Preliminary report of a toxicity study of hydroxyurea in sickle cell disease. French Study Group on Sickle Cell Disease

Sickle cell disease and acute leukemia: one case report and an extensive review

Population-based studies and case reports suggest that there may be an increased risk of acute leukemia associated with sickle cell disease (SCD). Following the description of a new case report, an extensive review of the literature identified 51 previously described cases. Most cases study showed myelodysplastic features confirmed, when available, by genetic markers such as chromosome 5 and/or chromosome 7 abnormalities and TP53 gene mutations. The increased risk of leukemogenesis is certainly multifactorial and related to the pathophysiologic mechanisms of the clinical manifestations of SCD. Chronic hemolysis and secondary hemochromatosis may cause increased chronic inflammation, resulting in persistent marrow stress, which could potentially compromise the genomic stability of the hematopoietic stem cells generating genomic damage and somatic mutations over the course of SCD and its treatment, resulting in a clone that led to acute myeloid leukemia.

The Use of Induced Pluripotent Stem Cells to Study the Effects of Adenosine Deaminase Deficiency on Human Neutrophil Development

Inherited defects that abrogate the function of the adenosine deaminase (ADA) enzyme and consequently lead to the accumulation of toxic purine metabolites cause profound lymphopenia and severe combined immune deficiency. Additionally, neutropenia and impaired neutrophil function have been reported among ADA-deficient patients. However, due to the rarity of the disorder, the neutrophil developmental abnormalities and the mechanisms contributing to them have not been characterized. Induced pluripotent stem cells (iPSC) generated from two unrelated ADA-deficient patients and from healthy controls were differentiated through embryoid bodies into neutrophils. ADA deficiency led to a significant reduction in the number of all early multipotent hematopoietic progenitors. At later stages of differentiation, ADA deficiency impeded the formation of granulocyte colonies in methylcellulose cultures, leading to a significant decrease in the number of neutrophils generated from ADA-deficient iPSCs. The viability and apoptosis of ADA-deficient neutrophils isolated from methylcellulose cultures were unaffected, suggesting that the abnormal purine homeostasis in this condition interferes with differentiation or proliferation. Additionally, there was a significant increase in the percentage of hyperlobular ADA-deficient neutrophils, and these neutrophils demonstrated significantly reduced ability to phagocytize fluorescent microspheres. Supplementing iPSCs and methylcellulose cultures with exogenous ADA, which can correct adenosine metabolism, reversed all abnormalities, cementing the critical role of ADA in neutrophil development. Moreover, chemical inhibition of the ribonucleotide reductase (RNR) enzyme, using hydroxyurea or a combination of nicotinamide and trichostatin A in iPSCs from healthy controls, led to abnormal neutrophil differentiation similar to that observed in ADA deficiency, implicating RNR inhibition as a potential mechanism for the neutrophil abnormalities. In conclusion, the findings presented here demonstrate the important role of ADA in the development and function of neutrophils while clarifying the mechanisms responsible for the neutrophil abnormalities in ADA-deficient patients.

Cutaneous reactions to pediatric cancer treatment: Part I. Conventional chemotherapy

Chemotherapies often cause side effects of the skin, nails, and mucosal surfaces. These mucocutaneous toxicities contribute to morbidity and affect quality of life. Identification and management of these drug-induced eruptions is vital to allow for continuation of essential therapies. This review demonstrates the wide range of chemotherapy-induced cutaneous toxicities in children and includes clues for diagnosis as well as tips for counseling and management.

The Evolving Pharmacotherapeutic Landscape for the Treatment of Sickle Cell Disease

Sickle cell disease (SCD) is an extremely heterogeneous disease that has been associated with global morbidity and early mortality. More effective and inexpensive therapies are needed. During the last five years, the landscape of the pharmacotherapy of SCD has changed dramatically. Currently, 54 drugs have been used or under consideration to use for the treatment of SCD. These fall into 3 categories: the first category includes the four drugs (Hydroxyurea, L-Glutamine, Crizanlizumab tmca and Voxelotor) that have been approved by the United States Food and Drug Administration (FDA) based on successful clinical trials. The second category includes 22 drugs that failed, discontinued or terminated for now and the third category includes 28 drugs that are actively being considered for the treatment of SCD. Crizanlizumab and Voxelotor are included in the first and third categories because they have been used in more than one trial. New therapies targeting multiple pathways in the complex pathophysiology of SCD have been achieved or are under continued investigation. The emerging trend seems to be the use of multimodal drugs (i.e. drugs that have different mechanisms of action) to treat SCD similar to the use of multiple chemotherapeutic agents to treat cancer.

