The risks and benefits of long-term use of hydroxyurea in sickle cell anemia: A 17.5 year follow-up

MicroRNAs in sickle cell disease: A comprehensive review

Sickle cell disease (SCD) is a multifactorial disease characterized by a high incidence of morbidity and mortality due to chronic hemolysis, inflammation and oxidative stress. Recent studies have highlighted the crucial role of microRNAs (miRNAs) in regulating key pathophysiological processes in SCD, including high levels of fetal hemoglobin production, and reduction in inflammation and cellular adhesion. This comprehensive review discusses the current understanding of miRNAs in SCD, including their potential as biomarkers and therapeutic targets. Furthermore, despite substantial evidences indicating that malaria exacerbates SCD, the review will explore the complex interplay between miRNAs and SCD, with a focus on the exacerbating effects of malaria on SCD severity. Understanding the complex interplay between miRNAs and SCD may lead to the development of novel therapeutic interventions aimed at ameliorating disease severity and improving patient outcomes. Future prospects, challenges and safety concerns related to miRNA-based therapies, highlighting the need for further research.

The Mortality of Adults With Sickle Cell Disease at a Comprehensive Sickle Cell Center

INTRODUCTION

Sickle cell disease (SCD) is the most common hemoglobinopathy in North America. The life expectancy of SCD has extended into adulthood with screenings, preventative care, and hydroxyurea. However, comorbidities arise as adults with SCD age, leading to early mortality.

METHODS

We conducted a retrospective chart review of the Georgia Comprehensive Sickle Cell Center at Grady Health System, analyzing records of deceased SCD patients from 2013 to 2020.

RESULTS

Amongst the 72 patients analysed, majority had severe complications from SCD and at least 1 cardiovascular comorbidity. The median age of death was 44 (STD = 15.5) for all genotypes with the median age of death at 39 (STD = 14.26) for SS and Sβ0 genotypes (n = 51). There was no difference in the median age of death for patients who maintained regular clinic visits (a visit in the last 6 months prior to death) compared to those who did not. Despite hydroxyurea's known benefits in reducing SCD morbidity and mortality, less than 50% of patients had a prescription.

CONCLUSION

As new therapies are approved, their impact on SCD-related morbidity and mortality must be evaluated. Improving access to, and education about, disease-modifying therapies like hydroxyurea for both patients and clinicians is essential to improving outcomes.

Efficacy and safety of thalidomide with hydroxyurea in sickle cell anemia: a quasi-experimental clinical trial

BACKGROUND

The clinical course of sickle cell anemia (SCA) is variable, with chronic hemolysis and end-organ damage caused by microvascular occlusion. We evaluated the efficacy and safety of thalidomide plus hydroxyurea (HU) compared with HU alone to determine whether the combination provides a superior clinical benefit and safety profile.

METHODS

This was an open-label quasi-experimental clinical trial (Clinical Trials Registry of India, CTRI Registration Number 2023/04/065682). Patients with SCA aged > 12 years and postmenopausal females aged > 45 years were allocated 1:1 to receive either HU (20 mg/kg/day) and thalidomide (50 mg/day) in Group A or HU (20 mg/kg/day) only in Group B.

RESULTS

The frequency of vaso-occlusive crises (VOCs), transfusion requirements, variations in hematological parameters (hemoglobin [Hb], fetal hemoglobin [HbF], and sickle hemoglobin [HbS]), and side effects between the groups were assessed over 12 months. Repeated-measures analysis of variance was used to determine changes across the observation period. The mean age of the 66 patients diagnosed with SCA (homozygous HbS mutation) was 32.9 (standard deviation ± 11.5) years, and 57.6% were males. Over the 12-month observation period, Group A had significantly fewer VOCs (3.48 ± 2.81) and packed red blood cell transfusions (3.61 ± 2.19) than Group B (11.36 ± 4.20 VOCs; 13.27 ± 3.70 transfusions) (p = 0.0001). There was a significant increase in Hb (8.2 ± 1.8 to 11.8 ± 1.2 g/dL), a decrease in HbS% (72.5 ± 5.5 to 64.5 ± 5.4), and a rise in HbF% (18.9 ± 5.1 to 28.4 ± 5.6) (p < 0.0001) in Group A.

CONCLUSION

Combining thalidomide with HU significantly reduced VOCs and transfusion requirements, improved Hb and HbF%, and decreased HbS levels.

Prevalence of Duffy Null and Its Impact on Hydroxyurea Dosing in Children With Sickle Cell Disease

Duffy null phenotype is common in people of African ancestry and is associated with lower baseline white blood cell (WBC) and neutrophil counts. We evaluated whether the presence of the Duffy null phenotype had any association with neutropenia in our patients with sickle cell disease on hydroxyurea (HU). We found a statistically significant difference (p = 0.006) in HU maximum tolerated dose (MTD) in patients with Duffy null phenotype compared with Duffy-positive individuals. Our study suggests that careful dose escalation is warranted in Duffy-null individuals.

Hematopoietic cell transplant compared with standard care in adolescents and young adults with sickle cell disease

ABSTRACT

Disease-modifying therapies are standard of care (SOC) for sickle cell disease (SCD), but hematopoietic cell transplantation (HCT) has curative potential. We compared outcomes prospectively through 2 years after biologic assignment to a donor or no donor (SOC) arm based on the availability of an HLA-matched sibling or unrelated donor (BMT CTN 1503). A donor search was commenced after eligibility confirmation. The primary end point was a comparison of survival between the treatment arms 2 years after biologic assignment. Power calculations required 60 participants in the donor arm and 140 in the no donor arm to determine if early transplant-related mortality might be balanced by disease-related mortality over a longer period of follow-up. Secondary objectives were a comparison of the changes in SCD-related events, functional outcomes, and organ function. The data were analyzed according to the intent-to-treat principle. A total of 113 participants were enrolled with 28 in the donor arm and 85 in the no donor arm. The 2-year probabilities of survival were 89% and 93%, in the donor vs no donor arms. Vaso-occlusive pain (VOC) was less frequent in the donor arm in the second year after biologic assignment (P < .001). Based on PROMIS-57 surveys, there was a decrease in fatigue (P = .003) and an increase in the ability to participate in social roles and activities (P = .003) in the donor arm 2 years after biologic assignment. Differences in other secondary outcomes did not reach statistical significance. Barriers to accrual prevented an objective comparison of survival. Assignment to the donor arm led to improvements in VOC, fatigue, and social function. This trial was registered at www.clinicaltrials.gov as #NCT02766465.

The Lived Experiences of Adults With Sickle Cell Disease Deciding Curative Therapies: A Descriptive Phenomenological Study

BACKGROUND

Bone marrow transplant and gene therapy are high-risk, high-reward treatment options that have the potential to cure sickle cell disease (SCD). Making the decision to pursue curative therapies remains challenging for adults living with SCD and little is known about their experience in deciding to cure it.

PURPOSE

The purpose of this study was to describe the lived experiences of adults living with SCD considering curative treatments.

METHODS

A qualitative descriptive phenomenological study was used for the study. Nine adults with SCD were recruited from a large, urban, academic medical center in the Northeast. Semi-structured interviews were recorded, transcribed, and analyzed using Amedeo Giorgi's 5-step data analysis for descriptive phenomenology.

RESULTS

Five major themes were derived from the data analysis: (1) the never-ending rollercoaster of uncertainty in SCD; (2) the hospital feeling like a second home; (3) the powerful influence of the provider; (4) changing the trajectory of the past in pursuit of new beginnings; and (5) going the distance to access a cure. The results revealed that the participants' experiences in deciding to pursue curative therapies were multifactorial, they had limited access to educational material, they delayed seeking curative therapies, and they required complex care management to navigate health systems when seeking curative options.

CONCLUSION

Findings underscored the importance of nurses understanding the experience of living with SCD, the patient-provider relationship, and barriers to accessing care. Findings can influence policies on SCD care pre- and post-transplant, and inform nursing practice and nursing education.

A review on disease modifying pharmacologic therapies for sickle cell disease

Sickle cell disease (SCD) is an inherited hematologic disease caused by sickle hemoglobin as the predominant RBC hemoglobin or by sickle hemoglobin in combination with other abnormal β-hemoglobin variants like HbC, HbD and others. Sickling of erythrocytes under deoxygenated conditions is the basis of inflammatory and thrombotic cascades which result in multiple serious complications, leading to early morbidity and mortality. While HLA-matched allogeneic bone marrow transplantation is potentially curative, it has considerable limitations due to potential severe toxicities. Despite slow progress towards novel therapeutic strategies for SCD and hydroxyurea being the sole medication that is shown to reduce vaso-occlusive events and mortality for almost 20 years, several pharmacological agents targeting different mechanisms have been examined in clinical trials and recently US- US-FDA-approved, including L-glutamine and crizanlizumab. Voxelotor was previously US-FDA-approved but has been voluntarily withdrawn from the market as the overall benefit did not outweigh the risks. Gene therapies based on CRISPR-Cas9 and lentiviral vectors have been very recently approved. However, excessive costs are a barrier to widespread use. Nonetheless, there is still a large area of unmet needs for patients with SCD, and further research towards better care is warranted.

