Systemic medications for sickle cell disease and potential applications for sickle cell retinopathy.

PURPOSE OF REVIEW: To review the literature evaluating systemic medications for treatment of sickle cell disease (SCD) and their applications for sickle cell retinopathy. RECENT FINDINGS: Prior studies have demonstrated the efficacy of traditional systemic therapies in reducing the risk of development of sickle cell retinopathy. Since 2017, several new and promising disease-modifying therapies for sickle cell disease have been approved for clinical use, including the first genetic therapies such as exagamglogene autotemcel (exa-cel) and lovotibeglogene autotemcel (lovo-cel). These treatments have shown promising results for systemic management but are not widely utilized due to limited access and high cost. The efficacy of these therapies for the prevention of sickle cell retinopathy remains unknown and opens the door to new avenues for research. Furthermore, the role of systemic therapy for the management of hemoglobin SC (HbSC) disease, which has milder systemic effects but higher likelihood of causing retinopathy, remains poorly understood. SUMMARY: Hydroxyurea has been a mainstay of systemic management of SCD with prior work suggesting its ability to reduce the likelihood of developing retinopathy. There are several new and potentially curative systemic therapies for SCD, though their role in retinopathy prevention and management has not been studied extensively. Future studies are necessary to understand the implications of these emerging therapies for sickle cell retinopathy.

Most adults with severe HbSC disease are not treated with hydroxyurea.

Sickle cell hemoglobin SC (HbSC) disease is the second most frequent sickle cell disease (SCD) genotype after sickle cell anemia (HbSS). Globally, ∼55 000 newborns with HbSC are delivered annually, with the highest HbC gene frequency in West Africa. In Ghana, 40% of adults visiting the Ghana Institute of Clinical Genetics SCD clinic have HbSC. Unlike HbSS, hydroxyurea use is not routinely recommended for individuals with HbSC because of the perceived high-risk to benefit ratio. To test the hypothesis that at least 5% of adults with HbSC will meet the American Society of Hematology criteria for severe disease, we conducted a retrospective descriptive cohort study of all individuals with HbSC (≥18 years) who visited the clinic in 2019. Adults with HbSC aged from 18 to 45 years were selected. We identified a comparison group of 639 individuals with HbSS and matched the frequency based on the age and sex of individuals with HbSC. Severe disease was defined as a history of ≥3 SCD-associated moderate or severe pain episodes per year, history of acute chest syndrome, and severe symptomatic chronic anemia that interferes with daily activities or quality of life. The study end points were the proportion of individuals with SCD who met the definition of severe disease and were eligible for hydroxyurea. In total, 64 of 639 (10.0%) individuals with HbSC met the eligibility criteria for hydroxyurea therapy compared with 154 of 639 (24.1%) individuals with HbSS. Less than 1% and 3% of individuals with severe HbSC and HbSS, respectively, were routinely prescribed with hydroxyurea in this tertiary care medical center.

Sickle cell disease: A distinction of two most frequent genotypes (HbSS and HbSC).

Sickle cell disease (SCD) consists of a group of hemoglobinopathies in which individuals present highly variable clinical manifestations. Sickle cell anemia (SCA) is the most severe form, while SC hemoglobinopathy (HbSC) is thought to be milder. Thus, we investigated the clinical manifestations and laboratory parameters by comparing each SCD genotype. We designed a cross-sectional study including 126 SCA individuals and 55 HbSC individuals in steady-state. Hematological, biochemical and inflammatory characterization was performed as well as investigation of previous history of clinical events. SCA patients exhibited most prominent anemia, hemolysis, leukocytosis and inflammation, whereas HbSC patients had increased lipid determinations. The main cause of hospitalization was pain crises on both genotypes. Vaso-occlusive events and pain crises were associated with hematological, inflammatory and anemia biomarkers on both groups. Cluster analysis reveals hematological, inflammatory, hemolytic, endothelial dysfunction and anemia biomarkers in HbSC disease as well as SCA. The results found herein corroborate with previous studies suggesting that SCA and HbSC, although may be similar from the genetic point of view, exhibit different clinical manifestations and laboratory alterations which are useful to monitor the clinical course of each genotype.