Occurrence of acute myeloid leukemia in hydroxyurea-treated sickle cell disease patient

Hydroxyurea (HU) has been widely used in sickle cell disease. Its potential long-term risk for carcinogenesis or leukemogenic risk remains undefined. Here, we report a 26 y old African-American female with Sickle Cell Disease (SCD) who developed refractory/relapsed acute myeloid leukemia (AML) 6 months after 26 months of HU use. That patient's cytogenetics and molecular genetics analyses demonstrated a complex mutation profile with 5q deletion, trisomy 8, and P53 deletion (deletion of 17p13.1). P53 gene sequence studies revealed a multitude of somatic mutations that most suggest a treatment-related etiology. The above-mentioned data indicates that the patient may have developed acute myeloid leukemia with myelodysplasia-related changes (AML-MRC) as a direct result of HU exposure.

Novel insights in the management of sickle cell disease in childhood

Sickle cell disease (SCD) is a life-threatening genetic disorder characterized by chronic hemolytic anemia, vascular injury and multiorgan dysfunctions. Over the last few decades, there have been significant improvements in SCD management in Western countries, especially in pediatric population. An early onset of prophylaxis with Penicillin and a proper treatment of the infections have increased the overall survival in childhood. Nevertheless, management of painful episodes and prevention of organ damage are still challenging and more efforts are needed to better understand the mechanisms behind the development of chronic organ damages. Hydroxyurea (Hydroxycarbamide, HU), the only medication approved as a disease-modifying agent by the United States Food and Drug Administration and the European Medicines Agency, is usually under-used, especially in developing countries. Currently, hematopoietic stem-cell transplantation is considered the only curative option, although its use is limited by lack of donors and transplant-related toxicity. SCD symptoms are similar in children and adults, but complications and systemic organ damages increase with age, leading to early mortality worldwide. Experts in comprehensive care of young patients with SCD, especially those approaching the transition age to adulthood, are missing, leading people to rely on urgent care, increasing health care utilization costs and inappropriate treatments. It would be important to establish programs of comprehensive healthcare for patients with SCD from birth to adulthood, to improve their quality and expectancy of life.

[From Hemoglobin SS to SF: interest of hydroxyurea in the management of sickle cell disease in two Congolese children and review of the literature]

La drépanocytose est une maladie grave par ses complications et par les difficultés liées à sa prise en charge, notamment en milieu sous-équipé. Les auteurs rapportent l'effet bénéfique de l'hydroxyurée dans la prise en charge de deux patients drépanocytaires, au prix cependant d'une surveillance hématologique rigoureuse. Une revue de la littérature étaye par ailleurs les modalités d'administration de ce médicament et les perspectives ultérieures d'un tel traitement dans la drépanocytose.

Improving outcomes in children with sickle cell disease: treatment considerations and strategies

Over the past decades there has been a significant improvement in the care of patients with sickle cell disease (SCD) in high-income countries. However, more needs to be learned about the complex pathophysiology and the factors that contribute to the development of end organ damage from the disease. While antibiotic prophylaxis and appropriate treatment of infections have resulted in a significant reduction of early mortality, management of the painful episodes and prevention of organ damage remain a challenge. Hydroxyurea is the only medication approved as disease-modifying therapy, and bone marrow transplant as curative treatment is not available to most patients. In low-income countries with the highest disease burden, early mortality is high due to limited resources for systematic screening, early diagnosis, and disease management. In order to improve outcomes in patients with SCD in high-income countries, better and widespread implementation of known disease-modifying therapies and the development of newer therapies targeting key pathophysiologic pathways are required. In low-income countries with high disease burden, innovative approaches to develop low-cost diagnostic devices and treatments that can be implemented to scale are needed to combat early mortality from the disease. Sustainable solutions in low-resource settings require evidence-based affordable interventions that can be integrated into primary and secondary healthcare systems.

Cytotoxicity and DNA damage in the neutrophils of patients with sickle cell anaemia treated with hydroxyurea

Hydroxyurea (HU) is the most important advance in the treatment of sickle cell anaemia (SCA) for preventing complications and improving quality of life for patients. However, some aspects of treatment with HU remain unclear, including their effect on and potential toxicity to other blood cells such as neutrophils. This study used the measurement of Lactate Dehydrogenase (LDH) and Methyl ThiazolTetrazolium (MTT) and the comet assay to investigate the cytotoxicity and damage index (DI) of the DNA in the neutrophils of patients with SCA using HU.In the LDH and MTT assays, a cytoprotective effect was observed in the group of patients treated, as well as an absence of toxicity. When compared to patients without the treatment, the SS group (n=20, 13 women and 07 men, aged 18-69 years), and the group of healthy individuals (AA) used as a control group (n=52, 28 women and 24 men, aged 19-60 years), The SSHU group (n=21, 11 women and 10 men, aged 19-63 years) showed a significant reduction (p<0.001) in LDH activity and an increase in the percentage of viable cells by the MTT (p<0.001). However, the SSHU group presented significantly higher DI values (49.57±6.0 U/A) when compared to the AA group (7.43 ± 0,94U/A) and the SS group (22.73 ±5.58 U/A) (p<0.0001), especially when treated for longer periods (>20 months), demonstrating that despite the cytoprotective effects in terms of cell viability, the use of HU can induce DNA damage in neutrophils.