Non - Invasive, smartphone image-based screening for sickle cell disease at the point-of-need

Leveraging the increasing accessibility of smartphones in healthcare settings, we developed a smartphone app aimed at enhancing sickle cell disease (SCD) screening, particularly in resource-limited settings. Our application provides accurate and non-invasive SCD screening with instant results at the point-of-need. The app operates by analyzing patient fingernail images via a smartphone image to gauge anemia severity and by using targeted inquiries to identify SCD-related symptoms. These inputs collectively generate an SCD IMage and Patient profile-based Likelihood Estimation (SIMPLE) score, which estimates disease probability. The accuracy of the score depends on two inputs: the patient's anemia status and their health survey responses. We tested the app on 485 pediatric patients at Children's Healthcare of Atlanta (CHOA), achieving an overall sensitivity of 74 % and specificity of 76 % in screening for SCD among children aged 6 months to 21 years. Notably, the app demonstrated enhanced performance in the target demographic, with 100 % sensitivity and 75 % specificity for screening SCD in children aged 6 months to 5 years. This cost-effective and scalable app efficiently pinpoints and stratifies individuals, particularly those who missed early screening, for formal screening programs.

Exposure to public housing reverses the association between neighborhood disadvantage and eosinophilic inflammation in patients with sickle cell disease

Sickle cell disease (SCD) is a single-gene illness characterized by chronic inflammation, decreased quality of life, and early mortality; however, outcomes are highly variable between individuals, suggesting a substantial role of social and environmental factors in disease outcomes. Data suggest that individuals living with SCD have greater eosinophil counts and activation, and higher prevalence of asthma and wheezing than those without SCD, suggesting a role for eosinophilic inflammation in SCD. In other diseases, eosinophilic inflammation has been linked to social and environmental factors, particularly in minoritized populations. To date, however, few human studies have explored the pathophysiology of social and environmental exposures in SCD. This study tested whether eosinophilic inflammation was related to location-based measures of social disadvantage or public housing in 79 individuals with SCD, without diagnoses of asthma, who were prospectively followed over one year. Home addresses were geocoded and matched to principal-components derived, validated measures of local neighborhood social disadvantage and to locations of public housing facilities. Serum peripheral eosinophils, IL-13 and IL-5 were measured every 8 weeks. In fully-adjusted models, statistically significant, linear relationships were observed between the degree of social disadvantage and level of eosinophilic inflammation; however, the direction of that relationship was opposite for patients who live in public housing and those who do not. For those living in public housing, greater social disadvantage was associated with increased eosinophilic inflammation. For those in private housing, greater social disadvantage was associated with progressively less eosinophilic inflammation. These strong, and somewhat unexpected, relationships demonstrate that subtle differences in social exposures and home environment have differential effects on inflammatory profiles which may have larger implications for disease and health, especially in chronic diseases such as SCD. To understand the mechanisms of these effects may require highly granular studies that catalog the many factors underlying the social environment and inflammation.

Long-Term Survival Rates of a Sickle Cell Disease Cohort in Saudi Arabia: A 2009-2023 Observational Study

BACKGROUND

Sickle cell disease (SCD) is prevalent in Saudi Arabia. This study evaluates the long-term survival rates of a cohort of SCD patients.

METHODS

This observational cohort study was conducted at King Saud University Medical City from January 2009 to September 2023. We enrolled 223 SCD patients between 2009 and 2014, collecting comprehensive data at baseline and during follow-up. The primary endpoint was overall survival.

RESULTS

The cohort had a median follow-up of 11.5 years, totaling 2,118 patient-years. The recent median age was 28.9 years (12.2-63.8). The survival rates at ages 20, 30, 40, and 50 years were 100%, 98.4%, 95.1%, and 89.0%, respectively, with no mortality observed before the age of 20 years. The incidence of mortality was 0.28 deaths per 100 patient-years. Among the six deaths (2.7%), causes included non-Hodgkin lymphoma, acute chest syndrome, and a sepsis-like condition, with three unknown causes. The median age of death was 36.3 years. The increased use of hydroxyurea, from 47% to 80%, was associated with reduced pain crises and acute chest syndrome, and improved hemoglobin and HbF levels. Of the patients, 43 (19.2%) were lost to follow-up, 16 (7.2%) were referred for stem cell transplant, and 16 (7.2%) were followed at other institutions.

CONCLUSIONS

This study highlights excellent survival rates for SCD patients in our cohort. Nonetheless, the considerable loss to follow-up highlights the need for strategies to address this issue and larger multicenter studies to confirm our results.

Novel clinical care models for patients with sickle cell disease

This educational program outlines the importance of evolving clinical care models in response to increased life expectancy and variability in individual patient experiences, particularly in the context of sickle cell disease (SCD). It emphasizes the need for personalized and adaptive care models, in which the patient should play a central role, and the need for collaborative networks of physicians and caregivers, taking into account the multisystemic nature of the disease. The proposal also discusses the role of personalized medicine and technological advances, highlighting the need for a shared medical record; the balance between rare center expertise and widespread dissemination of knowledge; and the challenges in high- and low-income countries. It emphasizes the need to move toward personalized medicine, given the significant interindividual variability in both follow-up and treatment, and the introduction of more appropriate biomarkers and predictive algorithms to aid decision-making. The proposal includes real-world examples of successful adaptation in clinical care models. It concludes with a summary of the importance and benefits of evolving clinical care models and a future outlook on the evolution of clinical care in response to demographic changes. These proposals are intended to provide a comprehensive overview of the current state and future directions of clinical care models for SCD.

Zinc finger nuclease-mediated gene editing in hematopoietic stem cells results in reactivation of fetal hemoglobin in sickle cell disease

BIVV003 is a gene-edited autologous cell therapy in clinical development for the potential treatment of sickle cell disease (SCD). Hematopoietic stem cells (HSC) are genetically modified with mRNA encoding zinc finger nucleases (ZFN) that target and disrupt a specific regulatory GATAA motif in the BCL11A erythroid enhancer to reactivate fetal hemoglobin (HbF). We characterized ZFN-edited HSC from healthy donors and donors with SCD. Results of preclinical studies show that ZFN-mediated editing is highly efficient, with enriched biallelic editing and high frequency of on-target indels, producing HSC capable of long-term multilineage engraftment in vivo, and express HbF in erythroid progeny. Interim results from the Phase 1/2 PRECIZN-1 study demonstrated that BIVV003 was well-tolerated in seven participants with SCD, of whom five of the six with more than 3 months of follow-up displayed increased total hemoglobin and HbF, and no severe vaso-occlusive crises. Our data suggest BIVV003 represents a compelling and novel cell therapy for the potential treatment of SCD.

Empirically derived profiles of neurocognitive functioning in youth and young adults with sickle cell disease

OBJECTIVE

Sickle cell disease (SCD) is an inherited blood disorder associated with neurocognitive deficits. In contrast to variable-centered approaches, no known research has utilized person-centered strategies to identify multidimensional patterns of neurocognitive functioning of an individual with SCD. The purpose of the present study was to create empirically derived profiles and identify predictors of neurocognitive functioning subgroups among youth and young adults with SCD.

METHODS

Individuals with SCD (N = 393, mean age 14.05 years, age range 8-24, 50.4% female/49.6% male) completed neurocognitive assessments. Latent profile analysis derived subgroups/classes of neurocognitive functioning and determined relations with demographic and medical variables.

RESULTS

Three latent classes emerged: average functioning (n = 102, 27%), low average functioning (n = 225, 60%), and exceptionally low functioning (n = 46, 12%). Older age was associated with membership in the low average and exceptionally low functioning groups (relative to the average group). Being prescribed hydroxyurea was associated with membership in the average functioning group (relative to the low average group) and absence of hydroxyurea use was associated with membership in the exceptionally low group (relative to the low average group). Lower social vulnerability was associated with membership in the average functioning group compared to the low average and exceptionally low groups.

CONCLUSIONS

Clinicians can help reduce disparities in cognitive development for individuals with SCD by promoting early treatment with hydroxyurea and implementing methods to reduce social vulnerabilities that can interfere with access to evidence-based care.

Hydroxyurea mobile directly observed therapy versus standard monitoring in patients with sickle cell anemia: a phase 2 randomized trial

BACKGROUND

Sickle cell anemia (SCA) prevalence remains high in sub-Saharan Africa. Long-term treatment with hydroxyurea (HU) increases survival, however, poor adherence to treatment could limit effectiveness. Whilst HU treatment adherence is currently high, this might decrease over time.

