Variant

Haemoglobin disorders represent a heterogeneous group of inherited conditions that involve at least one genetic abnormality in one or more of the globin chains, resulting in changes in the structure, function, and/or amount of haemoglobin molecules, which are very important for their related clinical aspects. Detecting and characterizing these disorders depends primarily on laboratory methods that employ traditional approaches and, when necessary, newer methodologies essential for solving a number of diagnostic challenges. This review provides an overview of key laboratory techniques in the diagnosis of haemoglobinopathies, focusing on the challenges, advancements, and future directions in this field. Moreover, many haemoglobinopathies are benign and clinically silent, but it is not uncommon to find unexpected variants during routine laboratory tests. The present work reported a rare and clinically interesting case of identification of haemoglobin fractions in an adult man by the determination of glycated haemoglobin (HbA1c) during a routine laboratory assessment, highlighting how the correct use of laboratory data can modify and improve the patient's clinical management.

An international learning collaborative phase 2 trial for haploidentical bone marrow transplant in sickle cell disease

ABSTRACT

In the setting of a learning collaborative, we conducted an international multicenter phase 2 clinical trial testing the hypothesis that nonmyeloablative-related haploidentical bone marrow transplant (BMT) with thiotepa and posttransplant cyclophosphamide (PTCy) will result in 2-year event-free survival (no graft failure or death) of at least 80%. A total of 70 participants were evaluable based on the conditioning protocol. Graft failure occurred in 8 of 70 (11.4%) and only in participants aged <18 years; all had autologous reconstitution. After a median follow-up of 2.4 years, the 2-year Kaplan-Meier-based probability of event-free survival was 82.6%. The 2-year overall survival was 94.1%, with no difference between children and adult participants. After excluding participants with graft failure (n = 8), participants with engraftment had median whole blood donor chimerism values at days +180 and +365 after transplant of 100% (n = 58), respectively, and 96.6% (57/59) were off immunosuppression 1 year after transplant. The 1-year grade 3 to 4 acute graft-versus-host disease (GVHD) rate was 10%, and the 2-year moderate-severe chronic GVHD rate was 10%. Five participants (7.1%) died from infectious complications. We demonstrate that nonmyeloablative haploidentical BMT with thiotepa and PTCy is a readily available curative therapy for most adults, even those with organ damage, compared to the more expensive myeloablative gene therapy and gene editing. Additional strategies are required for children to decrease graft failure rates. The trial was registered at www.clinicaltrials.gov as #NCT01850108.

Ferroptosis as an emerging target in sickle cell disease

Sickle cell disease (SCD) is an inherited hemoglobin disorder marked by red blood cell sickling, resulting in severe anemia, painful episodes, extensive organ damage, and shortened life expectancy. In SCD, increased iron levels can trigger ferroptosis, a specific type of cell death characterized by reactive oxygen species (ROS) and lipid peroxide accumulation, leading to damage and organ impairments. The intricate interplay between iron, ferroptosis, inflammation, and oxidative stress in SCD underscores the necessity of thoroughly understanding these processes for the development of innovative therapeutic strategies. This review highlights the importance of balancing the complex interactions among various factors and exploitation of the knowledge in developing novel therapeutics for this devastating disease.

Development of a Hematology-General Medicine Hybrid Team to Improve Care of Patients With Sickle Cell Disease

PROBLEM

Approximately 100,000 individuals in the United States have sickle cell disease (SCD). These individuals face multiple barriers to equitable care. At Brigham and Women's Hospital, existing health inequities for these patients were compounded by admitting, rounding, and team structures that assigned patients with SCD to multiple medicine teams with a hematologist attending, leading to delays in patient care and gaps in residents' hematology knowledge.

APPROACH

A hematology-general medicine hybrid team was created in September 2021 to enhance trainee knowledge, skill, and confidence in managing hematology conditions and improve the quality of care delivered to individuals with SCD. This allowed for regionalization of patients with classical hematology conditions to specific hospital floors under the care of one team with a hematologist as the attending of record.

