Malignancy in patients with sickle cell disease

The effect of prolonged administration of hydroxyurea on morbidity and mortality in adult patients with sickle cell syndromes: results of a 17-year, single-center trial (LaSHS)

The aim of this prospective study was to evaluate the long-term efficacy and safety of hydroxyurea (HU) in patients with sickle cell disease (SCD). Thirty-four patients with sickle cell anemia (hemoglobin S [HbS]/HbS), 131 with HbS/beta(0)-thal, and 165 with HbS/beta(+)-thal participated in this trial. HU was administered to 131 patients, whereas 199 patients were conventionally treated. The median follow-up period was 8 years for HU patients and 5 years for non-HU patients. HU produced a dramatic reduction in the frequency of severe painful crises, transfusion requirements, hospital admissions, and incidence of acute chest syndrome. The probability of 10-year survival was 86% and 65% for HU and non-HU patients, respectively (P = .001), although HU patients had more severe forms of SCD. The 10-year probability of survival for HbS/HbS, HbS/beta (0)-thal, and HbS/IVSI-110 patients was 100%, 87%, and 82%, respectively, for HU patients and 10%, 54%, and 66%, for non-HU patients. The multivariate analysis showed that fetal hemoglobin values at baseline and percentage change of lactate dehydrogenase between baseline and 6 months were independently predicted for survival in the HU group. These results highlight the beneficial effect of HU, which seems to modify the natural history of SCD and raise the issue of expanding its use in all SCD patients.

Advances in the use of hydroxyurea

Clinical experience with hydroxyurea for patients with sickle cell disease (SCD) has been accumulating for the past 25 years. The bulk of the current evidence suggests that hydroxyurea is well-tolerated, safe, and efficacious for most patients with SCD. Hydroxyurea has proven clinical efficacy for reducing acute vaso-occlusive events including pain episodes and acute chest syndrome. Salutary effects on hematological parameters include increases in fetal hemoglobin (HbF), hemoglobin, and MCV; also significant decreases occur in WBC, ANC, reticulocytes, LDH, and bilirubin. Treatment with hydroxyurea is usually considered for patients with recurrent vaso-occlusive events, but additional indications for treatment may include laboratory markers of disease severity and evidence of chronic organ dysfunction. Ten years ago, the US Food and Drug Administration approved hydroxyurea for adult patients with clinically severe SCD; however, its use in children remains off-label. Despite the large body of evidence regarding its efficacy and safety, hydroxyurea is currently prescribed only sparingly for patients with SCD and therefore has only limited effectiveness for this disorder; barriers to its use need to be identified and overcome.

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.

A cell stress signaling model of fetal hemoglobin induction: what doesn't kill red blood cells may make them stronger

A major goal of hemoglobinopathy research is to develop treatments that correct the underlying molecular defects responsible for sickle cell disease and beta-thalassemia. One approach to achieving this goal is the pharmacologic induction of fetal hemoglobin (HbF). This strategy is capable of inhibiting the polymerization of sickle hemoglobin and correcting the globin chain imbalance of beta-thalassemia. Despite this promise, none of the currently available HbF-inducing agents exhibit the combination of efficacy, safety, and convenience of use that would make them applicable to most patients. The recent success of targeted drug therapies for malignant diseases suggests that this approach could be effective for developing optimal HbF-inducing agents. A first step in applying this approach is the identification of specific molecular targets. However, while >70 HbF-inducing agents have been described, neither molecular mechanisms nor target molecules have been definitively verified for any of these compounds. To help focus investigation in this area, we have reviewed known HbF-inducing agents and their proposed mechanisms of action. We find that in many cases, current models inadequately explain key experimental results. By integrating features of the erythropoietic stress model of HbF induction with data from recent intracellular signaling experiments, we have developed a new model that has the potential to explain several findings that are inconsistent with previous models and to unify most HbF-inducing agents under a common mechanism: cell stress signaling. If correct, this or related models could lead to new opportunities for development of targeted therapies for the beta-hemoglobinopathies.

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.

Hydroxyurea for children with sickle cell disease

Hydroxyurea therapy offers promise for ameliorating the clinical course of children with sickle cell disease (SCD). Hydroxyurea is a prototypic therapeutic option; it can be administered with minimal side effects, has a relatively wide therapeutic window, and has mechanisms of action that address pathophysiologic pathways of sickling, vaso-occlusion, hemolysis, and organ damage. There are limited data regarding hydroxyurea's ability to prevent or diminish organ dysfunction, and the long-term risks of hydroxyurea therapy remain incompletely defined. Although clinical trials are underway to address long-term issues, hydroxyurea remains an effective but underutilized therapy for SCD.

Decreased transfusion needs associated with hydroxyurea therapy in Algerian patients with thalassemia major or intermedia

BACKGROUND

Studies of evolution of transfusion requirements in thalassemic patients treated with hydroxyurea have produced somewhat conflicting results, especially in patients with thalassemia major. Our aims were to determine the proportion of good responders to hydroxyurea in a population of transfusion-dependent thalassemic patients and to identify the factors associated with a decrease of transfusion needs.

