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PubMed2003

The effect of hydroxyurea on the coagulation system in sickle cell anemia and beta-thalassemia intermedia patients: a preliminary study.

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.

Adolescent↗
PubMed2003

Huge post-operative ulcer following hydroxyurea therapy in a patient with polycythemia vera.

A 75-year old woman was referred to our hospital due to a worsening post-operative cutaneous ulcer. She had a history of polycythemia vera and had been treated with a daily dose of 500mg hydroxyurea (HU) for six years. She underwent a right hernioplasty in another hospital in September 2002. Two days after the hernioplasty, the skin around the wound became erythematous and necrosis was observed. Even with the administration of antibiotics and debridment was performed three times, her condition deteriorated and she was referred to our hospital. On admission, a 22x15cm ulcer was observed on the lower abdomen. With termination of HU, the cutaneous ulcer became smaller and with the withdrawal of other medication, the ulcer size continued to decrease. Although post-operative cutaneous ulcer complicated by HU administration has rarely been reported, our case clearly indicates that early termination of HU should be considered when patients develop symptoms preceding cutaneous ulcer.

Aged↗
PubMed1992

[Treatment of polycythemia vera with hydroxyurea or pipobroman. Efficacy and toxicity analysed from a protocol of 96 patients under 65 years of age. Le Groupe d'Etude des Polyglobulies].

Between 1980 and 1991, 96 patients with documented polycythemia vera were treated by hydroxyurea or pipobroman, according to a protocol including randomization, and maintenance therapy. Complete remission was induced in all cases. Two cases treated with hydroxy-urea had a very severe granulothrombocytopenia during the initial phase. Maintenance was generally satisfactory on pipobroman, but the platelet count often remained high (400 to 900.10(9)/l) on low-dosage hydroxy-urea, with a risk of vascular events. Progressive resistance to these drugs was observed in 5 cases. Digestive and cutaneous troubles were more frequent on pipobroman maintenance, sometimes enough to legitimate a therapeutic change. It may be concluded that such a treatment is less easy to use and to follow than is currently accepted. In the present series (397/years/patients follow-up, median 5-3 years), only one leukemia and one cancer were observed, which however only demonstrates the absence of any carcinogenic risk at short- but not at long-term.

Digestive System Diseases↗
PubMed2004

Response to hydroxyurea treatment in Iranian transfusion-dependent beta-thalassemia patients.

BACKGROUND AND OBJECTIVES: Hydroxyurea (HU) is known to increase gamma-globin chain expression in postnatal life. The efficacy of HU treatment in thalassemia patients is still unclear. The aim of this study was to monitor treatment of a large cohort of patients with beta-thalassemia major in order to establish the response to HU and the associated elements. DESIGN AND METHODS: HU therapy was started in 133 patients diagnosed with transfusion-dependent beta-thalassemia in 1999. The molecular background of the disease, the polymorphisms of the promoter region of the genes, the haplotype of the beta-globin gene cluster, the alpha-gene deletions and the HS2 polymorphism at the locus control region (LCR) of the beta-globin gene cluster were studied. RESULTS: We were able to classify three categories of response: a good response (61%) in patients who shifted from monthly blood transfusion dependency to a stable transfusion-free condition at an average Hb level of more than 10 gm/dL; a moderate response (23%) in patients who remained transfusion dependent but at longer intervals (6 months or more), and non response in patients who, after one year of treatment, remained at the same level of transfusion dependency. The correlations with the molecular defects were found to be secondary to the presence of the (C-->T) at -158 of the Ggamma gene (XmnI polymorphism). The T allele, in linkage to the haplotype I (+----) and to the internal beta-globin gene framework 2, was the most significant modulating factor involved. INTERPRETATION AND CONCLUSIONS: The good response to HU treatment that a significant number of southwest Iranian patients with beta-thalassemia patients had seems to correlate with particular haplotypes. This indicates that HU treatment is a sensible option for transfusion-dependent beta-thalassemia patients with a favorable molecular background.

Adolescent↗
PubMed2005

Decreased plasma endothelin-1 levels in children with sickle cell disease treated with hydroxyurea.

