Sickle Cell Disease: Advances in Treatment

A critical review of therapeutic interventions in sickle cell disease: Progress and challenges

Sickle cell disease (SCD) is an autosomal recessive genetic disorder that occurs due to the point mutation in the β-globin gene, which results in the formation of sickle hemoglobin (HbS) in the red blood cells (RBCs). When HbS is exposed to an oxygen-depleted environment, it polymerizes, resulting in hemolysis, vaso-occlusion pain, and impaired blood flow. Still, there is no affordable cure for this inherited disease. Approved medications held promise but were met with challenges due to limited patient tolerance and undesired side effects, thereby inhibiting their ability to enhance the quality of life across various individuals with SCD. Progress has been made in understanding the pathophysiology of SCD during the past few decades, leading to the discovery of novel targets and therapies. However, there is a compelling need for research to discover medications with improved efficacy and reduced side effects. Also, more clinical investigations on various drug combinations with different mechanisms of action are needed. This review comprehensively presents therapeutic approaches for SCD, including those currently available or under investigation. It covers fundamental aspects of the disease, such as epidemiology and pathophysiology, and provides detailed discussions on various disease-modifying agents. Additionally, expert insights are offered on the future development of pharmacotherapy for SCD.

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.

Discovery of potent DNMT1 inhibitors against sickle cell disease using structural-based virtual screening, MM-GBSA and molecular dynamics simulation-based approaches

Sickle cell disease (SCD) is an autosomal recessive genetic disorder affecting millions of people worldwide. A reversible and selective DNMT1 inhibitor, GSK3482364, has been known to decrease the overall methylation activity of DNMT1, resulting in the increase of HbF levels and percentage of HbF-expressing erythrocytes in an in vitro and in vivo model. In this study, a structure-based virtual screening was done with GSK3685032, a co-crystalized ligand of DNMT1 (PDB ID: 6X9K) with an IC50 value of 0.036 μM and identified 3988 compounds from three databases (ChEMBL, PubChem and Drug Bank). Using this screening method, we identified around 15 compounds with XP docking scores greater than -8 kcal/mol. Further, prime MM-GBSA calculations have been performed and found compound SCHEMBL19716714 with the highest binding free energy of -83.31 kcal/mol. Finally, four compounds were identified based on glide energy and ΔG bind scores that have the most binding with DG7, DG19, DG20 bases and Lys1535, His1507, Trp1510, Ser1230, which were required for the target enzyme inhibition. Furthermore, molecular dynamics simulation studies of top ligands validate the stability of the docked complexes by examining root mean square deviations, root mean square fluctuations, solvent accessible surface area, and radius of gyration graphs from simulation trajectories. These findings suggest that the top four hit compounds may be capable of inhibiting DNMT1 and that additional in vitro and in vivo studies will be essential to prove the clinical effectiveness of the selected lead compounds.Communicated by Ramaswamy H. Sarma.

Quality of Web-Based Sickle Cell Disease Resources for Health Care Transition: Website Content Analysis

Background

Adolescents and young adults with sickle cell disease (SCD) transitioning from pediatric to adult health care face a high-risk period associated with increased use of acute health care services and mortality. Although 59% of American citizens report using the internet for health care information, the quality of web-based, patient-facing resources regarding transition in SCD care has not been evaluated.

Objective

This study aimed to evaluate the quality and readability of web-based health information on SCD, especially as it pertains to the transition to adulthood for inidividuals with SCD. The study also compared the readability and content scores of websites identified in 2018 to those from 2021 to assess any change in quality over time.

Methods

Keywords representing phrases adolescents may use while searching for information on the internet regarding transition in SCD care, including "hydroxyurea" and "SCD transition," were identified. A web-based search using the keywords was conducted in July 2021 using Google, Yahoo, and Bing. The top 20 links from each search were collected. Duplicate websites, academic journals, and websites not related to SCD health care transition were excluded. Websites were categorized based on the source: health department, hospital or private clinician, professional society, and other websites. Websites were assessed using Health On the Net Foundation code of conduct (HONcode), Flesch Reading Ease (FRE), Flesch-Kincaid Grade Level (FGL), Ensuring Quality Information for Patients (EQIP), and a novel SCD content checklist (SCDCC). EQIP and SCDCC scores range from 0- to 100. Each website was reviewed by 2 research assistants and assessed for interrater reliability. Descriptive statistics were calculated.

Results

Of the 900 websites collected, 67 (7.4%) met the inclusion criteria: 13 health department, 7 hospital or private clinician, 33 professional society, and 14 other websites. A total of 15 (22%) out of 67 websites had HONcode certification. Websites with HONcode certification had higher FRE and EQIP scores and lower FGL scores than those without HONcode certification, reflecting greater readability. Websites without HONcode certification had higher SCDCC scores, reflecting greater clinical content. Only 7 (10%) websites met the National Institutes of Health recommendation of a seventh-grade or lower reading level. Based on EQIP scores, 6 (9%) websites were of high quality. The mean SCDCC score was 20.60 (SD 22.14) out of 100. The interrater reliability for EQIP and SCDCC ratings was good (intraclass correlation: 0.718 and 0.897, respectively). No source of website scored significantly higher mean EQIP, FRE, FGL, or SCDCC scores than the others (all P<.05).

Conclusions

Although seeking health care information on the web is very common, the overall quality of information about transition in SCD care on the internet is poor. Changes to current web-based health care information regarding SCD care transitions would benefit transitioning youth by providing expectations, knowledge, skills, and tools to increase self-efficacy.

In Vitro Interaction of Tetrahydrouridine with Key Human Nucleoside Transporters

NDec is a novel combination of oral decitabine and tetrahydrouridine that is currently under clinical development for the treatment of sickle cell disease (SCD). Here, we investigate the potential for the tetrahydrouridine component of NDec to act as an inhibitor or substrate of key concentrative nucleoside transporters (CNT1-3) and equilibrative nucleoside transporters (ENT1-2). Nucleoside transporter inhibition and tetrahydrouridine accumulation assays were performed using Madin-Darby canine kidney strain II (MDCKII) cells overexpressing human CNT1, CNT2, CNT3, ENT1, and ENT2 transporters. Results showed that tetrahydrouridine did not influence CNT- or ENT-mediated uridine/adenosine accumulation in MDCKII cells at the concentrations tested (25 and 250 µM). Accumulation of tetrahydrouridine in MDCKII cells was initially shown to be mediated by CNT3 and ENT2. However, while time- and concentration-dependence experiments showed active accumulation of tetrahydrouridine in CNT3-expressing cells, allowing for estimation of Km (3,140 µM) and Vmax (1,600 pmol/mg protein/min), accumulation of tetrahydrouridine was not observed in ENT2-expressing cells. Potent CNT3 inhibitors are a class of drugs not generally prescribed to patients with SCD, except in certain specific circumstances. These data suggest that NDec can be administered safely with drugs that act as substrates and inhibitors of the nucleoside transporters included in this study.