Sequential development of human herpes virus 8-positive diffuse large B-cell lymphoma and chronic myelomonocytic leukemia in a 59 year old female patient with hemoglobin SC disease.

Hematolymphoid neoplasms, including lymphoma and myeloid neoplasms, can occur in patients with sickle cell disease (SCD) or equivalent hemoglobinopathy, but an underlying connection between the two conditions has yet to be fully determined. Herein, we report a unique case of sequential development of two separate hematolymphoid neoplasms, human herpes virus 8 (HHV8)-positive diffuse large B-cell lymphoma (DLBCL) and chronic myelomonocytic leukemia, in a 59 year-old African American female with hemoglobin SC disease. While etiology of immunodeficiency is unknown, the potential causes include hydroxyurea therapy, disease related immunomodulation, chronic inflammation, and relatively old age. The leukemia cells demonstrated profound trilineage dysplasia and harbored complex cytogenetic abnormalities with loss of chromosome 5q and 7q, which are often observed in therapy-related myeloid neoplasms. Besides the potential causes listed above, we propose that myeloid leukemia in this setting may result from genomic changes due to excessive hematopoietic replication triggered by a hemolysis-induced cytokine storm. While myeloid neoplasms in the setting of SCD seems to herald a dismal clinical outcome per the literature, the HHV8-positive DLBCL in our case was apparently indolent, opposing the current perception of its clinical outcome.

Clinical and hematological profile in a newborn cohort with hemoglobin SC / Perfil clínico e hematológico em uma coorte neonatal com hemoglobina SC

Abstract Objectives: Hemoglobin SC is the second most common variant of sickle-cell disease worldwide, after hemoglobin SS. The objectives of the study were to describe the clinical and laboratory characteristics of hemoglobin SC disease in children from a newborn screening program and treated at a blood center. Methodology: This study assessed a cohort of 461 infants born between 01/01/1999 and 12/31/2012 and followed-up until 12/31/2014. Clinical events were expressed as rates for 100 patient-years, with 95% confidence intervals. Kaplan-Meier survival curves were created. Results: The median age of patients was 9.2 years; 47.5% were female. Mean values of blood tests were: hemoglobin, 10.5 g/dL; reticulocytes, 3.4%; white blood cells, 11.24 × 109/L; platelets, 337.1 × 109/L; and fetal hemoglobin, 6.3%. Clinical events: acute splenic sequestration in 14.8%, blood transfusion 23.4%, overt stroke in 0.2%. The incidence of painful vaso-occlusive episodes was 51 (48.9-53.4) per 100 patient-years and that of infections, 62.2 episodes (59.8-64.8) per 100 patient-years. Transcranial Doppler ultrasonography (n = 71) was normal given the current reference values for SS patients. Hydroxyurea was given to ten children, all of whom improvement of painful crises. Retinopathy was observed in 20.3% of 59 children who underwent ophthalmoscopy. Avascular necrosis was detected in seven of 12 patients evaluated, predominantly in the left femur. Echocardiogram compatible with pulmonary hypertension was recorded in 4.6% of 130 children, with an estimated average systolic pulmonary artery pressure of 33.5 mmHg. The mortality rate from all causes was 4.3%. Conclusions: Clinical severity is variable in SC hemoglobinopathy. Several children have severe manifestations similar to those with SS disease.

