Improvement of medical care in a cohort of newborns with sickle-cell disease in North Paris: impact of national guidelines

Stroke without cerebral arteriopathy in sickle cell disease children: causes and treatment

Cerebral arteriopathy (CA) in children with sickle cell disease (SCD) is classically described as chronic stenosis of arteries in the anterior brain circulation, leading to ischemic stroke. Some studies have, however, reported strokes in children with SCD but without CA. In order to better understand the etiology and risk factors of these strokes, we retrospectively analyzed ischemic strokes occurring in a large cohort of children over a 13-year period. Between 2007 and 2020, 25 of 1,500 children with SCD had an ischemic stroke in our center. Among them, 13 (52%) had CA, described as anatomical arterial stenosis, while 12 (48%) did not. Patients with stroke without CA were older than patients with stroke attributed to SCD-CA (9.0 years old vs. 3.6 years old; P=0.008), and more frequently had SC genotype (25% vs. 0%, respectively). Their strokes more frequently involved the posterior circulation, with cerebellar involvement in 42%. Retained stroke etiologies in patients without typical SCD-related CA were reversible cerebral vasoconstriction syndrome, cerebral fat embolism, arterial thrombosis or thromboembolism, hyperviscosity, vasculitis in a context of infectious meningo-encephalitis, and severe hemodynamic failure. No recurrence was observed in the 24 months following stroke, even though 67% of the patients in this group were no longer receiving exchange transfusions. In conclusion, in a cohort of pediatric SCD patients with an efficient stroke screening strategy, half of the ischemic strokes that occurred were related to causes other than CA. They affected a different population of SCD children and systematic long-term transfusion programs may not be necessary in these cases.

Cost-effectiveness of newborn screening for sickle cell disease: a systematic review protocol

OBJECTIVE

The purpose of this systematic review is to assess the cost-effectiveness of targeted/selective newborn screening compared with universal screening for sickle cell disease across various countries and settings.

INTRODUCTION

The incidence of sickle cell disease is a widespread and potentially fatal hematologic disorder that affects thousands of newborns worldwide. The cost of newborn screening creates a burden on households and the economy.

INCLUSION CRITERIA

Studies will be eligible for inclusion in the review if they focus on the cost-effectiveness of newborn screening for sickle cell disease, comparing targeted/selective screening with universal screening.

METHODS

A preliminary search of MEDLINE (PubMed) was undertaken using MeSH terms, such as sickle cell disease, newborn , and economic evaluations . Two reviewers will screen the titles, abstracts, and full text independently against the inclusion criteria. Disagreements will be resolved by discussion or with a third reviewer. To assess methodological quality, the JBI checklist for economic evaluation will be used. Data will be extracted by 2 reviewers using a modified JBI data extraction form. The JBI dominance ranking matrix for economic evaluations will be used to summarize and compare the results. Cost-effectiveness will be measured on the basis of cost per test/case detected, quality-adjusted life years gained, or disability-adjusted life years averted. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) assessment will be conducted to evaluate the certainty of economic evidence, such as use of resources and expenditures, and to incorporate the results into the decision-making process.

REVIEW REGISTRATION

PROSPERO CRD42017057963.

MALDI-MS in first-line screening of newborns for sickle cell disease: results from a prospective study in comparison to HPLC

OBJECTIVES

Newborn screening (NBS) for sickle cell disease (SCD) requires a robust, high-throughput method to detect hemoglobin S (HbS). Screening for SCD is performed by qualitative methods, such as isoelectric focusing (IEF), and both qualitative and quantitative methods such as high performance liquid chromatography (HPLC), capillary electrophoresis (CE), and tandem mass spectrometry (MS/MS). All these methods detect HbS, as well as low-level or absent HbA, and also other variants of hemoglobin. HPLC is considered as a reference method for NBS, because of its high sensitivity and specificity in detecting HbS. NeoSickle®, a fully automated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) platform, combined with automated sample processing, a laboratory information management system and NeoSickle® software for automatic data interpretation, has increased the throughput of SCD testing. The purpose of this study was to compare the performances of NeoSickle® and HPLC.

METHODS

A prospective study was conducted including 9,571 samples from the NBS program to compare MALDI-MS using NeoSickle® with an HPLC method. Correlation between the two methods was studied. For the MALDI-MS method, sensitivity, specificity, NPV, and PPV were calculated.

RESULTS

We found over 99.4 % correlation between the HPLC and MALDI-MS results. NeoSickle® showed 100 % of sensitivity and specificity in detecting SCD syndrome, leading to positive and negative predictive values of 100 %.

CONCLUSIONS

NeoSickle® is adapted to NBS for SCD, and can be used in first-line high-throughput screening to detect HbS, and beta-thalassemia major warning. When HbS is detected, second-line use of another specific method as HPLC is necessary.

Hydroxyurea at escalated dose versus fixed low-dose hydroxyurea in adults with sickle cell disease

Hydroxyurea reduces the frequency of vaso-occlusive complications, increases hemoglobin, and decreases mortality in sickle cell disease (SCD). Although current guidelines recommend escalation to maximum tolerated dose (MTD), the use of fixed low-dose hydroxyurea is common in low-resource countries. We conducted a systematic review and meta-analysis to evaluate the efficacy of escalated doses versus fixed low-dose of hydroxyurea in adults with SCD. Nine studies were included in the quantitative synthesis, four evaluating fixed low-dose and five evaluating escalated doses of hydroxyurea. Average daily doses of hydroxyurea in the fixed low-dose and escalated dose studies were ~10 and 22 mg/kg, respectively. There was no difference in the estimate of vaso-occlusive crisis rate between escalated and fixed low-dose studies (p = .73). The mean difference in hemoglobin from baseline to follow-up was greater for fixed low-dose than escalated dose studies (1.07 g/dL vs. 0.54 g/dL, p = .01). No difference was seen in the mean estimate of fetal hemoglobin. Despite limited eligible studies and substantial heterogeneity of effect between the studies for several outcomes, there appears to be clinical equipoise regarding the most appropriate hydroxyurea dosing regimen in adults with SCD. Controlled studies of hydroxyurea at MTD versus fixed low-dose in adults with SCD are required.