Evidence-based interventions for reducing sickle cell disease-associated morbidity and mortality in sub-Saharan Africa: A scoping review

Objective

Sickle cell disease is a lifelong illness affecting millions of people globally, but predominantly burdensome in sub-Saharan Africa, where most affected children do not live to adulthood, despite available evidence-based interventions that reduce the disease burden in high-income countries.

Method

We reviewed studies evaluating evidence-based interventions that decrease sickle cell disease-related morbidity and mortality among children living in sub-Saharan Africa. We used the Joanna Briggs scoping review methodological framework and grouped identified evidence-based interventions into preventative pharmacotherapeutic agents, newborn screening and comprehensive healthcare, disease-modifying agents, nutritional supplementation, systemic treatment, supportive agents and patient/carer/population education.

Results

We included 36 studies: 18 randomized controlled trials, 11 observational studies, 5 before-and-after studies and 2 economic evaluation studies, with most of the studies performed in West African countries. Included studies suggest evidence-based interventions effectively to reduce the common morbidities associated with sickle cell disease such as stroke, vaso-occlusive crisis, acute chest syndrome, severe anaemia and malaria infection. Evidence-based interventions also improve survival among study participants. Specifically, our review shows hydroxyurea increases haemoglobin and foetal haemoglobin levels, a finding with practical implications given the challenges with blood transfusion in this setting. The feasibility of implementing individual interventions is hampered by challenges such as affordability, accessibility and the availability of financial and human resources.

Conclusion

Our review suggests that regular use of low-dose hydroxyurea therapy, sulphadoxine-pyrimethamine chemoprophylaxis, L-arginine and Omega-3 fatty acid supplementation and establishment of specialist stand-alone sickle cell clinics could reduce the sickle cell disease-associated morbidity and mortality in sub-Saharan Africa countries.

Therapeutic Antibodies in Medicine

Antibody engineering has developed into a wide-reaching field, impacting a multitude of industries, most notably healthcare and diagnostics. The seminal work on developing the first monoclonal antibody four decades ago has witnessed exponential growth in the last 10-15 years, where regulators have approved monoclonal antibodies as therapeutics and for several diagnostic applications, including the remarkable attention it garnered during the pandemic. In recent years, antibodies have become the fastest-growing class of biological drugs approved for the treatment of a wide range of diseases, from cancer to autoimmune conditions. This review discusses the field of therapeutic antibodies as it stands today. It summarizes and outlines the clinical relevance and application of therapeutic antibodies in treating a landscape of diseases in different disciplines of medicine. It discusses the nomenclature, various approaches to antibody therapies, and the evolution of antibody therapeutics. It also discusses the risk profile and adverse immune reactions associated with the antibodies and sheds light on future applications and perspectives in antibody drug discovery.

Pharmacokinetics and pharmacodynamics of an oral formulation of decitabine and tetrahydrouridine

BACKGROUND

Sickle cell disease (SCD) is caused by an inherited structural abnormality of adult hemoglobin causing polymerization. Fetal hemoglobin interferes with polymerization but is epigenetically silenced by DNA methyltransferase 1 (DNMT1) in adult erythropoiesis. Decitabine depletes DNMT1 and increases fetal and total hemoglobin in SCD patients, but is rapidly catabolized by cytidine deaminase (CDA) in vivo. Tetrahydrouridine (THU) inhibits CDA, safeguarding decitabine.

METHODS

The pharmacokinetics and pharmacodynamics of three oral combination formulations of THU and decitabine, with different coatings producing different delays in decitabine release, were investigated in healthy participants.

RESULTS

Tetrahydrouridine and decitabine were rapidly absorbed into the systemic circulation after a single combination oral dose, with relative bioavailability of decitabine ≥74% in fasted males compared with separate oral administration of THU followed by decitabine 1 h later. THU and decitabine Cmax and area under the plasma concentration versus time curve were higher in females versus males, and fasted versus fed states. Despite sex and food effect on pharmacokinetics, the pharmacodynamic effect of DNMT1 downregulation was comparable in males and females and fasted and fed states. Treatments were well tolerated.

CONCLUSION

Combination oral formulations of THU with decitabine produced pharmacokinetics and pharmacodynamics suitable for oral DNMT1-targeted therapy.

Hospitalizations among children with sickle cell disease enrolled in the Kumasi Sickle Cell Pan African Consortium (SPARCo) database: A cross sectional study

Background and Aims

Sickle cell disease (SCD) is the commonest monogenic haemolytic disorder in Africa. Despite strides made in its management, a significant proportion of patients are hospitalized from the various complications of the disease. This study set out to describe the main causes and outcomes of hospitalizations among pediatric patients with SCD.

Methods

A cross-sectional study was conducted at the Pediatric Emergency Unit of Komfo Anokye Teaching Hospital within a period of 12 months to recruit pediatric SCD patients. This study looked at causes of admission, length of hospital stay (LOS), and outcome of admission.

Results

Of the 201 SCD patients recruited, 57.2% were males and majority were of SCD-SS phenotype 83.1%. The median age was 6 years. The three leading causes of hospitalization were Vaso-occlusive pain events (VOPE) (39.8%), acute chest syndrome (ACS) (25.9%), and infections (12.4%). Ten (5.0%) of the patients presented with a stroke. High admissions were observed in June (12.4%) and November (16.9%). The median (interquartile range [IQR]) LOS was 6 days (IQR: 4-10). Six (3.0%) of the patients died from complications of the disease during hospitalization.

Conclusion

VOPE, ACS, infections, and acute anaemia from hyperhaemolysis were observed as the most common causes of admissions among SCD patients. A good outcome of discharge was seen in most of the patients that were hospitalized with a median length of stay of 6 days. This study also strengthens the importance of a good SCD database with patient follow-ups for better outcomes in SCD patients.

Cognitive-motor dual-task interference in adults with sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is a genetic disorder that causes physical and cognitive impairment due to hemolysis, painful vaso-occlusion episodes, joint avascular necrosis, and strokes. As individuals with SCD age and develop conditions impacting their physical and cognitive function, their ability to multitask successfully and safely may decline. Cognitive-motor dual-task interference occurs when there is deterioration in one or both tasks while dual-tasking relative to single-tasking. Dual-task assessment (DTA) is a valuable measure of physical and cognitive function; however, there is limited data on DTA in adults with SCD.

RESEARCH QUESTION

Is DTA a feasible and safe method of measuring physical and cognitive function in adults with SCD? What patterns of cognitive-motor interference occur in adults with SCD?

METHODS

We enrolled 40 adults with SCD (mean age 44 years, range 20-71) in a single-center prospective cohort study. We used usual gait speed as the measure of motor performance and verbal fluency (F, A, and S) as the measure of cognitive performance. We measured feasibility as the proportion of consented participants able to complete the DTA. We calculated the relative dual-task effect (DTE %) for each task and identified patterns of dual-task interference.

RESULTS

Most consented participants completed the DTA (91%, 40/44) and there were no adverse events. There were 3 main dual-task interference patterns for the first trial using letter 'A': Motor Interference (53%, n = 21), Mutual Interference (23%, n = 9), and Cognitive-Priority Tradeoff (15%, n = 6). For the second trial using letter 'S', there were two main dual-task interference patterns: Cognitive-Priority Tradeoff (53%, n = 21) and Motor Interference (25%, n = 10).