STUDY DESIGN AND METHODS

Hydroxyurea treatment was initiated in 9 patients with thalassemia intermedia (TI) and 45 with thalassemia major (TM). Patients received transfusions when their hemoglobin (Hb) levels dropped below 6 g per dL. A decrease in annual transfusion requirements greater than 70 percent defined a good response, between 40 and 70 percent a partial response, and smaller than 40 percent no response.

RESULTS

The response was good in 8 (90%) patients with TI and 20 (44.5%) with TM, partial in 9 (20%) patients with TM, and absent in 1 (10%) with TI and 16 (35.5%) with TM. In TM patients, transfusion needs decreased by 56 percent over the first year of hydroxyurea treatment. By univariate analysis, a better response to hydroxyurea was associated with older age at the first transfusion (p = 0.02), higher prehydroxyurea Hb (p = 0.0004), codon 6(-A) mutation (p = 0.002), TI (p = 0.03), and history of splenectomy (p = 0.05). Xmn1-/- was associated with a worse response (p = 0.0001). By multivariate analysis, a better response was associated with the Xmn1 polymorphism (p = 0.008).

CONCLUSION

Hydroxyurea may be an alternative to transfusions for TI patients as well as for TM patients in countries that have limited blood supplies.

How would I manage a case of essential thrombocythaemia presenting with an ischaemic toe

Essential thrombocythaemia (ET) is an acquired myeloproliferative disorder. The phenotypic and biological heterogeneity of ET can make management of individual cases problematic, especially in the era of changing ideas on the molecular pathogenesis of this disease process. This case discussion will explore the evidence base and rationale that guides treatment of a 46-year-old individual with ET presenting with an ischaemic episode.

Hodgkin lymphoma in a child with sickle cell anemia

There are reports of patients with sickle cell disease who developed hematological malignancies but the relationship between these malignancies and sickle cell disease (SCD) is not yet defined. The co-existence of a hematological malignancy with SCD poses certain challenges for the management of each condition. We describe a 7-year-old boy with sickle cell anemia who developed Hodgkin's lymphoma and the challenges of management. He presented with a 4-year history of bilateral neck swelling and a 2-month history of weight loss and high-grade fever. Histology of a lymph node biopsy was consistent with mixed cellularity Hodgkin's lymphoma. He was treated with five cycles of Cyclophosphamide, Vincristine, Procarbazine and Prednisolone (COPP) and had complete clinical response. Chemotherapy was associated with an increase in frequency of painful crises and complicated by septicaemia. Blood transfusion needs were minimal; apart from the transfusion preceding the first cycle of chemotherapy, there was no need for further transfusion. Myelosuppression was not a problem in the patient; he responded well to antibiotics during the two episodes of septicemia without the use of hemopoetic growth factor. Patients with sickle cell anaemia who develop Hodgkin's lymphoma can be successfully treated with chemotherapy along with supportive management for crises and infections.

Essential thrombocythemia: a review of diagnostic and pathologic features

CONTEXT

Essential thrombocythemia (ET) is a chronic myeloproliferative disorder (CMPD) characterized predominately by thrombocytosis and abnormal megakaryocyte proliferation. The current diagnostic criteria require a combination of clinical, histologic, and cytogenetic data. The diagnosis relies largely on exclusion of other causes of thrombocytosis.

OBJECTIVE

Describe historical, clinical, and laboratory features of ET in order to understand, clarify, and more accurately diagnose this entity.

DATA SOURCES

Review contemporary and historical literature on ET and other causes of thrombocytosis.

CONCLUSIONS

ET is a relatively indolent and often asymptomatic CMPD that is characterized primarily by a sustained elevation in platelets > or = 600 x 10(3)/microL (> or = 600 x 10(9)/L), proliferating enlarged and hyperlobated megakaryocytes, and minimal to absent bone marrow fibrosis. Significant changes and revisions to the diagnostic requirements and criteria for ET have occurred during the last 30 years. Recently, a mutation in the Janus kinase 2 (JAK2) gene has been found in a significant number of cases of ET and other CMPDs. In up to 57% of ET cases, a mutation in the JAK2 gene can be detected. In the absence of a JAK2 mutation and features of another CMPD, the diagnosis of ET remains a diagnosis of exclusion after other causes of thrombocytosis have been excluded.

Parents' assessment of risk in sickle cell disease treatment with hydroxyurea

Hydroxyurea is the only medication shown to reduce the severity of sickle cell disease (SCD), but its long-term risks are unknown. Families of 58 children with SCD were interviewed on their perception of the potential risks of hydroxyurea treatment, and whether disease severity was a major factor in their treatment decision. Parents rated the severity of their child's SCD (86% as severe, 26% moderate, and 47% mild) and then the highest levels of risk that they would tolerate for both potential cancer (range 1/1,000 to 1/2) and potential birth defects (range 1/1,000 to 1/3) to benefit their child with hypothetical hydroxyurea treatment. Parents of 29 of the 58 children were unwilling to take any cancer risk whatsoever as a potential side effect of treatment, and 29 of 58 (not all the same parents) were unwilling to take any risk for birth defects, including half the children with severe SCD. For those families who did accept some risk, higher acceptable risk correlated with higher disease severity in the child (P = 0.04). The study's mixed findings highlight the complexities of risk perception and suggest that future studies of risks and benefits from the parental viewpoint are needed as candidate therapies are developed for SCD.

