Acute myocardial infarction in sickle cell disease: a possible complication of hydroxyurea treatment

We describe a 28-year-old man treated with hydroxyurea for sickle cell anemia, who was admitted to the University Hospital with an acute myocardial infarction. The patient had evolved high hematocrit values during his long-term hydroxyurea treatment, suggesting a correlation between a possible increment in blood viscosity and the coronary occlusion without previous lesions. Indeed, several studies associate vasocclusive episodes and severe clinical course with high viscosity. Although hydroxyurea is considered an effective therapeutic option for these patients, care should be taken to monitor hematocrit levels and possible complications. Hematocrit and hemoglobin values of above 30% and 10.5 g/dl in SS patients on hydroxyurea therapy should be avoided or closely monitored.

Hydroxyurea for sickle cell disease in children and for prevention of cerebrovascular events: the Belgian experience

Hydroxyurea (HU) is considered to be the most successful drug therapy for severe sickle cell disease (SCD). Nevertheless, questions remain regarding its benefits in very young children and its role in the prevention of cerebrovascular events. There were 127 SCD patients treated with no attempt to reach maximal tolerated doses who entered the Belgian Registry: 109 for standard criteria and 18 who were at risk of stroke only. During 426 patient-years of follow-up for patients with standard criteria, 3.3 acute chest syndromes, 1.3 cerebrovascular events, and 1.1 osteonecrosis per 100 patient-years were observed. A subgroup of 32 patients followed for 6 years experienced significant benefit over this period. In each subgroup of children (younger than 2 years, 2-5, 6-9, and 10-19 years) followed for 2 years, clinical and biologic changes were similar, except for children younger than 2 years who had no total hemoglobin increase and remained at risk of severe anemia. In 72 patients evaluated by transcranial Doppler studies (TCD), 34 patients were at risk of primary stroke and only 1 had a cerebrovascular event after a follow-up of 96 patient-years. These results confirm the benefit of HU, even in very young children, and its possible role in primary stroke prevention.

Effects of a pharmacologically-induced shift of hemoglobin-oxygen dissociation on myocardial energetics during ischemia in patients with coronary artery disease

BACKGROUND

Conventional strategies to treat myocardial ischemia include interventions that reduce oxygen demand and/or increase myocardial blood flow. Animal experiments suggest that right-shifting the hemoglobin-oxygen dissociation curve may also attenuate the metabolic consequences of myocardial ischemia. We evaluated whether exercise-induced myocardial ischemia can be alleviated in subjects with coronary artery disease (CAD) by enhancing oxygen release with an allosteric modifier of hemoglobin's affinity for oxygen (RSR13).

METHODS AND RESULTS

Seven subjects with CAD underwent a randomized, double-blind, cross-over study of the metabolic consequences of RSR13 administration on myocardial ischemia. Myocardial high-energy phosphates were quantified with 31P nuclear magnetic resonance (NMR) spectroscopy before, during, and after isometric handgrip-exercise. Subjects underwent NMR studies at baseline and on two separate occasions following the infusion of RSR13 (100 mg/kg) or placebo. RSR13 infusion significantly increased mean p50 by 8.1 +/- 2.7 mmHg at the end of the infusion, and it was still elevated by 4.9 +/- 3.3 mmHg after the completion of the treadmill tests while placebo had no effect. The myocardial creatine-phosphate (PCr) to adenosine-triphosphate (ATP) ratio decreased during handgrip-exercise in the baseline studies (from 1.39 +/- 0.23 before exercise to 0.95 +/- 0.21 during handgrip-exercise, p = 0.0001) and in the placebo studies (from 1.29 +/- 0.16 to 0.98 +/- 0.37, p = 0.06) but not during administration of RSR13 (from 1.28 +/- 0.18 to 1.02 +/- 0.24, p = 0.12). However, the mean values of cardiac PCr/ATP during handgrip-exercise did not differ significantly among the three measurements (baseline, placebo, RSR13).

CONCLUSIONS

A single infusion of RSR13 to subjects with CAD increased mean p50 by 4.9-8.1 mmHg but did not significantly alter myocardial PCr/ATP during exercise. This is the largest right-shift in hemoglobin-oxygen binding affinity achieved in CAD subjects, and it did not provide clear evidence of protection from cardiac ischemia.

Sustained long-term hematologic efficacy of hydroxyurea at maximum tolerated dose in children with sickle cell disease

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.

