Ticagrelor vs placebo for the reduction of vaso-occlusive crises in pediatric sickle cell disease: the HESTIA3 study

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.

Sickle Cell Disease: Current Drug Treatments and Functional Foods with Therapeutic Potential

Sickle cell anemia (SCA), the most common form of sickle cell disease (SCD), is a genetic blood disorder. Red blood cells break down prematurely, causing anemia and often blocking blood vessels, leading to chronic pain, organ damage, and increased infection risk. SCD arises from a single-nucleotide mutation in the β-globin gene, substituting glutamic acid with valine in the β-globin chain. This review examines treatments evaluated through randomized controlled trials for managing SCD, analyzes the potential of functional foods (dietary components with health benefits) as a complementary strategy, and explores the use of bioactive compounds as functional food ingredients. While randomized trials show promise for certain drugs, functional foods enriched with bioactive compounds also hold therapeutic potential. Further research is needed to confirm clinical efficacy, optimal dosages, and specific effects of these compounds on SCD, potentially offering a cost-effective and accessible approach to managing the disease.

The challenge of clinical end points in sickle cell disease

As most patients with sickle cell disease (SCD) do not have access to curative therapies, the availability of drug therapies that can modify disease severity remains highly desirable. Despite an increased understanding of the pathophysiology of SCD, only 4 drugs are approved by the US Food and Drugs Administration. Most drug trials in SCD have involved the use of acute pain episodes as the primary clinical end point. These studies have typically been to prevent or shorten the duration of such episodes. To date, no drug has received regulatory approval for shortening the duration of acute vaso-occlusive complications, likely highlighting the complex pathophysiology of acute pain episodes. Trials to prevent acute pain episodes have largely evaluated those episodes requiring health care use as a surrogate end point. However, with differences in culture and health care practices among countries, health care use may not reliably predict clinically important effects on acute pain episodes. This article discusses issues related to the use of health care use as the primary end point for prevention trials of acute pain episodes and highlights the importance of evaluating patient-reported outcomes as well as other SCD-related complications as outcome measures.

Using disease-modifying therapies in sickle cell disease

As curative therapy using allogeneic hematopoietic stem cell transplantation as well as gene therapy and gene editing remains inaccessible to most patients with sickle cell disease, the availability of drug therapies that are safe, efficacious, and affordable is highly desirable. Increasing progress is being made in developing drug therapies based on our understanding of disease pathophysiology. Four drugs, hydroxyurea, L-glutamine, crizanlizumab, and voxelotor, are currently approved by the US Food and Drug Administration, with multiple others at various stages of testing. With the limited efficacy of individual agents, combinations of agents will likely be required for optimal outcomes.

Therapeutic perspective for children and young adults living with thalassemia and sickle cell disease

Hemoglobinopathies, including thalassemias and sickle cell disease, are the most common monogenic diseases worldwide, with estimated annual births of more than 330,000 affected infants. Hemoglobin disorders account for about 3.4% of deaths in children under 5 years of age. The distribution of these diseases is historically linked to current or previously malaria-endemic regions; however, immigration has led to a worldwide distribution of these diseases, making them a global health problem. During the last decade, new treatment approaches and novel therapies have been proposed, some of which have the potential to change the natural history of these disorders. Indeed, the first erythroid maturation agent, luspatercept, and gene therapy have been approved for beta-thalassemia adult patients. For sickle cell disease, molecules targeting vaso-occlusion and hemoglobin S polymerization include crizanlizumab, which has been approved for patients ≥ 16 years, voxelotor approved for patients ≥ 12 years, and L-glutamine for patients older than 5 years.    Conclusion: We herein present the most recent advances and future perspectives in thalassemia and sickle cell disease treatment, including new drugs, gene therapy, and gene editing, and the current clinical trial status in the pediatric populations. What is Known: • Red blood cell transfusions, iron chelation therapy and hematopoietic stem cell transplantation have been the mainstay of treatment of thalassemia patients for decades. • For sickle cell disease, until 2005, treatment strategies were mostly the same as those for thalassemia, with the option of simple transfusion or exchange transfusion. In 2007, hydroxyurea was approved for patients ≥ 2 years old. What is New: • In 2019, gene therapy with betibeglogene autotemcel (LentiGlobin BB305) was approved for TDT patients ≥ 12 years old non β0/β0 without matched sibling donor. • Starting from 2017 several new drugs, such as L-glutamine (approved only by FDA), crizanlizumab (approved by FDA and EMA for patients ≥ 16 years), and lastly voxelotor (approved by FDA and EMA for patients ≥ 12 years old).

Emerging drug targets for sickle cell disease: shedding light on new knowledge and advances at the molecular level

INTRODUCTION

In sickle cell disease (SCD), a single amino acid substitution at β6 of the hemoglobin (Hb) chain replaces glutamate with valine, forming HbS instead of the normal adult HbA. Loss of a negative charge, and the conformational change in deoxygenated HbS molecules, enables formation of HbS polymers. These not only distort red cell morphology but also have other profound effects so that this simple etiology belies a complex pathogenesis with multiple complications. Although SCD represents a common severe inherited disorder with life-long consequences, approved treatments remain inadequate. Hydroxyurea is currently the most effective, with a handful of newer treatments, but there remains a real need for novel, efficacious therapies.

AREAS COVERED

This review summarizes important early events in pathogenesis to highlight key targets for novel treatments.

EXPERT OPINION

A thorough understanding of early events in pathogenesis closely associated with the presence of HbS is the logical starting point for identification of new targets rather than concentrating on more downstream effects. We discuss ways of reducing HbS levels, reducing the impact of HbS polymers, and of membrane events perturbing cell function, and suggest using the unique permeability of sickle cells to target drugs specifically into those more severely compromised.