Resumo Objetivos: A hemoglobinopatia SC é a segunda variante mais comum da doença falciforme no mundo, após a hemoglobinopatia SS. Os objetivos do estudo foram descrever as características clínicas e laboratoriais da hemoglobinopatia SC em recém-nascidos diagnosticados por programa de triagem neonatal e encaminhados para acompanhamento em hemocentro. Metodologia: Coorte de 461 recém-nascidos SC nascidos entre 01/01/1999 e 31/12/2012 e seguidos até 31/12/2014. A incidência de eventos clínicos foi expressa por taxas relativas a 100 pacientes-ano, com limites de confiança a 95%. Curvas de sobrevida foram construídas segundo Kaplan-Meier. Resultados: Mediana de idade, 9,2 anos; 47,5%, feminino. Médias dos valores hematológicos: hemoglobina 10,5 g/dL; reticulócitos 3,4%; leucometria 11,24 x 109/L; plaquetometria 337,1x109/L; hemoglobina fetal 6,3%. Eventos clínicos: sequestro esplênico agudo em 14,8%, hemotransfusão 23,4%, AVC isquêmico 0,2%. A incidência de episódios vaso-oclusivos dolorosos foi de 51 (48,9-53,4) por 100 pacientes-ano; a de infecções, 62,2 episódios (59,8-64,8) por 100 pacientes-ano. Doppler transcraniano (n = 71) foi normal, se usados os valores de referência de crianças SS. Dez pacientes usaram hidroxiureia, todos com melhoria das crises dolorosas. Retinopatia foi observada em 20,3% das 59 crianças que fizeram fundoscopia. Necrose avascular foi detectada em 7 de 12 pacientes avaliados, com predomínio no fêmur esquerdo. Ecocardiograma compatível com hipertensão pulmonar foi registrado em 4,6% de 130 crianças, com média estimada de 33,5 mm Hg de pressão arterial pulmonar. A taxa de mortalidade por todas as causas foi de 4,3%. Conclusões: A hemoglobinopatia SC tem gravidade variável; várias crianças apresentam manifestações clínicas intensas, semelhantes às da hemoglobinopatia SS.

Clinical and hematological profile in a newborn cohort with hemoglobin SC.

OBJECTIVES: Hemoglobin SC is the second most common variant of sickle-cell disease worldwide, after hemoglobin SS. The objectives of the study were to describe the clinical and laboratory characteristics of hemoglobin SC disease in children from a newborn screening program and treated at a blood center. METHODOLOGY: This study assessed a cohort of 461 infants born between 01/01/1999 and 12/31/2012 and followed-up until 12/31/2014. Clinical events were expressed as rates for 100 patient-years, with 95% confidence intervals. Kaplan-Meier survival curves were created. RESULTS: The median age of patients was 9.2 years; 47.5% were female. Mean values of blood tests were: hemoglobin, 10.5g/dL; reticulocytes, 3.4%; white blood cells, 11.24×109/L; platelets, 337.1×109/L; and fetal hemoglobin, 6.3%. Clinical events: acute splenic sequestration in 14.8%, blood transfusion 23.4%, overt stroke in 0.2%. The incidence of painful vaso-occlusive episodes was 51 (48.9-53.4) per 100 patient-years and that of infections, 62.2 episodes (59.8-64.8) per 100 patient-years. Transcranial Doppler ultrasonography (n=71) was normal given the current reference values for SS patients. Hydroxyurea was given to ten children, all of whom improvement of painful crises. Retinopathy was observed in 20.3% of 59 children who underwent ophthalmoscopy. Avascular necrosis was detected in seven of 12 patients evaluated, predominantly in the left femur. Echocardiogram compatible with pulmonary hypertension was recorded in 4.6% of 130 children, with an estimated average systolic pulmonary artery pressure of 33.5mmHg. The mortality rate from all causes was 4.3%. CONCLUSIONS: Clinical severity is variable in SC hemoglobinopathy. Several children have severe manifestations similar to those with SS disease.

Hydroxyurea (hydroxycarbamide) for sickle cell disease.