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.

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.

Autonomic and Vascular Responses during Reactive Hyperemia in Healthy Individuals and Patients with Sickle Cell Anemia

Background and Objectives: To compare autonomic and vascular responses during reactive hyperemia (RH) between healthy individuals and patients with sickle cell anemia (SCA). Materials and Methods: Eighteen healthy subjects and 24 SCA patients were subjected to arterial occlusion for 3 min at the lower right limb level. The pulse rate variability (PRV) and pulse wave amplitude were measured through photoplethysmography using the Angiodin^® PD 3000 device, which was placed on the first finger of the lower right limb 2 min before (Basal) and 2 min after the occlusion. Pulse peak intervals were analyzed using time-frequency (wavelet transform) methods for high-frequency (HF: 0.15-0.4) and low-frequency (LF: 0.04-0.15) bands, and the LF/HF ratio was calculated. Results: The pulse wave amplitude was higher in healthy subjects compared to SCA patients, at both baseline and post-occlusion (p < 0.05). Time-frequency analysis showed that the LF/HF peak in response to the post-occlusion RH test was reached earlier in healthy subjects compared to SCA patients. Conclusions: Vasodilatory function, as measured by PPG, was lower in SCA patients compared to healthy subjects. Moreover, a cardiovascular autonomic imbalance was present in SCA patients with high sympathetic and low parasympathetic activity in the basal state and a poor response of the sympathetic nervous system to RH. Early cardiovascular sympathetic activation (10 s) and vasodilatory function in response to RH were impaired in SCA patients.

Knowledge and awareness of sickle cell disease: a cross sectional study amongst unmarried adults in Nigeria's capital city

Sickle cell disease is a genetic disorder characterised by the tendency of haemoglobin to polymerise and deform red blood cells to a sickle or crescent shape; this consequently results in vaso-occlusive condition. A better knowledge and awareness about sickle cell disease amongst the population can help reduce its prevalence. This study aimed at assessing awareness and knowledge of unmarried adults in Nigeria's capital. A cross sectional survey was undertaken amongst unmarried individuals residing in the Federal Capital Territory. Questionnaires were administered to participants using convenience sampling strategy. Data were analysed using Statistical Package for Social Sciences version 25. Descriptive and inferential statistical analyses were carried out. A total of 1423 questionnaires were completed and returned, response rate was 83.71%, male participants were in the majority as indicated by 52% of the sample, and the dominant age group was 21 to 30 years (47.90%). Almost all the study participants (92.50%), have heard about sickle cell disease. Knowledge about sickle cell disease was average, as mean score for all the participants was 9.01 ± 3.18, with a range of 0 to 17. Some misconceptions were observed, for instance some participants believed that bacterial or viral infections could cause sickle cell disease. Male participants had a higher knowledge score compared to females (p < 0.001), and older participants were more knowledgeable about sickle cell disease (p < 0.001). This study identified that knowledge gaps exist about sickle cell disease. Emergent findings can underpin government, policymakers' and stakeholders' contextual strategies to prevent sickle cell through public health enlightenment and other relevant means.

Debating the Future of Sickle Cell Disease Curative Therapy: Haploidentical Hematopoietic Stem Cell Transplantation vs. Gene Therapy

Hematopoietic stem cell transplantation (HSCT) is a well-established curative therapy for patients with sickle cell disease (SCD) when using a human leukocyte antigen (HLA)-matched sibling donor. Most patients with SCD do not have a matched sibling donor, thereby significantly limiting the accessibility of this curative option to most patients. HLA-haploidentical HSCT with post-transplant cyclophosphamide expands the donor pool, with current approaches now demonstrating high overall survival, reduced toxicity, and an effective reduction in acute and chronic graft-vs.-host disease (GvHD). Alternatively, autologous genetic therapies appear promising and have the potential to overcome significant barriers associated with allogeneic HSCT, such as donor availability and GvHD. Here the authors each take a viewpoint and discuss what will be the future of curative options for patients with SCD outside of a matched sibling transplantation, specifically haploidentical HSCT vs. gene therapy.

Long-Term Health Effects of Curative Therapies on Heart, Lungs, and Kidneys for Individuals with Sickle Cell Disease Compared to Those with Hematologic Malignancies

The goal of curing children and adults with sickle cell disease (SCD) is to maximize benefits and minimize intermediate and long-term adverse outcomes so that individuals can live an average life span with a high quality of life. While greater than 2000 individuals with SCD have been treated with curative therapy, systematic studies have not been performed to evaluate the long-term health effects of hematopoietic stem cell transplant (HSCT) in this population. Individuals with SCD suffer progressive heart, lung, and kidney disease prior to curative therapy. In adults, these sequalae are associated with earlier death. In comparison, individuals who undergo HSCT for cancer are heavily pretreated with chemotherapy, resulting in potential acute and chronic heart, lung, and kidney disease. The long-term health effects on the heart, lung, and kidney for children and adults undergoing HSCT for cancer have been extensively investigated. These studies provide the best available data to extrapolate the possible late health effects after curative therapy for SCD. Future research is needed to evaluate whether HSCT abates, stabilizes, or exacerbates heart, lung, kidney, and other diseases in children and adults with SCD receiving myeloablative and non-myeloablative conditioning regimens for curative therapy.

Bringing Sickle Cell Disease Care Closer to Home: Feasibility and Efficacy of a Quality Improvement Initiative at a Community Hospital

Comprehensive care for patients with sickle cell disease has been shown to improve morbidity. However, few studies have focused on community hospitals where the burden of disease is highest. From 2017 to 2019, a series of quality improvement interventions was implemented in Brampton, Toronto, ON, Canada, directed toward pediatric and adult sickle cell disease populations. This included a new adult clinic and education directed at patients and healthcare providers. There were 206 visits from 88 unique patients at the clinic and hydroxyurea (HU) uptake increased from 41.0 to 60.0% over that time (p < 0.001). The annual admission rate by adult patients before and after intervention was 90.0 and 75.0% respectively (p = 0.010). The length of stay of pediatric patients decreased from 3.5 to 2.9 days (p = 0.039). These interventions resulted in significant improvements in acute care utilization and HU use by sickle cell disease patients locally, but larger studies are required to confirm these findings.

