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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A number of pharmacological agents are currently available for the induction of fetal hemoglobin (HbF) in patients with sickle cell disease and beta-thalassemia. Here we review the development of this new class of therapeutics and summarize the clinical trials that investigate their efficacy in patients with hemoglobin disorders. Hydroxyurea is the first of these drugs to be approved by the Food and Drug Administration for the treatment of sickle cell disease. Currently, the major focus is the development of safer agents and combinations of drugs that can increase HbF to levels high enough to prevent all complications of the disease. Progress in adapting the same strategy to the treatment of thalassemic disorders has been much slower. Although all the agents that are effective in sickle cell disease have similar HbF-inducing activity in beta-thalassemia, their use has rarely resulted in significant amelioration of the anemia. More research and more effective agents will be needed to make a significant impact on thalassemia. Nonetheless, success in this relatively young field has been very gratifying; before the end of this decade, clinically meaningful induction of HbF may become an achievable goal in most patients with hemoglobin disorders.
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PMID:Pharmacological induction of fetal hemoglobin in sickle cell disease and beta-thalassemia. 1160 72

Excessive ineffective erythropoiesis in thalassemia intermedia may cause paravertebral pseudotumors of extramedullary hematopoiesis. Due to the proximity to the spinal canal, these paravertebral masses carry the risk of severe neurological damage. Treatment strategies include hypertransfusion, radiotherapy, and laminectomy. Hydroxyurea, stimulating fetal hemoglobin synthesis, may represent an alternative therapeutic approach. We report on a 26-year-old patient suffering from thalassemia intermedia with progressive anemia symptoms and presenting multiple intrathoracic paravertebral pseudotumors of extramedullary hematopoiesis. Hypertransfusion therapy and splenectomy were followed by regular transfusion (baseline hemoglobin 10 g/dl) and chelation with desferrioxamine. With this treatment, clinical symptoms disappeared, paravertebral hematopoietic masses did not progress, but severe hemosiderosis developed within a few years. Hydroxyurea therapy was initiated to increase the efficacy of erythropoiesis, thereby reducing the required transfusion volume but suppressing concomitantly further expansion of extramedullary hematopoiesis, and finally leading to a reduction of transfusional iron load. Treatment was started with 4 mg/kg per day and stepwise increased to 12.5 mg/kg per day. The fetal hemoglobin concentration increased from 4.5 to 5.5 g/dl after 1 year and to 9.9 g/dl after 2 years of treatment. The yearly transfusion volume was halved during the 1st year of treatment. At present, after 26 months of treatment, the patient has been transfusion-independent for 10 months. Serum ferritin levels decreased from 2844 to 1335 ng/ml. Size and shape of paravertebral hematopoietic pseudotumors remained stable. No side effects of hydroxyurea have been observed. In thalassemia intermedia patients with extramedullary hematopoiesis, hydroxyurea may lead to independence from regular transfusion therapy without further expansion of ectopic hematopoietic tissue.
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PMID:Treatment with hydroxyurea in thalassemia intermedia with paravertebral pseudotumors of extramedullary hematopoiesis. 1222 8

Hydroxyurea (HU) has been shown to increase the proportion of fetal haemoglobin (HbF) in most sickle cell patients. A low-dosage regimen increased total haemoglobin (Hb) levels in some thalassaemia intermedia patients by preferentially increasing beta-globin biosynthesis. To further characterize these apparent dose-dependent effects of HU, we examined erythroid cells exposed to HU (5-100 micro mol/l) in two-phase liquid culture. Low doses (from 5 to 25 micro mol/l) increased Hb levels by up to 2.7-fold, and a high dose (100 micro mol/l) increased Hb levels when added at d 3-6 of phase II, with no significant changes in response to HU during the late stage of phase II culture (> or = 9 d). HU exposure during d 0-3 of phase II culture increased the number of erythroid colonies to a maximum of fivefold at 5 micro mol/l HU. GATA-1 mRNA was downregulated at a high dose and GATA-2 was dose dependently upregulated over a lower dosage range. Treatment with 100 micro mol/l HU dramatically upregulated the death receptor DR-5, caspase 3, as determined by cDNA microarray analysis. In contrast, 10 micro mol/l HU modestly upregulated mRNA levels of the early growth response gene. Our results suggest that HU exerts concentration-dependent effects on HbF production and erythropoiesis and that these two effects are mediated by distinct molecular mechanisms.
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PMID:Hydroxyurea exerts bi-modal dose-dependent effects on erythropoiesis in human cultured erythroid cells via distinct pathways. 1247 94

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.
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PMID:Hydroxyurea can eliminate transfusion requirements in children with severe beta-thalassemia. 1270 5