Development of myelodysplastic syndrome and acute myeloid leukemia 15 years after hydroxyurea use in a patient with sickle cell anemia

We report a 41 year old male with sickle cell disease who developed a myelodysplastic syndrome and acute myeloid leukemia with complex karyotype involving chromosomes 5, 7 and 17 after 15 years of hydroxyurea treatment. He responded poorly to induction chemotherapy with cytarabine/idarubicin followed by high dose cytarabine and succumbed to neutropenic sepsis. Multiple systematic reviews, observational studies and clinical trials were conducted to identify the toxicity profile of hydroxurea. Only six cases of leukemia/myelodysplastic syndrome were identified in patients with sickle cell anemia treated with hydroxyurea. Subsequently, it was concluded that hydroxyurea is not leukemogenic. However, it was noted that most of the published studies had only up to 9 years of follow-up. Our patient was started on hydroxyurea in 1990, before the widespread use of the drug and took hydroxyurea for 15 years. His presentation may reflect an outcome otherwise not yet observed because of the short follow-up of prior studies. We believe that the leukemogenic risk of hydroxyurea should be discussed with the patients and their families. Studies evaluating the adverse effects of hydroxyurea should have longer follow-up before definitive conclusions are drawn.

Genotype-phenotype relationship of patients with β-thalassemia taking hydroxyurea: a 13-year experience in Iran

We evaluated the clinical responses to hydroxyurea (HU), adverse effects, and β-globin gene variants in a large series of β-thalassemic patients over a 13-year period in Iran. The patients (n = 232) were divided into two groups: transfusion-dependent β-thalassemia patients 2 years of age and older (n = 126; Group 1), and β-thalassemia intermedia (βTI) patients without any history of blood transfusion or with a long-interval transfusion (n = 106; Group 2). In Group 1, 86 patients became transfusion-free, and 25 patients needed 1-2 transfusions per year at the end of study. All except three patients in Group 2 were completely transfusion free with a significant increase in Hb level after 1 year compared to the baseline Hb value (P < 0.0001). We did not find a significant correlation of response to HU with XmnI polymorphism or IVS II-I (G > A) mutation (P > 0.05). In our study, HU at a dose of 8-15 mg/kg/day was effective in decreasing or effecting cessation of the need for regular blood transfusion, as well as in increasing Hb levels in β-thalassemia patients, without any major side effects. Hydroxyurea may thus represent a safe alternative to blood transfusion in transfusion-dependent β-thalassemia patients, or help to increase Hb level in untransfused βTI patients.

Current strategies for the management of children with sickle cell disease

Children with sickle cell disease may present to doctors anywhere in the world. In developed countries, neonatal screening allows early identification and management of the disease, mostly through daily antibioprophylaxis, immunizations and education of the parents. Stroke prevention relies on the detection of high-risk patients by annual transcranial Doppler ultrasonography from 2 to 16 years of age. Annual check-ups aim to detect early organ deficiencies. The most frequent complications are pain, infections and acute anemia; they may occur in combination. Approximately 10% of children have severe sickle cell disease that may require chronic blood transfusion, hydroxyurea or hematopoietic stem cell transplantation. Comprehensive management programs have dramatically increased survival, and most patients now reach adulthood.

Gated myocardial perfusion scintigraphy in children with sickle cell anemia: correlation with echocardiography

OBJECTIVES

The heart is one of the organs affected by sickle cell anemia (SCA). This prospective study has aimed to evaluate myocardial perfusion and left ventricle (LV) function in children with SCA by gated myocardial perfusion scintigraphy (G-MPS) and to compare the results with echocardiographic parameters.

METHODS

Forty-three patients with SCA were evaluated by G-MPS and echocardiography. Myocardial perfusion and motion with thickening function were analyzed both visually and quantitatively. End-diastolic (EDV), end-systolic volumes (ESV), ejection fraction (EF), lung-to-heart (L/H) ratio were also calculated.

RESULTS

None of the patients showed stress perfusion impairment in G-MPS. LV dilatation in 15 patients was observed both by G-MPS and echocardiography. EF values were within normal limits. Correlation between EF values calculated by two methods was not statistically significant. However, LV dilatation detected by both methods and EDV-ESV values in G-MPS were correlated to end-diastolic and end-systolic diameters calculated in echocardiography (p<0.05). M-Mode echocardiography revealed higher myocardial performance index (LV-MPI) in patients with LV dilatation. There was also a significant relationship between LV dilatation and frequent blood transfusions (>5/years) and acute chest syndrome (p<0.05).

