An update review of new therapies in sickle cell disease: the prospects for drug combinations

INTRODUCTION

Sickle cell disease (SCD) is an inherited disorder characterised by polymerisation of deoxygenated haemoglobin S and microvascular obstruction. The cardinal feature is generalised pain referred to as vaso-occlusive crises (VOC), multi-organ damage and premature death. SCD is the most prevalent inherited life-threatening disorders in the world and over 85% of world's 400,000 annual births occur low-and-middle-income countries. Hydroxyurea remained the only approved disease modifying therapy (1998) until the FDA approved L-glutamine (2017), Crizanlizumab and Voxelotor (2019) and gene therapies (Exa-cel and Lovo-cel, 2023).

AREAS COVERED

Clinical trials performed in the last 10 years (November 2013 - November 2023) were selected for the review. They were divided according to the mechanisms of drug action. The following pubmed central search terms [sickle cell disease] or [sickle cell anaemia] Hydroxycarbamide/ Hydroxyurea, L-Glutamine, Voxelotor, Crizanlizumab, Mitapivat, Etavopivat, gene therapy, haematopoietic stem cell transplantation, and combination therapy.

EXPERT OPINION

We recommend future trials of combination therapies for specific complications such as VOCs, chronic pain and renal impairment as well as personalised medicine approach based on phenotype and patient characteristics. Following recent approval of gene therapy for SCD, the challenge is addressing the role of shared decision-making with families, global access and affordability.

Sickle cell disease: embedding patient participation into an international conference can transform the role of lived experience

BACKGROUND

Sickle cell disease (SCD) is an inherited chronic life-threatening disorder with increasing prevalence in Europe. People living with SCD in Europe mainly belong to vulnerable minorities, have a lower level of health education and suffer from isolation compared to those living with other chronic conditions. As a result, SCD patients are much less likely to partner in the design of research related to their condition and are limited in their ability to influence the research agenda. Aiming to increase the influence of patient voice in the development of SCD-related research, we set out to develop patient centered actions in the frame of International Scientific Conferences in collaboration with the ERN-EuroBloodNet, Oxford Blood Group, Annual Sickle Cell Disease and Thalassaemia Conference (ASCAT), the European Hematology Association and the British Society of Hematology.

RESULTS

Two events were organized: a one-day research prioritization workshop and a series of education sessions based on topics chosen by SCD patients and their families. Methodology and outcomes were analyzed in terms of influence on scientific, medical and patient communities.

CONCLUSION

The ERN-EuroBloodNet workshops with patients at annual ASCAT conferences have provided an opportunity to enhance patient experience and empowerment in SCD in Europe, producing benefits for patients, caregivers, patient associations and health professionals. Future work should focus on delivering the research questions identified at this workshop and the opportunities to share information for patient education.

Reliability of different estimated glomerular filtration rate as measures of renal function in children with sickle cell disease

BACKGROUND

There is no reliable marker for detecting early renal disease in early children with sickle cell disease (SCD). Estimation of glomerular filtration rate (eGFR) as derived from the height/plasma creatinine formula is dependent on the accuracy of the creatinine analytical method used. The aim of this study was to evaluate different equations for eGFR.

METHODS

Children aged 5-16 years recruited. mGFR was obtained using plasma disappearance of Inutest/Iohexol, serum creatinine (SCr) was measured either by standard laboratory method or by tandem mass spectrometry (MSMS). Estimated GFR was then calculated either by "Bedside Schwartz method" or by the full-age spectrum (FAS) equation.

FINDINGS

A total of 79 patients (mean age 9.8 ± 4.0 years). A revised eGFR constant was calculated for Schwartz equation from the slope of the plot of height/plasma creatinine versus mGFR. Mean values for mGFR (132.7 ± 32.1 ml/min/1.73m²) and eGFR methods compared: eGFR from standard SCr was significantly higher (144.2 ± 37.3 ml/min/1.73m², p = 0.008). The MSMS eGFR showed the lowest SD (SD = 27.5), while both FAS eGFR and FAS-height eGFR showed the highest correlation coefficient (r = 0.67).

INTERPRETATION

eGFR calculation based on height and SCr determined with MSMS traceable creatinine is more reliable than Schwartz formula using jaffe/enzymatic methods in SCD children.