STATEMENT OF SIGNIFICANCE

DTA was feasible and safe in adults with SCD. We identified specific patterns of cognitive-motor interference. This study supports further evaluation of DTA as a potentially useful tool to measure physical and cognitive function in ambulatory adults with SCD.

A Rare Report of the Coexistence of Sickle Cell Disease, Neurofibromatosis Type 1, and Intracranial Hypertension in a Pediatric Patient

A pediatric female with sickle cell disease (SCD) and neurofibromatosis type 1 was noted to have incidental papilledema, with subsequent workup showing an elevated opening pressure. She was diagnosed with intracranial hypertension and began treatment with acetazolamide. Hydroxyurea was also discontinued. Acetazolamide was tapered off, and hydroxyurea was restarted with no worsening in her ophthalmologic exam. We report this case due to the rare occurrence of all 3 conditions, and while intracranial hypertension has been reported in SCD, the diagnostic workup for papilledema in hemoglobinopathies is not well defined. This case helps delineate the presentation and diagnostic workup of papilledema in SCD.

Crizanlizumab

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are available online to subscribers. Monographs can be customized to meet the needs of a facility. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service, contact Wolters Kluwer customer service at 866-397-3433.

Development of curative therapies for sickle cell disease

Recent advances in managing Sickle Cell Disease (SCD) significantly improved patient survival and quality of life. Disease-modifying drug therapies such as hydroxyurea, L-glutamine, voxelotor, and crizanlizumab reduce pain crises and severe complications. Allogeneic hematopoietic stem cell transplantation using matched-sibling donors is currently the only standard curative option; however, only a small proportion of patients have such donors. Cord blood and haploidentical transplantation with a modified conditioning regimen have expanded the allogeneic donor pool, making the therapy available to more patients. Gene therapy is a promising cure that is currently undergoing clinical trials and different approaches have demonstrated efficacy. Multidisciplinary expertise is needed in developing the best treatment strategy for patients with SCD.

Clinical outcome of pre-operative blood transfusion for sickle cell disease patients in post-operative complications

BACKGROUND

Preoperative blood transfusion for patients with sickle cell disease is a debatable topic and it can be lifesaving. Sickle cell disease patients are at high risk for vaso-occlusive crisis due to the large concentration of sickle hemoglobin (HgbS) in their blood. Despite the current extensive research into this disease, there is still no consensus over whether blood transfusion is a preferable preoperative modality among patients undergoing elective surgical procedures.

METHOD

A retrospective observational study, which enrolled 204 patients with Sickle cell disease who underwent surgery at King Fahad Hospital of the University (KFHU) over the last five years. The primary objective was to determine whether there is evidence that preoperative blood transfusion for SCD patients undergoing surgical procedures will reduce postoperative complications related to SCD.

RESULTS

A total of 204 patients were included, of which 30% had preoperative blood transfusion. Majority of patient 44% had undergone cholecystectomy. On multivariate logistic regression analysis, patients who did not undergo blood transfusion had significantly higher risk to develop post-operative SCD complications (OR=3.07, P value= 0.002). In addition, they had significantly prolonged hospitalization (OR= 2.22, P value= 0.08). In contrast, patients who received blood transfusion had lower risk for developing post-operative SCD related complications (OR=1.87, P value= 0.29), and decrease in the duration of hospitalization by (OR=0.49, P value= 0.045).

CONCLUSION

Our study showed that patients who had not undergo preoperative blood transfusion had higher risk to develop postoperative complications and prolonged hospital stay compared to those who underwent blood transfusion.

Sickle Cell Disease in Bahia, Brazil: The Social Production of Health Policies and Institutional Neglect

A disease is considered neglected when it is not given due priority in health policies despite the social relevance of that disease, either in terms of the number of individuals affected by it or its morbidity or mortality. Although the causes are structural, neglect in health does not occur in a vacuum. In this paper, we explore how sickle cell disease (SCD) is constructed and neglected in Brazil, based on insights from our long-term participatory qualitative research in the state of Bahia. We present five overarching themes relevant to the social production of SCD, and associated health policies in Brazil: (1) The achievements and setbacks to overcome neglect in SCD, (2) Continuity of comprehensive SCD care; (3) Social movements of people with SCD; (4) Biocultural citizenship; and (5) Academic advocacy. We conclude that it is insufficient to merely recognize the health inequities that differentiate white and black populations in Brazil; racism must be understood as both a producer and a reproducer of this process of neglect. We conclude with a set of recommendations for the main SCD stakeholder groups committed to improving the lives of people living with SCD.

Advances in the Management of Sickle Cell Disease: New Concepts and Future Horizons

Sickle cell disease is a chronic and life-limiting disorder. Approximately 100,000 Americans are affected with sickle cell disease with most being African Americans. Newborn screening for sickle cell is available in the United States, leading to early detection and management of the disease beginning in infancy. According to the 2014 National Heart, Lung, and Blood Institute sickle cell disease guidelines, supportive care has been primary management of sickle cell disease, with hydroxyurea being the only FDA-approved, disease-modifying pharmacotherapy available and allogeneic hematopoietic stem cell transplant the only cure. Since 2017, three new disease-modifying therapies have been approved by the FDA: L-glutamine, crizanlizumab, and voxelotor. This review will discuss pertinent trials, dosing, interactions, side effects, access, cost, and their role in sickle cell management.

A Systematic Review on the Management of Transfusion-Related Acute Lung Injury in Transfusion-Dependent Sickle Cell Disease

The onset of respiratory distress and acute lung injury (ALI) following a blood transfusion is known as transfusion-related acute lung injury (TRALI), although its pathophysiology remains unknown. Even though sickle cell disease (SCD) has been studied for more than a century, few therapeutic and management strategies adequately address the emergence of TRALI. TRALI, an immune-mediated transfusion response that can result in life-threatening consequences, is diagnosed based on clinical signs and symptoms. Early detection and treatment increase the chances of survival and, in most cases, result in a complete recovery. Our objective is to provide a firm grasp of the present status of SCD-related TRALI care and therapy.

After exploring multiple databases, this study offers evidence-based guidelines to aid clinicians and other healthcare professionals make decisions concerning transfusion assistance for SCD and the management of transfusion-related complications. Other risk factors for acute lung injury including sepsis aspiration should be ruled out throughout the diagnostic process. Several recent studies have shown that immunotherapy or immunological targets can effectively prevent these complications. Red cell transfusions, red cell antigen matching optimization, and iron chelation can also help reduce negative consequences. It is to be noted that poor clinical outcomes can be avoided by early detection and treatment of hemolytic transfusion reactions. Finally, preventing the onset of TRALI may be the most effective therapeutic strategy for SCD patients who rely on blood transfusions for survival.

Association and Risk Factors of Osteonecrosis of Femoral Head in Sickle Cell Disease: A Systematic Review

OBJECTIVE

The objective was to evaluate the level of evidence about the associated factors and the risk factors of osteonecrosis of femoral head (ONFH) in sickle cell individuals.