BACKGROUND: Sickle cell disease (SCD) is one of the most common inherited diseases worldwide. It is associated with lifelong morbidity and a reduced life expectancy. Hydroxyurea (hydroxycarbamide), an oral chemotherapeutic drug, ameliorates some of the clinical problems of SCD, in particular that of pain, by raising fetal haemoglobin. This is an update of a previously published Cochrane Review. OBJECTIVES: To assess the effects of hydroxyurea therapy in people with SCD (all genotypes), of any age, regardless of setting. SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Register, comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also searched online trial registries.Date of the most recent search: 16 January 2017. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials, of one month or longer, comparing hydroxyurea with placebo, standard therapy or other interventions for people with SCD. DATA COLLECTION AND ANALYSIS: Authors independently assessed studies for inclusion, carried out data extraction and assessed the risk of bias. MAIN RESULTS: Seventeen studies were identified in the searches; eight randomised controlled trials were included, recruiting 899 adults and children with SCD (haemoglobin SS (HbSS), haemoglobin SC (HbSC) or haemoglobin Sߺthalassaemia (HbSߺthal) genotypes). Studies lasted from six to 30 months.Four studies (577 adults and children with HbSS or HbSߺthal) compared hydroxyurea to placebo; three recruited individuals with only severe disease and one recruited individuals with all disease severities. There were statistically significant improvements in terms of pain alteration (using measures such as pain crisis frequency, duration, intensity, hospital admissions and opoid use), measures of fetal haemoglobin and neutrophil counts and fewer occurrences of acute chest syndrome and blood transfusions in the hydroxyurea groups. There were no consistent statistically significant differences in terms of quality of life and adverse events (including serious or life-threatening events). Seven deaths occurred during the studies, but the rates by treatment group were not statistically significantly different.Two studies (254 children with HbSS or HbSߺthal also with risk of primary or secondary stroke) compared hydroxyurea and phlebotomy to transfusion and chelation; there were statistically significant improvements in terms of measures of fetal haemoglobin and neutrophil counts, but more occurrences of acute chest syndrome and infections in the hydroxyurea and phlebotomy group. There were no consistent statistically significant differences in terms of pain alteration and adverse events (including serious or life-threatening events). Two deaths occurred during the studies (one in a the hydroxyurea treatment arm and one in the control arm), but the rates by treatment group were not statistically significantly different. In the primary prevention study, no strokes occurred in either treatment group but in the secondary prevention study, seven strokes occurred in the hydroxyurea and phlebotomy group (none in the transfusion and chelation group) and the study was terminated early.The quality of the evidence for the above two comparisons was judged as moderate to low as the studies contributing to these comparisons were mostly large and well designed (and at low risk of bias); however evidence was limited and imprecise for some outcomes such as quality of life, deaths during the studies and adverse events and results are applicable only to individuals with HbSS and HbSߺthal genotypes.Of the remaining two studies, one (22 children with HbSS or HbSߺthal also at risk of stoke) compared hydroxyurea to observation; there were statistically significant improvements in terms of measures of fetal haemoglobin and neutrophil counts but no statistically significant differences in terms of adverse events (including serious or life-threatening events).The final study (44 adults and children with HbSC) compared treatment regimens with and without hydroxyurea - there was statistically significant improvement in terms of measures of fetal haemoglobin, but no statistically significant differences in terms of adverse events (including serious or life-threatening events). No participants died in either of these studies and other outcomes relevant to the review were not reported.The quality of the evidence for the above two comparisons was judged to be very low due to the limited number of participants, the lack of statistical power (as both studies were terminated early with approximately only 20% of their target sample size recruited) and the lack of applicability to all age groups and genotypes. AUTHORS' CONCLUSIONS: There is evidence to suggest that hydroxyurea is effective in decreasing the frequency of pain episodes and other acute complications in adults and children with sickle cell anaemia of HbSS or HbSߺthal genotypes and in preventing life-threatening neurological events in those with sickle cell anaemia at risk of primary stroke by maintaining transcranial doppler velocities. However, there is still insufficient evidence on the long-term benefits of hydroxyurea, particularly in preventing chronic complications of SCD, recommending a standard dose or dose escalation to maximum tolerated dose. There is also insufficient evidence about the long-term risks of hydroxyurea, including its effects on fertility and reproduction. Evidence is also limited on the effects of hydroxyurea on individuals with HbSC genotype. Future studies should be designed to address such uncertainties.

Original Research: Use of hydroxyurea and phlebotomy in pediatric patients with hemoglobin SC disease.