Long-term hydroxyurea therapy for infants with sickle cell anemia: the HUSOFT extension study

The long-term efficacy and toxicity of hydroxyurea for infants are undefined, and its role in preventing organ dysfunction is unknown. Short-term feasibility of hydroxyurea administration, toxicities, hematologic effects, and effect on spleen function in infants with sickle cell anemia (SCA) were reported (Hydroxyurea Safety and Organ Toxicity [HUSOFT] trial). These infants completing 2 years of hydroxyurea therapy (20 mg/kg/d) were offered study extension with dose escalation to 30 mg/kg/d. Patients were monitored with laboratory tests and biannual imaging studies. Hematologic indices were compared with predicted age-specific values and event rates compared with historic rates. All 21 subjects completing the original trial enrolled in the extension study: median age, 3.4 years old (range, 2.6 to 4.4 years); 12 females; 20 with Hb SS, 1 with Hb S/beta0-thalassemia. Seventeen patients completed 4 years of hydroxyurea, and 11 completed 6 years. After 4 years, hydroxyurea was associated with increased hemoglobin concentration, percentage of fetal hemoglobin (Hb F), and mean corpuscular volume (MCV) and decreased reticulocytes, white blood cells (WBCs), and platelets (P < .01). Patients experienced 7.5 acute chest syndrome (ACS) events per 100 person-years, compared with 24.5 events per 100 person-years among historic controls (P = .001). Treated patients had better spleen function than expected and improved growth rates. Infants with SCA tolerate prolonged hydroxyurea therapy with sustained hematologic benefits, fewer ACS events, improved growth, and possibly preserved organ function.

Clinical studies with fetal hemoglobin-enhancing agents in sickle cell disease

Fetal hemoglobin (HbF, alpha2gamma2) decreases polymerization of sickle hemoglobin, and high levels correlate with decreased morbidity and mortality in sickle cell disease (SCD). Therefore, a therapeutic goal for patients with SCD is pharmacologic reactivation of HbF. Decreased HbF production is associated with DNA methylation (by DNA methyltransferase [DNMT]) at the gamma-globin (HbF) gene promoter. The cytosine analogs 5-azacytidine and 5-aza-2'-deoxycytidine (decitabine) hypomethylate DNA by inhibiting DNMT. In early studies, 5-azacytidine produced significant HbF elevations in patients with thalassemia and SCD, but clinical development of this class of agent was halted after a poorly controlled animal study suggested that 5-azacytidine might be carcinogenic. However, the majority of preclinical studies with decitabine have suggested a chemopreventive rather than carcinogenic effect. Furthermore, decitabine, unlike 5-azacytidine, does not incorporate into RNA and is a more directed DNA-hypomethylating agent. Therefore, we have pursued studies of decitabine to pharmacologically reactivate HbF in patients with SCD. In phase I/II studies, decitabine at DNA-hypomethylating, but noncytotoxic, doses was well tolerated and effective at increasing HbF and total hemoglobin levels both in patients who had and had not responded to prior hydroxyurea therapy. In treated patients, there were marked improvements in a range of surrogate clinical endpoints measuring red blood cell adhesion, endothelial damage, and coagulation pathway activity. Pharmacologic reactivation of HbF through DNA hypomethylation holds promise as an effective disease-modifying intervention for patients with SCD. Larger studies are required to confirm the safety and effectiveness of decitabine with chronic use, and to more clearly establish its role in patients with SCD.

DNA hypo-methylating agents and sickle cell disease

Fetal haemoglobin (HbF, alpha2) decreases polymerization of sickle haemoglobin (HbS) and high levels correlate with decreased morbidity and mortality in sickle cell disease (SSD). Therefore, a therapeutic goal in SSD is the pharmacologic reactivation of HbF. Silencing of the globin (HbF) gene is associated with DNA methylation. The cytosine analogues 5-azacytidine and 5-aza-2'-deoxycytidine (decitabine) hypomethylate DNA by inhibiting DNA methyl-transferase. In clinical trials, 5-azacytidine and decitabine have demonstrated the greatest efficacy in HbF reactivation. Clinical development of these drugs has been delayed by concerns regarding the carcinogenic potential of 5-azacytidine. Furthermore, controversy regarding DNA hypomethylation versus more generic cytotoxic effects as the mechanism of action suggested that other cytotoxic/cytostatic agents might be as effective. Additional preclinical data and clinical studies of decitabine have tempered many safety concerns and have confirmed that DNA hypomethylation is the mechanism of action. Pharmacologic reactivation of HbF through DNA hypomethylation holds promise as an effective disease modifying intervention for patients with SSD. Larger studies are required to confirm safety and effectiveness with chronic use.