METHODS

The review was based on the search and selection of studies available in the electronic databases PubMed, SCIELO, LILACS, BVS. As descriptors, the terms of Medical Subject Headings (MeSH) and Health Sciences Descriptors (DeCS) corresponding to "Osteonecrosis", "Necrosis avascular" and "Aseptic necrosis" and "Femoral head" and "sickle cell disease" and "risk factor" and "predictor".

RESULTS

Among clinical and laboratorial factors the most promising risk factors were the severity of sickle cell disease and acute chest syndrome. As a result, from studies of a moderate level of quality, blood pressure, body weight, previous trauma, haemoglobin to haematocrit ratio (Hb/HCT), and number of hospitalizations can be highlighted. Others, such as genetic markers and male gender, have also been positively associated in lower quality studies.

CONCLUSION

For a better clarification of what the risk factors are for the ONFH, it is necessary to study with populations of different origins, different ages, different profiles of Hb, which present greater methodological rigor and perform a multivariate analysis to control confounding factors. Further study is also needed to understand the genetic determinants of ONFH.

Experiences of African Americans Living With Sickle Cell Disease

Introduction:

About 100,000 individuals in the United States live with sickle cell disease (SCD). Palliative care (PC) can improve symptom management for these individuals. The purpose of the study was to explore (a) the experiences of people living with SCD, and (b) their knowledge and perceptions of PC.

Method:

Using a qualitative, descriptive design, adults with SCD were recruited from a foundation in the southeastern United States. Data included social and SCD-related demographics and audio-recorded, semi-structured focus groups. Analysis took a thematic analysis approach.

Results:

Participants: There were 16 African Americans who participated in the study, 75% of whom were females, and aged 22 to 71 years. Five themes were identified: unique and unpredictable impact of SCD on daily life, the changing experience of SCD over time, stigmatization/marginalization in health care interactions, perceptions of support in managing SCD symptoms/crises, and PC: “What is it?”

Discussion:

Participants lacked PC knowledge. PC should be offered to individuals with SCD as part of comprehensive SCD management.

The burden of sleep disordered breathing in children with sickle cell disease

Children with sickle cell disease (SCD) have an increased risk of sleep disordered breathing (SDB) compared with the general pediatric population. There has been a growing research interest on this field in recent years, yet many questions regarding risk factors and clinical implications of SDB remain unclear. The aim of this review is to provide a concise narrative and systematic synthesis of the available evidence on the epidemiology, clinical presentation, complications, and management, of SDB in children with SCD. An electronic search was conducted on studies published from the 1st of January 2000 to the 31st of December 2020 in PubMed/Medline, Scopus, and Cochrane databases. All studies focusing on SDB in children with SCD aged from 0 to 20 years were included. Studies were eligible for inclusion if available in the English language. A quantitative synthesis of the included studies was performed. Only studies focusing on specific treatment outcomes were included in a meta-analytic process. A total of 190 papers were initially identified. After screening the title and abstract, 112 articles were evaluated for eligibility. At the end of the selection process, 62 studies were included in the analysis. Sleep disordered breathing is associated with worse neurological, neurocognitive, and cardiological outcomes, whereas the association with frequency or severity of vaso-occlusive pain events and acute chest syndrome was not clarified. Therapeutic interventions like adenotonsillectomy or oxygen supplementation may result in a significant increase in mean nocturnal oxygen saturation but effective clinical implications remain still unclear.

Crizanlizumab for the Prevention of Vaso-Occlusive Pain Crises in Sickle Cell Disease

Objective: To review the efficacy and safety of crizanlizumab (Adakveo) in the prevention of vaso-occlusive pain crises in sickle cell disease. Data Sources: An English-language literature search of PubMed, MEDLINE, and Ovid (1946 to January 2021) was completed using the terms crizanlizumab, SEG101, SelG1, and sickle cell disease. Manufacturer prescribing information, article bibliographies, and data from clinicaltrials.gov were incorporated in the reviewed data. Study Selection/Data Extraction: All studies registered on clinicaltrials.gov were incorporated in the reviewed data. Data Synthesis: Crizanlizumab is the first monoclonal antibody approved for sickle cell disease to reduce the frequency of vaso-occlusive crises. One phase 2 clinical trial and a post hoc analysis of the trial have been published. Relevance to Patient Care and Clinical Practice: Crizanlizumab is a monthly intravenous infusion approved by the Food and Drug Administration for patients with sickle cell disease 16 years of age and older to reduce the frequency of vaso-occlusive crises. Conclusion: Crizanlizumab appears to be an efficacious therapy for patients with sickle cell disease to reduce the frequency of vaso-occlusive crises. Concerns include drug cost and administration. Long-term benefits and risks have not been determined.

Applications of CRISPR as a potential therapeutic

Genetic disorders and congenital abnormalities are present in 2-5% of births all over the world and can cause up to 50% of all early childhood deaths. The establishment of sophisticated and controlled techniques for customizing DNA manipulation is significant for the therapeutic role in such disorders and further research on them. One such technique is CRISPR that is significant towards optimizing genome editing and therapies, metabolic fluxes as well as artificial genetic systems. CRISPR-Cas9 is a molecular appliance that is applied in the areas of genetic and protein engineering. The CRISPR-CAS system is an integral element of prokaryotic adaptive immunity that allows prokaryotic cells to identify and kill any foreign DNA. The Gene editing property of CRISPR finds various applications like diagnostics and therapeutics in cancer, neurodegenerative disorders, genetic diseases, blindness, etc. This review discusses applications of CRISPR as a therapeutic in various disorders including several genetic diseases (including sickle cell anemia, blindness, thalassemia, cystic fibrosis, hereditary tyrosinemia type I, duchenne muscular dystrophy, mitochondrial disorders), Cancer, Huntington's disease and viral infections (like HIV, COVID, etc.) along with the prospects concerning them. CRISPR-based therapy is also being researched and defined for COVID-19. The related mechanism of CRISPR has been discussed alongside highlighting challenges involved in therapeutic applications of CRISPR.

The non-coding genome in genetic brain disorders: new targets for therapy?

The non-coding genome, consisting of more than 98% of all genetic information in humans and once judged as ‘Junk DNA’, is increasingly moving into the spotlight in the field of human genetics. Non-coding regulatory elements (NCREs) are crucial to ensure correct spatio-temporal gene expression. Technological advancements have allowed to identify NCREs on a large scale, and mechanistic studies have helped to understand the biological mechanisms underlying their function. It is increasingly becoming clear that genetic alterations of NCREs can cause genetic disorders, including brain diseases. In this review, we concisely discuss mechanisms of gene regulation and how to investigate them, and give examples of non-coding alterations of NCREs that give rise to human brain disorders. The cross-talk between basic and clinical studies enhances the understanding of normal and pathological function of NCREs, allowing better interpretation of already existing and novel data. Improved functional annotation of NCREs will not only benefit diagnostics for patients, but might also lead to novel areas of investigations for targeted therapies, applicable to a wide panel of genetic disorders. The intrinsic complexity and precision of the gene regulation process can be turned to the advantage of highly specific treatments. We further discuss this exciting new field of ‘enhancer therapy’ based on recent examples.