Plasma endothelin-1 (ET-1) is elevated in patients with sickle cell disease (SCD). Hydroxyurea (HU) is the only drug with demonstrated clinical efficacy in SCD. Here we show that treatment with HU results in a decreased concentration of circulating ET-1 which is not correlated with the HU-induced increase in HbF level. Blunting of the ET-1 vasoconstrictive stimulus could contribute to the beneficial effects of HU.

Anemia, Sickle Cell↗
PubMed1992

Macrophage-inflammatory protein protects multipotent hematopoietic cells from the cytotoxic effects of hydroxyurea in vivo.

Macrophage inflammatory protein-1 alpha (MIP-1 alpha) has been assessed for its potential in vivo to protect hematopoietic progenitor cells from the cytotoxic effects of a cycle-specific drug--in this case hydroxyurea (HU). Two doses of HU, 7 hours apart, were administered to mice to induce spleen colony-forming unit (CFU-S) cycling and then to kill them during DNA-synthesis. MIP-1 alpha, in a variety of dose and time combinations, was injected before the second dose of HU in an attempt to prevent recruitment or maintain CFU-S quiescence, and thus protect them from the second dose of HU. Without MIP-1 alpha, recovery of the CFU-S population was complete in 7 days. In a dose-dependent manner, MIP-1 alpha either reduced the initial kill and accelerated recovery, or completely protected the CFU-S population. We conclude that MIP-1 alpha does protect multipotent progenitor cells in vivo and that these observations provide a base from which to build practical clinical applications.

Animals↗
PubMedDate not supplied

Association of cutaneous side-effects of hydroxyurea and neuroendocrine carcinoma.

Many cutaneous side-effects of long term use of hydroxyurea (HU) therapy are well known. We report the first case, to our knowledge, of a neuroendocrine carcinoma located on the finger associated with other cutaneous changes due to this drug. Our patient received HU for two years for an thrombocytemia. This treatment was stopped because of a dermatomyositis-like eruption. Two years later, she developed multiple keratotic lesions, and eight years later, an Merkel cell carcinoma on the third left finger with metastasic evolution. This case suggests HU could be a cofactor of this neuroendocrine carcinoma but a simple coincidence could not be excluded.

Aged↗
PubMed2004

The bone density of thalassemic patients of Boo Ali Sina Hospital, Sari, Iran in 2002 does hydroxyurea help?

Osteopenia and osteoporosis are well known complications in beta thalassemia major (TM) patients. Their main cause is bone marrow hyperfunctioning. Hydroxyurea (HU) has recently been used successfully in TM to control ineffective erythropoiesis. This study was designed to measure the bone density of TM patients and evaluate whether the use of HU in these patients affects the development of osteoporosis. Sixty three patients with TM, 67% female, aged 25 -/+ 7.2, were included in the study. Forty four percent were on HU and 56% had regular blood transfusions. Z-scores of the BD of femur and lumbar spine were -1.85 -/+ .78 and -1.61 -/+ 1.03 respectively and were the same in both sexes. Twenty two percent had normal BD, 45% were osteopenic, 17% had osteoporosis, and 16% had severe osteoporosis. There was no statistically significant correlation between BD and age. In a case-control analysis, BDs of 16 patients taking HU for at least 2 years were compared to 16 patients matched by sex and age who did not use HU. The bone densities in each group were not statistically different. Osteopenia is common in our patients. As a more severe osteopenia was expected in patients who were not on blood transfusions, HU may have some beneficial effect.

Absorptiometry, Photon↗
PubMed2004

Paraplegia due to spinal cord compression by extramedullary erythropoietic tissue in a thalassaemia intermedia patient with gynecomastia secondary to cirrhosis: successful treatment with hydroxyurea.

We report a 24 years old patient with thalassaemia intermedia and gynecomastia, complicated by paraplegia and urinary/fecal incontinence due to spinal cord compression by an extramedullary erythropoiesis (EE) mass, treated with long-term hydroxyurea (HU). Neurological improvement occurred during the first 6 weeks of HU therapy (1,000 mg/day) and magnetic resonance imaging showed a reduction in EE mass. HU dosage was reduced to 500 mg/day after 5 months, and treatment was discontinued after 25 months. Five months later there was a partial recurrence of neurological symptoms, which responded to radiotherapy. HU may have a role in the symptomatic treatment of spinal cord compression due to EE, particularly when radiotherapy is unavailable.