OUTCOMES

From October 1, 2021, to January 11, 2022, the majority (745/824, 90%) of in-hospital days for patients with a primary hematology diagnosis were under the care of the hematology-general medicine hybrid team. Regionalization to the home floor of the hybrid team was achieved on 331 (40%) of these 824 hospital days, consistent with regionalization rates for other teams. From October 1, 2021, to September 30, 2022, there were 128 unique patients with SCD admitted over 511 encounters and cared for by approximately 78 residents and 12 medical students. Feedback from residents reported improved knowledge in the management of hematology conditions, especially SCD.

NEXT STEPS

The authors are working on a comprehensive analysis of the hybrid team's impact on trainee skill and confidence in managing SCD. The authors believe that this model can be replicated at other institutions to optimize trainee education, consolidate care, and address implicit bias against patients with SCD, even with the hematology attending as a consultant instead of as the attending of record.

Fatal Case of Exercise Collapse Associated with Sickle Cell Trait with Novel Underlying LAMA2 Mutation

ABSTRACT

Sickle cell trait is typically thought to be an asymptomatic carrier state, but it is rarely associated with exertional rhabdomyolysis in cases termed Exercise Collapse Associated with Sickle Cell Trait (ECAST). In a subset of these cases, underlying disease contributes to the development and/or severity of the ensuing medical complications. We describe the first ever case of ECAST reported in a previously asymptomatic, multiply deployed, highly physically active service member with an underlying heterozygous LAMA2 mutation. Moreover, the mutation identified via whole exome sequencing is a novel, likely pathogenic variant that has yet to be described in the literature.

Unraveling DEHP influence on hemoglobin S polymerization in sickle cell disease: Ex vivo, in vitro and in silico analysis

Sickle cell disease (SCD) is a hereditary hemoglobinopathy, caused by a mutation at position 6 of the β-globin chain and patients are frequently exposed to several blood transfusions in order to maintain physiological function. Transfusion blood bags are composed of PVC and phthalates (as DEHP) are often introduced to the material in order to confer malleability. In this sense, DEHP can easily elute to the blood and cause harmful effects. This study aimed to unravel DEHP effect on SCD patient's hemoglobin function. We found that HbS polymerization using whole erythrocytes is decreased by DEHP in ex vivo experiments and this effect might be mediated by the DEHP-VAL6 interaction, evaluated in silico. Isolated HbS exhibited less polymerization at low DEHP concentrations and increased polymerization rate at higher concentration. When analyzing the propensity to aggregate, HbS is more inclined to aggregate when compared to HbA due to the residue 6 mutation. Circular dichroism showed characteristic hemoglobin peaks for oxygenated HbS that are lost when oxygen is sequestered, and DEHP at higher concentration mildly recovers a peak close to the second hemoglobin one. Finally, by transmission electron microscopy we demonstrated that high DEHP concentration increased polymer formation with a more organized structure. These findings show for the first-time the beneficial effect of low-dose DEHP on HbS polymerization.

Association of ZBTB38 gene polymorphism (rs724016) with height and fetal hemoglobin in individuals with sickle cell anemia

Objectives

Our study evaluated the association of the polymorphism rs724016 in the ZBTB38 gene, previously associated with height in other populations, with predictors of height, clinical outcomes, and laboratory parameters in sickle cell anemia (SCA).

Methods

Cross-sectional study with individuals with SCA and aged between 3 and 20 years. Clinical, laboratory, molecular, and bone age (BA) data were evaluated. Levels of IGF-1 and IGFBP-3 were adjusted for BA, target height (TH) was calculated as the mean parental height standard deviation score (SDS), and predicted adult height (PAH) SDS was calculated using BA.

Results

We evaluated 80 individuals with SCA. The homozygous genotype of the G allele of rs724016 was associated with a lower height SDS (p < 0.001) and, in a additive genetic model, was negatively associated with HbF levels (p = 0.016). Lower adjusted IGF-1 levels were associated with co-inheritance of alpha-thalassemia and with the absence of HU therapy. Elevated HbF levels were associated with a lower deficit in adjusted growth potential (TH minus PAH).