An increase in fetal hemoglobin (Hb F) ameliorates the clinical symptoms of the underlying disease in the beta hemoglobinopathies-sickle cell anemia and beta-thalassemia (thal). Hydroxyurea (HU) can elevate Hb F production in erythroid cells and is the agent currently in clinical use for patients with sickle cell anemia; it is presently being tested in clinical trials for thalassemia. We have developed a two-phase liquid culture system that mimics the in vivo hematological changes that are observed in patients treated with HU. Adding HU during the second phase of the culture increases the proportion of Hb F, increases the levels of total hemoglobin (Hb) content per cell and increases cell size, but it decreases the numbers of cells and the total amount of Hb produced. In the present study we developed and utilized a double labeling procedure for flow cytometric analysis of the cellular distribution of Hb F. Cells exposed to various concentrations of HU on day 6 of the second phase of the culture were harvested on day 12, and stained simultaneously with fluorochrome-conjugated monoclonal antibodies specific for human glycophorin A, an erythroid specific marker, and human Hb F. Both the percentage of the Hb F-containing cells and their intensity of fluorescence were recorded. The latter value gives a semi-quantitative estimation of the mean cellular Hb F content. The results indicated that cultures derived from different beta-thalassemic patients differ in their response to HU. In most patients, low doses of HU decreased the percentage of Hb F-cells as well as their Hb F content. At high doses, some patients showed an increase in both parameters, while others showed an increase in the percentage of Hb F-cells with minimal increase in their mean Hb F content, while still other patients showed little effect at all. In all patients, high doses of HU caused a decrease in cell numbers. These results suggest that HU has mixed effects on erythroid precursors. Both the two-phase liquid culture and the flow cytometric analysis procedures described herein provide the experimental tools for screening of Hb F-inducing drugs and for evaluating patients' cell response prior to treatment.
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PMID:Flow cytometric analysis of hydroxyurea effects on fetal hemoglobin production in cultures of beta-thalassemia erythroid precursors. 1277 69

Hydroxyurea improves hematologic parameters for children with sickle cell disease (SCD), but its long-term efficacy at maximum tolerated dose (MTD) has not been determined. Between 1995 and 2002, hydroxyurea therapy was initiated for 122 pediatric patients with SCD including 106 with homozygous sickle cell anemia (HbSS), 7 with sickle hemoglobin C (HbSC), 7 with sickle/beta-thalassemia (HbS/ beta-thalassemia [6 HbS/beta0, 1 HbS/beta+]), and 2 with sickle hemoglobin OArab (HbS/OArab). Median age at initiation of therapy was 11.1 years. Hydroxyurea was escalated to MTD, with an average dose of 25.4 +/- 5.4 mg/kg per day; the average duration of hydroxyurea therapy has been 45 +/- 24 months (range, 6-101 months). Hydroxyurea was discontinued for 15 (12%) children with poor compliance. Mild transient neutropenia occurred, but no hepatic or renal toxicity was noted. Hydroxyurea therapy led to significant increases in hemoglobin level, mean corpuscular volume, and fetal hemoglobin (HbF) level, whereas significant decreases occurred in reticulocyte, white blood cell, and platelet counts and serum bilirubin levels. Children with variant SCD genotypes also had hematologic responses to hydroxyurea. HbF induction has been sustained for up to 8 years without adverse effects on growth or increased numbers of acquired DNA mutations. Long-term hydroxyurea therapy at MTD is well tolerated by pediatric patients with SCD and has sustained hematologic efficacy with apparent long-term safety.
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PMID:Sustained long-term hematologic efficacy of hydroxyurea at maximum tolerated dose in children with sickle cell disease. 1463 Jul 91

Hydroxyurea (HU) has been shown to reduce the frequency of vaso-occlusive manifestations in both adults and children with sickle cell disease (SCD), and the induction of hemoglobin F (HbF) is thought to be the underlying mechanism responsible for clinical improvement in some patients. However, there exists no good correlation between the amount of HbF increase and clinical response. Recent studies suggest that increased activity of the coagulation system may be important in the pathogenesis of vascular occlusion in sickle cell disease. To analyze the effect of HU on the coagulation system in children, the authors studied the levels of some coagulation factors and natural inhibitors. Eleven children who had been treated with HU because of SCD (5 patients), sickle-beta-thalassemia (3 patients), and beta-thalassemia intermedia (3 patients) were enrolled in the study. Levels of the coagulation factors II, V, VII, VIII, IX, X, XI, and XII, and of protein C and protein S, prothrombin times, activated partial thromboplastine times, thrombin times, and reptilase times were measured before the treatment and at the 5th or 6th months of HU therapy when the patients were in a steady-state condition. There was a decrease in all of the coagulation factors except for FIX and FXII and in inhibitors such as protein C and protein S. However, statistically significant decreases were observed only in factor VIII and protein C levels. The rates of decrease were 54.8 and 12.5% (p = .015 and p = .018) in FVIII and protein C, respectively. This result shows that HC has significant effects on the coagulation and natural inhibitory systems.
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PMID:The effect of hydroxyurea on the coagulation system in sickle cell anemia and beta-thalassemia intermedia patients: a preliminary study. 1463 15

