Sickle Cell Disease: A Continued Call to Action

Targeted therapeutic management based on phytoconstituents for sickle cell anemia focusing on molecular mechanisms: Current trends and future perspectives

The global epidemic of Sickle cell anemia (SCA) is causing thousands of children to die. SCA, a genetic disorder affecting the hemoglobin-globin chain, affects millions globally. The primary physiological issue in these patients is the polymerization of sickle hemoglobin within their red blood cells (RBCs) during their deoxygenating state. The RBC undergoes a sickle shape due to the polymerization of mutant hemoglobin within it and membrane deformation during anoxic conditions. To prevent complications, it is essential to effectively stop the sickling of RBCs of the patients. Various medications have been studied for treating SCA patients, focusing on antisickling, γ-globulin induction, and antiplatelet action. Natural and synthetic anti-sickling agents can potentially reduce patient clinical morbidity. Numerous clinical trials focused on using natural remedies for the symptomatic therapy of SCA. Medicinal plants and phytochemical agents have antisickling properties. Recent studies on plant extracts' natural compounds have primarily focused on in vitro RBCs sickling studies, with limited data on in vivo studies. This review discussed the potential role of phytoconstituents in the management of SCA.

Updated Recommendations on the Prevention and Treatment of Infections in Children With Asplenia/Hyposplenism

Children with congenital or acquired asplenia or hyposplenism have an increased risk for severe and even life-threatening infections mainly due to encapsulated bacteria. Current practice focuses on preventing severe infections with timely administration of vaccinations, antibacterial prophylaxis when indicated, and urgent evaluation and treatment of febrile events. As new vaccines are now available for both children and adults with asplenia/hyposplenism, we present an up-to-date recommendation on the prevention and management of acute infections in children with asplenia/hyposplenism.

"The project did not come to us with a solution": Perspectives of research teams on implementing a study about electronic health record-embedded individualized pain plans for emergency department treatment of vaso-occlusive episodes in adults with sickle cell disease

BACKGROUND

This study aimed to capture the implementation process of the ALIGN Study, (An individualized Pain Plan with Patient and Provider Access for Emergency Department care of Sickle Cell Disease). ALIGN aimed to embed Individualized Pain Plans in the electronic health record (E-IPP) and provide access to the plan for both adult patients with sickle cell disease (SCD) and emergency department providers when a person with SCD comes to the emergency department in vaso-occlusive crises.

METHODS

Semi-structured interviews were conducted with research teams from the 8 participating sites from the ALIGN study. Seventeen participants (principal investigators and study coordinators) shared their perspectives about the implementation of ALIGN in their sites. Data were analyzed in three phases using open coding steps adapted from grounded theory and qualitative content analysis.

RESULTS

A total of seven overarching themes were identified: (1) the E-IPP structure (location and upkeep) and collaboration with the informatics team, (2) the role of ED champion, (3) the role of research coordinators, (4) research team communication, and communication between research team and clinical team, (5) challenges with the study protocol, (6) provider feedback: addressing over-utilizers, patient mistrust, and the positive feedback about the intervention, and (7) COVID-19 and its effects on study implementation.

CONCLUSIONS

Findings from this study contribute to learning how to implement E-IPPs for adult patients with SCD in ED. The study findings highlight the importance of early engagement with different team members, a champion from the emergency department, study coordinators with different skills and enhancement of communication and trust among team members. Further recommendations are outlined for hospitals aiming to implement E-IPP for patients with SCD in ED.

Economic and Clinical Burden of Managing Sickle Cell Disease with Recurrent Vaso-Occlusive Crises in the United States

INTRODUCTION

The aim of this study was to describe the clinical complications, treatment use, healthcare resource utilization (HCRU), and costs among patients with sickle cell disease (SCD) with recurrent vaso-occlusive crises (VOCs) in the US.

METHODS

Merative MarketScan Databases were used to identify patients with SCD with recurrent VOCs from March 1, 2010, to March 1, 2019. Inclusion criteria were ≥ 1 inpatient or  ≥ 2 outpatient claims for SCD and ≥ 2 VOCs per year in any 2 consecutive years after the first qualifying SCD diagnosis. Individuals without SCD in these databases were used as matched controls. Patients were followed for ≥ 12 months, from their second VOC in the 2nd year (index date) to the earliest of inpatient death, end of continuous enrollment in medical/pharmacy benefits, or March 1, 2020. Outcomes were assessed during follow-up.