Azithromycin Reduces Markers of Vascular Damage in Pediatric Patients With Sickle Cell Disease

Background

Immunomodulatory effects of macrolides in chronic inflammation are well known. In this study, we tested our hypothesis that azithromycin (AZT) can decrease inflammation in pediatric patients with sickle cell disease (SCD).

Methods

The use of AZT as an anti-inflammatory agent was evaluated in double-blind, placebo-controlled, cross-over study for 8 weeks of treatment with 8 weeks of washout. Blood samples were collected before (PRE) and after (POST) each 8-week treatment period. Repeated measures analysis of variance (ANOVA) with post hoc multiple comparison procedures and Chi-square test were used for statistical analysis of the data. Complete blood count, distribution of the lymphocyte subsets, and plasma levels of markers of vascular damage were analyzed.

Results

A significant decrease in the number of leucocytes and granulocytes was observed in AZT group following treatment. An opposite dynamic was observed in placebo group; numbers of granulocytes significantly increased at POST interval. All markers of vascular damage were reduced in AZT group at POST interval with overall significance (P = 0.026). The most prominent significant changes were observed in levels of myeloid-related protein 8/14 (MRP8/14), lipocalin A (NGAL), matrix metalloproteinases (MMP) 9, and insulin-like growth factor-binding protein (IGFBP) 4. Plasma level of C-reactive protein (CRP) was significantly decreased in AZT group as well.

Conclusions

Data suggested that AZT may be beneficial in management of microvascular injury in SCD.

Quality-by-Design-Based Development of a Voxelotor Self-Nanoemulsifying Drug-Delivery System with Improved Biopharmaceutical Attributes

Low aqueous solubility and poor oral bioavailability are limiting factors in the oral delivery of voxelotor, an antisickling agent. To overcome these limitations, a voxelotor self-nanoemulsifying drug delivery system was developed. Various oils, surfactants, and cosurfactants were screened for their solubilization potential for the drug. The area of nanoemulsification was identified using a ternary phase diagram. An experimental mixture design and a desirability function were applied to select SNEDDSs that contain a maximum amount of lipids and a minimum amount of surfactant, and that possess optimal emulsification properties (i.e., droplet sizes, polydispersity index (PDI), emulsification time, and transmittance percentage). The optimized SNEDDS formulation was evaluated for the self-emulsifying time (32 s), droplet size (35 nm), and zeta potential (−8 mV). In vitro dissolution studies indicated a 3.1-fold improvement in drug solubility from the optimized SNEDDS over pure drug powder. After 60 min of in vitro lipolysis, 88% of the voxelotor loaded in the SNEDDS remained in the aqueous phase. Cytotoxicity evaluation, using Caco-2 cells, indicated the safety of the formulation at 0.9 mg/mL. The transport of the voxelotor SNEDDS across Caco-2 monolayers was significantly enhanced compared to that of the free drug. Compared to the drug suspension, the developed SNEDDS enhanced the oral bioavailability (1.7-fold) of voxelotor in rats. The results suggest that further development of SNEDDSs for the oral delivery of voxelotor is needed.

Prevalence of Stroke in Asian Patients with Sickle Cell Anemia: A Systematic Review and Meta-Analysis

Sickle cell anemia (SCA) is an inherited autosomal recessive disease. It is caused due to point mutation that substitutes glutamate with valine at the sixth amino acid position of the beta chain of hemoglobin molecules leading to the sickling of the red blood cells and decreased structural deformability. Silent cerebral infarcts are the most common neurological complication of SCA, while overt stroke comprises substantial burden in patients with SCA. This meta-analysis aimed to find the pooled prevalence of overt stroke in SCA patients and discuss the importance of screening them. PubMed, Embase, and Google Scholar were the electronic databases used to search the studies. A total of 765 articles were retrieved upon detailed searching in the abovementioned databases. After a series of removing duplicate articles, title and abstract screening, and full-text review, 20 articles were found eligible and included in the study. The total number of participants from all the included studies was 3,956, and pooled prevalence of stroke in patients with sickle cell anemia in Asia was found to be 5% (95% CI: 4%, 6%) with a range from 1 to 41%. Stroke occurrence in sickle cell anemia patients is an emergency complication that needs immediate intervention and management. Because of the high prevalence of stroke in patients with sickle cell anemia, clinicians should focus on its prevention and treatment strategies.

Clinical Features and Outcome of Sickle Cell Disease in a Tertiary Center in Northern Lebanon: A Retrospective Cohort Study in a Local, Hospital-Associated Registry

Sickle cell disease affects more than 30 million people worldwide, including 0.1% of the population in Lebanon. It is characterized by unpredictable and painful vaso-occlusive crises (VOCs) that may lead to serious complications. This study describes the clinical burden of sickle cell disease in a cohort of patients treated at a comprehensive sickle cell disease referral center in Tripoli, Northern Lebanon. Patient demographics, clinical events, treatment, and survival were evaluated from a local, hospital-based registry of 334 sickle cell disease patients treated at the Nini Hospital, Tripoli, Lebanon, between 2009 and 2019. Mean age at sickle cell disease diagnosis and at first clinic visit was 2.9 and 8.5 years, respectively. Pain was the most common clinical event observed among all patients. Over the 10-year follow-up period, 15 (4.5%) patients died. Hydroxyurea (HU) and red blood cell (RBC) transfusions were the most commonly used therapies. One hundred and thirty-one (39.0%) patients were diagnosed with sickle cell disease at the Nini Hospital; the remaining patients were referred to and subsequently followed-up at the Nini Hospital. Eighty-seven (66.0%) Nini Hospital-diagnosed patients experienced a VOC. Seventy-four (85.0%) of these patients with a VOC event required HU during follow-up. Patients with a VOC required more RBC transfusions, cholecystectomy, and splenectomy than non-VOC patients. The high disease burden observed in this population of sickle cell disease patients illustrates a continued, unmet need to both prevent and manage VOC events and other sickle cell disease-associated complications.

Facile L-Glutamine delivery to erythrocytes via DOPC-DPPG mixed liposomes

Sickle cell disease (SCD) is a mortal erythrocyte-based disease which is hard to treat effectively. Development of a treatment method that can prevent deoxygenation of erythrocytes or reduce the oxidative stress of sickle erythrocytes is one of the important issues towards SCD. Among a wide variety of potential drug carriers, liposomes are advantageous and preferable with their easy preparation and biocompatibility. In this study, L-Glutamine (Gln) loaded liposomes were prepared with 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-Dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt (DPPG). Liposomes were characterized via zeta potential, size measurements, differential scanning calorimetry, Fourier Transform Infra-red Spectroscopy and they were visualized via transmission electron microscopy and scanning electron microscopy. Effect of the encapsulated amount of Gln was investigated by encapsulating Gln at three different concentrations (i.e0.20 mM, 40 mM and 60 mM). Drug encapsulation and release studies were implemented with high pressure liquid chromatography (HPLC). The encapsulation efficiency of Gln was determined to be the higher than the ones reported in the literature: 83.6%, 87.1% and 84.9% for 20 mM, 40 mM and 60 mM Gln, respectively. It was found that after 6 hours, liposomes loaded with 60 mM of Gln had released 45.7% of Gln. Optical microscopy images of the erythrocytes after 3 hours of incubation and haemolysis measurements proved that presence of liposomes did not cause any structural changes on the erythrocyte shape. Overall, it was concluded that L-Gln loaded PC/PG liposomes provide promising results in terms of developing a new drug delivery platform for SCD.