METHODS

We conducted a single-center, randomized, open-label, parallel group phase 2 controlled clinical trial to determine whether mobile Directly Observed Therapy (m-DOT) increases HU treatment adherence (NCT02844673). Eligible participants were adults with homozygous SCA. People on a chronic blood transfusion program, with hemoglobin (Hb) A levels greater than 20% of the total Hb, total Hb less than 4 g/dL, pregnant or HIV positive were excluded. After a 3-month pre-treatment period participants were randomized to either m-DOT or standard monitoring arm. All participants received smart mobile phones and were treated with HU (15 mg/kg) daily for three months. In the m-DOT arm, drug intake was video recorded on cell phone by the participant and the video sent to the study team. The primary objective was to evaluate the effect of m-DOT on adherence to HU treatment by medication possession ratio (MPR).

RESULTS

Of the 86 participants randomized, 76 completed the trial (26.13 ± 6.97 years, 63.5 % female). Adherence was high (MPR > 95 %) in both groups, 29 (80.6 %) in m-DOT versus 37 (94.9 %) in the standard monitoring arm (P = 0.079). No HU treatment was withheld from participants due to safety concerns.

CONCLUSIONS

m-DOT did not increase adherence to HU treatment. We recommend that further testing in larger trials with a longer follow up period be undertaken.

Sickle cell disease and infertility risks: implications for counseling and care of affected girls and women

INTRODUCTION

Sickle cell disease (SCD), its treatments and cures present infertility risks. Fertility counseling is broadly indicated for affected girls and women and fertility preservation may appeal to some. Several streams of evidence suggest that the reproductive lifespan of women with SCD is reduced. Pregnancy is associated with high miscarriage rates. There are enduring questions about the effects of highly effective hydroxyurea treatment on female fertility. Current conditioning regimens for gene therapy or hematopoietic stem cell transplant are gonadotoxic. Fertility preservation methods exist as non-experimental standards of care for girls and women. Clinicians are challenged to overcome multifactorial barriers to incorporate fertility counseling and fertility preservation care into routine SCD care.

AREAS COVERED

Here we provide a narrative review of existing evidence regarding fertility and infertility risks in girls and women with SCD and consider counseling implications of existing evidence.

EXPERT OPINION

Addressing fertility for girls and women with SCD requires engaging concerns that emerge across the lifespan, acknowledging uncertainty and identifying barriers to care, some of which may be insurmountable without public policy changes. The contemporary SCD care paradigm can offer transformative SCD treatments alongside comprehensive counselling that addresses fertility risks and fertility preservation opportunities.

Utilization and Perceptions of Hydroxyurea Therapy Among Adult Patients With Sickle Cell Disease in Al Ahsa, Saudi Arabia: A Cross-Sectional Study

BACKGROUND

Sickle cell disease (SCD) is a prevalent genetic disorder characterized by abnormal hemoglobin formation, resulting in severe complications. Hydroxyurea (HU) therapy has demonstrated efficacy in reducing SCD-related complications; however, its utilization patterns and patient perceptions remain underexplored, particularly in the Al Ahsa region of Saudi Arabia.

OBJECTIVE

This cross-sectional study aimed to assess the prevalence of HU usage among adult patients with SCD in Al Ahsa; identify the barriers to starting, maintaining, and discontinuing HU therapy; and evaluate the patient-reported outcomes associated with its use.

METHODS

Data were collected through face-to-face surveys and medical record reviews of adult SCD patients attending outpatient clinics in the Hereditary Blood Diseases Center of Al Ahsa, Saudi Arabia, between December 2023 and March 2024. Descriptive statistics and inferential analyses were performed using SPSS version 26.

RESULTS

A total of 345 adult SCD patients were included, with a mean age of 34.12 ± 11.1 years. Most participants were male (58.6%) and unmarried (55.4%). HU utilization was reported by 57.1% of the participants, with the highest adherence observed among older age groups (p = 0.001). Significant improvements in pain severity, hospitalization rates, and quality of life were reported among HU users (p < 0.001). Common barriers to HU use included concerns about side effects, lack of medical justification, and absence of medical advice.

CONCLUSION

This study provides valuable insights into the utilization and perceptions of HU therapy among adults with SCD in Al Ahsa, Saudi Arabia. Addressing identified barriers and promoting patient education are crucial for optimizing therapy adherence and improving clinical outcomes in this population.

Sickle Cell Disease in Brazil: Current Management

Sickle cell disease (SCD) comprises inherited red blood cell disorders due to a mutation in the β-globin gene (c20A > T, pGlu6Val) and is characterized by the presence of abnormal hemoglobin, hemoglobin S, hemolysis, and vaso-occlusion. This mutation, either in a homozygous configuration or in compound states with other β-globin mutations, leads to polymerization of hemoglobin S in deoxygenated conditions, causing modifications in red blood cell shape, particularly sickling. Vaso-occlusive crisis (VOC) is the hallmark of the disease, but other severe complications may arise from repeated bouts of VOCs. SCD is considered a global health problem, and its incidence has increased in some areas of the world, particularly the Americas and Africa. Management of the disease varies according to the region of the world, mainly due to local resources and socioeconomic status. This review aimed to describe more recent data on SCD regarding available treatment options, especially in Brazil. New treatment options are expected to be available to all patients, particularly crizanlizumab, which is already approved in the country.

Red Blood Cells as Therapeutic Target to Treat Sickle Cell Disease

Significance: Sickle cell disease (SCD) is the most common inherited diathesis affecting mostly underserved populations globally. SCD is characterized by chronic pain and fatigue, severe acute painful crises requiring hospitalization and opioids, strokes, multiorgan damage, and a shortened life span. Symptoms may appear shortly after birth, and, in less developed countries, most children with SCD die before attaining age 5. Hematopoietic stem cell transplant and gene therapy offer a curative therapeutic approach, but, due to many challenges, are limited in their availability and effectiveness for a majority of persons with SCD. A critical unmet need is to develop safe and effective novel targeted therapies. A wide array of drugs currently undergoing clinical investigation hold promise for an expanded pharmacological armamentarium against SCD. Recent Advances: Hydroxyurea, the most widely used intervention for SCD management, has improved the survival in the Western world and more recently, voxelotor (R-state-stabilizer), l-glutamine, and crizanlizumab (anti-P-selectin antibody) have been approved by the Food and Drug Administration (FDA) for use in SCD. The recent FDA approval emphasizes the need to revisit the advances in understanding the core pathophysiology of SCD to accelerate novel evidence-based strategies to treat SCD. The biomechanical breakdown of erythrocytesis, the core pathophysiology of SCD, is associated with intrinsic factors, including the composition of hemoglobin, membrane integrity, cellular volume, hydration, andoxidative stress. Critical Issues and Future Directions: In this context, this review focuses on advances in emerging nongenetic interventions directed toward the therapeutic targets intrinsic to sickle red blood cells (RBCs), which can prevent impaired rheology of RBCs to impede disease progression and reduce the sequelae of comorbidities, including pain, vasculopathy, and organ damage. In addition, given the intricate pathophysiology of the disease, it is unlikely that a single pharmacotherapeutic intervention will comprehensively ameliorate the multifaceted complications associated with SCD. However, the availability of multiple drug options affords the opportunity for individualized therapeutic regimens tailored to specific SCD-related complications. Furthermore, it opens avenues for combination drug therapy, capitalizing on distinct mechanisms of action and profiles of adverse effects.

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.

Successes and pitfalls in orphan drug development for sickle cell disease

ABSTRACT

Sickle cell disease (SCD) is a hereditary red cell disorder with a large disease burden at a global level. In the United States and Europe, medicines may qualify for orphan designation (OD), a regulatory status that provides incentives to boost development. We evaluated the development of new therapies for SCD using data for OD granted in the United States and Europe over the last 2 decades (2000-2021). We analyzed their characteristics, pathophysiological targets, trends, and OD sponsors. We then investigated the approval outcomes, including the phase success rate and reasons for discontinuation across different variables. We identified 57 ODs for SCD: 43 (75.4%) small molecules, 32 (56.1%) for oral administration, and 36 (63.1%) for chronic use to prevent SCD complications. At the end of the study (2021), development of 34 of 57 ODs was completed. Four ODs were approved with a success rate of 11.8%. Products targeting upstream causative events of SCD pathophysiology had a 1.8 higher success rate compared with products targeting disease consequences. Large companies showed a fourfold higher success rate compared with small-medium enterprises. Failures in clinical development were mainly seen in phase 3 for a lack of efficacy on vaso-occlusive crisis as the primary study end point, likely related to variable definitions and heterogeneity of pain scoring and treatment. Both advances in SCD knowledge and regulatory incentives paved the way for new therapies for SCD. Our finding of high failure rates in late-stage clinical development signals the need for better early-stage predictive models, also in the context of meaningful clinical end points.

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.