Hydroxyurea-induced splenic regrowth in an adult patient with severe hemoglobin SC disease

Hydroxyurea has been extensively used in patients with sickle cell anemia and severe sickle cell-hemoglobin C (SC) disease to reduce the severity of their diseases. We report here our experience with an adult patient with severe SC disease who developed symptomatic splenomegaly requiring splenectomy while being treated with hydroxyurea. This case suggests that hydroxyurea might restore some splenic function in functionally asplenic patients with sickle cell anemia or SC disease, but also raises the clinical concern that hydroxyurea may induce splenic regrowth, resulting in symptomatic splenomegaly. With the increasing use of hydroxyurea in the management of SS disease or other hemoglobinopathies, the importance of spleen monitoring must be further emphasized in these patients.

Are we underestimating the leukemogenic risk of hydroxyurea

Hydroxyurea is an established drug that has been used for the treatment of myeloproliferative disorders and some solid tumors for some time. In recent years it has also been found to be effective in the treatment of sickle cell disease. Short term side effects are not serious, and are manageable. The major concern is the potential leukemogenesis with long term use. The risk of leukemogenesis is not defined with its use in benign hematological conditions. We report a case of acute myeloid leukemia with no preceding myelodysplastic syndrome, occurring after 2 years of hydroxyurea therapy in a patient with sickle cell disease.

Personal exposure and long-term health effects in survivors of the union carbide disaster at bhopal

Nine years after the Bhopal methyl isocyanate disaster, we examined the effects of exposures among a cross-section of current residents and a subset of those with persistent symptoms. We estimated individual exposures by developing exposure indices based on activity, exposure duration, and distance of residence from the plant. Most people left home after the gas leak by walking and running. About 60% used some form of protection (wet cloth on face, splashing water). Mean and median values of the exposure indices showed a declining trend with increasing distance from the plant. For those subjects reporting any versus no exposure, prevalence ratios were elevated for most respiratory and nonrespiratory symptoms. We examined exposure-response relationships using exposure indices to determine which were associated with health outcomes. The index total exposure weighted for distance was associated with most respiratory symptoms, one measure of pulmonary function in the cross-sectional sample [mid-expiratory flow (FEF)(25-75), p = 0.02], and two measures of pulmonary function in the hospitalized subset [forced expiratory volume (FEV)(1), p = 0.02; FEF(25-75), p = 0.08). Indices that correlated with FEV(1) and forced vital capacity in the hospitalized subset did not correlate with the cross-sectional sample, and most indices (except total exposure) that correlated with the hospitalized subset did not correlate with the cross-sectional sample. Incorporation of distance into every index increased the number of symptoms associated; an improvement was also noted in the strength of the association for respiratory symptoms, but not for pulmonary function. The sum of duration (p = 0.02) and total exposure (p = 0.03) indices independently demonstrated stronger associations with percent predicted FEF(25-75) than the distance variable (p = 0.04). The results show that total exposure weighted for distance has met the criteria for a successful index by being associated with most respiratory symptoms as well as FEF(25-75), features of obstructive airways disease.

Hydroxyurea therapy associated with declining serum levels of magnesium in children with sickle cell anemia

OBJECTIVE

To obtain quantitative serum levels of total and ionized magnesium (Mg(2+)) in children with homozygous sickle cell anemia (SCA) undergoing therapy with hydroxyurea.

STUDY DESIGN

Five children, ages 11 to 14 years with homozygous SCA, were enrolled in a dose-escalating trial of hydroxyurea over an 18-month period. Serum levels of total and ionized magnesium together with ionized K(+), Na(+), and Ca(2+) were measured before hydroxyurea and every 6 months during hydroxyurea therapy.

RESULTS

Before treatment, 4 of the 5 patients had low or below-normal serum concentrations of Mg(2+) (normal range, 0.51-0.67 mmol/L). All 5 became Mg(2+)-deficient during hydroxyurea therapy, with no indication of recovery until after 12 to 18 months of drug administration (P <.05). Similar changes were noted for total magnesium concentrations. Mean serum levels of K(+), Na(+), and Ca(2+) remained consistently within normal ranges.

CONCLUSIONS

These findings warrant a controlled study of the effects of magnesium supplementation in patients with SCA receiving hydroxyurea. Potentially, such therapy could alleviate or prevent vaso-occlusive crises.