CONCLUSION

Myocardial perfusion impairment in children with SCA is not frequently observed. Thus, performing the scintigraphy only in patients with cardiac symptoms should be considered. Since EF values of the children with SCA are not deteriorated in early stages, LV-MPI and LV dilatation should be considered as a significant parameter other than EF or perfusion data.

How I use hydroxyurea to treat young patients with sickle cell anemia

Hydroxyurea has many characteristics of an ideal drug for sickle cell anemia (SCA) and provides therapeutic benefit through multiple mechanisms of action. Over the past 25 years, substantial experience has accumulated regarding its safety and efficacy for patients with SCA. Early proof-of-principle studies were followed by prospective phase 1/2 trials demonstrating efficacy in affected adults, then adolescents and children, and more recently infants and toddlers. The phase 3 National Heart, Lung and Blood Institute-sponsored Multicenter Study of Hydroxyurea trial proved clinical efficacy for preventing acute vaso-occlusive events in severely affected adults. Based on this cumulative experience, hydroxyurea has emerged as an important therapeutic option for children and adolescents with recurrent vaso-occlusive events; recent evidence documents sustained long-term benefits with prevention or reversal of chronic organ damage. Despite abundant evidence for its efficacy, however, hydroxyurea has not yet translated into effective therapy for SCA. Because many healthcare providers have inadequate knowledge about hydroxyurea, patients and families are not offered treatment or decline because of unrealistic fears. Limited support for hydroxyurea by lay organizations and inconsistent medical delivery systems also contribute to underuse. Although questions remain regarding its long-term risks and benefits, current evidence suggests that many young patients with SCA should receive hydroxyurea treatment.

Adverse effects of hydroxyurea in beta-thalassemia intermedia patients: 10 years' experience

The aim of this study was to evaluate the tolerance and adverse effects of hydroxyurea (HU) in thalassemia intermedia (TI) patients who had been treated by HU for a period of 10 years. One hundred forty-three TI patients, including 78 male and 65 female, median age 21 years old (range: 5-37 years old), who were treated by HU were investigated as a case study, and 106 TI, including 63 male and 43 female, median age 22 years old (range: 5-39 years old), who were not treated by any HU as a control group. Mean dose of HU treatment was 10.74 mg/kg/day (range: 8-12 mg/kg/day) and adverse effects of HU were recorded in 44 (30.7%) patients. Dermatologic side effects were most commonly seen, followed by neurological and gastrointestinal adverse effects. There were not any reports of hematologic toxicity or any signs of bone marrow suppression during HU treatment. Statistical analysis showed a positive correlation between advancing age and the presence of adverse effects during HU treatment (P < .001). But there were not any significant relations among gender, HU dose, and duration of HU treatment and the presence of adverse effects (P > .05). It was also observed that splenectomized patients more frequently experienced adverse effects of HU (P < .05). According to these results, it seems that most of adverse effects in low-dose HU therapy in patients with TI, at least in short and medium terms, are minor and can be tolerated without needs of discontinuation of treatment.

Clinical and Laboratory Effects of Hydroxyurea in Children and Adolescents with Sickle Cell Anemia: A Portuguese Hospital Study

Our aim was to assess the efficacy and safety of hydroxyurea (HU) in children with severe forms of sickle cell anemia followed in a Portuguese hospital. We carried out an open-label uncontrolled prospective study, which included children with severe forms of sickle cell anemia. Hydroxyurea was started at 15 mg/kg/day and increased to a maximum dose of 25 mg/kg/day. Patients were monitored to assess compliance, clinical and hematological response and toxicity. Nine children and adolescents, five girls and four boys, with a median age of 13 years (range 8 to 16) were enrolled in the study during a period of 24 months. All patients completed at least 15 months of therapy. Hb F was significantly increased, from a mean of 7.0 +/- 3.9% to 13.7 +/- 5.3% (p = 0.028). Clinically, all patients responded significantly with a reduction of 80% in the number of vaso-occlusive crises (VOC), 69% in hospital admissions, 76% in hospitalization days and 67% in transfusion requirements, without significant toxicity. We concluded that, in our population, HU proved to be effective in increasing Hb F levels, and in decreasing hospitalizations for VOC and transfusion requirements with no major side effects. Long-term clinical follow-up is important to certify benefit maintenance.