Hydroxyurea is commonly used in the treatment of various myeloproliferative disorders. In conventional pediatric clinical practice, its use is limited to benign hematologic conditions such as sickle cell disease and thalassemia. Long-term hydroxyurea use is associated with various adverse mucocutaneous effects including hyperpigmentation, alopecia, leg ulcers, and lichenoid eruptions. We report a 10-year-old boy with chronic myelogenous leukemia who presented with hyperpigmentation of the skin and nails 3 months after the start of hydroxyurea therapy. Melanonychia of all 20 nails with involvement of all three mucocutaneous areas (skin, nails, and mucosa) at presentation was a unique feature in our patient. With the recently increasing pediatric use of hydroxyurea in a variety of disorders, its benign and not so uncommon cutaneous adverse effects are emphasized here.
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PMID:Cutaneous manifestations of hydroxyurea therapy in childhood: case report and review. 1507 51

Hydroxyurea (HU) is a well-known chemotherapeutic agent that has been used largely for the treatment of various myeloproliferative conditions over the past 20 years. In beta-thalassemia, the role for HU is much less clear and remains controversial. This study was undertaken to describe the hematologic and clinical responses of thalassemia intermedia patients to HU treatment during 6 years in Southern Iran. One hundred sixty-three thalassemia intermedia patients were selected among the 3,000 cases of beta-thalassemia in Southern Iran from 1998 to 2003. All patients underwent laboratory tests and quantitative hemoglobin electrophoresis. Group 1 comprised patients receiving regular blood transfusions (after age 2 years old). Group 2 comprised those without any history of blood transfusions suffering from chronic anemia or long-interval transfusions. The state of energy, fatigability, and mood were recorded before the trial. Facial change was compared before and after treatment with HU. Electrocardiogram and echocardiography were carried out before and during treatment with HU. All patients were treated with HU; the starting dose was 8 to 12 mg/kg/d given orally once a day. Of the 163 patients, 149 tolerated the HU well and showed a dramatic response to the drug. Eighty-three of 106 transfusion-dependent patients (group 1) became completely transfusion-free, and 23 had one or two transfusions throughout the study. Sixteen of 43 patients (group 2) who were on long-interval transfusions became transfusion-free and 27 group 2 patients were transfusion-free, with developing acceptable hemoglobin levels. After treatment, 97% of patients described an increase in exercise tolerance, and no significant facial change was observed after therapy. No change in spleen size was observed in 83% of the patients. HU therapy was also associated with a marked increase in hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin. HU may be administered in thalassemia intermedia patients to minimize or even obviate the need for regular transfusions and concomitant iron overload, and HU therapy appears to be safe and effective when administered in thalassemic patients.
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PMID:Hematologic and clinical responses of thalassemia intermedia patients to hydroxyurea during 6 years of therapy in Iran. 1646 86

Thalassemia intermedia patients show variable phenotypes. Hydroxyurea (HU) may benefit some of the thalassemia intermedia cases (1), however, the parameters influencing the response to HU have not been reported. In this study, the molecular parameters, alpha-globin and beta-globin genotype and the Xmn I polymorphism, were correlated with the HU response. Twenty patients with thalassemia intermedia were given HU (10-20 mg/kg) and responses were evaluated over a one year period. Twelve patients (60%) showed a good response to therapy with a significant increase in Hb and HbF levels and with elimination of the transfusion requirement in four patients. Four out of the twelve (33%) patients were positive for -alpha(3.7) deletions whereas none of the 8 non-responders were positive for alpha deletions. One each of the responders and non-responders were positive for alpha alpha alpha(anti-3.7) triplication. Three (25%) responsive and one non-responsive patients were homozygous for the IVS1-1 (G-->T) mutation. Three of the responsive patients with alpha deletions were also homozygous positive for Xmn I polymorphism. Thus, in addition to acting in synergy with the XmnI polymorphism, alpha deletions may be an independent factor predicting good response to HU in thalassemia intermedia, although this needs to be confirmation in larger studies.
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PMID:Do alpha deletions influence hydroxyurea response in thalassemia intermedia? 1601 48


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