[Sickle cell disease, a genetic haemoglobin disease]

Sickle cell disease is the number one genetic disease in France in terms of the number of children diagnosed each year in the neonatal period. Throughout their lives, people with sickle cell disease are likely to develop acute complications that require urgent treatment. Chronic complications are more common amongst adults than in children.

Chronic organ injuries in children with sickle cell disease

Median life expectancy of patients with sickle cell disease has increased to up to 55 years but there are still frequent cases of premature death, mostly in patients with pre-existing organ failure such as pulmonary hypertension, kidney injury, and cerebral vasculopathy. Most organ injuries remain asymptomatic for a long time and can only be detected through early systematic screening. Protocols combining assessment of velocities on transcranial Doppler and regular transfusions in patients with abnormal velocities have been demonstrated to dramatically reduce the risk of stroke. In contrast, no consensus has been reached on systematic screening or therapy for silent cerebral infarcts. The prognostic significance of increased tricuspid regurgitant jet velocity on echocardiography has not yet been identified in children, whereas increased albuminuria is a good predictor of kidney injury. Finally, screening for hip and eye disorder is recommended; however, different countries adopt different screening strategies. Hydroxyurea is probably of potential benefit in preventing chronic organ damage but this requires further study in order to be fully demonstrated. Efficacy and safety of the other new drugs available are also under investigation.

Stroke and stroke prevention in sickle cell anemia in developed and selected developing countries

This comprehensive review provides an insight into the pathophysiology, epidemiology, evaluation, and treatment of sickle cell anemia (SCA)-related stroke in developed and developing countries. Vascular injury, hypercoagulability and vaso-occlusion play a role in the pathophysiology of stroke in SCA. Transcranial Doppler ultrasound (TCD) has lowered the incidence of ischemic stroke from 11% to 1% as TCD identifies children who are at risk for stroke, providing opportunities for interventions to reduce this risk. Whereas blood exchange is indicated in acute stroke, chronic transfusions (either simple or exchange on a monthly basis) are used for primary as well as secondary stroke prevention in developed countries. Children with abnormally high TCD velocities (≥ 200 cm/s) are at high risk of stroke and might benefit from hydroxyurea or hydroxycarbamide (HU) after a period of a successful transition from chronic transfusions. Hematopoietic stem cell transplant presents a cure for SCA. Gene therapy is currently investigated and may be offered to patients with SCA who had a stroke or who are at high risk of stroke if proven efficacious and safe. However, gene therapy is not likely to be implemented in low-income countries due to cost. Alternatively, HU is utilized for primary and secondary stroke prevention in developing countries. Further expansion of TCD implementation should be a priority in those settings.

[Newborn screening for sickle cell disease in France]

Newborn screening (NBS) for sickle cell disease (SCD) in France has allowed the identification of 9,260 children with SCD since 1989, including 583 in 2019. In mainland France, however, SCD screening is targeted to newborns identified at risk of SCD, i.e born from parents originating from countries with a high SCD prevalence. This screening program, combined to prophylactic measures and a well-organized social and health network in France, has demonstrated considerable efficacy in reducing childhood mortality as well as severe infectious, anemic and neurovascular complications in childhood. SCD NBS has additionally allowed the identification of 180,687 heterozygous (AS) children since 1989. The increasing incidence of SCD (1/1,303 new-borns identified in 2019 versus 1/2,089 in 2009) now pleads for universal NBS and strong advocacy regarding SCD, the most frequent disease identified by NBS in France, and a major public health issue.

Feasibility and acceptability of early infant screening for sickle cell disease in Lagos, Nigeria-A pilot study

In Nigeria, about 150000 babies are born annually with sickle cell disease (SCD), and this figure has been estimated to increase by 100% by the year 2050 without effective and sustainable control strategies. Despite the high prevalence, newborn screening for SCD which allows for early prophylactic treatment, education of parents/guardians and comprehensive management is not yet available. This study explored a strategy for screening in early infancy during the first and second immunization visits, determined the prevalence, feasibility and acceptability of early infant screening for SCD and the evaluation of the HemoTypeSC diagnostic test as compared to the high-performance liquid chromatography (HPLC) gold standard. A cross-sectional study was conducted in two selected primary health care centres in Somolu local government area (LGA) in Lagos, Nigeria. Two hundred and ninety-one mother-infant pairs who presented for the first or second immunization visit were consecutively enrolled in the study following written informed consent. The haemoglobin genotype of mother-infant pairs was determined using the HemoTypeSC rapid test kit. Confirmation of the infants’ Hb genotype was done with HPLC. Data were analysed with SPSS version 22. Validity and Predictive value of HemotypeSC rapid screening test were also calculated. Infant screening for SCD was acceptable to 86% of mothers presenting to the immunization clinics. The prevalence of SCD among the infant cohort was 0.8%. The infants diagnosed with SCD were immediately enrolled in the paediatric SCD clinic for disease-specific care. The HemoTypeSC test had 100% sensitivity and specificity for sickle cell disease in early infancy compared to HPLC. This study affirms that it is feasible and acceptable for mothers to implement a SCD screening intervention program in early infancy in Lagos State. The study also demonstrates the utility of the HemotypeSC rapid testing for ease and reduced cost of screening infants for SCD.