Conclusion

Our analysis shows that SNP rs724016 in the ZBTB38 is associated with shorter height and lower HbF levels, an important modifier of SCA.

Is There any Relationship Between the Repeated Complications of Sickle Cell Disease and the Potential Development of Acute Leukemia?

Sickle cell disease (SCD) is a severe monogenic hereditary hemoglobinopathy that is characterized by repeated clinical and biological manifestations able to generate stress erythopoiesis. A clonal hematopoiesis involving mainly variants of TP53, DNMT3A, ASXL1, and/or TET2 may be more prevalent in patients with SCD, suggesting that mutations in these genes may lead to an increased risk of leukemia. An increased prevalence of leukemia in patients with SCD has been confirmed by an increasing number of acute myeloid leukemia cases with myelodysplastic features reported in this patient population even in the absence of disease-modifying treatments. This leads to the hypothesis of a mechanism involving multifactorial causes through the pathophysiologic manifestations of SCD, in which cells are undergoing constant hematopoietic hyperplasia, inducing genomic damage and somatic mutations.

Evaluation of the effect of voxelotor and darbepoetin alfa on hemoglobin levels in patients with sickle cell disease

BACKGROUND

To date, there is limited evidence on patients utilizing both voxelotor and darbepoetin alfa and its impact on hemoglobin levels. The objective is to evaluate the effect of voxelotor and darbepoetin alfa on hemoglobin levels in patients with SCD.

RESEARCH DESIGN AND METHODS

This was a retrospective chart review study that assessed the primary independent variable as the utilization of either voxelotor alone, darbepoetin alfa alone, or the concurrent administration of voxelotor and darbepoetin alfa. Descriptive statistics were utilized to obtain the mean standard deviation for numerical variables and proportions for categorical variables.

RESULTS

A total of 23 participants were included in this study. When comparing baseline to 2 months and 3 months, participants on voxelotor alone experienced a 3% decrease and a 6.6% increase in hemoglobin, darbepoetin alfa alone group a 4.3% decrease and a 0.6% increase in hemoglobin and voxelotor and darbepoetin group a 4.4% decrease and a 0.5% decrease in hemoglobin levels. Fifty percent of the participants in the voxelotor group and 6 (66.7%) participants in the voxelotor plus darbepoetin alfa group experienced adverse drug events.

CONCLUSIONS

Voxelotor resulted in a clinically significant difference in the percent change of hemoglobin from baseline to 3 months.

MALDI-MS in first-line screening of newborns for sickle cell disease: results from a prospective study in comparison to HPLC

OBJECTIVES

Newborn screening (NBS) for sickle cell disease (SCD) requires a robust, high-throughput method to detect hemoglobin S (HbS). Screening for SCD is performed by qualitative methods, such as isoelectric focusing (IEF), and both qualitative and quantitative methods such as high performance liquid chromatography (HPLC), capillary electrophoresis (CE), and tandem mass spectrometry (MS/MS). All these methods detect HbS, as well as low-level or absent HbA, and also other variants of hemoglobin. HPLC is considered as a reference method for NBS, because of its high sensitivity and specificity in detecting HbS. NeoSickle®, a fully automated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) platform, combined with automated sample processing, a laboratory information management system and NeoSickle® software for automatic data interpretation, has increased the throughput of SCD testing. The purpose of this study was to compare the performances of NeoSickle® and HPLC.

METHODS

A prospective study was conducted including 9,571 samples from the NBS program to compare MALDI-MS using NeoSickle® with an HPLC method. Correlation between the two methods was studied. For the MALDI-MS method, sensitivity, specificity, NPV, and PPV were calculated.

RESULTS

We found over 99.4 % correlation between the HPLC and MALDI-MS results. NeoSickle® showed 100 % of sensitivity and specificity in detecting SCD syndrome, leading to positive and negative predictive values of 100 %.

CONCLUSIONS

NeoSickle® is adapted to NBS for SCD, and can be used in first-line high-throughput screening to detect HbS, and beta-thalassemia major warning. When HbS is detected, second-line use of another specific method as HPLC is necessary.