Ginsenoside Rg1 promotes fetal hemoglobin production in vitro: A potential therapeutic avenue for β-thalassemia

β-thalassemia, a globally prevalent genetic disorder, urgently requires innovative treatment options. Fetal hemoglobin (HbF) induction stands as a key therapeutic approach. This investigation focused on Ginsenoside Rg1 from the Panax genus for HbF induction. Employing K562 cells and human erythroid precursor cells (ErPCs) derived from neonatal cord blood, the study tested Rg1 at different concentrations. We measured its effects on γ-globin mRNA levels and HbF expression, alongside assessments of cell proliferation and differentiation. In K562 cells, Rg1 at 400 μM significantly increased γ-globin mRNA expression by 4.24 ± 1.08-fold compared to the control. In ErPCs, the 800 μM concentration was most effective, leading to an over 80% increase in F-cells and a marked upregulation in HbF expression. Notably, Rg1 did not adversely affect cell proliferation or differentiation, with the 200 μM concentration showing an increase in γ-globin mRNA by 2.33 ± 0.58-fold, and the 800 μM concentration enhancing HbF expression by 2.59 ± 0.03-fold in K562 cells. Our results underscore Rg1's potential as an effective and safer alternative for β-thalassemia treatment. By significantly enhancing HbF levels without cytotoxicity, Rg1 offers a notable advantage over traditional treatments like Hydroxyurea. While promising, these in vitro findings warrant further in vivo exploration to confirm Rg1's therapeutic efficacy and to unravel its underlying mechanistic pathways.

Diagnosis and management of chronic thromboembolic pulmonary hypertension (CTEPH) in sickle cell disease: A review

Pulmonary hypertension in sickle cell disease (SCD) is a complex phenomenon resulting from multiple overlapping etiologies, including pulmonary vasoconstriction in the setting of chronic hemolytic anemia, diastolic dysfunction, and chronic thromboembolic disease. The presence of pulmonary hypertension of any cause in SCD confers a significant increase in mortality risk. Evidence to guide the management of patients with sickle cell disease and chronic thromboembolic pulmonary hypertension (CTEPH) is scant and largely the realm of case reports and small case series. Centered on a discussion of a complex young patient with hemoglobin hemoglobin SC who ultimately underwent treatment with pulmonary thromboendarterectomy, we review the available literature to guide management and discuss and overview of treatment of CTEPH in SCD, considering the unique considerations and challenges facing patients suffering from this multisystem disease.

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.

Development of chimeric antigen receptor (CAR)-T cells targeting A56 viral protein implanted by oncolytic virus

To address the challenge of solid tumor targeting in CAR-T therapy, we utilized the A56 antigen, which is uniquely expressed on a diverse range of cancer cells following the systemic administration of an oncolytic vaccinia virus (OVV). Immunohistochemical assays precisely confirmed exclusive localization of A56 to tumor tissues. In vitro studies demonstrated a distinct superiority of A56-dependent CAR-T cytotoxicity across multiple cancer cell lines. Building on these in vitro observations, we strategically administered A56 CAR-T cells, OVV, and hydroxyurea (HU) combination in HCT-116 tumor-bearing non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice, leading to a significant reduction in tumor size and an extended time to progression. Consequently, A56-targeting combinatorial immunotherapy provides the benefit of reducing inadvertent CAR-T effects on normal cells while preserving its effectiveness against cancer cells. Furthermore, our approach of implanting A56 via OVV on tumors facilitates a wide therapeutic application of CAR-T cells across various solid tumors.

Defining curative endpoints for sickle cell disease in the era of gene therapy and gene editing

A growing number of gene therapy- and gene editing-based treatments for patients with sickle cell disease (SCD) are entering clinical trials. These treatments, designed to target the underlying cause of SCD, have the potential to provide functional cures, which until now were possible only through allogeneic hematopoietic stem cell transplant. However, as these novel approaches advance from early- to late-stage clinical trials, it is essential to identify physiologically and clinically relevant endpoints that can demonstrate the achievement of a functional cure for SCD. Here, we present an overview of the pathophysiology of SCD and current treatment options, review ongoing SCD clinical trials using gene therapy or gene editing approaches, and identify the most relevant endpoints for demonstrating the attainment of a functional cure for SCD.

Àgô Sankofa: an overview of the progression of sickle cell disease in Brazil in the past two decades

Sickle cell disease (SCD) is an emblematic case of historical health neglect in Brazil and reflects how institutional racism produces health inequalities. This article engaged in a historical journey of this disease, showing the delayed implementation of health policies for people with sickle cell disease, often concealed in Public Power's (in)actions and omissions. The lack of commitment to implement the recommendations of the Brazilian Ministry of Health, such as neonatal screening, and the difficulty in incorporating technologies for health care result from this modus operandi. The advances and setbacks in programmatic actions and the constant pressure on several governmental entities have characterized the reported saga in the last twenty years. The present text discusses the policies for people with SCD, appropriating the Sankofa symbol, meaning that building the present is only possible by remembering past mistakes. Thus, we recognize this trajectory and this historical moment in which there is a concrete possibility of moving forward and achieving the longed-for comprehensive care for people with SCD. There is an invitation to glance at a new perspective, one in which hope is the trigger for the movements needed to guarantee the rights of people with SCD.

Impact of community health workers on quality of life in adolescents and young adults with sickle cell disease: The SHIP-HU study

Health-related quality of life (HRQoL) is an important outcome for patients with sickle cell disease (SCD). It is often poor compared with other chronic medical conditions or measured as a multidomain disease-specific construct. We previously reported outcomes in the Start Healing in Patients with Hydroxyurea (SHIP-HU) randomized controlled trial in adolescents and adults with SCD at six clinical sites. Besides the primary outcomes, we also measured HRQoL as a secondary outcome. Patients in the intervention arm were each assigned community health workers (CHWs) who provided case management services. CHW services were independent of medical management, and medical managers were blinded to the study arm. Patients in the control arm received only standard of care. We hypothesized that having a CHW would improve HRQoL in patients enrolled in SHIP-HU. We did not find significant differences between domains of HRQoL in the two study arms. Possible explanations include selection bias of enrolled versus unenrolled patients, selection bias of sites, medical providers and medical management, enforced blinding, and a lack of cooperation between medical managers and CHWs. The importance of CHWs and HRQoL is nonetheless recognized based on the literature. Future interventions on HRQoL in SCD should consider alternative study designs and multimodal interventions.

Post-transfusion severe headache in a patient with thalassemia with superficial siderosis of the central nervous system: a case report and literature review

BACKGROUND

Patients with severe thalassemia may experience adverse effects from transfusion such as fever, rash, and iron overload after long-term transfusion therapy. Severe headaches as a side effect of blood transfusion in patients with thalassemia are not commonly observed, especially when combined with superficial siderosis of the central nervous system, which is easily misdiagnosed and requires excessive examination and treatment.

CASE PRESENTATION

A 31-year-old woman was admitted with severe headache and vomiting over 3 days following blood transfusion. She was diagnosed with intermediate α-thalassemia at 2 years of age and had a history of irregular blood transfusions. Physical examination revealed horizontal nystagmus with no other abnormal neurological signs. Magnetic resonance (MR) imaging, MR venography, MR arteriography, and cerebrospinal fluid analysis were normal. However, susceptibility-weighted imaging showed abnormal signals in the bilateral and fourth ventricles. Initial antibiotics, antivirals, decompression of intracranial pressure, iron chelation, and symptomatic treatments were administered; subsequently, small intermittent blood transfusions were cautiously administered for severe anemia. The patient's headache was gradually relieved, and she was discharged on day 9. At the 5-month follow-up, the patient's headache recurred following another transfusion.

CONCLUSIONS

Severe post-transfusion headache in patients with thalassemia has not been fully recognized and is easily misdiagnosed, leading to excessive examination and treatment. Understanding the clinical features of transfusion-related headaches can help identify this complication, but the exact pathophysiological mechanism requires further research.

Haematopoietic stem cell health in sickle cell disease and its implications for stem cell therapies and secondary haematological disorders

Gene modification of haematopoietic stem cells (HSCs) is a potentially curative approach to sickle cell disease (SCD) and offers hope for patients who are not eligible for allogeneic HSC transplantation. Current approaches require in vitro manipulation of healthy autologous HSC prior to their transplantation. However, the health and integrity of HSCs may be compromised by a variety of disease processes in SCD, and challenges have emerged in the clinical trials of gene therapy. There is also concern about increased susceptibility to haematological malignancies during long-term follow up of patients, and this raises questions about genomic stability in the stem cell compartment. In this review, we evaluate the evidence for HSC deficits in SCD and then discuss their potential causation. Finally, we suggest several questions which need to be addressed in order to progress with successful HSC manipulation for gene therapy in SCD.

Polycythemia Vera: Barriers to and Strategies for Optimal Management

Polycythemia vera (PV) is a subtype of myeloproliferative neoplasms characterized by impaired quality of life and severe complications. Despite the increasingly in-depth knowledge of this condition, it necessitates a multifaceted management approach to mitigate symptoms and prevent thrombotic and hemorrhagic events, ensuring prolonged survival. The therapeutic landscape has been revolutionized in recent years, where venesection and hydroxycarbamide associated with antiplatelet therapy have a central role and are now accompanied by other drugs, such as interferon and Janus kinase inhibitors. Ongoing research and advancements in targeted therapies hold promise for further enhancing the therapeutic choice for PV management.