Adult↗
PubMed2004

Healing of leg ulcers with hydroxyurea in thalassaemia intermedia patients with associated endocrine complications.

We report a preliminary clinical experience in the use of hydroxyurea (HU) for the treatment of leg ulcers in thalassaemia intermedia patients with associated endocrine complications. We administered HU 1 g/day to 6 adult patients with thalassaemia intermedia for 90 days. We observed an improvement (3 patients) or healing (3 patients) of chronic leg ulcers. Recurrence was observed in the absence of maintenance therapy (2 patients). Two patients discontinued HU because of adverse effects (stomach pain and fever). No significant increase in total Hb or HbF levels occurred. In conclusion, HU appears suitable for the treatment of leg ulcers unresponsive to conventional treatment in patients with thalassaemia intermedia.

Adult↗
PubMed2006

Combination erythropoietin-hydroxyurea therapy in sickle cell disease: experience from the National Institutes of Health and a literature review.

Erythropoietin is being used more widely in the management of sickle cell disease (SCD, inclusive of homozygous sickle beta, SS, and compound heterozygous sickle beta thalassemia, Sbeta0 thal), often in conjunction with hydroxyurea (HU). Herein, we summarize the published experience with erythropoietin use in SCD, in 39 patients (SS, n = 30; Sb0 thal, n = 9) who were treated between 1990 and 1996; and in 13 patients with sickle syndromes (SS, n = 12, compound heterozygous SC disease, n = 1) who were treated with erythropoietin or darbepoietin at the National Institutes of Health (NIH) since 2002. The dose range of erythropoietin for SCD in the published series, at a median of > 200 U/Kg/dose, is higher than that used in end-stage renal disease. The median duration of erythropoietin therapy was > or =3 months, with minimal reported side-effects. At the NIH, the median age of sickle syndrome patients who received erythropoietin or darbepoietin (both referred to as EPO in the NIH series) was 51 (24 to 70) years; 12/13 patients had sickle-associated pulmonary hypertension. Eleven out of the 13 patients were treated with both HU and EPO for > 4 months (median of 11 months on EPO) without complication. Of the 13 patients, five (all SS) with pulmonary hypertension were given EPO for reticulocytopenia (< 100,000/mL) on HU; 5/13 patients (all SS), with pulmonary hypertension, were given EPO and HU concurrently, in the light of an estimated glomerular filtration rate of < 80 mL/minute. Three of the 13 patients (2 SS, 1 SC) were treated with EPO for miscellaneous reasons. Hematologic responses, detailed herein, suggest that EPO therapy may allow more aggressive HU dosing in high-risk SCD patients and in the setting of mild renal insufficiency, common to the aging sickle cell population. Furthermore EPO appears to be safe in SCD, particularly when used in conjunction with HU. We outline our current therapeutic strategy for EPO use in SCD.

Anemia, Sickle Cell↗
PubMedDate not supplied

Modulating ICBP90 to suppress human ribonucleotide reductase M2 induction restores sensitivity to hydroxyurea cytotoxicity.

BACKGROUND: Ribonucleotide reductase (RR) inhibition by hydroxyurea (HU) causes deoxyribonucleotide (dNTP) depletion, which activates the replication checkpoint, a part of the S-phase checkpoint that responds to DNA damage by inhibiting late origin firing. It also transactivates RR and other genes involved in DNA replication and repair. ICBP90 (overexpressed in breast cancer) is a novel Rb-associating transactivator for the human topoisomerase IIalpha gene and responds to DNA damage-induced checkpoint signaling. MATERIALS AND METHODS: ICBP90 expression was monitored by Western blot. Promoter activity was detected via the luciferase assay and gene silencing via siRNA. Cell death was monitored by the MTT assay. RESULTS: dNTP depletion by HU induced ICBP90, ICBP90 transactivated RR's M2 subunit gene, and ICBP90 induction was necessary for HU-induced M2 accumulation. Blocking the M2 accumulation via anti-ICBP90 siRNA caused greater sensitivity in HU-resistant human cancer. CONCLUSION: A transcriptional intervention strategy is presented through which HU-resistant cancers may be eradicated without dose escalation.