Predictors of fetal hemoglobin response in children with sickle cell anemia receiving hydroxyurea therapy

In the phase I/II pediatric hydroxyurea safety trial (HUG-KIDS), school-aged children with sickle cell anemia receiving hydroxyurea at the maximally tolerated dose (MTD) had variable increases in the percentage of fetal hemoglobin (%HbF). To identify predictors of the HbF response to hydroxyurea therapy, baseline clinical and laboratory values (age, sex, hemoglobin concentration, %HbF, reticulocytes, white blood cell [WBC], platelets, and serum chemistries), as well as treatment variables (number of toxicities, noncompliance, MTD dose, and MTD blood counts) were analyzed in 53 HUG-KIDS children who achieved MTD. Baseline %HbF values (P =.001), baseline hemoglobin concentration (P =.01), MTD dose (P =.02), and compliance (P =.02) were significantly associated with a higher %HbF at MTD; in contrast, age, sex, number of toxicities, and other baseline hematologic parameters were not. After adjusting for variations in baseline %HbF, the baseline reticulocyte count (P =.05) and baseline WBC count (P =.05) were also significantly associated with a higher %HbF at MTD. Hydroxyurea-induced increases in the hemoglobin concentration and mean corpuscular volume (both higher absolute values at MTD and larger positive changes from baseline values), as well as hydroxyurea-induced decreases in reticulocytes and WBC count, were significantly associated with a higher %HbF at MTD. These data suggest that selected baseline laboratory parameters, a higher MTD dose with attention to compliance, and greater therapy-related changes in blood counts may predict the HbF response to hydroxyurea therapy for children with sickle cell anemia. The HbF response to hydroxyurea is variable and complex, however, and even children with low baseline %HbF values can develop substantial increases in %HbF at MTD.

A two-year pilot trial of hydroxyurea in very young children with sickle-cell anemia

OBJECTIVE

Hydroxyurea improves hematologic values and decreases vaso-occlusive complications in adults and children with sickle cell anemia (SCA), but has not been tested in infants before the onset of chronic organ dysfunction. We conducted a collaborative pilot trial of hydroxyurea in infants with SCA to assess its (1) feasibility of administration, (2) toxicity, (3) hematologic effects, and (4) effect on spleen function.

STUDY DESIGN

Patients with hemoglobin (Hb) SS or Sbeta(0) thalassemia (n = 28, median age 15 months) received hydroxyurea for 2 years at 20 mg/kg/day. Hydroxyurea was temporarily discontinued for predefined toxicity.

RESULTS

Seven patients exited the study early: five for noncompliance or refusal to continue, one for mild stroke, and one for fatal splenic sequestration. The predominant toxicity was transient neutropenia, which was usually associated with a viral-like illness. After 2 years of treatment, mean Hb level = 8.8 g/dL and Hb F = 20.3%, both higher than predicted age-specific levels. Radionuclide splenic uptake was absent in 47% of patients at study completion, compared with predicted functional asplenia in 80% of the patients.

CONCLUSIONS

Hydroxyurea therapy for infants with SCA is feasible and well tolerated, has hematologic efficacy, and may delay functional asplenia. The potential for hydroxyurea to preserve organ function in SCA should be further evaluated.

Hydroxyurea therapy for pediatric patients with hemoglobin SC disease

PURPOSE

Hydroxyurea (HU) has laboratory and clinical efficacy in hemoglobin SS (HbSS) disease, but its benefits in hemoglobin SC (HbSC) disease are unknown. A recent adult HbSC disease pilot trial with HU therapy documented a modest laboratory benefit. Our goal was to evaluate the laboratory and clinical responses of selected pediatric patients with severe HbSC disease to HU therapy.

PATIENTS AND METHODS

As part of a retrospective case series, patients were selected from the Duke Pediatric Sickle Cell Program based on the frequency and severity of their vasoocclusive events or an episode of acute chest syndrome. Oral HU therapy was started as a single daily dose and increased to the maximally tolerated dose based on myelosuppression. Laboratory evaluation was performed at baseline and monthly thereafter. Once the maximum tolerated dose was reached, laboratory data were monitored bimonthly.

RESULTS

We treated six severely affected pediatric HbSC patients with HU for a median of 27 months. Mean corpuscular volume increased significantly (+26 fL) without change in hemoglobin concentration (-0.1 g/dL); neutrophils decreased significantly. Percentage of fetal hemoglobin (+8.5%) and percentage of F cells (+35.7%) increased significantly. Two experienced only mild and reversible toxicity.