Tricuspid regurgitation velocity and other biomarkers of mortality in children, adolescents and young adults with sickle cell disease in the United States: The PUSH study

In the US, mortality in sickle cell disease (SCD) increases after age 18-20 years. Biomarkers of mortality risk can identify patients who need intensive follow-up and early or novel interventions. We prospectively enrolled 510 SCD patients aged 3-20 years into an observational study in 2006-2010 and followed 497 patients for a median of 88 months (range 1-105). We hypothesized that elevated pulmonary artery systolic pressure as reflected in tricuspid regurgitation velocity (TRV) would be associated with mortality. Estimated survival to 18 years was 99% and to 25 years, 94%. Causes of death were known in seven of 10 patients: stroke in four (hemorrhagic two, infarctive one, unspecified one), multiorgan failure one, parvovirus B19 infection one, sudden death one. Baseline TRV ≥2.7 m/second (>2 SD above the mean in age-matched and gender-matched non-SCD controls) was observed in 20.0% of patients who died vs 4.6% of those who survived (P = .012 by the log rank test for equality of survival). The baseline variable most strongly associated with an elevated TRV was a high hemolytic rate. Additional biomarkers associated with mortality were ferritin ≥2000 μg/L (observed in 60% of patients who died vs 7.8% of survivors, P < .001), forced expiratory volume in 1 minute to forced vital capacity ratio (FEV1/FVC) <0.80 (71.4% of patients who died vs 18.8% of survivors, P < .001), and neutrophil count ≥10x10⁹ /L (30.0% of patients who died vs 7.9% of survivors, P = .018). In SCD children, adolescents and young adults, steady-state elevations of TRV, ferritin and neutrophils and a low FEV1/FVC ratio may be biomarkers associated with increased risk of death.

Drug Therapies for the Management of Sickle Cell Disease

Sickle cell disease (SCD) afflicts millions of people worldwide but is referred to as an orphan disease in the United States. Over the past several decades, there has been an increasing understanding of the pathophysiology of SCD and its complications. While most individuals with SCD in resource-rich countries survive into adulthood, the life expectancy of patients with SCD remains substantially shorter than for the general African-American population. SCD can be cured using hematopoietic stem cell transplantation and possibly gene therapy, but these treatment approaches are not available to most patients, the majority of whom reside in low- and middle-income countries. Until relatively recently, only one drug, hydroxyurea, was approved by the US Food and Drug Administration to ameliorate disease severity. Multiple other drugs (L-glutamine, crizanlizumab, and voxelotor) have recently been approved for the treatment of SCD, with several others at various stages of clinical testing. The availability of multiple agents to treat SCD raises questions related to the choice of appropriate drug therapy, combination of multiple agents, and affordability of recently approved products. The enthusiasm for new drug development provides opportunities to involve patients in low- and middle-income nations in the testing of potentially disease-modifying therapies and has the potential to contribute to capacity building in these environments. Demonstration that these agents, alone or in combination, can prevent or decrease end-organ damage would provide additional evidence for the role of drug therapies in improving outcomes in SCD.

Newborn screening for sickle cell disease: an innovative pilot program to improve child survival in Dar es Salaam, Tanzania

BACKGROUND

Sickle cell disease (SCD) is a recognized cause of childhood mortality. Tanzania has the fifth highest incidence of SCD (with an estimated 11 000 SCD annual births) worldwide. Although newborn screening (NBS) for SCD and comprehensive healthcare have been shown to reduce under-5 mortality by up to 94% in high-income countries such as the USA, no country in Africa has maintained NBS for SCD as a national health program. The aims of this program were to establish and evaluate NBS-SCD as a health intervention in Tanzania and to determine the birth prevalence of SCD.

METHODS

Muhimbili University of Health and Allied Sciences conducted NBS for SCD from January 2015 to November 2016. Dried blood spot samples were collected and tested for SCD using isoelectric focusing.

RESULTS

Screening was conducted on 3981 newborns. Thirty-one (0.8%) babies had SCD, 505 (12.6%) had sickle cell trait and 26 (0.7%) had other hemoglobinopathies. Twenty-eight (90.3%) of the 31 newborns with SCD were enrolled for comprehensive healthcare.

CONCLUSIONS

This is the first report on NBS as a health program for SCD in Tanzania. The SCD birth prevalence of 8 per 1000 births is of public health significance. It is therefore important to conduct NBS for SCD with enrollment into a comprehensive care program.

Sickle cell disease: a comprehensive program of care from birth

As more children are appropriately being diagnosed, the burden of sickle cell disease is increasing greatly in Africa and in high-resource countries such as the United States and Europe. Early management is mandatory, but newborn screening is not implemented everywhere. Point-of-care testing devices are increasingly being used in low-resource countries, showing good sensitivity and specificity. Because the diagnosis is often traumatic for the families, the announcement should be made by an experienced person. The development of care networks is urgently required to facilitate daily life by defining the respective functions of nearby and highly specialized health care professionals, who should work in close collaboration. Comprehensive programs targeting the prevention of pneumococcal infections, malaria in infested zones, and stroke may substantially improve patient care. Hydroxyurea is increasingly being used, but whether it should be systematically prescribed in all children is debated, and its access is still limited in many African countries. Yearly checkups should be organized early in life in order to screen and then treat any organ impairment. Enhancing parents' and patients' knowledge and skills is mandatory.

The current state of sickle cell trait: implications for reproductive and genetic counseling

Sickle cell trait (SCT) is unique among the carrier states that are identified during newborn screening. Unlike other heterozygous states for rare recessive diseases, SCT is exceedingly prevalent throughout regions of the world, making sickle cell disease one of the most common monogenetic diseases worldwide. Because of this high frequency, reproductive counseling is of paramount importance. In addition, unlike other carrier states, SCT seems to be a risk factor for several clinical complications, such as extreme exertional injury, chronic kidney disease, and venous thromboembolism. Increasing knowledge about these clinical outcomes can help inform genetic counseling recommendations. Expanding research and clinical efforts are needed to ensure that the promises of modern and precision medicine can be delivered to the millions of SCT carriers and their children.

Evaluation of Outcomes and Quality of Care in Children with Sickle Cell Disease Diagnosed by Newborn Screening: A Real-World Nation-Wide Study in France

This study's objective was to assess, on a national scale, residual risks of death, major disease-related events, and quality of care during the first five years in children diagnosed at birth with sickle cell disease (SCD). Data were retrospectively collected from medical files of all children with SCD born between 2006-2010 in France. Out of 1792 eligible subjects, 1620 patients (71.8% SS or S/beta°-thalassemia -SB°-) had available follow-up data, across 69 centers. Overall probability of survival by five years was 98.9%, with 12/18 deaths related to SCD. Probability of overt stroke by five years in SS/SB° patients was 1.1%, while transcranial Doppler (TCD) was performed in 81% before three years of age. A total of 26 patients had meningitis/septicemia (pneumococcal in eight cases). Prophylactic penicillin was started at a median age of 2.2 months and 87% of children had received appropriate conjugate pneumococcal vaccination at one year. By five years, the probability of survival without SCD-related events was 10.7% for SS/SB° patients. In contrast, hydroxyurea was prescribed in 13.7% and bone marrow transplant performed in nine patients only. In this study, residual risks of severe complications were low, probably resulting from a good national TCD, vaccination, and healthcare system coverage. Nonetheless, burden of disease remained high, stressing the need for disease-modifying or curative therapy.