RESULTS

In total, 3420 patients with SCD with recurrent VOCs and 16,722 matched controls were identified. Patients with SCD with recurrent VOCs had a mean of 5.0 VOCs (standard deviation [SD] = 6.0), 2.7 inpatient admissions (SD 2.9), and 5.0 emergency department visits (SD 8.0) per patient per year during follow-up. Compared to matched controls, patients with SCD with recurrent VOCs incurred higher annual ($67,282 vs. $4134) and lifetime ($3.8 million vs. $229,000 over 50 years) healthcare costs.

CONCLUSION

Patients with SCD with recurrent VOCs experience substantial clinical and economic burden driven by inpatient costs and frequent VOCs. There is a major unmet need for treatments that alleviate or eliminate clinical complications, including VOCs, and reduce healthcare costs in this patient population.

Design, Synthesis, and Evaluation of Allosteric Effectors for Hemoglobin

ConspectusSickle cell disease (SCD) is an inherited blood disorder caused by a point mutation in hemoglobin (Hb), the protein in the red blood cell (RBC) responsible for the transport of oxygen (O₂) throughout the body. The mutation leads to the expression of sickle cell hemoglobin (HbS). Both Hb and HbS exist in equilibrium between oxygenated and deoxygenated forms; however, deoxygenated HbS can polymerize to form long fibers which distort the shape of RBCs into the characteristic sickled shape. The misshapen RBCs can obstruct blood vessels and capillaries, resulting in a vaso-occlusive crisis. Vaso-occulsion deprives tissues and organs of O₂ and can cause intense pain which often results in hospitalization. Chronic organ damage is a major cause of reduced life expectancy for SCD patients.Allosteric effectors are molecules which regulate protein function. HbS allosteric effectors can be used to decrease polymerization by stabilizing the oxygenated form of HbS, which leads to an increase in O₂ uptake and a decrease in the sickling of RBCs. Allosteric effectors that have been evaluated for the treatment of SCD include vanillin, 5-hydroxymethyl furfural (5-HMF), and voxelotor, which was approved by the U.S. Food and Drug Administration (FDA) for the treatment of SCD in 2019. 5-HMF did not progress to phase III clinical trials since it suffered from rapid metabolic degradation. However, several derivatives of 5-HMF and vanillin have been synthesized and evaluated as potential candidates for SCD treatment. Derivatives of these compounds have shown promise, but their shortcomings, such as high levels of oxidative metabolism, have prevented them from progressing into marketable drugs. Our efforts have produced multiple 5-HMF derivatives which have been evaluated for their potential to treat SCD. Each derivative was evaluated for its ability to increase O₂ affinity (i.e., P₅₀, the partial pressure at which hemoglobin is 50% saturated with O₂). The synthesized aryl ether derivatives were evaluated, and results suggest that compounds with multiple aromatic aldehydes may have enhanced biological properties. One such derivative, compound 5, which features two furan aldehyde rings, exhibited increased O₂ affinity (P₅₀ = 8.82 ± 1.87 mmHg) over that of unmodified Hb (P₅₀ = 13.67 ± 0.22 mmHg). Future studies include obtaining crystal structures of the 5-HMF derivatives complexed with HbS to confirm the protein-allosteric effector interactions.

Allogeneic hematopoietic stem cell transplantation to cure sickle cell disease: A review

Sickle cell disease (SCD) had first been mentioned in the literature a century ago. Advancement in the molecular basis of the pathophysiology of the disease opens the door for various therapeutic options. Though life-extending treatments are available for treating patients with SCD, allogeneic hematopoietic stem cell transplantation (HSCT) is the only option as of yet. A major obstacle before HSCT to cure patients with SCD is the availability of donors. Matched sibling donors are available only for a small percentage of patients. To expand the donor pool, different contrasting approaches of allogeneic HSCT like T-cell replete and deplete have been tested. None of those tested approaches have been without the risk of GvHD and graft rejection. Other limitations such as transplantation-related infections and organ dysfunction caused by the harsh conditioning regimen need to be addressed on a priority basis. In this review, we will discuss available allogeneic HSCT approaches to cure SCD, as well as recent advancements to make the approach safer. The center of interest is using megadose T-cell-depleted bone marrow in conjugation with donor-derived CD8 veto T cells to achieve engraftment and tolerance across MHC barriers, under reduced intensity conditioning (RIC). This approach is in phase I/II clinical trial at the MD Anderson Cancer Centre and is open to patients with hemoglobinopathies.