Hydroxyurea is an excellent therapeutic agent for the pharmacological induction of HbF in patients with sickle cell disease (SCD). However, all completed clinical trials of hydroxyurea have excluded patients with hemoglobin SC (HbSC) disease. HbSC differs significantly in pathophysiology from HbSS, as HbC does not sickle, but instead causes cellular dehydration which potentiates sickling of HbS. Many severely affected HbSC patients have been placed on hydroxyurea on a case by case basis, but there are no large scale prospective data on safety or efficacy of hydroxyurea in this subset of patients with SCD. Here, we report a case series of 14 pediatric patients with HbSC treated to maximum tolerated dose (MTD) with hydroxyurea. Those who failed to show clinical improvement after at least six months at MTD were offered phlebotomy in addition to hydroxyurea. Five out of 11 patients with HbSC who achieved MTD failed to demonstrate clinical improvement on hydroxyurea. Of the four placed on dual hydroxyurea and phlebotomy therapy, all showed at least partial clinical improvement. Percent dense red blood cells (%DRBC) were measured via an ADVIA hematology analyzer. A marked rise in percent dense cells preceded clinical complications in three patients. Dual therapy with hydroxyurea and phlebotomy may be an effective approach to patients with HbSC that do not experience improvement with hydroxyurea alone. Monitoring of %DRBC may predict adverse events and aid in assessing hydroxyurea compliance. Large scale clinical trials are needed to evaluate the safety and efficacy of hydroxyurea and hydroxyurea with phlebotomy in patients with HbSC disease.

The impact of sickle cell disease on oral health-related quality of life.

PURPOSE: The purpose of this study was to characterize the impact of sickle cell disease (SCD) on oral health and examine its impact on quality of life. METHODS: Fifty-four study subjects were recruited from the sickle cell clinic and 52 control subjects from the adolescent medicine clinic at Nationwide Children's Hospital, Columbus, Ohio. A dental exam was performed to determine each participant's caries burden. The Child Oral Health Impact Profile survey was used to assess their oral health-related quality of life (OHRQoL). RESULTS: Most subjects in both the SCD and control groups rated their overall health and oral health as "good" or "excellent." There was no statistically significant difference in OHRQoL between these groups. Additionally, no significant relationship was found between white blood cell count, medication intake, or the number of sickle cell crises as related to the caries burden. Statistically significant differences were detected in caries burden between the control group and the sickle cell hemoglobin C disease (HbSC) group (P<.02) and between the sickle cell anemia and HbSC subjects (P=.04). CONCLUSIONS: Adolescents with sickle cell hemoglobin C disease had fewer caries than peers with sickle cell anemia or controls, though the cause of this finding is not clear.

Hydroxyurea treatment of children with hemoglobin SC disease.

The efficacy of hydroxyurea in hemoglobin SC (HbSC) patients is not well documented. We describe the long-term response to hydroxyurea in children with clinically severe HbSC. In 15 patients, hydroxyurea resulted in a significant increase in mean corpuscular volume (MCV) and fetal hemoglobin (HbF) and a significant decrease in episodes of acute chest syndrome and hospitalization for pain; there was no effect on hemoglobin level. The most significant side effect was thrombocytopenia, which led to discontinuation of treatment in one patient. This study suggests that hydroxyurea has efficacy and is safe for long-term therapy in patients with HbSC.

The effects of hydroxycarbamide and magnesium on haemoglobin SC disease: results of the multi-centre CHAMPS trial.

In a phase-II multi-centre double-blinded trial, we evaluated haematological effects of oral hydroxycarbamide (HC) and magnesium (Mg) in patients with HbSC, aged 5-53 years old. Subjects were randomized to HC + placebo, Mg + placebo, HC + Mg, or placebo + placebo. The primary endpoint was the proportion of hyperdense red blood cells after 8 weeks. Thirty-six subjects were evaluable, but the study was terminated early because of slow enrollment. In the combined HC groups, mean cell volume and HbF were increased, but differences were not seen in hyperdense red cells or vaso-occlusive events. Mg had no effects. Further investigation of hydroxycarbamide as monotherapy in HbSC disease is warranted.

Low dose, oral epsilon aminocaproic acid for renal papillary necrosis and massive hemorrhage in hemoglobin SC disease.

Renal papillary necrosis in sickling hemoglobinopathies can lead to significant complications, including hemorrhage, obstruction, and infection. Despite its frequency, there are limited therapies for protracted hemorrhage. In the past, massive hemorrhage was managed with nephrectomy. Here, we report a patient with hemoglobin SC disease and prolonged, life-threatening hemorrhage from papillary necrosis successfully treated with oral, low-dose epsilon aminocaproic acid (EACA). Although further study is warranted, this case illustrates the need to consider EACA in the conservative management of renal papillary necrosis and significant hemorrhage in sickle cell hemoglobinopathies.