CONCLUSION

The laboratory responses in our pediatric patients with HbSC disease were striking, with increases in percentage of fetal hemoglobin and percentage of F-cells approaching responses observed in adult and pediatric patients with HbSS disease. All patients improved clinically. Our findings demonstrate that HU therapy benefits pediatric patients with severe HbSC disease, although larger clinical trials of HU therapy in HbSC disease are warranted.

Skin and nail changes in children with sickle cell anemia receiving hydroxyurea therapy

Skin and nail changes from long-term hydroxyurea therapy are reported in adults. Skin and nail changes, including nail hyperpigmentation, longitudinal bands, and hyperpigmentation of the palms and other skin surfaces, developed in 7 children with sickle cell anemia after 6 to 16 weeks of hydroxyurea therapy. Cutaneous and nail changes may occur in children receiving hydroxyurea.

Cutaneous adverse reactions to hydroxyurea in patients with sickle cell disease

BACKGROUND

Treatment with hydroxyurea may alleviate the symptoms of sickle cell disease (SCD). Because treatment with hydroxyurea may be responsible for several cutaneous side effects and is often lifelong in patients with SCD, we conducted this study to evaluate the risk of cutaneous adverse reactions in SCD patients treated with hydroxyurea.

OBSERVATIONS

Seventeen adult patients with SCD treated with hydroxyurea at one institution were examined by a dermatologist. Hydroxyurea was given for a mean of 3.04 years (range, 0.42-6.5 years). None of the patients had skin cancer, but 5 (29%) had disabling hydroxyurea-induced leg ulcers. Four of these 5 patients had a previous history of SCD ulcer, compared with none of the 12 patients without hydroxyurea-induced leg ulcers (P<.05). The mean age of patients with induced ulcers was 35.8 years and for those without ulcers was 23.5 years (P<.01).

CONCLUSIONS

Our rate of hydroxyurea-induced leg ulcers (29%) is higher than that reported for patients with myeloproliferative syndromes (9%). In addition, use of hydroxyurea has induced ulcers mainly in patients with previous SCD ulcers, suggesting that hydroxyurea could act in conjunction with other vascular abnormalities. Careful attention should be required when giving hydroxyurea to patients with SCD with previous ulcers as well as in older patients with SCD.

Hydroxyurea therapy in sickle cell anemia patients in Curaçao, The Netherlands Antilles

We have treated 9 patients with sickle cell anemia (SS) with hydroxyurea (HU). All 9 patients carried 4 alpha-globin genes and the beta s-globin haplotypes 19/19 (Benin/Benin), except for 1 who had haplotype 19 together with type 3 (Benin/Senegal). Six patients received HU for 10 months and were again treated with the drug for 5 months after an interval of 1 year. One patient was given HU for 22 consecutive months. A record was kept of hematological and biochemical data, Hb F and G gamma levels, as well as possible clinical complications. Our data show that HU generally improves the hematological and biochemical values and the level of Hb F, and reduces painful crises in some patients. However, although the clinical symptoms improved in some patients during HU therapy, the older patients did not observe any changes in their general condition; the same is the case for the patient with haplotype 19/3. One patient also experienced life-threatening liver sequestration during treatment. We conclude that the selection of patients who may benefit from HU therapy needs further evaluation.

Clinical and hematological responses to hydroxyurea in Sicilian patients with Hb S/beta-thalassemia

Although, several reports have detailed that hydroxyurea can ameliorate the clinical course of adult and pediatric patients with sickle cell anemia (Hb S or beta(S)), few clinical studies have been carried out in patients with beta(S)/beta-thalassemia. In a two-year clinical study, we evaluated the efficacy of hydroxyurea in a group of 22 adult Sicilian patients with beta(S)/beta-thalassemia with severe phenotypes. Among the 20 patients evaluated during 2 years of treatment, we observed a very good clinical response with a 93% reduction of the annual number of crises (median 7 versus 0.5 crises per year; P < 0.001) and of days in hospital (mean 22+/- 21.9 versus 1.2 +/- 2.3; P < 0.001), a significant increase in Hb F (7.5 +/- 5.3% versus 25.2 +/- 5.2%; P < 0.001) and in MCV (73.1 +/- 4.8 fL versus 96.4 +/- 7.2 fL; P < 0.001), and no significant modifications in Hb (9.6 +/- 1.3 g/dL versus 10.0 +/- 1.5 g/dL; P > 0.05) and in WBC (11.4 +/- 3.9 x 10(9)/L versus 10.2 +/- 3.9 x 10(9)/L; P > 0.05). Twelve patients had no crises from the first month of treatment; 16 patients showed a 2-3-fold increase over baseline in Hb F. During the study no severe complications and no important side effects of hydroxyurea were observed. Our data suggest that hydroxyurea efficacy in patients with beta(S)/beta-thalassemial may be greater than that described in patients with sickle cell disease. This pattern and durability of response will need to be confirmed in a larger, randomized, clinical trial.