Incidence and risk factors for osteonecrosis of the femoral head in five hundred and ten sickle cell disease paediatric patients

PURPOSE

Osteonecrosis of the femoral head (ONFH) is a degenerative and progressive disorder that mainly affects people with sickle cell disease (SCD). Herein, we aimed to search for a better understanding of markers that can act as risk factors for ONFH in patients with SCD.

METHODS

We conducted a retrospective study including 510 SCD patients followed over 23 years. Patients were divided into the ONFH group and the no-ONHF control group. Univariate and multivariate logistic regression analyses were performed to identify risk factors.

RESULTS

Among 510 SCD patients, 41(8%) were diagnosed with ONFH at a mean age of 167 months ± 64 (72-288). The cumulative incidence of ONHF increased from 2.3% at ten years to 18.3% at 20 years of age. The radiological grade 3 ONHF was predominant. No significant differences in sex, age at diagnosis of SCD, and Hb genotype were found between groups. The patient age and the time since diagnosis of SCD were statistically higher in patients with ONHF in univariate and multivariate analysis. ONHF was also associated with higher creatinine level (p = 0.001) lower LDH level (p = 0.006), and higher number of vaso-occlusive crisis (VOC)/patient/year (p < 0.001). The cumulative incidence of ONHF in patients having more than 3 VOC/year was significantly higher (43% versus 18.9% at 20 years, p < 0.001). In addition, infections, gallstones, growth delay, delayed initiation of hydroxyurea, and a higher transfusion rate were significantly associated with ONFH.

CONCLUSION

These findings confirm that ONFH is closely related to the age, severity, and duration of SCD. Better management of this disease prevents acute and chronic complications, and early screening of the ONFH as soon as the first signs of the severity of the disease are detected provides a better functional prognosis.

Precision, integrative medicine for pain management in sickle cell disease

Sickle cell disease (SCD) is a prevalent and complex inherited pain disorder that can manifest as acute vaso-occlusive crises (VOC) and/or chronic pain. Despite their known risks, opioids are often prescribed routinely and indiscriminately in managing SCD pain, because it is so often severe and debilitating. Integrative medicine strategies, particularly non-opioid therapies, hold promise in safe and effective management of SCD pain. However, the lack of evidence-based methods for managing SCD pain hinders the widespread implementation of non-opioid therapies. In this review, we acknowledge that implementing personalized pain treatment strategies in SCD, which is a guideline-recommended strategy, is currently fraught with limitations. The full implementation of pharmacological and biobehavioral pain approaches targeting mechanistic pain pathways faces challenges due to limited knowledge and limited financial and personnel support. We recommend personalized medicine, pharmacogenomics, and integrative medicine as aspirational strategies for improving pain care in SCD. As an organizing model that is a comprehensive framework for classifying pain subphenotypes and mechanisms in SCD, and for guiding selection of specific strategies, we present evidence updating pain research pioneer Richard Melzack's neuromatrix theory of pain. We advocate for using the updated neuromatrix model to subphenotype individuals with SCD, to better select personalized multimodal treatment strategies, and to identify research gaps fruitful for exploration. We present a fairly complete list of currently used pharmacologic and non-pharmacologic SCD pain therapies, classified by their mechanism of action and by their hypothesized targets in the updated neuromatrix model.

Frequency of Painful Crisis and Other Associated Complications of Sickle Cell Anemia Among Children

Background Sickle cell disease (SCD) represents a group of inherited health conditions that affect red blood cells. SCD is a relatively common genetic disorder in Saudi Arabia, with the highest prevalence found in the Eastern Province region. The most common complications of SCD include acute chest syndrome, vaso-occlusive crisis, stroke, and avascular necrosis of the femoral head. The disease itself is not a cause of mortality but systemic complications are. Methodology In this retrospective study, we aimed to determine the frequency of painful crisis and the associated complications of sickle cell anemia (SCA) among children at King Saud Medical City (KSMC) in Riyadh, Saudi Arabia. Results This study included a total of 70 children with SCA below the age of 14 years who were admitted to KSMC from January 2021 to December 2021. Overall, 60% of the participants had one painful crisis attack per year, whereas 27% had two attacks. Furthermore, 94% of the participants were being treated with hydroxyurea. The most frequent cause of admission was painful crises with acute chest syndrome. Conclusions This study highlights the frequency of hydroxyurea use among SCA patients. Our results showed that participants who developed one to two painful crises per year were hospitalized for four to nine days on average with increased utilization of hydroxyurea.

Prospective identification of variables as outcomes for treatment (PIVOT): study protocol for a randomised, placebo-controlled trial of hydroxyurea for Ghanaian children and adults with haemoglobin SC disease

BACKGROUND

Haemoglobin SC (HbSC) is a common form of sickle cell disease (SCD), especially among individuals of West African ancestry. Persons with HbSC disease suffer from the same clinical complications and reduced quality of life that affect those with sickle cell anaemia (HbSS/Sβ0). Retrospective anecdotal data suggest short-term safety and benefits of hydroxyurea for treating HbSC, yet rigorous prospective data are lacking regarding optimal dosing, clinical and laboratory effects, long-term safety and benefits, and appropriate endpoints to monitor. Prospective Investigation of Variables as Outcomes for Treatment (PIVOT) was designed with three aims: (1) to measure the toxicities of hydroxyurea treatment on laboratory parameters, (2) to assess the effects of hydroxyurea treatment on sickle-related clinical and laboratory parameters, and (3) to identify study endpoints suitable for a future definitive phase III trial of hydroxyurea treatment of HbSC disease.

METHODS

PIVOT is a randomised, placebo-controlled, double blind clinical trial of hydroxyurea. Approximately 120 children and 120 adults ages 5-50 years with HbSC disease will be enrolled, screened for 2 months, and then randomised 1:1 to once-daily oral hydroxyurea or placebo. Study treatment will be prescribed initially at 20 ± 5 mg/kg/day with an opportunity to escalate the dose twice over the first 6 months. After 12 months of blinded study treatment, all participants will be offered open-label hydroxyurea for up to 4 years. Safety outcomes include treatment-related cytopenias, whole blood viscosity, and adverse events. Efficacy outcomes include a variety of laboratory and clinical parameters over the first 12 months of randomised treatment, including changes in haemoglobin and fetal haemoglobin, intracranial arterial velocities measured by transcranial Doppler ultrasound, cerebral oxygenation using near infrared spectrometry, spleen volume and kidney size by ultrasound, proteinuria, and retinal imaging. Exploratory outcomes include functional erythrocyte analyses with ektacytometry for red blood cell deformability and point-of-sickling, patient-reported outcomes using the PROMIS questionnaire, and 6-min walk test.

DISCUSSION

For children and adults with HbSC disease, PIVOT will determine the safety of hydroxyurea and identify measurable changes in laboratory and clinical parameters, suitable for future prospective testing in a definitive multi-centre phase III clinical trial.

TRIAL REGISTRATION

PACTR, PACTR202108893981080. Registered 24 August 2021, https://pactr.samrc.ac.za.

Creating an automated contemporaneous cohort in sickle cell anemia to predict survival after disease-modifying therapy

The Food and Drug Administration requires contemporaneous controls to compare clinical outcomes for participants receiving experimental gene therapy or gene editing clinical trials. However, developing a contemporaneous cohort of rare diseases requires multiple person-hours. In a single referral center for sickle cell disease, we tested the hypothesis that we could create an automated contemporaneous cohort of children and adults with sickle cell anemia (SCA) to predict mortality. Data were obtained between 1 January 2004 and 30 April 2021. We identified 419 individuals with SCA with consistent medical care defined as followed continuously for >0.5 years with no visit gaps >3.0 years. The median age was 10.2 years (IQR, 1-24 years), with a median follow-up of 7.4 years (IQR, 3.6-13.5 years) and 47 deaths. A total of 98% (274 of 277) of the children remained alive at 18 years of age, and 34.3% (94 of 274) of those children were followed into adulthood. For adults, the median age of survival was 49.3 years. Treatment groups were mutually exclusive and in a hierarchical order: hematopoietic stem cell transplant (n = 22)>regular blood transfusion for at least 2 years (n = 56)>hydroxyurea for at least 1 year (n = 243)>no disease-modifying therapy (n = 98). Compared to those receiving no disease-modifying treatment, those treated with hydroxyurea therapy had a significantly lower hazard of mortality (hazard ratio = 0.38; P = 0.016), but no statistical difference for those receiving regular blood transfusions compared to no disease-modifying therapy (hazard ratio = 0.71; P = 0.440). An automated contemporaneous SCA cohort can be generated to estimate mortality in children and adults with SCA.