Effect of hydroxyurea on extramedullary haematopoiesis in thalassaemia intermedia: case reports and literature review

Extramedullary haematopoiesis (EH) is the production of blood cell precursors outside the bone marrow that occurs in various disorders, such as thalassaemia, sickle cell anaemia, hereditary spherocytosis, polycythaemia vera, myelofibrosis and other haematological diseases. In chronic anaemia, it is a physiological response to increased erythropoietin. In some other conditions, such as myeloid metaplasia, polycythaemia vera or chronic myeloid leukaemia, EH is due to a clonal disorder of haematopoiesis that enables progenitor cells to escape from the marrow and lodge in other organs. EH usually involves the liver, spleen and lymph nodes or it can be paravertebral, intrathoracic, pelvic. It is often asymptomatic but can sometimes lead to symptomatic tumour-like masses. Treatment options are still controversial and limited, including hypertransfusion regimen, surgical treatment, radiotherapy and hydroxyurea (HU). We describe intrathoracic and symptomatic pelvic EH masses in a 48-year-old woman and intrathoracic bilateral masses causing respiratory insufficiency with pleural effusion in a 42-year-old male, both affected by thalassaemia intermedia. Both patients showed a clinical improvement with hydroxyurea therapy and occasional blood transfusions.

Hydroxyurea for sickle cell disease: a systematic review for efficacy and toxicity in children

CONTEXT

Hydroxyurea is the only approved medication for the treatment of sickle cell disease in adults; there are no approved drugs for children.

OBJECTIVE

Our goal was to synthesize the published literature on the efficacy, effectiveness, and toxicity of hydroxyurea in children with sickle cell disease.

METHODS

Medline, Embase, TOXLine, and the Cumulative Index to Nursing and Allied Health Literature through June 2007 were used as data sources. We selected randomized trials, observational studies, and case reports (English language only) that evaluated the efficacy and toxicity of hydroxyurea in children with sickle cell disease. Two reviewers abstracted data sequentially on study design, patient characteristics, and outcomes and assessed study quality independently.

RESULTS

We included 26 articles describing 1 randomized, controlled trial, 22 observational studies (11 with overlapping participants), and 3 case reports. Almost all study participants had sickle cell anemia. Fetal hemoglobin levels increased from 5%-10% to 15%-20% on hydroxyurea. Hemoglobin concentration increased modestly (approximately 1 g/L) but significantly across studies. The rate of hospitalization decreased in the single randomized, controlled trial and 5 observational studies by 56% to 87%, whereas the frequency of pain crisis decreased in 3 of 4 pediatric studies. New and recurrent neurologic events were decreased in 3 observational studies of hydroxyurea compared with historical controls. Common adverse events were reversible mild-to-moderate neutropenia, mild thrombocytopenia, severe anemia, rash or nail changes (10%), and headache (5%). Severe adverse events were rare and not clearly attributable to hydroxyurea.

CONCLUSIONS

Hydroxyurea reduces hospitalization and increases total and fetal hemoglobin levels in children with severe sickle cell anemia. There was inadequate evidence to assess the efficacy of hydroxyurea in other groups. The small number of children in long-term studies limits conclusions about late toxicities.

Systematic review: Hydroxyurea for the treatment of adults with sickle cell disease

BACKGROUND

Hydroxyurea is the only approved drug for treatment of sickle cell disease.

OBJECTIVE

To synthesize the published literature on the efficacy, effectiveness, and toxicity of hydroxyurea when used in adults with sickle cell disease.

DATA SOURCES

MEDLINE, EMBASE, TOXLine, and CINAHL were searched through 30 June 2007.

STUDY SELECTION

Randomized trials, observational studies, and case reports evaluating efficacy and toxicity of hydroxyurea in adults with sickle cell disease, and toxicity studies of hydroxyurea in other conditions that were published in English.

DATA EXTRACTION

Paired reviewers abstracted data on study design, patient characteristics, and outcomes sequentially and did quality assessments independently.

DATA SYNTHESIS

In the single randomized trial, the hemoglobin level was higher in hydroxyurea recipients than placebo recipients after 2 years (difference, 6 g/L), as was fetal hemoglobin (absolute difference, 3.2%). The median number of painful crises was 44% lower than in the placebo group. The 12 observational studies that enrolled adults reported a relative increase in fetal hemoglobin of 4% to 20% and a relative reduction in crisis rates by 68% to 84%. Hospital admissions declined by 18% to 32%. The evidence suggests that hydroxyurea may impair spermatogenesis. Limited evidence indicates that hydroxyurea treatment in adults with sickle cell disease is not associated with leukemia. Likewise, limited evidence suggests that hydroxyurea and leg ulcers are not associated in patients with sickle cell disease, and evidence is insufficient to estimate the risk for skin neoplasms, although these outcomes can be attributed to hydroxyurea in other conditions.

LIMITATION

Only English-language articles were included, and some studies were of lower quality.

CONCLUSION

Hydroxyurea has demonstrated efficacy in adults with sickle cell disease. The paucity of long-term studies limits conclusions about toxicity.