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.

Hydroxyurea-induced marked oscillations of platelet counts in patients with polycythemia vera

Two prospectively studied patients with polycythemia vera (PV) whose platelet counts showed marked periodic fluctuation during treatment with hydroxyurea (HU) are reported. Cycle lengths in both were approximately 28 to 30 days. In one patient, the cyclic process was no longer evident when treatment with HU was withheld, and it reappeared on treatment rechallenge. Circulating thrombopoietin (TPO) levels fluctuated out of phase with the platelet count despite markedly reduced TPO-receptor (c-Mpl) expression in bone marrow megakaryocytes. These observations suggest that the cyclic phenomenon may be related to both a transient state of HU-induced depletion of megakaryocytes and a concentration-dependent mitigation by TPO of the HU effect on megakaryocytes and their precursors. It is conceivable that the affected patients harbor a megakaryocyte progenitor pool whose apoptotic activity is differently modulated by either HU or high concentrations of TPO. (Blood. 2000;96:1582-1584)

Acquired DNA mutations associated with in vivo hydroxyurea exposure

Hydroxyurea (HU) is an effective therapeutic agent for patients with myeloproliferative disorders (MPDs) or sickle cell disease (SCD). Short-term HU toxicities primarily include transient myelosuppression, but long-term HU risks have not been defined. The mutagenic and carcinogenic potential of HU is not established, although HU has been associated with an increased risk of leukemia in some patients with MPD. In this study, 2 assays were used to quantitate acquired somatic DNA mutations in peripheral blood mononuclear cells (PBMCs) after in vivo HU exposure. The HPRT assay measures hypoxanthine phosphoribosyl transferase (hprt) mutations, while the VDJ assay identifies "illegitimate" T-cell receptor Vgamma-Jbeta interlocus recombination events. PBMCs were analyzed from patients with MPD, adults and children with SCD, and normal controls. MPD patients with prolonged HU exposure had numbers of DNA mutations equivalent to patients with low HU exposure or controls. Similarly, adults with SCD had equivalent numbers of DNA mutations regardless of HU exposure. Children with SCD and 30-month HU exposure had equivalent hprt(-) mutations but significantly more VDJ mutations (1.82 +/- 1.20 events per microg DNA) than children with 7-month HU exposure (1.58 +/- 0.87 events) or no HU exposure (1.06 +/- 0.45 events), P =.04 by analysis of variance. Taken together, these data suggest that the mutagenic and carcinogenic potential of in vivo HU therapy is low. Although increased numbers of illegitimate VDJ recombination events do not directly portend leukemia, young patients with SCD and HU exposure should be monitored serially for increases in DNA mutations.

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

AIM

To evaluate the tolerance of hydroxyurea in children affected with sickle cell disease.

DESIGN

Questionnaire study of French physicians likely to treat patients with sickle cell disease. Data were collected on 101 children with sickle cell disease, treated for a median of 22 months, 36 of whom were treated for more than three years. 13 children were younger than 5 years of age at inclusion.

RESULTS

Hydroxyurea was stopped for medical reasons in 11 patients: 6 failures, 1 pregnancy, 1 cutaneous rash, 1 leg ulcer, 1 lupus. Acute lymphoblastic leukaemia occurred in a girl treated for 1.5 months with hydroxyurea, this short interval arguing against a causative association. One 17 year old boy had paraparesis after 8 years of treatment.

CONCLUSIONS

No major short or medium term toxicity was related to hydroxyurea in this cohort of 101 children. However, the number of children treated for more than 3 years is too few to make firm conclusions on the long term tolerance of this drug.