Association between pulmonary function and cardiac enzymes in sickle cell disease

BACKGROUND

There is scarcity of data on association between lung function and cardiac markers in patients with sickle cell disease (SCD). Meanwhile, SCD affects multi-organs in any one population. There seem to be an association between reduced pulmonary function with cardiac dysfunction. The current study examined the association between pulomanry function with cardiac markers in patients with SCD.

METHODOLOGY

This was a cross-sectional study with cases and controls. The cases (n=117) were made up of patients with SCD. The control subjects (n=58) were voluntary blood donors without SCD. The cellulose acetate electrophoresis was used to determine the genotypes of the study subjects. Blood samples were collected from all the study subjects for full blood count and measurement of cardiac enzymes. The cardiac enzymes measured were lactate dehydrogenase (LDH) and creatine kinase-myocardial band (CK-MB). Lung function test, using the vitalograph was done on all the study subjects. The Global Lung Initiative criteria were used to categorize lung disease as obstruction, restriction, mixed obstruction/restriction and normal.

RESULTS

The prevalence of elevated CK-MB and LDH among the SCD patients was 76.92% and 9.40% respectively, higher than the non-SCD controls (51.72% and 0% for elevated CK-MB and LDH respectively). Of all the impaired lung function, lung restriction was prevalent in all the study groups (30.77% and 15.52% for SCD patients and non-SCD controls respectively). In the fully adjusted model, reduced FEV1 was associated with nearly 3.5-fold higher odds of elevated CK-MB (odds ratio 3.35, 95% CI 1.26-8.90, p-value 0.015) in individuals with SCD.

CONCLUSION

Reduced FEV₁ which reflects airflow impairments are associated with CK-MB elevations in patients with SCD, suggesting a possible damage to the cardiomyocytes.

In utero Therapy for the Treatment of Sickle Cell Disease: Taking Advantage of the Fetal Immune System

Sickle Cell Disease (SCD) is an autosomal recessive disorder resulting from a β-globin gene missense mutation and is among the most prevalent severe monogenic disorders worldwide. Haematopoietic stem cell transplantation remains the only curative option for the disease, as most management options focus solely on symptom control. Progress in prenatal diagnosis and fetal therapeutic intervention raises the possibility of in utero treatment. SCD can be diagnosed prenatally in high-risk patients using chorionic villus sampling. Among the possible prenatal treatments, in utero stem cell transplantation (IUSCT) shows the most promise. IUSCT is a non-myeloablative, non-immunosuppressive alternative conferring various unique advantages and may also offer safer postnatal management. Fetal immunologic immaturity could allow engraftment of allogeneic cells before fetal immune system maturation, donor-specific tolerance and lifelong chimerism. In this review, we will discuss SCD, screening and current treatments. We will present the therapeutic rationale for IUSCT, examine the early experimental work and initial human experience, as well as consider primary barriers of clinically implementing IUSCT and the promising approaches to address them.

Blood plasma metabolomics of children and adolescents with sickle cell anaemia treated with hydroxycarbamide: a new tool for uncovering biochemical alterations

Sickle cell anaemia (SCA) is a debilitating genetic haemoglobinopathy predominantly affecting the disenfranchised strata of society in Africa and the Americas. The most common pharmacological treatment for this disease is the administration of hydroxycarbamide (HC) for which questions remain regarding its mechanism of action, efficacy and long-term toxicity specifically in paediatric individuals. A multiplatform metabolomics approach was used to assess the metabolome of plasma samples from a population of children and adolescents with SCA with and without HC treatment along with non-SCA individuals. Fifty-three metabolites were identified by ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) and ¹ H nuclear magnetic resonance (NMR) with a predominance of membrane lipids, amino acids and organic acids. The partial least-squares discriminant analysis (PLS-DA) analysis allowed a clear discrimination between the different studied groups, revealing clear effects of the HC treatment in the patients' metabolome including rescue of specific metabolites to control levels. Increased creatine/creatinine levels under HC treatment suggests a possible increase in the arginine pool and increased NO synthesis, supporting existing models for HC action in SCA. The metabolomics results extend the current knowledge on the models for SCA pathophysiology including impairment of Lands' cycle and increased synthesis of sphingosine 1-phosphate. Putative novel biomarkers are suggested.

Measurement of Alcohol-Dependent Physiological Changes in Red Blood Cells Using Resistive Pulse Sensing

Alcohol exposure has been postulated to adversely affect the physiology and function of the red blood cells (RBCs). The global pervasiveness of alcohol abuse, causing health issues and social problems, makes it imperative to resolve the physiological effects of alcohol on RBC physiology. Alcohol consumed recreationally or otherwise almost immediately alters cell physiology in ways that is subtle and still unresolved. In this paper, we introduce a high-resolution device for quantitative electrofluidic measurement of changes in RBC volume upon alcohol exposure. We present an exhaustive calibration of our device using model cells to measure and resolve volume changes down to 0.6 fL. We find an RBC shrinkage of 5.3% at 0.125% ethanol (the legal limit in the United States) and a shrinkage of 18.5% at 0.5% ethanol (the lethal limit) exposure. Further, we also measure the time dependence of cell volume shrinkage (upon alcohol exposure) and then recovery (upon alcohol removal) to quantify shrinkage and recovery of RBC volumes. This work presents the first direct quantification of temporal and concentration-dependent changes in red blood cell volume upon ethanol exposure. Our device presents a universally applicable high-resolution and high-throughput platform to measure changes in cell physiology under native and diseased conditions.

Therapeutic application of Carica papaya leaf extract in the management of human diseases

INTRODUCTION

Papaya (Carica papaya Linn.) belongs to the family Caricaceae and is well known for its therapeutic and nutritional properties all over the world. The different parts of the papaya plant have been used since ancient times for its therapeutic applications. Herein, we aimed to review the anticancer, anti-inflammatory, antidiabetic and antiviral activities of papaya leaf.

METHODS

All information presented in this review article regarding the therapeutic application of Carica papaya leaf extract has been acquired by approaching various electronic databases, including Scopus, Google scholar, Web of science, and PubMed. The keywords Carica papaya, anticancer, anti-inflammatory, immunomodulatory, and phytochemicals were explored until December 2019.

RESULTS

The papaya plant, including fruit, leaf, seed, bark, latex, and their ingredients play a major role in the management of disease progression. Carica papaya leaf contains active components such as alkaloids, glycosides, tannins, saponins, and flavonoids, which are responsible for its medicinal activity. Additionally, the leaf juice of papaya increases the platelet counts in people suffering from dengue fever.