Emerging Therapies and Advances in Sickle Cell Disease with a Focus on Renal Manifestations

The underlying mechanisms of disease in sickle cell disease (SCD) contribute to a multifaceted nephropathy, commonly manifested as albuminuria. In severe SCD genotypes ( e.g. , Hemoglobin SS [HbSS]), albuminuria and CKD are major predictors of mortality in this population. Therefore, the monitoring and management of renal function is an intrinsic part of comprehensive care in SCD. Management of nephropathy in SCD can be accomplished with SCD-directed therapies and/or CKD-directed therapies. In the past 5 years, novel disease-modifying and palliative therapies have been approved in SCD to target aspects of the disease, such as anemia, inflammation, and vasculopathy. Along with conventional hydroxyurea and chronic transfusion, l -glutamine, crizanlizumab, and voxelotor have all been shown to mitigate some adverse effect of SCD, and their effect on nephropathy is being investigated. CKD-directed therapies such as renin-angiotensin-aldosterone system blockers have long been used in SCD nephropathy; however, more complete long-term studies on benefits are needed. Given the effect of renal disease on survival, further assessment of the mechanisms and efficacy of these SCD-directed or CKD-directed therapeutic agents is essential.

Sickle cell disease and acute leukemia: one case report and an extensive review

Population-based studies and case reports suggest that there may be an increased risk of acute leukemia associated with sickle cell disease (SCD). Following the description of a new case report, an extensive review of the literature identified 51 previously described cases. Most cases study showed myelodysplastic features confirmed, when available, by genetic markers such as chromosome 5 and/or chromosome 7 abnormalities and TP53 gene mutations. The increased risk of leukemogenesis is certainly multifactorial and related to the pathophysiologic mechanisms of the clinical manifestations of SCD. Chronic hemolysis and secondary hemochromatosis may cause increased chronic inflammation, resulting in persistent marrow stress, which could potentially compromise the genomic stability of the hematopoietic stem cells generating genomic damage and somatic mutations over the course of SCD and its treatment, resulting in a clone that led to acute myeloid leukemia.

Leveraging mathematical modeling to analyze nonadherence for hydroxyurea therapy in sickle cell disease

Nonadherence is common in individuals with sickle cell disease (SCD) on hydroxyurea therapy and can be observed with waning improvements in hematologic parameters or biomarkers like mean cell volume and fetal hemoglobin level over time. We modeled the impact of hydroxyurea nonadherence on longitudinal biomarker profiles. We estimated the potential nonadherent days in individuals exhibiting a drop in biomarker levels by modifying the dosing profile using a probabilistic approach. Incorporating additional nonadherence using our approach besides existing ones in the dosing profile improves the model fits. We also studied how different patterns in adherence give rise to various physiological profiles of biomarkers. The key finding is consecutive days of nonadherence are less favorable than when nonadherence is interspersed. These findings improve our understanding of nonadherence and how appropriate intervention strategies can be applied for individuals with SCD susceptible to the severe impacts of nonadherence.

Mechanisms underlying the adaptive pulp and jaw bone trabecular changes in sickle cell anemia

OBJECTIVE

Mechanisms underlying the oral outcomes in sickle cell anemia (HbSS) have been less explored. This study aimed to investigate the association of morbimortality indicators and hydroxyurea use with adaptive pulp and jaw bone trabecular changes in HbSS.

METHODS

This cross-sectional study included 123 individuals with HbSS. The exposures were the morbimortality indicators of HbSS (number of vaso-occlusive crises, organ damage, hemoglobin level, and leukocyte count) and the use of hydroxyurea for HbSS treatment. The outcomes were adaptive pulp and jaw bone trabecular changes confirmed by radiographic examination. Associations were estimated by Poisson regression in crude and adjusted analyses for sex, skin color, socioeconomic class, and age.

RESULTS

The vaso-occlusive crises (mean ratio (MR) = 3.5, p = 0.045), lower hemoglobin (MR = 2.4, p = 0.037), and higher leukocyte count (MR = 2.17, p = 0.036) were risk factors, while the use of hydroxyurea was inversely associated with adaptive pulp changes (MR = 0.23, p = 0.024). The vaso-occlusive crises were associated with jaw bone trabecular changes (MR = 1.33, p = 0.02).

CONCLUSION

Adaptive pulp changes may be a potential clinical marker of chronic vasculopathy in HbSS. The use of hydroxyurea may reduce the frequency of adaptive pulp changes.

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

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

Foetal haemoglobin inducers for reducing blood transfusion in non-transfusion-dependent beta-thalassaemias

BACKGROUND

Non-transfusion-dependent β-thalassaemia (NTDβT) is a subset of inherited haemoglobin disorders characterised by reduced production of the β-globin chain of haemoglobin leading to anaemia of varying severity. Although blood transfusion is not a necessity for survival, it may be required to prevent complications of chronic anaemia, such as impaired growth and hypercoagulability. People with NTDβT also experience iron overload due to increased iron absorption from food sources which becomes more pronounced in those requiring blood transfusion. People with a higher foetal haemoglobin (HbF) level have been found to require fewer blood transfusions, thus leading to the emergence of treatments that could increase its level. HbF inducers stimulate HbF production without altering any gene structures. Evidence for the possible benefits and harms of these inducers is important for making an informed decision on their use.

OBJECTIVES

To compare the effectiveness and safety of the following for reducing blood transfusion for people with NTDβT: 1. HbF inducers versus usual care or placebo; 2. single HbF inducer with another HbF inducer, and single dose with another dose; and 3. combination of HbF inducers versus usual care or placebo, or single HbF inducer.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 21 August 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs comparing single HbF inducer with placebo or usual care, with another single HbF inducer or with a combination of HbF inducers; or comparing different doses of the same HbF inducer.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were blood transfusion and haemoglobin levels. Our secondary outcomes were HbF levels, the long-term sequelae of NTDβT, quality of life and adverse events.

MAIN RESULTS

We included seven RCTs involving 291 people with NTDβT, aged two to 49 years, from five countries. We reported 10 comparisons using eight different HbF inducers (four pharmacological and four natural): three RCTs compared a single HbF inducer to placebo and seven to another HbF inducer. The duration of the intervention lasted from 56 days to six months. Most studies did not adequately report the randomisation procedures or whether and how blinding was achieved. HbF inducer against placebo or usual care Three HbF inducers, HQK-1001, Radix Astragali or a 3-in-1 combined natural preparation (CNP), were compared with a placebo. None of the comparisons reported the frequency of blood transfusion. We are uncertain whether Radix Astragali and CNP increase haemoglobin at three months (mean difference (MD) 1.33 g/dL, 95% confidence interval (CI) 0.54 to 2.11; 1 study, 2 interventions, 35 participants; very low-certainty evidence). We are uncertain whether Radix Astragali and CNP have any effect on HbF (MD 12%, 95% CI -0.74% to 24.75%; 1 study, 2 interventions, 35 participants; very low-certainty evidence). Only medians on haemoglobin and HbF levels were reported for HQK-1001. Adverse effects reported for HQK-1001 were nausea, vomiting, dizziness and suprapubic pain. There were no prespecified adverse effects for Radix Astragali and CNP. HbF inducer versus another HbF inducer Four studies compared a single inducer with another over three to six months. Comparisons included hydroxyurea versus resveratrol, hydroxyurea versus thalidomide, hydroxyurea versus decitabine and Radix Astragali versus CNP. No study reported our prespecified outcomes on blood transfusion. Haemoglobin and HbF were reported for the comparison Radix Astragali versus CNP, but we are uncertain whether there were any differences (1 study, 24 participants; low-certainty evidence). Different doses of the same HbF inducer Two studies compared two different types of HbF inducers at different doses over two to six months. Comparisons included hydroxyurea 20 mg/kg/day versus 10 mg/kg/day and HQK-1001 10 mg/kg/day, 20 mg/kg/day, 30 mg/kg/day and 40 mg/kg/day. Blood transfusion, as prespecified, was not reported. In one study (61 participants) we are uncertain whether the lower levels of both haemoglobin and HbF at 24 weeks were due to the higher dose of hydroxyurea (haemoglobin: MD -2.39 g/dL, 95% CI -2.80 to -1.98; very low-certainty evidence; HbF: MD -10.20%, 95% CI -16.28% to -4.12%; very low-certainty evidence). The study of the four different doses of HQK-1001 did not report results for either haemoglobin or HbF. We are not certain if major adverse effects may be more common with higher hydroxyurea doses (neutropenia: risk ratio (RR) 9.93, 95% CI 1.34 to 73.97; thrombocytopenia: RR 3.68, 95% CI 1.12 to 12.07; very low-certainty evidence). Taking HQK-1001 20 mg/kg/day may result in the fewest adverse effects. A combination of HbF inducers versus a single HbF inducer Two studies compared three combinations of two inducers with a single inducer over six months: hydroxyurea plus resveratrol versus resveratrol or hydroxyurea alone, and hydroxyurea plus l-carnitine versus hydroxyurea alone. Blood transfusion was not reported. Hydroxyurea plus resveratrol may reduce haemoglobin compared with either resveratrol or hydroxyurea alone (MD -0.74 g/dL, 95% CI -1.45 to -0.03; 1 study, 54 participants; low-certainty evidence). We are not certain whether the gastrointestinal disturbances, headache and malaise more commonly reported with hydroxyurea plus resveratrol than resveratrol alone were due to the interventions. We are uncertain whether hydroxyurea plus l-carnitine compared with hydroxyurea alone may increase mean haemoglobin, and reduce pulmonary hypertension (1 study, 60 participants; very low-certainty evidence). Adverse events were reported but not in the intervention group. None of the comparisons reported the outcome of HbF.