Systematic review: Hydroxyurea for the treatment of adults with sickle cell disease

BACKGROUND

Hydroxyurea is the only approved drug for treatment of sickle cell disease.

OBJECTIVE

To synthesize the published literature on the efficacy, effectiveness, and toxicity of hydroxyurea when used in adults with sickle cell disease.

DATA SOURCES

MEDLINE, EMBASE, TOXLine, and CINAHL were searched through 30 June 2007.

STUDY SELECTION

Randomized trials, observational studies, and case reports evaluating efficacy and toxicity of hydroxyurea in adults with sickle cell disease, and toxicity studies of hydroxyurea in other conditions that were published in English.

DATA EXTRACTION

Paired reviewers abstracted data on study design, patient characteristics, and outcomes sequentially and did quality assessments independently.

DATA SYNTHESIS

In the single randomized trial, the hemoglobin level was higher in hydroxyurea recipients than placebo recipients after 2 years (difference, 6 g/L), as was fetal hemoglobin (absolute difference, 3.2%). The median number of painful crises was 44% lower than in the placebo group. The 12 observational studies that enrolled adults reported a relative increase in fetal hemoglobin of 4% to 20% and a relative reduction in crisis rates by 68% to 84%. Hospital admissions declined by 18% to 32%. The evidence suggests that hydroxyurea may impair spermatogenesis. Limited evidence indicates that hydroxyurea treatment in adults with sickle cell disease is not associated with leukemia. Likewise, limited evidence suggests that hydroxyurea and leg ulcers are not associated in patients with sickle cell disease, and evidence is insufficient to estimate the risk for skin neoplasms, although these outcomes can be attributed to hydroxyurea in other conditions.

LIMITATION

Only English-language articles were included, and some studies were of lower quality.

CONCLUSION

Hydroxyurea has demonstrated efficacy in adults with sickle cell disease. The paucity of long-term studies limits conclusions about toxicity.

[Hydroxyurea treatment in patients affected with sickle cell anemia: efficacy and safety]

Hydroxyurea is the unique drug having demonstrated an efficacy in preventing recurrences of painful crises, acute chest syndromes and in reducing transfusional needs in patients severely affected with sickle cell disease. However, there is a wide variation in the clinical response to hydroxyurea in sickle cell patients, with children generally experiencing greater benefits than adults. Short- and middle-term tolerances are good. Our uncertainties about long-term tolerance are mainly that we do not know the consequences of the drug on ulterior fertility in boys treated early and for long periods. Hydroxyurea has just been licensed for sickle cell adults and children in Europe. Its prescription for the moment must be restricted to severely affected patients, enrolled in long-term follow-up protocols.

[The use of hydroxyurea in severe forms of sickle cell disease: study of 47 Tunisian paediatric cases]

INTRODUCTION

The Sickle Cell Disease (SCD) is a serious illness considering its complications. For the children seriously affected, three therapeutic options are currently validated: transfusion therapy, hydroxyurea and bone-marrow transplantation.

OBJECTIVES

To see the contribution of hydroxyurea therapy on severe forms of SCD in affected Tunisian children.

MATERIAL AND METHODS

This investigative study lasted over 6 years and 9 months, (September 2000-May 2007), enrolling 47 patients including 27 homozygous SCD and 20 double heterozygote SCD-S/beta thalassemia. The median age was 12 years and a half. The average dosage were 20mg/kg/d (14-30 mg/kg/d). The average duration of treatment was 52 months (18-81 months).

RESULTS

The main indication for hydroxyurea treatment was prevention of recurrence of an acute chest syndrome in seven cases; episodic vaso-occlusive crises exceeding three events per year in 38 cases and prevention of deterioration of cerebral vascular accident in two cases. We observed a fast and sustained improvement of the clinical expression of the disease with a significant decrease of the number of days of hospitalization per patient and per annum from 29.3 d (10-84 d) to 3.2 d/(p<0.01). Treatment was well tolerated. We observed a significant increase of haemoglobin fetus (HbF) rates from 3 to 30% (p<0.01), hemoglobin from 7.8 to 9.6g/dl (p<0.05), average blood cells volume from 79.1 to 100.3 fl (p<0.05) and a significant fall of the white blood cells rates from 14,914 to 8464 per millimetre cube (p<0.05), polynuclear neutrophils from 6799 to 3486 per millimetre cube (p<0.05) and platelets from 508,666 to 293,500 per millimetre cube (p<0.05).

CONCLUSIONS

Hydroxyurea represents a privileged choice of treatment in the severe forms of SCD in children, for homozygous SCD-SS as well as for double heterozygote SCD-S/beta thalassemia. Used carefully, with frequent monitoring, it appeared as a safe treatment in short and medium term, but studies of long-term tolerance should be undertaken.