Antineoplastic Agents↗
PubMed2006

Effect of hydroxyurea on the deformability of the red blood cell membrane in patients with sickle cell anemia.

Sickle cell disease is characterized by vaso-occlusive episodes, mainly in the small vessels, resulting in tissue ischemia, multi-organ failure, and, occasionally, death. Hydroxyurea (HU) is an agent with important and effective role in the treatment of patients suffering from this disease. The purpose of this study was to estimate the effect of HU on the deformability of the red blood cell's membrane (RBCM) in an effort to possibly improve the rheological properties of the RBCs of patients with sickle cell anemia (SCA), as well as to investigate the mechanical and rheological properties of these cells using micropipette and filtration techniques. The rigidity index, IR, which is a measure of cell rigidity and the elastic shear modulus, mu, which is a measure of cell's membrane deformability (CMd), of the RBCs from normal subjects, used as normal controls, were found significantly lower as compared to those of patients with SCA, regardless the treatment with HU. Patients under treatment with HU exhibited values better than those of untreated patients, in both, IR as well as mu, although still worse than the values of normal controls.

Adult↗
PubMed1990

Hydroxyurea as a suppressor of the radioprotective effect of dextran sulfate on bone marrow hemopoietic stem cells in mice.

The changes in hemopoiesis of mice following intraperitoneal administration of dextran sulfate (DS) 24 h before irradiation, as well as the effect of injecting them with hydroxyurea (HU), were analyzed. DS increased the proliferation activity and number of hemopoietic stem cells (CFUs) in the bone marrow. The content of CFUs in the bone marrow and the number of endogenous spleen colonies (ESC) of hemopoietic tissue were higher after irradiation in mice treated with DS than in control groups. The survival rate following a lethal radiation dose was also higher. Injection with HU decreased the number of CFUs in animals injected with DS to the level of controls and suppressed its radioprotective effect.

Animals↗
PubMed2006

[Radical mechanism of hydroxyurea side toxicity].

It has been shown that hydroxyurea (HU) induces free radicals which exert cytotoxic effects on cells. However, the molecular mechanism of this effect is still obscure. A possible mechanism for HU-mediated cell death induced by unbalanced growth could be the overproduction, altered accumulation, and progressive leakage of many hydrolytic enzymes through the cell membrane, leading to "lytic" cell death. Protection by antioxidants and radicals scavengers does not change the inhibition of DNA synthesis dependent on ribonucleotide reductase, the main mechanism of the antineoplastic activity of HU. These observations support the hypothesis that membranes are targets for the side effects of HU toxicity. Damage of erythrocytes and granulocytes seems to be an important clinical feature of the HU side toxicity generating free radicals.

Antineoplastic Agents↗
PubMed1991

Effects of hydroxyurea on hemoglobin F and water content in the red blood cells of dogs and of patients with sickle cell anemia.

A rationale for clinical trials of hydroxyurea (HU) treatment in sickle cell disease is that the agent increases red blood cell (RBC) fetal hemoglobin content. However, an additional effect of HU is to raise the mean corpuscular volume (MCV). To investigate the action of HU in a species that makes no electrophoretically distinguishable fetal hemoglobin, we treated dogs with the drug and compared their response to that of five patients with sickle cell anemia. Both dogs and patients had an increase in MCV, but the effect of HU treatment on the mean corpuscular hemoglobin concentration (MCHC), density, and water content of the RBCs differed in the two species. The dog RBCs became low in MCHC, high in ion and water content, and low in mean density. Thus, HU can raise MCV and lower MCHC without influencing fetal hemoglobin synthesis. A different pattern was seen in the sickle cell patients during HU treatment. Although the MCV of their RBCs increased, there was no change in MCHC, ion content, or mean density. A notable change in the sickle cell patients' blood was that two subpopulations of cells were nearly eliminated during HU treatment; the hypodense reticulocyte fraction and the hyperdense fraction that contains irreversibly sickled cells. These findings lead us to suggest that trials of HU in sickle cell disease must recognize the possibility that any beneficial effect of this agent might be due not only to an increase in hemoglobin F alone, but perhaps also to the associated increase in MCV or the altered RBC density profile.

Administration, Oral↗