Current perspectives of sickle cell disease in Nigeria: changing the narratives

Introduction: Sickle cell disease (SCD) is an inherited blood disorder characterized by clinical heterogeneity that may be influenced by environmental factors, ethnicity, race, social and economic factors as well as genetic and epigenetic factors. Areas covered: The present review was carried out to provide a comprehensive assessment of the current burden of SCD and treatments available for persons with SCD in Nigeria with the aim of identifying surveillance and treatment gaps, informing to guide the planning and implementation of better crisis prevention measures for SCD patients and set an agenda for new areas of SCD research in the country. This review assessed medical, biomedical and genetic studies on SCD patients in Nigeria and other endemic countries of the world. Expert opinion: Integration of hydroxyurea therapy into the management of SCD and surveillance via new-born screening (NBS) for early detection and management will improve the survival of persons with SCD in Nigeria. However, it will be important to carry out pilot studies, initiate strategic advocacy initiatives to educate the people about NBS benefits, develop collaborations between potential stakeholders and design sustainable financing scheme.

Results of a multicenter universal newborn screening program for sickle cell disease in Italy: A call to action

BACKGROUND

Sickle cell disease (SCD) is a chronic multisystem disorder requiring comprehensive care that includes newborn screening (NBS) as the first step of care. Italy still lacks a national SCD NBS program and policy on blood disorders. Pilot single-center screening programs and a regional targeted screening have been implemented so far, but more evidence is needed in order to impact health policies.

POPULATION AND METHODS

NBS was offered to parents of newborns in gynecology clinics in Padova and Monza, tertiary care university hospitals in northern Italy. High-performance liquid chromatography (HPLC) was performed as the first test on samples collected on Guthrie cards. Molecular analysis of the beta-globin gene was performed on positive samples.

RESULTS

A total of 5466 newborns were enrolled; for 5439, informed consents were obtained. A similar family origin was seen in the two centers (65% Italians, 9% mixed couples, 26% immigrants). Compared with SCD NBS programs in the United States and Europe, our results show a similar incidence of SCD patients and carriers. All SCD patients had a Sub-Saharan family background; HbS carriers were 15% Caucasians (Italian, Albanians) and 10% from other areas (North Africa-India-South America); carriers of other hemoglobin variants were mainly (47%) from other areas.

CONCLUSIONS

Our results demonstrate the feasibility of a multicentric NBS program for SCD, give information on HbS epidemiology in two Northern Italian Areas, and support previous European recommendation for a universal NBS program for SCD in Italy: a high incidence of patients and carriers has been detected, with a high percentage of Caucasian carriers, impossible to identify in a targeted NBS.

Neurologic complications in children under five years with sickle cell disease

INTRODUCTION

Sickle Cell Disease (SCD) is one of the most common genetic diseases in the world affecting every organ. The major challenge in the medical care of children with SCD is preventing end-organ dysfunction, particularly the brain. Major neurologic complications in children less than five years with SCD include, but are not limited to, Silent cerebral infarct, cerebral sinus thrombosis, epilepsy, reversible encephalopathy syndrome, and ischemic and hemorrhagic stroke. Recurrent headaches and migraine are not rare in children under five years with SCD. This review will focus on the neurologic complications and the description of the modifiable risk factors in children less than 5 years of age with emphasis on differences between high and low resource settings.

AREAS COVERED

Neurologic complications of children under 5 years of age and the modifiable risk factors. The PUBMED database was searched using medical subject headings (MeSH) and keywords for articles regarding neurologic complications in children under 5 years of age.

CONCLUSION

Neurologic complications in children under five years of age with SCD may be more frequent than currently reported, among which Silent cerebral infarct and cognitive impairment are the most common.

Newborn Screening for Sickle Cell Disease in Europe

The history of newborn screening (NBS) for sickle cell disease (SCD) in Europe goes back almost 40 years. However, most European countries have not established it to date. The European screening map is surprisingly heterogenous. The first countries to introduce sickle cell screening on a national scale were France and England. The French West Indies started to screen their newborns for SCD as early as 1983/84. To this day, all countries of the United Kingdom of Great Britain and Northern Ireland have added SCD as a target disease to their NBS programs. The Netherlands, Spain and Malta also have national programs. Belgium screens regionally in the Brussels and Liège regions, Ireland has been running a pilot for many years that has become quasi-official. However, the Belgian and Irish programs are not publicly funded. Italy and Germany have completed several pilot studies but are still in the preparatory phase of national NBS programs for SCD, although both countries have well-established concepts for metabolic and endocrine disorders. This article will give a brief overview of the situation in Europe and put a focus on the programs of the two pioneers of the continent, England and France.

Improving Screening Programmes for Sickle Cell Disorders and Other Haemoglobinopathies in Europe: The Role of Patient Organisations

This discussion paper has been written to show the unique contribution and added value that Patient Organisations can give to the development and improvement of newborn screening programmes for sickle cell disorder (SCD) and other haemoglobinopathies in Europe. As an example, the action of the Sickle Cell Society (SCS) in partnership with statutory organisations in the U.K., such as the National Health Service (NHS) Sickle Cell and Thalassaemia Screening Programme (NHS SCT SP), will be described.