Long-term results of related myeloablative stem-cell transplantation to cure sickle cell disease

Allogeneic hematopoietic stem-cell transplantation (HSCT) is the only curative treatment for sickle cell disease (SCD); nevertheless, its use has been limited by the risk of transplantation-related mortality (TRM). Between November 1988 and December 2004, 87 consecutive patients with severe SCD ranging from 2 to 22 years of age received transplants in France. Cerebral vasculopathy was the principal indication for transplantation (55 patients). All the patients received grafts from a sibling donor after a myeloablative conditioning regimen (CR). The only change in the CR during the study period was the introduction of antithymocyte globulin (ATG) in March 1992. The rejection rate was 22.6% before the use of ATG but 3% thereafter. With a median follow-up of 6 years (range, 2.0 to 17.9 years), the overall and event-free survival (EFS) rates were 93.1% and 86.1%, respectively. Graft versus host disease (GVHD) was the main cause of TRM. Importantly, cord blood transplant recipients did not develop GVHD. No new ischemic lesions were detected after engraftment, and cerebral velocities were significantly reduced. The outcome improved significantly with time: the EFS rate among the 44 patients receiving transplants after January 2000 was 95.3%. These results indicate that HLA-identical sibling HSCT after myeloablative conditioning with ATG should be considered as a standard of care for SCD children who are at high risk for stroke.

Myelosuppression in patients benefiting from imatinib with hydroxyurea for recurrent malignant gliomas

Reports suggest reasonable efficacy and minimal myelosuppression from combination imatinib and hydroxyurea for recurrent malignant glioma. We retrospectively reviewed 16 patients treated with this regimen who were evaluable for toxicity; 14 were also evaluable for response. The incidence of grade 3-4 hematologic toxicity was 25%. The best radiographic response, by Macdonald criteria, was partial response (PR) in three patients (21%), stable disease (SD) in four (29%), and progressive disease (PD) in seven (50%). One patient with a PR developed therapy-limiting hematologic toxicity on day 19 of treatment, progressing to grade 4 on day 64, and persisting until death on day 127 despite discontinuing both drugs. Another patient with PR and two of four patients with SD also developed grade 3 hematologic toxicity. All patients with grade 3-4 hematologic toxicity had disease control (PR or SD) as best radiographic response, whereas none with PD suffered grade 3-4 hematologic toxicity. Combining imatinib with hydroxyurea is effective in some patients with malignant glioma. However, myelosuppression can persist for months after discontinuing the regimen, precluding further chemotherapy. Disease control may also correlate with hematologic toxicity (p = 0.08), suggesting that glioma and marrow stem cells may share a common sensitivity to this chemotherapy regimen.

Transfusion Management in Sickle Cell Disease

Sickle cell disease (SCD) is the most commonly inherited hemoglobinopathy in the United States. Blood transfusion is a critical part of the multidisciplinary approach necessary in the management of SCD; however, blood transfusions are not without complications. The successful use of transfusion as a treatment strategy in SCD requires the critical review and knowledge of transfusion methods, generally accepted indications, clinical situations in which transfusion generally is not considered, the selection of blood products, and strategies to prevent transfusion-related complications.

Hydroxyurea treatment for sickle cell disease: impact on haematopoietic stem cell transplantation's outcome

Since 1988, 24 children have undergone haematopoietic stem cell transplantation (HSCT) for severe sickle cell disease (SCD) in our unit, 13 being grafted after having been exposed to hydroxyurea (HU) to control SCD-related complications. Different pre-transplant conditioning regimens were given over time: Bu14/Cy200 in six patients (group 1), Bu16/Cy200/antithymocyte globulin (ATG) in five (group 2) and Bu16/Cy200/ATG with HU prior to HSCT in 13 (group 3). The aim of this study is to compare the outcome after HSCT of these groups of patients, which differ according to pre-transplant drug exposure. Overall, 20 of the 24 transplanted children had stable engraftment and have remained free of SCD-related symptoms after HSCT; 19 of them are currently alive and cured of SCD. In group 1 (HU-, ATG-), we observed one unexplainable late death, one absent engraftment, one late rejection and one mixed stable chimerism. In group 2 (HU-, ATG+), we observed the absence of engraftment in two patients and one early rejection. In group 3 (HU+, ATG+), we observed no cases of either absent engraftment, mixed stable chimerism or late rejection. In our experience, pre-transplant treatment with HU seems to be associated with a lower incidence of rejection/absent engraftment in severe SCD patients. These results need to be confirmed with a larger number of patients.

Myocardial ischaemia in children with sickle cell disease

BACKGROUND

The heart may be involved in children affected with sickle cell disease (SCD) via several mechanisms. Principally, chronic anaemia increases cardiac output and may cause left ventricular enlargement and cardiac insufficiency.

AIMS

To investigate whether the heart also suffers from ischaemia in SCD, as has already been shown for other organs (bone, brain, etc), and to look for risk factors predisposing to this complication.