Neurocognitive outcome in children with sickle cell disease after myeloimmunoablative conditioning and haploidentical hematopoietic stem cell transplantation: a non-randomized clinical trial

Background

Due to the risk of cerebral vascular injury, children and adolescents with high-risk sickle cell disease (SCD) experience neurocognitive decline over time. Haploidentical stem cell transplantation (HISCT) from human leukocyte antigen-matched sibling donors may slow or stop progression of neurocognitive changes.

Objectives

The study is to determine if HISCT can ameliorate SCD-associated neurocognitive changes and prevent neurocognitive progression, determine which specific areas of neurocognitive functioning are particularly vulnerable to SCD, and determine if there are age-related differences in neurocognitive functioning over time.

Methods

We performed neurocognitive and neuroimaging in SCD recipients following HISCT. Children and adolescents with high-risk SCD who received parental HISCT utilizing CD34+ enrichment and mononuclear cell (T-cell) addback following myeloimmunoablative conditioning received cognitive evaluations and neuroimaging at three time points: pre-transplant, 1 and 2 years post-transplant.

Results

Nineteen participants (13.1 ± 1.2 years [3.3-20.0]) received HISCT. At 2 years post-transplant, neuroimaging and cognitive function were stable. Regarding age-related differences pre-transplantation, older children (≥13 years) had already experienced significant decreases in language functioning (p < 0.023), verbal intelligence quotient (p < 0.05), non-verbal intelligence quotient (p < 0.006), and processing speed (p < 0.05), but normalized post-HISCT in all categories.

Conclusion

Thus, HISCT has the potential to ameliorate SCD-associated neurocognitive changes and prevent neurocognitive progression. Further studies are required to determine if neurocognitive performance remains stable beyond 2 years post-HISCT.Clinical trial registration: The study was conducted under an investigator IND (14359) (MSC) and registered at clinicaltrials.gov (NCT01461837).

Lipid and hemolysis parameters predicting acute chest syndrome in adulthood with sickle cell disease

Sickle cell disease (SCD) is a lifelong blood disorder affecting approximately 100,000 people in the United States and is one of the most common monogenic diseases. A serious complication of SCD is acute chest syndrome (ACS). ACS is a condition with a high rate of morbidity and mortality. The aim of the study was to assess hemolysis and lipid parameters in a cohort of confirmed SCD patients to predict ACS development in the following year.Standard lipid were performed (triglycerides, total cholesterol, high-density cholesterol, low-density cholesterol) panel to calculate of non-HDL-C, large buoyant LDL cholesterol (lbLDL-C) and small dense LDL cholesterol (sdLDL-C) with Sampson equation. Hemolysis and hematologic parameters were also evaluated.Among 91 patients included between September 2018 and June 2021, thirty-seven patients had history of ACS and 6 patients developed ACS during following year. In unadjusted logistic regression, total bilirubin was associated with ACS occurrence (RR: 1.2 [1.05-1.51] p = 0.013). Concerning lipid profile, non-HDL-C (RR: 0.87 [0.0.67-0.99] p = 0.04) and sdLDL-C (RR: 0.78 [0.49-0.96] p = 0.03) were associated with ACS occurrence decrease. C-reactive protein was associated with ACS occurrence (RR: 1.27 [1.065-1.85] p = 0.011).Based on these findings, this study demonstrated that several biomarker easily available can be used at steady state to predict ACS in the following year. The validation of these results are required to ensure the reproducibility of the findings.

Current and Future Therapeutics for Treating Patients with Sickle Cell Disease

Sickle cell disease (SCD) is the most common genetic blood disorder in the United States, with over 100,000 people suffering from this debilitating disease. SCD is caused by abnormal hemoglobin (Hb) variants that interfere with normal red blood cell (RBC) function. Research on SCD has led to the development and approval of several new SCD therapies in recent years. The recent FDA-approved novel gene therapies are potentially curative, giving patients an additional option besides a hematopoietic bone marrow transplant. Despite the promise of existing therapies, questions remain regarding their long-term pharmacological effects on adults and children. These questions, along with the exorbitant cost of the new gene therapies, justify additional research into more effective therapeutic options. Continual research in this field focuses on not only developing cheaper, more effective cures/treatments but also investigating the physiological effects of the current therapies on SCD patients, particularly on the brain and kidneys. In this article, we undertake a comprehensive review of ongoing clinical trials with completion dates in 2024 or later. Our exploration provides insights into the landscape of current therapeutics and emerging novel therapies designed to combat and potentially eradicate SCD, including the latest FDA-approved gene therapies.