AUTHORS' CONCLUSIONS

We are uncertain whether any of the eight HbF inducers in this review have a beneficial effect on people with NTDβT. For each of these HbF inducers, we found only one or at the most two small studies. There is no information on whether any of these HbF inducers have an effect on our primary outcome, blood transfusion. For the second primary outcome, haemoglobin, there may be small differences between intervention groups, but these may not be clinically meaningful and are of low- to very low-certainty evidence. Data on adverse effects and optimal doses are limited. Five studies are awaiting classification, but none are ongoing.

Managing the Cerebrovascular Complications of Sickle Cell Disease: Current Perspectives

The importance of protecting brain function for people with sickle cell disease (SCD) cannot be overstated. SCD is associated with multiple cerebrovascular complications that threaten neurocognitive function and life. Without screening and preventive management, 11% of children at 24% of adults with SCD have ischemic or hemorrhagic strokes. Stroke screening in children with SCD is well-established using transcranial Doppler ultrasound (TCD). TCD velocities above 200 cm/s significantly increase the risk of stroke, which can be prevented using chronic red blood cell (RBC) transfusion. RBC transfusion is also the cornerstone of acute stroke management and secondary stroke prevention. Chronic transfusion requires long-term management of complications like iron overload. Hydroxyurea can replace chronic transfusions for primary stroke prevention in a select group of patients or in populations where chronic transfusions are not feasible. Silent cerebral infarction (SCI) is even more common than stroke, affecting 39% of children and more than 50% of adults with SCD; management of SCI is individualized and includes careful neurocognitive evaluation. Hematopoietic stem cell transplant prevents cerebrovascular complications, despite the short- and long-term risks. Newer disease-modifying agents like voxelotor and crizanlizumab, as well as gene therapy, may treat cerebrovascular complications, but these approaches are investigational.

The BACH1 inhibitor ASP8731 inhibits inflammation and vaso-occlusion and induces fetal hemoglobin in sickle cell disease

In sickle cell disease (SCD), heme released during intravascular hemolysis promotes oxidative stress, inflammation, and vaso-occlusion. Conversely, free heme can also activate expression of antioxidant and globin genes. Heme binds to the transcription factor BACH1, which represses NRF2-mediated gene transcription. ASP8731, is a selective small molecule inhibitor of BACH1. We investigated the ability of ASP8731 to modulate pathways involved in SCD pathophysiology. In HepG2 liver cells, ASP8731 increased HMOX1 and FTH1 mRNA. In pulmonary endothelial cells, ASP8731 decreased VCAM1 mRNA in response to TNF-α and blocked a decrease in glutathione in response to hemin. Townes-SS mice were gavaged once per day for 4 weeks with ASP8731, hydroxyurea (HU) or vehicle. Both ASP8731 and HU inhibited heme-mediated microvascular stasis and in combination, ASP8731 significantly reduced microvascular stasis compared to HU alone. In Townes-SS mice, ASP8731 and HU markedly increased heme oxygenase-1 and decreased hepatic ICAM-1, NF-kB phospho-p65 protein expression in the liver, and white blood cell counts. In addition, ASP8731 increased gamma-globin expression and HbF+ cells (F-cells) as compared to vehicle-treated mice. In human erythroid differentiated CD34+ cells, ASP8731 increased HGB mRNA and increased the percentage of F-cells 2-fold in manner similar to HU. ASP8731 and HU when given together induced more HbF+ cells compared to either drug alone. In CD34+ cells from one donor that was non-responsive to HU, ASP8731 induced HbF+ cells ~2-fold. ASP8731 and HU also increased HBG and HBA, but not HBB mRNA in erythroid differentiated CD34+ cells derived from SCD patients. These data indicate that BACH1 may offer a new therapeutic target to treat SCD.

Fertility preservation for pediatric patients with hemoglobinopathies: Multidisciplinary counseling needed to optimize outcomes

Hemoglobinopathies are autosomal recessive disorders that occur when genetic mutations negatively impact the function of hemoglobin. Common hemoglobinopathies that are clinically significant include sickle cell disease, alpha thalassemia, and beta thalassemia. Advancements in disease-modifying and curative treatments for the common hemoglobinopathies over the past thirty years have led to improvements in patient quality of life and longevity for those who are affected. However, the diseases, their treatments and cures pose infertility risks, making fertility preservation counseling and treatment an important part of the contemporary comprehensive patient care. Sickle cell disease negatively impacts both male and female infertility, primarily by testicular failure and decreased ovarian reserve, respectively. Fertility in both males and females with beta thalassemia major are negatively impacted by iron deposition due to chronic blood transfusions. Hematopoietic stem cell transplant (HSCT) is currently the only curative treatment for SCD and transfusion dependent beta thalassemia. Many of the conditioning regimens for HSCT contain chemotherapeutic agents with known gonadotoxicity and whole-body radiation. Although most clinical studies on toxicity and impact of HSCT on long-term health do not evaluate fertility, gonadal failure is common. Male fertility preservation modalities that exist prior to gonadotoxic treatment include sperm banking for pubertal males and testicular cryopreservation for pre-pubertal boys. For female patients, fertility preservation options include oocyte cryopreservation and ovarian tissue cryopreservation. Oocyte cryopreservation requires controlled ovarian hyperstimulation (COH) with ten to fourteen days of intensive monitoring and medication administration. This is feasible once the patient has undergone menarche. Follicular growth is monitored via transvaginal or transabdominal ultrasound, and hormone levels are monitored through frequent blood work. Oocytes are then harvested via a minimally invasive approach under anesthesia. Complications of COH are more common in patients with hemoglobinopathies. Ovarian hyperstimulation syndrome creates a greater risk to patients with underlying vascular, pulmonary, and renal injury, as they may be less able to tolerate fluids shifts. Thus, it is critical to monitor patients undergoing COH closely with close collaboration between the hematology team and the reproductive endocrinology team. Counseling patients and families about future fertility must take into consideration the patient's disease, treatment history, and planned treatment, acknowledging current knowledge gaps.

Hydroxyurea (hydroxycarbamide) for sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is one of the most common inherited diseases worldwide. It is associated with lifelong morbidity and a reduced life expectancy. Hydroxyurea (hydroxycarbamide), an oral chemotherapeutic drug, ameliorates some of the clinical problems of SCD, in particular that of pain, by raising foetal haemoglobin (HbF). This is an update of a previously published Cochrane Review.

OBJECTIVES

The aims of this review are to determine through a review of randomised or quasi-randomised studies whether the use of hydroxyurea in people with SCD alters the pattern of acute events, including pain; prevents, delays or reverses organ dysfunction; alters mortality and quality of life; or is associated with adverse effects. In addition, we hoped to assess whether the response to hydroxyurea in SCD varies with the type of SCD, age of the individual, duration and dose of treatment, and healthcare setting.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Haemoglobinopathies Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also searched online trial registries. The date of the most recent search was 17 February 2022.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials (RCTs and quasi-RCTs), of one month or longer, comparing hydroxyurea with placebo or standard therapy in people  with SCD.

DATA COLLECTION AND ANALYSIS

Authors independently assessed studies for inclusion, carried out data extraction, assessed the risk of bias and assessed the quality of the evidence using GRADE.