Neonatal Screening for Sickle Cell Disease in Belgium for More than 20 Years: An Experience for Comprehensive Care Improvement

Our previous results reported that compared to sickle cell patients who were not screened at birth, those who benefited from it had a lower incidence of a first bacteremia and a reduced number and days of hospitalizations. In this context, this article reviews the Belgian experience on neonatal screening for sickle cell disease (SCD). It gives an update on the two regional neonatal screening programs for SCD in Belgium and their impact on initiatives to improve clinical care for sickle cell patients. Neonatal screening in Brussels and Liège Regions began in 1994 and 2002, respectively. Compiled results for the 2009 to 2017 period demonstrated a birth prevalence of sickle cell disorder above 1:2000. In parallel, to improve clinical care, (1) a committee of health care providers dedicated to non-malignant hematological diseases has been created within the Belgian Haematology Society; (2) a clinical registry was implemented in 2008 and has been updated in 2018; (3) a plan of action has been proposed to the Belgian national health authority. To date, neonatal screening is not integrated into the respective Belgian regional neonatal screening programs, the ongoing initiatives in Brussels and Liège Regions are not any further funded and better management of the disease through the implementation of specific actions is not yet perceived as a public health priority in Belgium.

The current state of sickle cell trait: implications for reproductive and genetic counseling

Sickle cell trait (SCT) is unique among the carrier states that are identified during newborn screening. Unlike other heterozygous states for rare recessive diseases, SCT is exceedingly prevalent throughout regions of the world, making sickle cell disease one of the most common monogenetic diseases worldwide. Because of this high frequency, reproductive counseling is of paramount importance. In addition, unlike other carrier states, SCT seems to be a risk factor for several clinical complications, such as extreme exertional injury, chronic kidney disease, and venous thromboembolism. Increasing knowledge about these clinical outcomes can help inform genetic counseling recommendations. Expanding research and clinical efforts are needed to ensure that the promises of modern and precision medicine can be delivered to the millions of SCT carriers and their children.

Haploidentical Bone Marrow Transplantation with Post-Transplantation Cyclophosphamide Plus Thiotepa Improves Donor Engraftment in Patients with Sickle Cell Anemia: Results of an International Learning Collaborative

Curative therapy for individuals with severe sickle cell disease (SCD) who lack an HLA-identical sibling donor has been frustratingly elusive. In with the goal of improving engraftment while minimizing transplantation-related morbidity, a multi-institutional learning collaborative was developed in the context of a Phase II clinical trial of nonmyeloablative, related HLA-haploidentical (haplo) bone marrow transplantation (BMT) with post-transplantation cyclophosphamide. All eligible participants had hemoglobin SS, and 89% (16 of 18) had an identifiable donor. The median patient age was 20.9 years (IQR, 12.1 to 26.0 years), and the most common indication for transplantation was overt stroke (in 69%; 11 of 16). In the first 3 patients, the conditioning regimen consisted of antithymocyte globulin, fludarabine, cyclophosphamide, and low-dose total body irradiation. Graft-versus-host disease (GVHD) prophylaxis included post-transplantation cyclophosphamide, mycophenolate mofetil, and sirolimus. Primary graft rejection occurred in 2 of the 3 patients (67%), which triggered the study-stopping rule. To reduce graft rejection risk, thiotepa was added to the conditioning regimen, and then 15 patients (including 2 with previous graft rejection) underwent haplo-BMT with this thiotepa-augmented conditioning regimen. At a median follow-up of 13.3 months (interquartile range [IQR], 3.8 to 23.1 months), 93% (14 of 15) had >95% stable donor engraftment at 6 months, with 100% overall survival. The median time to neutrophil engraftment (>500) was 22 days (IQR, 19 to 27 days), and that for platelet engraftment (>50 x 10^9/L) was 28 days (IQR, 27 days to not reached). Two patients had grade III-IV acute GVHD, 1 patient had mild chronic GVHD, and 86% of patients (6 of 7) were off immunosuppression therapy by 1-year post-transplantation. Our data suggest that haplo-BMT with post-transplantation cyclophosphamide and thiotepa improves donor engraftment without significantly increasing morbidity or mortality and could dramatically expand curative options for individuals with SCD.

Prognostic factors of disease severity in infants with sickle cell anemia: A comprehensive longitudinal cohort study

In order to identify very early prognostic factors that can provide insights into subsequent clinical complications, we performed a comprehensive longitudinal multi-center cohort study on 57 infants with sickle cell anemia (55 SS; 2 Sβ°) during the first 2 years of life (ClinicalTrials.gov: NCT01207037). Time to first occurrence of a severe clinical event-acute splenic sequestration (ASS), vaso-occlusive (VOC) event requiring hospitalization, transfusion requirement, conditional/ abnormal cerebral velocities, or death-was used as a composite endpoint. Infants were recruited at a mean age of 4.4 ±1 months. Median follow-up was 19.4 months. During the study period, 38.6% of infants experienced ≥1 severe event: 14% ASS, 22.8% ≥ 1 VOC (median age: 13.4 and 12.8 months, respectively) and 33.3% required transfusion. Of note, 77% of the cohort was hospitalized, with febrile illness being the leading cause for admission. Univariate analysis of various biomarkers measured at enrollment showed that fetal hemoglobin (HbF) was the strongest prognostic factor of subsequent severe outcome. Other biomarkers measured at enrolment including absolute neutrophil or reticulocyte counts, expression of erythroid adhesion markers, % of dense red cells, cellular deformability or ϒ-globin genetic variants, failed to be associated with severe clinical outcome. Multivariate analysis demonstrated that higher Hb concentration and HbF level are two independent protective factors (adjusted HRs (95% CI) 0.27 (0.11-0.73) and 0.16 (0.06-0.43), respectively). These findings imply that early measurement of HbF and Hb levels can identify infants at high risk for subsequent severe complications, who might maximally benefit from early disease modifying treatments.

New approach to accurate interpretation of sickle cell disease newborn screening by applying multiple of median cutoffs and ratios

BACKGROUND

The main goal of newborn screening (NBS) for sickle cell disease (SCD) is to detect affected neonates so that specific preventive care can be implemented. High-performance liquid chromatography (HPLC) used for NBS has high sensitivity and specificity, but we lack guidelines for quantitative hemoglobin (Hb) fraction interpretation. The purpose of this study was to determine cutoff values to standardize quantitative interpretation in SCD NBS for different clinical situation such as, red blood cell transfusion or beta-thalassemia, which can be real screening pitfalls.