Exagamglogene Autotemcel for Severe Sickle Cell Disease

BACKGROUND

Exagamglogene autotemcel (exa-cel) is a nonviral cell therapy designed to reactivate fetal hemoglobin synthesis by means of ex vivo clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 gene editing of autologous CD34+ hematopoietic stem and progenitor cells (HSPCs) at the erythroid-specific enhancer region of BCL11A.

METHODS

We conducted a phase 3, single-group, open-label study of exa-cel in patients 12 to 35 years of age with sickle cell disease who had had at least two severe vaso-occlusive crises in each of the 2 years before screening. CD34+ HSPCs were edited with the use of CRISPR-Cas9. Before the exa-cel infusion, patients underwent myeloablative conditioning with pharmacokinetically dose-adjusted busulfan. The primary end point was freedom from severe vaso-occlusive crises for at least 12 consecutive months. A key secondary end point was freedom from inpatient hospitalization for severe vaso-occlusive crises for at least 12 consecutive months. The safety of exa-cel was also assessed.

RESULTS

A total of 44 patients received exa-cel, and the median follow-up was 19.3 months (range, 0.8 to 48.1). Neutrophils and platelets engrafted in each patient. Of the 30 patients who had sufficient follow-up to be evaluated, 29 (97%; 95% confidence interval [CI], 83 to 100) were free from vaso-occlusive crises for at least 12 consecutive months, and all 30 (100%; 95% CI, 88 to 100) were free from hospitalizations for vaso-occlusive crises for at least 12 consecutive months (P<0.001 for both comparisons against the null hypothesis of a 50% response). The safety profile of exa-cel was generally consistent with that of myeloablative busulfan conditioning and autologous HSPC transplantation. No cancers occurred.

CONCLUSIONS

Treatment with exa-cel eliminated vaso-occlusive crises in 97% of patients with sickle cell disease for a period of 12 months or more. (CLIMB SCD-121; ClinicalTrials.gov number, NCT03745287.).

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.

Autologous gene therapy for hemoglobinopathies: From bench to patient's bedside

In recent years, a growing number of clinical trials have been initiated to evaluate gene therapy approaches for the treatment of patients with transfusion-dependent β-thalassemia and sickle cell disease (SCD). Therapeutic modalities being assessed in these trials utilize different molecular techniques, including lentiviral vectors to add functional copies of the gene encoding the hemoglobin β subunit in defective cells and CRISPR-Cas9, transcription activator-like effector protein nuclease, and zinc finger nuclease gene editing strategies to either directly address the underlying genetic cause of disease or induce fetal hemoglobin production by gene disruption. Here, we review the mechanisms of action of these various gene addition and gene editing approaches and describe the status of clinical trials designed to evaluate the potentially for these approaches to provide one-time functional cures to patients with transfusion-dependent β-thalassemia and SCD.

[Transition in sickle cell disease - recommendations of the transition initiative sickle cell disease]

Sickle cell disease is a rare, but complex multi-systemic disorder with high need of interdisciplinary and specialized care and new structural requirements. Besides care of those chronically sick patients, transition process is a vulnerable phase which highly influences further treatment. To make matters worse, patients often have migration background with subsequent communication problems. A national guidance for a standardized transition process is lacking in Germany. In context of a structured consensus process, the "transition initiative sickle cell disease" developed specific recommendations for a structured transition of sickle cell patients on the basis of the S3 transition guideline of the DGfTM. These recommendations should improve this vulnerable process in this complex disease to ensure adequate further treatment and to avoid acute and chronic complications but also mental, social or job-related issues. Besides improvement of quality of life, medical treatment and survival, health economic aspects arise. Documents were developed to support and facilitate the transition process and are available under www.sichelzellkrankheit.info/transition/.