Paediatric to adult transition care for patients with sickle cell disease: a global perspective

Sickle cell disease is a life-threatening inherited condition designated as a public health priority by WHO. Increased longevity of patients with sickle cell disease in high-income, middle-income, and low-income countries present unprecedented challenges for all settings; however, a globally standardised solution for patient transition from paediatric to adult sickle cell disease health care is unlikely to address the challenges. We established a task force of experts from a multicountry (the USA, Europe, Middle East, and Africa) consortium. We combined themes from the literature with viewpoints from members of the task force and invited experts to provide a global overview of transition care practice, highlighting barriers to effective transition care and provide baseline recommendations that can be adapted to local needs. We highlighted priorities to consider for any young person with sickle cell disease transitioning from paediatric to adult health care: skills transfer, increasing self-efficacy, coordination, knowledge transfer, linking to adult services, and evaluating readiness (the SICKLE recommendations). These recommendations aim to ensure appropriate benchmarking of transition programming, but multisite prospective studies are needed to address this growing public health need.

Geographic Differences in Phenotype and Treatment of Children with Sickle Cell Anemia from the Multinational DOVE Study

Background: DOVE (Determining Effects of Platelet Inhibition on Vaso-Occlusive Events) was a Phase 3, randomized, double-blind, placebo-controlled study conducted in children with sickle cell anemia at 51 sites in 13 countries across four continents. Procedure: Data from DOVE were assessed for regional differences in subject phenotype and treatment. Demographics, baseline clinical and laboratory data, hydroxyurea (HU) use, vaso-occlusive crisis (VOCs; composite endpoint of painful crisis or acute chest syndrome (ACS)), serious adverse events (SAEs), hospitalization, and treatments were compared across the Americas, Europe, North Africa/Middle East, and Sub-Saharan Africa (SSA). Results: Race, body mass index, and blood pressures differed by region. Pre-enrollment VOCs were highest in the Americas. For subjects not on HU, baseline hemoglobin was lowest in SSA; reticulocyte count was lowest in the Americas. Within SSA, Kenya subjects presented higher baseline hemolysis. Painful crisis was the most common SAE, followed by ACS in the Americas and infections in other regions. VOC rate and percentage of VOC hospitalizations were highest in Europe. Regardless of region, most VOCs were treated with analgesics; approximately half were treated with intravenous fluids. The proportion of VOC-related transfusions was greatest in Europe. Lengths of hospital stay were similar across regions. Conclusions: Overall differences in SAEs and hospitalization for VOCs may be due to cultural diversities, resource utilization, disease severity, or a combination of factors. These data are of importance for the planning of future trials in SCA in a multinational setting.

Low-dose hydroxycarbamide therapy may offer similar benefit as maximum tolerated dose for children and young adults with sickle cell disease in low-middle-income settings

The multiple clinical benefits of hydroxycarbamide in sickle cell disease are supported by a large body of evidence. The maximum tolerated dose (MTD) is the regimen recommended by guidelines from a panel of National Heart, Lung, and Blood Institute (NHLBI) experts, but other dosage regimens have been used in babies (BABY-HUG) 9 to 18 months old (20 mg/kg per day) and developing countries such as India (10 mg/kg per day); however, there has been no direct comparison of the efficacy, effectiveness, or cost-effectiveness of these different regimens. The purpose of this review was to investigate the current situation with various hydroxycarbamide regimens with particular relevance to low-middle-income countries. In regard to methodology, a literature review was undertaken by using multiple databases in PubMed and Google and the search terms included sickle cell disease, hydroxyurea, hydroxycarbamide, sickle cell anaemia, low-middle-income countries, Sub-Saharan Africa, and India. Although MTD regimens have been widely used in research, especially within North America, clinical trials elsewhere tend to use fixed-dose regimens. In a survey of haematologists across Europe and Africa, 60% (75% response rate) did not use the MTD regimen for hydroxycarbamide treatment of sickle cell disease. The recommendations are (1) for practical purposes to commence using fixed-dose hydroxycarbamide in line with BABY-HUG recommendations and then (2) to consider or propose a trial comparing MTD escalation with various fixed doses and to include as end points health-related quality of life, haemoglobin F levels, adherence, and cost-effectiveness.