METHODS

Retrospective study of 75,026 samples from the neonatal screening program analyzed in our laboratory. Precise HbA and HbS percentages at birth were recorded and median values established for each gestational age, allowing percentage results to be expressed in normal gestation-specific multiples of the median (MoM). Three threshold values of clinical interest were determined.

RESULTS

High levels of HbA (>2.5 MoM) allowed identification of newborns who received transfusions. Low levels of HbS (≤0.7 MoM) allowed detection of the association between HbS and other mutations of the beta-globin gene (i.e., HbHope, β0-thalassemia, etc.). An HbA/HbS ratio <0.5 to distinguish healthy carriers from SCD with S/β+-thalassemia. The screening accuracy for each threshold was established. The screening accuracy of low-level HbA, which is determinant in identifying the subgroup of patients at risk of β-thalassemia, will be determined prospectively.

CONCLUSIONS

This new approach introduces tools for a quantitative interpretation in SCD NBS by HPLC methods and could allow standardization of interpretation between centers.

Sickle Cell Clinical Research and Intervention Program (SCCRIP): A lifespan cohort study for sickle cell disease progression from the pediatric stage into adulthood

BACKGROUND

Previous natural history studies have advanced the understanding of sickle cell disease (SCD), but generally have not included sufficient lifespan data or investigation of the role of genetics in clinical outcomes, and have often occurred before the widespread use of disease-modifying therapies, such as hydroxyurea and chronic erythrocyte transfusions. To further advance knowledge of SCD, St. Jude Children's Research Hospital established the Sickle Cell Clinical Research and Intervention Program (SCCRIP), to conduct research in a clinically evaluated cohort of individuals with SCD across their lifetime.

PROCEDURES

Initiated in 2014, the SCCRIP study prospectively recruits patients diagnosed with SCD and includes retrospective and longitudinal collection of clinical, neurocognitive, geospatial, psychosocial, and health outcomes data. Biological samples are banked for future genomics and proteomics studies. The organizational structure of SCCRIP is based upon organ/system-specific working groups and is opened to the research community for partnerships.

RESULTS

As of August 2017, 1,044 (92.3% of eligible) patients with SCD have enrolled in the study (860 children and 184 adults), with 11,915 person-years of observation. Population demographics included mean age at last visit of 11.3 years (range 0.7-30.1), 49.8% females, 57.7% treated with hydroxyurea, 8.5% treated with monthly transfusions, and 62.9% hemoglobin (Hb) SS or HbSB⁰ -thalassemia, 25.7% HbSC, 8.4% HbsB⁺ -Thalassemia, 1.7% HbS/HPFH, and 1.2% other.

CONCLUSIONS

The SCCRIP cohort will provide a rich resource for the conduct of high impact multidisciplinary research in SCD.

Clustering of end-organ disease and earlier mortality in adults with sickle cell disease: A retrospective-prospective cohort study

Chronic end-organ complications result in morbidity and mortality in adults with sickle cell disease (SCD). In a retrospective-prospective cohort of 150 adults with SCD who received standard care screening for pulmonary function abnormalities, cardiac disease, and renal assessment from January 2003 to 2016, we tested the hypothesis that clustering of end-organ disease is common and multiple organ impairment predicts mortality. Any end-organ disease occurred in 59.3% of individuals, and 24.0% developed multiple organ (>1) end-organ disease. The number of end-organs affected was associated with mortality (P ≤ .001); 8.2% (5 of 61) of individuals with no affected end-organ, 9.4% (5 of 53) of those with 1 affected organ, 20.7% (6 of 29) of those with 2 affected end-organs, and 85.7% (6 of 7) with 3 affected end-organs died over a median follow up period of 8.7 (interquartile range 3.5-11.4) years. Of the 22 individuals who died, 77.3% had evidence of any SCD-related end-organ impairment, and this was the primary or secondary cause of death in 45.0%. SCD-related chronic impairment in multiple organs, and its association with mortality, highlights the need to understand the common mechanisms underlying chronic end-organ damage in SCD, and the urgent need to develop interventions to prevent irreversible end-organ complications in SCD.

Advances in new drug therapies for the management of sickle cell disease

Introduction

Sickle cell disease (SCD) is an orphan disease in the United States, but is highly prevalent worldwide. Only two drugs, hydroxyurea and L-glutamine, are approved for this disease. With an improved understanding of the pathophysiology of SCD as well as the success of several recently approved drugs for other orphan diseases, there is an increased interest in the development of drugs for SCD.

Areas covered

This review summarizes published studies of drug therapies and ongoing trials of novel agents.

Expert opinion

The development of drugs with different mechanisms of action offers opportunities for combination and individualized therapy in SCD. In addition to acute pain crisis, the evaluation of other SCD-related complications, exercise capacity, patient reported outcomes and validated surrogate endpoints are necessary to advance drug development. It is important to involve sites in sub-Saharan Africa and India, which have the highest burden of SCD, in trials of novel therapies.

Hydroxyurea prescription, availability and use for children with sickle cell disease in Italy: Results of a National Multicenter survey

BACKGROUND

The number of patients with sickle cell disease (SCD) has increased in Italy in the past decade due to immigration. In spite of the established efficacy of hydroxyurea (HU) in childhood, population-based data regarding its prescription and effectiveness come mainly from studies performed in adults or outside Europe.

POPULATION AND METHODS

The Hydroxyurea in SCD: A Large Nation-wide Cohort Study from Italy was a retrospective cohort study of adult and pediatric patients with SCD attending 32 centers. Pediatric data are analyzed separately.

RESULTS

Out of 504 children followed in 11 centers, 206 (40%) were on HU (194 SS/Sβ°, 12 SC/Sß+); 74% came from Sub-Saharian Africa and 18% from Europe. HU therapy indications for SS/Sβ° patients were as follows: 57% painful vaso-occlusive crisis, acute chest syndrome or both, 24% anemia, 8% anemia, and other reasons (the majority had Hb ≤ 8-8.5 g/dl, revealing scarce acceptance of low Hb values by pediatric hematologist). Mean starting dose was 15.5 mg/kg, and dose at full regimen was 17.1 mg/kg. Mean age at HU therapy was 7.68 years, although it was lower for SS/Sβ° patients. Only 10% started HU before 3 years. In 92%, 500 mg capsule was used; in 6%, the galenic was used; and in 2%, 100 mg tablet was used. Significant reduction of clinical events and inpatients admissions, with improvement in hematological parameters, was observed for SS/Sβ° patients and a trend toward improvement for SC/Sß+ patients was also observed.