Hematopoietic stem cell collection for sickle cell disease gene therapy

PURPOSE OF REVIEW

Gene therapy for sickle cell disease (SCD) is advancing rapidly, with two transformative products recently approved by the US Food and Drug Administration and numerous others under study. All current gene therapy protocols require ex vivo modification of autologous hematopoietic stem cells (HSCs). However, several SCD-related problems impair HSC collection, including a stressed and damaged bone marrow, potential cytotoxicity by the major therapeutic drug hydroxyurea, and inability to use granulocyte colony stimulating factor, which can precipitate severe vaso-occlusive events.

RECENT FINDINGS

Peripheral blood mobilization of HSCs using the CXCR4 antagonist plerixafor followed by apheresis collection was recently shown to be safe and effective for most SCD patients and is the current strategy for mobilizing HSCs. However, exceptionally large numbers of HSCs are required to manufacture an adequate cellular product, responses to plerixafor are variable, and most patients require multiple mobilization cycles, increasing the risk for adverse events. For some, gene therapy is prohibited by the failure to obtain adequate numbers of HSCs.

SUMMARY

Here we review the current knowledge on HSC collection from individuals with SCD and potential improvements that may enhance the safety, efficacy, and availability of gene therapy for this disorder.

Between hope and reality: treatment of genetic diseases through nucleic acid-based drugs

Rare diseases (RD) affect a small number of people compared to the general population and are mostly genetic in origin. The first clinical signs often appear at birth or in childhood, and patients endure high levels of pain and progressive loss of autonomy frequently associated with short life expectancy. Until recently, the low prevalence of RD and the gatekeeping delay in their diagnosis have long hampered research. The era of nucleic acid (NA)-based therapies has revolutionized the landscape of RD treatment and new hopes arise with the perspectives of disease-modifying drugs development as some NA-based therapies are now entering the clinical stage. Herein, we review NA-based drugs that were approved and are currently under investigation for the treatment of RD. We also discuss the recent structural improvements of NA-based therapeutics and delivery system, which overcome the main limitations in their market expansion and the current approaches that are developed to address the endosomal escape issue. We finally open the discussion on the ethical and societal issues that raise this new technology in terms of regulatory approval and sustainability of production.

Real-world evidence of the burden of sickle cell disease: a 5-year longitudinal study at a Brazilian reference center

INTRODUCTION

Sickle cell disease (SCD) is an inherited and multisystem blood disorder characterized by hemolytic anemia, vaso-occlusive crises (VOCs), progressive multiorgan damage and increased mortality. In Brazil, it is one of the most common monogenic diseases afflicting 60,000 to 100,000 individuals, however, there are sparse epidemiological data, as well as information on the utilization of public healthcare resources.

METHOD

This was a 5-year (2016 - 2020) retrospective study conducted at one Brazilian reference center on SCD - Santa Casa de Sao Paulo, in Sao Paulo, Brazil.

RESULTS

Among a total of 100 eligible adult patients, the median age was 31.0 years old, 84% of the patients were aged between 18 and 45 years old; 59% were women and 91% presented the genotype HbSS. The number of hematologist and non-hematologist visits at the outpatient unit were 2,198 and 1,436, respectively. The number of hospital ER visits was 758, of which 51% required 864 days of hospitalization. The main cause for seeking hospital medical care was the VOCs. The numbers and ratios of VOCs were: 1 to 10 VOCs, 64%; 11 to 20, 15%, and; 21 or more, 1%. There was a statistically significant difference between the number of VOCs and hospitalizations, as well as infection.

CONCLUSION

Results indicate the burden of SCD on Brazilian patients' daily lives, the impact of VOCs on public healthcare resources, the importance of having a national surveillance program to improve resource utilization and clinical outcomes of patients with SCD and the urgent need for the revitalizing of the current national comprehensive SCD care programs.