CONCLUSION

The major findings revealed that papaya leaf extract has strong medicinal properties such as antibacterial, antiviral, antitumor, hypoglycaemic and anti-inflammatory activity. Furthermore, clinical trials are needed to explore the medicative potential of papaya leaf. Graphical abstract Graphical abstract showing the medicinal properties of Carica papaya leaf.

Voxelotor: A Hemoglobin S Polymerization Inhibitor for the Treatment of Sickle Cell Disease

Sickle cell disease (SCD) affects millions of people throughout the world. Hemoglobin S (HbS) polymerization is the fundamental cause of SCD pathophysiology, which leads to hemolysis, increased viscosity, and acute vaso-occlusive episodes. Novel agents have been developed to target the pathophysiology of SCD and decrease the frequency of SCD complications. Voxelotor (Oxbryta) is an HbS polymerization inhibitor that is approved by the U.S. Food & Drug Administration for the treatment of SCD in adults and pediatric patients 12 years and older.

Voxelotor: First Approval

Voxelotor (Oxbryta™) is a haemoglobin S polymerization inhibitor that has been developed for the treatment of sickle cell disease. In November 2019, voxelotor received its first global approval in the USA for the treatment of sickle cell disease in adults and paediatric patients aged ≥ 12 years. The drug was granted accelerated approval based on the results of the phase III HOPE trial. Phase III clinical development of voxelotor for sickle cell disease is ongoing worldwide. Voxelotor also has Orphan Drug designation and Priority Medicine status in Europe for the treatment of sickle cell disease. This article summarizes the milestones in the development of voxelotor leading to this first approval as a disease-modifying agent for sickle cell disease.

Post-translational modification as a response to cellular stress induced by hemoglobin oxidation in sickle cell disease

Intracellular oxidative stress and oxidative modification of sickle hemoglobin (HbS) play a role in sickle cell disease (SCD) pathogenesis. Recently, we reported that Hb-dependent oxidative stress induced post-translational modifications (PTMs) of Hb and red blood cell (RBC) membrane proteins of transgenic SCD mice. To identify the mechanistic basis of these protein modifications, we followed in vitro oxidative changes occurring in intracellular Hb obtained from RBCs and RBC-derived microparticles (MPs) from the blood of 23 SCD patients (HbSS) of which 11 were on, and 12, off hydroxyurea (HU) treatment, and 5 ethnic matched controls. We used mass spectrometry-based proteomics to characterize these oxidative PTMs on a cross-sectional group of these patients (n = 4) and a separate subgroup of patients (n = 2) studied prior to initiation and during HU treatment. Collectively, these data indicated that band-3 and its interaction network involved in MPs formation exhibited more protein phosphorylation and ubiquitination in SCD patients than in controls. HU treatment reversed these oxidative PTMs back to level observed in controls. These PTMs were also confirmed using orthogonal immunoprecipitation experiments. Moreover, we observed specific markers reflective of oxidative stress, including irreversible oxidation of βCys93 and ubiquitination of Hb βLys145 (and βLys96). Overall, these studies strongly suggest that extensive erythrocyte membrane protein phosphorylation and ubiquitination are involved in SCD pathogenesis and provide further insight into the multifaceted effects of HU treatment.

[Sickle cell disease]

The term "sickle cell disease" covers a group of genetic blood disorders caused by sickle hemoglobin (HbS) alone or in combination with other variants of the β‑globin locus. Sickle cell disease occurs frequently in sub-Saharan Africa, but is also common in Turkey, Greece, Sicily, the Middle East, India, and the Americas. Polymerization of deoxygenated sickle hemoglobin leads to decreased deformability of red blood cells. These altered erythrocytes can obstruct small blood vessels and cause acute episodes of pain, hemolytic anemia, and organ damage. Complications can vary between the different genotypes and it is important to be aware of the special features of the disease. Hydroxycarbamide has been shown to reduce the morbidity and mortality of patients with sickle cell disease. New drugs and novel treatment approaches such as gene therapy are currently being tested.

Crizanlizumab: First Approval

Crizanlizumab (Adakveo^®; crizanlizumab-tmca) is an intravenously administered monoclonal antibody developed by Novartis Pharmaceuticals for the prevention of vaso-occlusive crises (VOCs) in patients with sickle cell disease. Crizanlizumab binds to P-selectin, thereby blocking its interaction with P-selectin glycoprotein ligand-1. In November 2019, crizanlizumab received its first global approval in the USA, where it is indicated to reduce the frequency of VOCs in adults and paediatric patients aged ≥ 16 years with sickle cell disease. The drug is also under regulatory review in the EU for the prevention of VOCs in patients with sickle cell disease. The use of crizanlizumab (in combination with ruxolitinib) in myelofibrosis is also being evaluated in Australia, Spain, Germany and Hungary. This article summarizes the milestones in the development of crizanlizumab leading to this first approval for the reduction of VOCs in patients with sickle cell disease.

Development of gene editing strategies for human β-globin (HBB) gene mutations

Recent developments in gene editing technology have enabled scientists to modify DNA sequence by using engineered endonucleases. These gene editing tools are promising candidates for clinical applications, especially for treatment of inherited disorders like sickle cell disease (SCD). SCD is caused by a point mutation in human β-globin gene (HBB). Clinical strategies have demonstrated substantial success, however there is not any permanent cure for SCD available. CRISPR/Cas9 platform uses a single endonuclease and a single guide RNA (gRNA) to induce sequence-specific DNA double strand break (DSB). When this accompanies a repair template, it allows repairing the mutated gene. In this study, it was aimed to target HBB gene via CRISPR/Cas9 genome editing tool to introduce nucleotide alterations for efficient genome editing and correction of point mutations causing SCD in human cell line, by Homology Directed Repair (HDR). We have achieved to induce target specific nucleotide changes on HBB gene in the locus of mutation causing SCD. The effect of on-target activity of bone fide standard gRNA and newly developed longer gRNA were examined. It is observed that longer gRNA has higher affinity to target DNA while having the same performance for targeting and Cas9 induced DSBs. HDR mechanism was triggered by co-delivery of donor DNA repair templates in circular plasmid form. In conclusion, we have suggested methodological pipeline for efficient targeting with higher affinity to target DNA and generating desired modifications on HBB gene.

Challenges in the Management of Sickle Cell Disease During SARS-CoV-2 Pandemic

The management of sickle cell disease (SCD) and its complications in the COVID-19 era is very challenging. The recurrent sickling process in SCD causes tissue hypoxemia and micro-infarcts, resulting in end organ damage. Since the outbreak of SARS-CoV-2 pandemic, little data has been published about SCD concerning clinical presentation with COVID-19 and management. Hydroxyurea has been the cornerstone of management in children and adults with SCD, with evidence of its effect on controlling end organ damage. There are several anti-sickling drugs that have been approved recently that might have an additive value toward the management of SCD and its complications. The role of simple and exchange transfusions is well established and should always be considered in the management of various complications. The value of convalescent plasma has been demonstrated in small case series, but large randomized controlled studies are still awaited. Immunomodulatory agents may play a role in reducing the damaging effects of cytokines storm that contributes to the morbidity and mortality in advanced cases. Prophylactic anticoagulation should be considered in every management protocol because SCD and COVID-19 are thrombogenic conditions. Management proposals of different presentations of patients with SCD and COVID-19 are outlined.