Insights into elevated distortion product otoacoustic emissions in sickle cell disease: comparisons of hydroxyurea-treated and non-treated young children.

Distortion product otoacoustic emissions (DPOAEs) were examined in 15 normal-hearing African-American children between the ages of 6 and 14 years with homozygous sickle cell disease (SCD), who were on a regimen of hydroxyurea (HDU), a drug that reduces inflammatory processes and symptoms of SCD; a matched group of 15 African-American children with homozygous SCD not on HDU; and 15 African-American children with normal hemoglobin. DPOAEs were evoked by 13 primary tone pairs with f2 frequencies ranging from 1000 to 4500 Hz. Increased DPOAE amplitudes, believed to be a precursor of eventual hearing loss, were evident in children with SCD who were not receiving HDU. Those taking HDU had DPOAE amplitudes similar to normal controls. These findings suggest that HDU, in addition to reducing symptoms of SCD, may play a role in inhibiting or preventing cochlear pathology and hearing loss in individuals with SCD.

Immunosuppressive therapy for kidney transplant prevents vaso-occlusive crisis in a haemoglobin SC disease patient.

Although the molecular basis of sickle cell disease (SCD) is well established, the wide variability in clinical manifestations still puzzles haematologists and clinicians. Recently, SCD started to be considered by different groups as a chronic inflammatory condition, where the inflammatory tendency of each individual could drive more or less severe clinical features. Here we describe a haemoglobin SC disease patient (heterozygous to both HbS and HbC variants) that experienced several vaso-occlusive crises before underwent a successful kidney transplantation. Since then (16 years ago), she is on uninterruped immunosuppressive therapy, and do not experienced any severe vaso-occlusive crisis. Considering SCD associated morbidity as a result of exacerbated immune responses, we suggest that the immunosuppressive therapy directed to the kidney graft maintenance is actually also helping in the control of the chronic inflammatory responses associated to SCD.

Oral citrulline as arginine precursor may be beneficial in sickle cell disease: early phase two results.

L-Arginine may be a conditionally essential amino acid in children and adolescents with sickle cell disease, particularly as required substrate in the arginine-nitric oxide pathway for endogenous nitrovasodilation and vasoprotection. Vasoprotection by arginine is mediated partly by nitric oxide-induced inhibition of endothelial damage and inhibition of adhesion and activation of leukocytes. Activated leukocytes may trigger many of the complications, including vasoocclusive events and intimal hyperplasias. High blood leukocyte counts during steady states in the absence of infection are significant laboratory risk factors for adverse complications. L-Citrulline as precursor amino acid was given orally twice daily in daily doses of approximately 0.1 g/kg in a pilot Phase II clinical trial during steady states in four homozygous sickle cell disease subjects and one sickle cell-hemoglobin C disease patient (ages 10-18). There soon resulted dramatic improvements in symptoms of well-being, raised plasma arginine levels, and reductions in high total leukocyte and high segmented neutrophil counts toward or to within normal limits. Continued L-citrulline supplementation in compliant subjects continued to lessen symptomatology, to maintain plasma arginine concentrations greater than control levels, and to maintain nearly normal total leukocyte and neutrophil counts. Side effects or toxicity from citrulline were not experienced. Oral L-citrulline may portend very useful for palliative therapy in sickle cell disease. Placebo-controlled, long-term trials are now indicated.

Hydroxyurea therapy for pediatric patients with hemoglobin SC disease.