CONCLUSIONS

HU effectiveness is demonstrated in a national cohort of children with SCD living in Italy, even at a lower dose than recommended, revealing good adherence to a treatment program by a socially vulnerable group of patients such as immigrants.

[Cerebral vasculopathy in children with sickle cell disease: Key issues and the latest data]

Cerebral vasculopathy is a common and severe complication of sickle cell disease in children. The pathophysiology consists of progressive damage to the basal intracranial arteries and cerebral microcirculation, while chronic anemia worsens exposure to cerebral hypoxia. It results in stroke and subclinical or poorly symptomatic ischemic lesions. Many clinical, biological, and radiological risk factors have been identified. The prevention strategy through systematic transcranial Doppler screening of large-vessel vasculopathy has revolutionized the management of this disease and has greatly decreased the risk of developing stroke. MRI-MRA is a complementary diagnostic tool for anatomical analysis of parenchymal and vascular lesions, which is used for chronic disease monitoring or in the context of an acute neurological event. New exploration opportunities are offered by submandibular Doppler sonography and indirect evaluation methods of cerebral oxygenation and perfusion. If chronic blood transfusion therapy is used to prevent the occurrence and recurrence of cerebral complications of sickle cell disease, only allogeneic hematopoietic stem cell transplantation can safely and definitively stop the transfusion program. It should therefore be proposed early, before irreversible cerebral or vascular lesions occur. Hydroxycarbamide treatment has recently emerged as a potential substitute for chronic transfusions for the maintenance of transcranial Doppler velocities, but only after an initial treatment by transfusions and provided there is close follow-up. In the long run, cerebral vascular damage can cause progressive cognitive impairment and disability, even in children without radiologically identified lesions, indicating the importance of systematic and repeated neuropsychological testing.

Primum non nocere: the case against transplant for children with sickle cell anemia without progressive end-organ disease

This article has a companion Point by Fitzhugh and Walters.

Sickle cell disease

Sickle cell disease is a common and life-threatening haematological disorder that affects millions of people worldwide. Abnormal sickle-shaped erythrocytes disrupt blood flow in small vessels, and this vaso-occlusion leads to distal tissue ischaemia and inflammation, with symptoms defining the acute painful sickle-cell crisis. Repeated sickling and ongoing haemolytic anaemia, even when subclinical, lead to parenchymal injury and chronic organ damage, causing substantial morbidity and early mortality. Currently available treatments are limited to transfusions and hydroxycarbamide, although stem cell transplantation might be a potentially curative therapy. Several new therapeutic options are in development, including gene therapy and gene editing. Recent advances include systematic universal screening for stroke risk, improved management of iron overload using oral chelators and non-invasive MRI measurements, and point-of-care diagnostic devices. Controversies include the role of haemolysis in sickle cell disease pathophysiology, optimal management of pregnancy, and strategies to prevent cerebrovascular disease.

Neonatal screening improves sickle cell disease clinical outcome in Belgium

Objectives

To compare the outcomes of sickle cell disease patients diagnosed through neonatal screening with those who were not.

Methods

In an observational multicenter study in Belgium, 167 screened and 93 unscreened sickle cell disease patients were analyzed for a total of 1116 and 958 patient-years of follow-up, respectively. Both groups were compared with propensity score analysis, with patients matched on three covariates (gender, genotype, and central Africa origin). Bonferroni correction was applied for all comparisons.

Results

Kaplan–Meier estimates of survival without bacteremia were significantly higher in the screened group than the unscreened group (94.47%; [95% CI, 88.64–97.36%] versus 83.78% [95% CI, 72.27–90.42%]), p = 0.032. Non-significant differences between both groups were reported for survival without acute chest syndrome, acute anemia, cerebral complication, severe infection, and vaso-occlusive crisis. Significantly lower hospitalization rate and days per 100 patient-years were observed in the screened compared with the unscreened group (0.27 vs. 0.63 and 1.25 vs. 2.82, p = 0.0006 and <0.0001).

Conclusion

These data confirm the benefit of a neonatal screening programme in reducing bacteremia and hospitalization.

Cyclophosphamide improves engraftment in patients with SCD and severe organ damage who undergo haploidentical PBSCT

Peripheral blood stem cell transplantation (PBSCT) offers a curative option for sickle cell disease (SCD). Although HLA-matched sibling transplantation is promising, the vast majority of patients lack such a donor. We sought to develop a novel nonmyeloablative HLA-haploidentical PBSCT approach that could safely be used for patients with severe organ damage. Based on findings in our preclinical model, we developed a phase 1/2 trial using alemtuzumab, 400 cGy total body irradiation, and escalating doses of posttransplant cyclophosphamide (PT-Cy): 0 mg/kg in cohort 1, 50 mg/kg in cohort 2, and 100 mg/kg in cohort 3. A total of 21 patients with SCD and 2 with β-thalassemia received a transplant. The mean hematopoietic cell transplant-specific comorbidity index of 6 reflected patients with cirrhosis, heart failure, and end-stage renal disease. The engraftment rate improved from 1 (33%) of 3 in cohort 1 to 5 (63%) of 8 in cohort 2 and 10 (83%) of 12 in cohort 3. Percentage of donor myeloid and CD3 chimerism also improved with subsequent cohorts. There was no transplant-related mortality, and overall survival was 87%. At present, 0% in cohort 1, 25% in cohort 2, and 50% in cohort 3 remain free of their disease. There was no grade 2 to 4 acute or extensive chronic graft-versus-host disease (GVHD). Therefore, PT-Cy improves engraftment and successfully prevents severe GVHD after nonmyeloablative conditioning in patients with SCD who are at high risk for early mortality. Additional strategies are necessary to decrease the graft rejection rate and achieve a widely available cure for all patients with SCD. This trial was registered at www.clinicaltrials.gov as #NCT00977691.