Emerging drugs in randomized controlled trials for sickle cell disease: are we on the brink of a new era in research and treatment?

Introduction: Sickle cell disease (SCD) is caused by a mutation in the HBB gene which is key for making a component of hemoglobin. The mutation leads to the formation of an abnormal hemoglobin molecule called sickle hemoglobin (HbS). SCD is a chronic, complex disease with a multiplicity of pathophysiological targets; it has high morbidity and mortality.Hydroxyurea has for many years been the only approved drug for SCD; hence, the development of new therapeutics is critical.Areas covered: This article offers an overview of the key studies of new therapeutic options for SCD. We searched the PubMed database and Cochrane Database of Systemic Reviews for agents in early phase clinic trials and preclinical development.Expert opinion: Although knowledge of SCD has progressed, patient survival and quality of life must be improved. Phase II and phase III clinical trials investigating pathophysiology-based novel agents show promising results in the clinical management of SCD acute events. The design of long-term clinical studies is necessary to fully understand the clinical impact of these new therapeutics on the natural history of the disease. Furthermore, the building of global collaborations will enhance the clinical management of SCD and the design of primary outcomes of future clinical trials.

Rational Drug Design of Peptide-Based Therapies for Sickle Cell Disease

Sickle cell disease (SCD) is a group of inherited disorders affecting red blood cells, which is caused by a single mutation that results in substitution of the amino acid valine for glutamic acid in the sixth position of the β-globin chain of hemoglobin. These mutant hemoglobin molecules, called hemoglobin S, can polymerize upon deoxygenation, causing erythrocytes to adopt a sickled form and to suffer hemolysis and vaso-occlusion. Until recently, only two drug therapies for SCD, which do not even fully address the manifestations of SCD, were approved by the United States (US) Food and Drug Administration. A third treatment was newly approved, while a monoclonal antibody preventing vaso-occlusive crises is also now available. The complex nature of SCD manifestations provides multiple critical points where drug discovery efforts can be and have been directed. These notwithstanding, the need for new therapeutic approaches remains high and one of the recent efforts includes developments aimed at inhibiting the polymerization of hemoglobin S. This review focuses on anti-sickling approaches using peptide-based inhibitors, ranging from individual amino acid dipeptides investigated 30-40 years ago up to more promising 12- and 15-mers under consideration in recent years.

Emerging point-of-care technologies for sickle cell disease diagnostics

Sickle cell disease (SCD) is a serious and life-threatening disorder. SCD is considered a public health issue affecting 25% of the population in Central and West Africa. Some countries in this region lack the necessary resources to treat and diagnose many diseases including SCD. Current methods for screening SCD are time-consuming and require expensive laboratory equipment and facilities. This leads to an inability to diagnose the disease early. Lack of early diagnosis and treatment can lead to childhood death. The number of childhood deaths is significantly higher in developing countries. There is unmet need to develop novel methods for diagnosing and monitoring SCD that are both cost effective and portable. The point-of-care (POC) platforms provide the cost effectiveness and portability that allows for the potential diagnosis of millions of people in countries with few resources. In this review, we summarized the important features, benefits, limitations and potential of POC devices. We conducted a comprehensive literature analysis to compare the sensitivity and specificity of several POC diagnostics developed for SCD with a focus on their usages in resource limited settings.

To Join Or Not To Join? A Case Of Sickle Cell Clubs, Stigma And Discrimination In Secondary Schools In Butambala District, Uganda

Background

People living with sickle cell face a lot of stigma and discrimination in Uganda. This stigma is as a result of the lack of the general conceptualization of this condition. For students, the stigma is often due to their differences like jaundice, delayed sexual maturation, and physical growth. This makes individuals with SCD targets for teasing and bullying. This study assessed the knowledge and perception among secondary school students in a rural district of Butambala at nine selected schools. The study also evaluated the use of sickle cell clubs as a tool for behavior change towards the associated stigma and discrimination.

Methods

A school-based cross-sectional study design was used to assess knowledge and perception towards sickle cell disease in secondary schools in Butambala district using self-administered questionnaires prior to and after set up of the sickle cell clubs.

Results

Out of the 375 student participants (59.5% female, 40.5% male) the majority (87.5%) were below 18 years; 68% of the respondents did not know that sickle cell is a genetic condition; 87.5% of the respondents highlighted that it is important for people with SCD to attend school; 54.4% of the respondents reported that people with SCD should not be given equal rights, while 56.0% of the respondents noted that people with SCD should not socialize.

Conclusion

It is evident the there is a big gap in sickle cell awareness among secondary school students coupled with a high level of stigma and discrimination. Sickle cell clubs have a positive effect towards behavior change while providing SCD knowledge and information.

Allogenic hematopoietic stem cell transplantation in sickle cell disease

PURPOSE OF REVIEW

Discussing the currently available HSCT options for Hb SS patients highlighting advantages and disadvantages of each modality in the light of recently published data.

RECENT FINDINGS

When MSD is available, myeloablative regimen is the preferred approach for otherwise healthy children whereas the nonmyeloablative (NMA) regimen is of choice for adults as well as children with SCD-associated morbidities. Mixed chimerism is common especially with NMA conditioning and is usually enough for cure. Alternative donor HSCT outcomes are progressively improving especially with posttransplant cyclophosphamide for GVHD prophylaxis.

SUMMARY

Recent studies comparing HSCT and chronic transfusion in Hb SS patients increasingly come in favor of HSCT arm. Advances in HSCT field led to donor pool expansion and better tolerated regimens. It is easier now to tailor a personalized transplantation plan for almost every patient. A successful management plan should be sufficiently comprehensive addressing patients' and families' social and psychological concerns to ensure compliance and improve outcome.

Sickle Cell Disease-Genetics, Pathophysiology, Clinical Presentation and Treatment

Sickle cell disease (SCD) is a monogenetic disorder due to a single base-pair point mutation in the β-globin gene resulting in the substitution of the amino acid valine for glutamic acid in the β-globin chain. Phenotypic variation in the clinical presentation and disease outcome is a characteristic feature of the disorder. Understanding the pathogenesis and pathophysiology of the disorder is central to the choice of therapeutic development and intervention. In this special edition for newborn screening for haemoglobin disorders, it is pertinent to describe the genetic, pathologic and clinical presentation of sickle cell disease as a prelude to the justification for screening. Through a systematic review of the literature using search terms relating to SCD up till 2019, we identified relevant descriptive publications for inclusion. The scope of this review is mainly an overview of the clinical features of pain, the cardinal symptom in SCD, which present following the drop in foetal haemoglobin as young as five to six months after birth. The relative impact of haemolysis and small-vessel occlusive pathology remains controversial, a combination of features probably contribute to the different pathologies. We also provide an overview of emerging therapies in SCD.