Evidence-Based Minireview: In young children with severe sickle cell disease, do the benefits of HLA-identical sibling donor HCT outweigh the risks?

In case 1, a 14-month-old male child with sickle cell disease (SCD) was referred for evaluation for an allogeneic hematopoietic stem cell transplant (HCT). The patient had a history of dactylitis 3 times in his first year of life and febrile episodes twice at the consult. His 4-year-old sister was found to be human leukocyte antigen (HLA) identical. The patient was started on hydroxyurea (HU) at 2.5 years of age. His parents again sought consultation when he was 5 years old because of concerns about his medical condition. At the time, the patient had experienced 2 vaso-occlusive pain episodes (VOEs) requiring hospitalization during the previous 2 years. He had also experienced intermittent pain crises requiring rest at home for 2 to 3 days. The child has not attended school in person due to the COVID-19 pandemic. The family is considering HCT but is ambivalent about it because of potential toxicity. In case 2, an 8-year-old female child is 3 years out from HCT for SCD from her HLA-identical sibling. Before HCT, despite receiving HU, she had experienced >5 VOEs requiring hospitalization and 2 episodes of acute chest syndromes in the previous 3 years. She had also been missing almost 50 days of school days each year. After HCT, she is now attending school regularly and participating in all normal age-appropriate activities. The parents believe that HCT has been transformative in their child's life.

Recent Advances in the Treatment of Sickle Cell Disease

Sickle cell anemia (SCA) was first described in the Western literature more than 100 years ago. Elucidation of its molecular basis prompted numerous biochemical and genetic studies that have contributed to a better understanding of its pathophysiology. Unfortunately, the translation of such knowledge into developing treatments has been disproportionately slow and elusive. In the last 10 years, discovery of BCL11A, a major γ-globin gene repressor, has led to a better understanding of the switch from fetal to adult hemoglobin and a resurgence of efforts on exploring pharmacological and genetic/genomic approaches for reactivating fetal hemoglobin as possible therapeutic options. Alongside therapeutic reactivation of fetal hemoglobin, further understanding of stem cell transplantation and mixed chimerism as well as gene editing, and genomics have yielded very encouraging outcomes. Other advances have contributed to the FDA approval of three new medications in 2017 and 2019 for management of sickle cell disease, with several other drugs currently under development. In this review, we will focus on the most important advances in the last decade.

A Growing Population of Older Adults with Sickle Cell Disease

In countries with organized access to health care, survival of patients with sickle cell disease (SCD) has greatly improved, shifting the burden of care from a pediatrician to an internal medicine physician. As a consequence, cumulative disease complications related to chronic vasculopathy are becoming more apparent, adding to organ dysfunction from physiologic aging. The time has come for us to reevaluate the approach to managing the older adult with SCD by putting a greater emphasis on geriatric conditions while proactively considering curative options once previously offered only to younger patients, with comprehensive annual assessments and joint clinics with relevant specialists.

Specifying sickle cell disease interventions: a study protocol of the Sickle Cell Disease Implementation Consortium (SCDIC)

BACKGROUND

Sickle cell disease (SCD) is an inherited blood disorder that results in a lifetime of anemia, severe pain, and end-organ damage that can lead to premature mortality. While the SCD field has made major medical advances, much needs to be done to improve the quality of care for people with SCD. This study capitalizes on the Sickle Cell Disease Implementation Consortium (SCDIC), a consortium of eight academic sites aiming to test implementation strategies that could lead to more accelerated application of the NHLBI guidelines for treating SCD. This report documents the process to support the consortium by specifying the interventions being developed.

METHODS

This study consists of three steps. The Principal Investigator of each site and two site representatives who are knowledgeable of the intervention (e.g., study coordinator or the person delivering the intervention) will answer an online survey aiming to capture components of the interventions. This survey will be completed by the site representatives three times during the study: during the development of the interventions, after one year of the interventions being implemented, and at the end of this study (after 2 years). A site visit and semi-structured interview (Step 2) in the first year of the process will capture the context of the sites. Step 3 comprises of the development of a framework with the details of the multi-component SCDIC interventions at the sites.

DISCUSSION

The outcome of this study, a framework of the SCDIC, will enable accurate replication and extension of published research, facilitating the translation of SCD studies to diverse populations and settings and allowing for theory testing of the effects of the intervention components across studies in different contexts and for different populations.

TRIAL REGISTRATION

ClinicalTrial.Gov (# NCT03380351 ). Registered December 21, 2017.