MAIN RESULTS

We included nine RCTs recruiting 1104 adults and children with SCD (haemoglobin SS (HbSS), haemoglobin SC (HbSC) or haemoglobin Sβºthalassaemia (HbSβºthal) genotypes). Studies lasted from six to 30 months. We judged the quality of the evidence for the first two comparisons below as moderate to low as the studies contributing to these comparisons were mostly large and well-designed (and at low risk of bias); however, the evidence was limited and imprecise for some outcomes such as quality of life, deaths during the studies and adverse events, and the results are applicable only to individuals with HbSS and HbSβºthal genotypes. We judged the quality of the evidence for the third and fourth comparisons to be very low due to the limited number of participants, the lack of statistical power (both studies were terminated early with approximately only 20% of their target sample size recruited) and the lack of applicability to all age groups and genotypes. Hydroxyurea versus placebo Five studies (784 adults and children with HbSS or HbSβºthal) compared hydroxyurea to placebo; four recruited individuals with only severe disease and one recruited individuals with all disease severities. Hydroxyurea probably improves pain alteration (using measures such as pain crisis frequency, duration, intensity, hospital admissions and opoid use) and life-threatening illness, but we found no difference in death rates (10 deaths occurred during the studies, but the rates did not differ by treatment group) (all moderate-quality evidence). Hydroxyurea may improve measures of HbF (low-quality evidence) and probably decreases neutrophil counts (moderate-quality evidence). There were no consistent differences in terms of quality of life and adverse events (including serious or life-threatening events) (low-quality evidence). There were fewer occurrences of acute chest syndrome and blood transfusions in the hydroxyurea groups.  Hydroxyurea and phlebotomy versus transfusion and chelation Two studies (254 children with HbSS or HbSβºthal also with risk of primary or secondary stroke) contributed to this comparison. There were no consistent differences in terms of pain alteration, death or adverse events (low-quality evidence) or life-threatening illness (moderate-quality evidence). Hydroxyurea with phlebotomy probably increased HbF and decreased neutrophil counts (moderate-quality evidence), but there were more occurrences of acute chest syndrome and infections. Quality of life was not reported. In the primary prevention study, no strokes occurred in either treatment group but in the secondary prevention study, seven strokes occurred in the hydroxyurea and phlebotomy group (none in the transfusion and chelation group) and the study was terminated early.  Hydroxyurea versus observation One study (22 children with HbSS or HbSβºthal also at risk of stoke) compared hydroxyurea to observation. Pain alteration and quality of life were not reported. There were no differences in life-threatening illness, death (no deaths reported in either group) or adverse events (very low-quality evidence). We are uncertain if hydroxyurea improves HbF or decreases neutrophil counts (very low-quality evidence). Treatment regimens with and without hydroxyurea One study (44 adults and children with HbSC) compared treatment regimens with and without hydroxyurea. Pain alteration, life-threatening illness and quality of life were not reported. There were no differences in death rates (no deaths reported in either group), adverse events or neutrophil levels (very low-quality evidence). We are uncertain if hydroxyurea improves HbF (very low-quality evidence).

AUTHORS' CONCLUSIONS

There is evidence to suggest that hydroxyurea may be effective in decreasing the frequency of pain episodes and other acute complications in adults and children with sickle cell anaemia of HbSS or HbSβºthal genotypes and in preventing life-threatening neurological events in those with sickle cell anaemia at risk of primary stroke by maintaining transcranial Doppler velocities. However, there is still insufficient evidence on the long-term benefits of hydroxyurea, particularly with regard to preventing chronic complications of SCD, or recommending a standard dose or dose escalation to maximum tolerated dose. There is also insufficient evidence about the long-term risks of hydroxyurea, including its effects on fertility and reproduction. Evidence is also limited on the effects of hydroxyurea on individuals with the HbSC genotype. Future studies should be designed to address such uncertainties.

Barriers to hydroxyurea use from the perspectives of providers, individuals with sickle cell disease, and families: Report from a U.S. regional collaborative

Sickle cell disease (SCD) is an inherited blood disorder that affects about 100,000 people in the U.S., primarily Blacks/African-Americans. A multitude of complications negatively impacts quality of life. Hydroxyurea has been FDA approved since 1998 as a disease-modifying therapy for SCD, but is underutilized. Negative and uninformed perceptions of hydroxyurea and barriers to its use hinder adherence and promotion of the medication. As the largest real-world study to date that assessed hydroxyurea use for children and adults with SCD, we gathered and analyzed perspectives of providers, individuals with SCD, and families. Participants provided information about socio-demographics, hospital and emergency admissions for pain, number of severe pain episodes interfering with daily activities, medication adherence, and barriers to hydroxyurea. Providers reported on indications for hydroxyurea, reasons not prescribed, and current laboratory values. We found that hydroxyurea use was reported in over half of eligible patients from this large geographic region in the U.S., representing a range of sickle cell specialty clinical settings and practices. Provider and patient/caregiver reports about hydroxyurea use were consistent with one another; adults 26 years and older were least likely to be on hydroxyurea; and the likelihood of being on hydroxyurea decreased with one or more barriers. Using the intentional and unintentional medication nonadherence framework, we found that, even for patients on hydroxyurea, challenges to taking the medicine at the right time and forgetting were crucial unintentional barriers to adherence. Intentional barriers such as worry about side effects and “tried and it did not work” were important barriers for young adults and adults. For providers, diagnoses other than HgbSS or HgbS-β0 thalassemia were associated with lower odds of prescribing, consistent with evidence-based guidelines. Our results support strengthening provider understanding and confidence in implementing existing SCD guidelines, and the importance of shared decision making. Our findings can assist providers in understanding choices and decisions of families; guide individualized clinical discussions regarding hydroxyurea therapy; and help with developing tailored interventions to address barriers. Addressing barriers to hydroxyurea use can inform strategies to minimize similar barriers in the use of emerging and combination therapies for SCD.

Ten-year Longitudinal Analysis of Hydroxyurea Implementation in a Pediatric Sickle Cell Program

Hydroxyurea (HU) has proven benefit in sickle cell anemia (SCA), but HU is still underutilized. The Pediatric Sickle Cell Program of Northern Virginia prescribes HU regardless of symptoms to all SCA patients age ≥ 9 months and prospectively tracks outcomes. HU is dosed to maximum tolerated dosing (MTD), targeting 30% Hgb F. Longitudinal data from 2009-2019 encompassing 1222 HU-eligible and 950 HU-exposure patient-years were analyzed in 2-year intervals for hemoglobin (Hgb), fetal hemoglobin (Hgb F), hospitalizations, transfusions, and treat-and-release ED visits. Comparing HU-eligible patients in the interval prior to HU implementation (2009-2011) to the last interval analyzed after HU implementation (2017-2019), HU usage increased from 33% to 93%, average Hgb increased from 8.3±0.98 to 9.8±1.3 g/dL (p<0.0001), average Hgb F rose from 13±8.7% to 26±9.9% (p<0.0001), hospitalizations decreased from 0.71 (95% CI 0.54-0.91) to 0.2 (95% CI 0.13-0.28) admissions/person-year, sporadic transfusions decreased from 0.4 (95% CI 0.27-0.55) to 0.05 (95% CI 0.02-0.12) transfusions/person-year. Treat-and-release ED visit rates remained unchanged, varying between 0.49 (95% CI 0.36-0.64) and 0.64 (95% CI 0.48-0.83) visits/person-year. By the last interval, 72% of patients had Hgb ≥ 9g/dL, 42% had Hgb F ≥ 30%, 79% experienced no hospitalizations, and 94% received no transfusions. Uniform HU prescription for SCA patients with close monitoring to achieve high Hgb F resulted in significant improvements in laboratory and clinical outcomes within 2 years, which continued to improve over the next 6 years. Rigorous HU implementation in a pediatric sickle cell population is feasible, effective, and sustainable. This article is protected by copyright. All rights reserved.

Stability evaluation of compounded hydroxyurea 100 mg/mL oral liquids using a novel analytical method involving chemical derivatization

This study assessed the stability of six extemporaneously compounded hydroxyurea oral liquids stored at room temperature. Hydroxyurea oral liquids (100 mg/mL) were prepared using three different mixing methods (mortar, mixer or QuartetRx) from either bulk powder, capsule content, or whole capsules. Two brands of capsules were tested in this study. All formulations were stored at room temperature (25°C / 60% RH) in amber plastic bottles for 90 days and amber plastic syringes for 14 days. Physical stability was assessed visually, while chemical stability was evaluated using a stability-indicating high-performance liquid chromatography method. Chemical derivatization with xanthydrol allowed the retention of hydroxyurea on a reverse-phase column. At least 93.9% and 97.0% of the initial concentration of hydroxyurea remained after 90 days in bottles and 14 days in syringes, respectively. There were no visual changes in formulations over the study period. Changes in pH up to 1.6 units were observed after 90 days of storage and were explained most likely by an ammonium generating degradation pathway. Ammonium was quantified and remained within safe levels in each HU 100 mg/mL oral preparations. Hydroxyurea oral liquids were all stable for 90 days in amber plastic bottles and 14 days in amber plastic syringes.

Pharmacological Induction of Fetal Hemoglobin in β-Thalassemia and Sickle Cell Disease: An Updated Perspective

A significant amount of attention has recently been devoted to the mechanisms involved in hemoglobin (Hb) switching, as it has previously been established that the induction of fetal hemoglobin (HbF) production in significant amounts can reduce the severity of the clinical course in diseases such as β-thalassemia and sickle cell disease (SCD). While the induction of HbF using lentiviral and genome-editing strategies has been made possible, they present limitations. Meanwhile, progress in the use of pharmacologic agents for HbF induction and the identification of novel HbF-inducing strategies has been made possible as a result of a better understanding of γ-globin regulation. In this review, we will provide an update on all current pharmacological inducer agents of HbF in β-thalassemia and SCD in addition to the ongoing research into other novel, and potentially therapeutic, HbF-inducing agents.