PURPOSE: Hydroxyurea (HU) has laboratory and clinical efficacy in hemoglobin SS (HbSS) disease, but its benefits in hemoglobin SC (HbSC) disease are unknown. A recent adult HbSC disease pilot trial with HU therapy documented a modest laboratory benefit. Our goal was to evaluate the laboratory and clinical responses of selected pediatric patients with severe HbSC disease to HU therapy. PATIENTS AND METHODS: As part of a retrospective case series, patients were selected from the Duke Pediatric Sickle Cell Program based on the frequency and severity of their vasoocclusive events or an episode of acute chest syndrome. Oral HU therapy was started as a single daily dose and increased to the maximally tolerated dose based on myelosuppression. Laboratory evaluation was performed at baseline and monthly thereafter. Once the maximum tolerated dose was reached, laboratory data were monitored bimonthly. RESULTS: We treated six severely affected pediatric HbSC patients with HU for a median of 27 months. Mean corpuscular volume increased significantly (+26 fL) without change in hemoglobin concentration (-0.1 g/dL); neutrophils decreased significantly. Percentage of fetal hemoglobin (+8.5%) and percentage of F cells (+35.7%) increased significantly. Two experienced only mild and reversible toxicity. CONCLUSION: The laboratory responses in our pediatric patients with HbSC disease were striking, with increases in percentage of fetal hemoglobin and percentage of F-cells approaching responses observed in adult and pediatric patients with HbSS disease. All patients improved clinically. Our findings demonstrate that HU therapy benefits pediatric patients with severe HbSC disease, although larger clinical trials of HU therapy in HbSC disease are warranted.

Hydroxyurea for sickle cell disease.

BACKGROUND: Sickle cell disease is one of the most common inherited diseases world wide. It is associated with life long morbidity and a reduced life expectancy. Hydroxyurea, a chemotherapeutic drug taken by mouth, raises fetal haemoglobin and, as such, is expected to ameliorate some of the clinical problems of sickle cell disease. OBJECTIVES: To assess the effects of hydroxyurea therapy in sickle cell disease patients of all types, of any age, regardless of setting. SEARCH STRATEGY: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group specialised register of controlled trials for haemoglobinopathies, which comprises references identified from comprehensive electronic database searches, hand-searching relevant journals, and hand-searching abstract books of conference proceedings. Date of the most recent search(es): November 2000. SELECTION CRITERIA: All randomised or quasi-randomised controlled trials comparing the use of oral hydroxyurea for one month or longer with placebo, standard therapy or other interventions for the treatment of patients with sickle cell disease. DATA COLLECTION AND ANALYSIS: Both reviewers independently assessed trial quality and extracted data from the two studies included. MAIN RESULTS: Twenty trials were found of which two trials, which reported results from a total of 324 adults and children were suitable for inclusion in the review. From the data provided in the published reports only one study (the MSH study to the United States of America) could be analysed. This study showed marked differences in favour of hydroxyurea treatment as compared with placebo in terms of annual crisis rate, use of transfusions, and life-threatening complications (in particular, the acute sickle chest syndrome). No serious adverse effects were reported from either study. REVIEWER'S CONCLUSIONS: While hydroxyurea appears both effective and safe in the severely affected SS adults over a two year period; further studies are required to elucidate its role in other patient groups and for other conditions.

Maximum urine concentrating ability in children with Hb SC disease: effects of hydroxyurea.

Studies in adults with Hb SC disease suggested that hydroxyurea reduced hemolysis and increased red cell hydration. Because increased hydration should diminish the polymerization tendency of Hb S we hypothesized that hydroxyurea might repair the urine concentration defect of HbSC disease. Eight Hb SC disease patients, aged 10 to 17 years, were given hydroxyurea daily. Maximal urine concentrating ability following overnight fasting and after subcutaneous arginine vasopressin (dDAVP), blood counts, and cell volumes were observed for 12-15 months. All patients had impaired urine concentrating ability prior to hydroxyurea treatment and failed to increase their ability to concentrate urine following treatment (maximum urine concentration after an overnight fast and dDAVP, 520-530 mOsm). Mean corpuscular volume (MCV) and reticulocyte MCV increased after administration of hydroxyurea, and the reticulocyte count and ratio of red cell hemoglobin to reticulocyte hemoglobin fell but there was little change in PCV. Hb F increased substantially in 2 patients but showed little change in the remaining patients. There was no evidence that hydroxyurea was associated with increased urine concentrating ability in children with Hb SC disease. These results may reflect irreversible renal medullary damage prior to beginning treatment or insufficient intensity or duration of treatment.