METHODS

Twenty two children with SCD, and chest pain or ECG or echocardiographic signs (left ventricle dilation or hypokinesis) suggesting myocardial ischaemia were subjected to thallium-201 (201Tl) single photon emission computed tomography (SPECT).

RESULTS

Eight children had a normal SPECT, 14 an abnormal one. Myocardial perfusion defects were reversible in nine, fixed in five. Patients with perfusion defects tended to be older and have more severe disease. Five had had cardiac symptoms (episodes of cardiac failure in three, ventricular fibrillation in one, angina in one). Myocardial perfusion was reassessed after six months of hydroxyurea treatment in three patients, and was found to be improved.

CONCLUSIONS

Myocardial perfusion defects are present in children with SCD and may be demonstrated using SPECT. Hydroxyurea improved perfusion in three patients.

Hydroxyurea can eliminate transfusion requirements in children with severe beta-thalassemia

Hydroxyurea (HU) enhances fetal hemoglobin (Hb) production. An increase in total Hb level has been repeatedly reported during HU treatment in patients with sickle cell disease and in several patients with beta-thalassemia intermedia. Effects in patients with beta-thalassemia major are controversial. We now report a marked elevation of total Hb levels with HU that permitted regular transfusions to be stopped in 7 children with transfusion-dependent beta-thalassemia. The median follow-up was 19 +/- 3 months (range, 13-21 months). We conclude that HU can eliminate transfusional needs in children with beta-thalassemia major, which could be particularly useful in countries such as Algeria, where supplies of blood or chelating agents are limited.

Pathophysiological-based approaches to treatment of sickle cell disease

Sickle hemoglobin (HbS), as a result of its polymer-related and oxidant effects, damages the sickle erythrocyte, provokes inflammation, and causes endothelial injury. All these elements cause the phenotype of sickle cell disease. Novel treatments inhibit HbS polymerization by inducing fetal hemoglobin expression, prevent or repair erythrocyte dehydration by slowing cellular potassium and water loss, and replace HbS-producing erythroid progenitors by stem cell transplantation. Future treatment prospects include gene therapy, interruption of the interaction of sickle cells with the endothelium, inhibition of oxidative damage, and protection of an injured endothelium.

The role of hydroxyurea in the management of sickle cell disease

Sickle cell disease (SCD) is one of the most common genetic diseases with some 250,000 new births each year. Most patients suffer intermittent pain crises and life-threatening events while life expectancy is considerably reduced. Until the last decade management was purely preventative or supportive aimed at symptom control. Apart from stem cell transplant, there is no cure but the oral chemotherapeutic drug hydroxyurea (HU) has now established a role in ameliorating the disease and improving life expectancy for most patients. There are side effects and risks of HU treatment in SCD but for moderate and severely affected patients, the benefits can be significant.

Developing treatment for sickle cell disease

Sickle cell disease pathophysiology results from sickle haemoglobin polymerisation and its effects on the sickle erythrocyte and the vasculature. Many of the abnormalities of sickle cell disease are secondary to the damage caused by the polymer and the injured red cell. Pharmacological treatment of the disease is focused on the inhibition of sickle haemoglobin polymerisation, prevention or repair of red cell dehydration and interruption of the interaction of sickle cells with the endothelium.

Reduction of the clinical severity of sickle cell/beta-thalassemia with hydroxyurea: the experience of a single center in Greece

The use of hydroxyurea for the prevention of sickle cell crises in patients with homozygous HbS disease is now well established. The beneficial effects of this compound stem from (a) selective enrichment of red cells containing an increased amount of fetal hemoglobin, which inhibits HbS polymerization, and (b) a decrease of leukocytes, platelets, and reticulocytes, which significantly limits their adherence to the vascular wall. We report the results of a clinical trial of hydroxyurea on 55 Greek-origin patients with sickle cell/beta-thalassemia and 14 patients with homozygous HbS disease who have been treated with hydroxyurea for several years. Such patients have a higher probability to benefit from hydroxyurea therapy, since in addition to its antisickling effect, the increase of gamma-chain synthesis is expected to diminish the deleterious effects of the unbound alpha-globin chains. Selection of patients and monitoring throughout the whole trial were done by the same clinicians. Quantitative expression of the clinical condition was done using a system scoring several outcome parameters. For a period of 52 months prior to starting treatment, the total score of severity for 59 evaluable patients was 1182 points (3068 patient-weeks), while for the 12,018 patient-weeks of the trial this parameter fell to only 82 points. Other observations of interest include the significant improvement of a group of patients with hepatic cholestasis, the development of leg ulcers possibly related to the treatment, and the dramatic increase of hemoglobin F, often in association with an increase of the total hemoglobin levels as a result of decreased hemolysis.