Hydroxyurea for children with sickle cell disease.
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ABSTRACT:
SUBMITTER: Heeney MM
PROVIDER: S-EPMC4765496 | biostudies-other | 2010 Feb
REPOSITORIES: biostudies-other
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Hydroxyurea for children with sickle cell disease.
Heeney Matthew M MM Ware Russell E RE
Hematology/oncology clinics of North America 20100201 1
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 ris ...[more]
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Project description:BackgroundGrowth impairment is a known complication of sickle cell disease. Effects of hydroxyurea (HU) on growth in very young children are not known.MethodsHeight, weight, BMI, and head circumference (HC) were compared with World Health Organization (WHO) standards in BABY HUG, a multicenter, randomized, double-blinded, placebo-controlled 2-year clinical trial of HU in 193 children 9 to 18 months of age. Anthropometric data were closely monitored and converted to z scores by using WHO standardized algorithms for descriptive analyses. The treatment and placebo groups were compared longitudinally by using a mixed model analysis.ResultsAt entry, the z scores of BABY HUG children were higher than WHO norms. After 2 years of HU or placebo treatment, there were no significant differences between the groups, except for the mean HC z scores at study exit (HU: +0.8 versus placebo: +1.0, P = .05). Baseline z scores were the best predictors of z scores at study exit. The absolute neutrophil count, absolute reticulocyte count, and total white blood cell count had significant negative correlations with growth measures.ConclusionsBoth groups had normal or near normal anthropometric measures during the study. The HC z scores at study entry and exit were slightly greater than WHO norms. Higher baseline white blood cell count, absolute reticulocyte count, and absolute neutrophil count were associated with poorer growth. The significance of the slightly lower HC in the treatment group at study exit is not clear. Trends toward normalization of weight and height and effects on HC will be monitored in ongoing BABY HUG follow-up studies.
| S-EPMC4144002 | biostudies-literature
Project description: Not available
| S-EPMC6478259 | biostudies-literature
Project description:BackgroundFetal hemoglobin level is a heritable complex trait that strongly correlates swith the clinical severity of sickle cell disease. Only few genetic loci have been identified as robustly associated with fetal hemoglobin in patients with sickle cell disease, primarily adults. The sole approved pharmacologic therapy for this disease is hydroxyurea, with effects largely attributable to induction of fetal hemoglobin.Methodology/principal findingsIn a multi-site observational analysis of children with sickle cell disease, candidate single nucleotide polymorphisms associated with baseline fetal hemoglobin levels in adult sickle cell disease were examined in children at baseline and induced by hydroxyurea therapy. For baseline levels, single marker analysis demonstrated significant association with BCL11A and the beta and epsilon globin loci (HBB and HBE, respectively), with an additive attributable variance from these loci of 23%. Among a subset of children on hydroxyurea, baseline fetal hemoglobin levels explained 33% of the variance in induced levels. The variant in HBE accounted for an additional 13% of the variance in induced levels, while variants in the HBB and BCL11A loci did not contribute beyond baseline levels.Conclusions/significanceThese findings clarify the overlap between baseline and hydroxyurea-induced fetal hemoglobin levels in pediatric disease. Studies assessing influences of specific sequence variants in these and other genetic loci in larger populations and in unusual hydroxyurea responders are needed to further understand the maintenance and therapeutic induction of fetal hemoglobin in pediatric sickle cell disease.
| S-EPMC3567082 | biostudies-literature
Project description:BACKGROUND:Hydroxyurea is an effective treatment for sickle cell anemia, but few studies have been conducted in sub-Saharan Africa, where the burden is greatest. Coexisting conditions such as malnutrition and malaria may affect the feasibility, safety, and benefits of hydroxyurea in low-resource settings. METHODS:We enrolled children 1 to 10 years of age with sickle cell anemia in four sub-Saharan countries. Children received hydroxyurea at a dose of 15 to 20 mg per kilogram of body weight per day for 6 months, followed by dose escalation. The end points assessed feasibility (enrollment, retention, and adherence), safety (dose levels, toxic effects, and malaria), and benefits (laboratory variables, sickle cell-related events, transfusions, and survival). RESULTS:A total of 635 children were fully enrolled; 606 children completed screening and began receiving hydroxyurea at a mean (±SD) dose of 17.5±1.8 mg per kilogram per day. The retention rate was 94.2% at 3 years of treatment. Hydroxyurea therapy led to significant increases in both the hemoglobin and fetal hemoglobin levels. Dose-limiting toxic events regarding laboratory variables occurred in 5.1% of the participants, which was below the protocol-specified threshold for safety. During the treatment phase, 20.6 dose-limiting toxic effects per 100 patient-years occurred, as compared with 20.7 events per 100 patient-years before treatment. As compared with the pretreatment period, the rates of clinical adverse events decreased with hydroxyurea use, including rates of vaso-occlusive pain (98.3 vs. 44.6 events per 100 patient-years; incidence rate ratio, 0.45; 95% confidence interval [CI], 0.37 to 0.56), nonmalaria infection (142.5 vs. 90.0 events per 100 patient-years; incidence rate ratio, 0.62; 95% CI, 0.53 to 0.72), malaria (46.9 vs. 22.9 events per 100 patient-years; incidence rate ratio, 0.49; 95% CI, 0.37 to 0.66), transfusion (43.3 vs. 14.2 events per 100 patient-years; incidence rate ratio, 0.33; 95% CI, 0.23 to 0.47), and death (3.6 vs. 1.1 deaths per 100 patient-years; incidence rate ratio, 0.30; 95% CI, 0.10 to 0.88). CONCLUSIONS:Hydroxyurea treatment was feasible and safe in children with sickle cell anemia living in sub-Saharan Africa. Hydroxyurea use reduced the incidence of vaso-occlusive events, infections, malaria, transfusions, and death, which supports the need for wider access to treatment. (Funded by the National Heart, Lung, and Blood Institute and others; REACH ClinicalTrials.gov number, NCT01966731 .).
| S-EPMC6454575 | biostudies-literature
Project description:Hydroxyurea (HU) is the sole approved pharmacological therapy for sickle cell disease (SCD). Higher levels of fetal hemoglobin (HbF) diminish deoxygenated sickle globin polymerization in vitro and clinically reduce the incidence of disease morbidities. Clinical and laboratory effects of HU largely result from induction of HbF expression, though to a highly variable extent. Baseline and HU-induced HbF expression are both inherited complex traits. In children with SCD, baseline HbF remains the best predictor of drug-induced levels, but this accounts for only a portion of the induction. A limited number of validated genetic loci are strongly associated with higher baseline HbF levels in SCD. For induced HbF levels, genetic approaches using candidate single-nucleotide polymorphisms (SNPs) have identified some of these same loci as being also associated with induction. However, SNP associations with induced HbF are only partially independent of baseline levels. Additional approaches to understanding the impact of HU on HbF and its other therapeutic effects on SCD include pharmacokinetic, gene expression-based, and epigenetic analyses in patients and through studies in existing murine models for SCD. Understanding the genetic and other factors underlying the variability in therapeutic effects of HU for pediatric SCD is critical for prospectively predicting good responders and for designing other effective therapies.
| S-EPMC3917141 | biostudies-literature
Project description:OBJECTIVE:To evaluate the impact of an initiative to increase hydroxyurea use among children with sickle cell anemia (SCA) who presented to the emergency department (ED). STUDY DESIGN:This observational cohort study included children with SCA not taking hydroxyurea who presented to the ED with pain or acute chest syndrome and then attended a Quick-Start Hydroxyurea Initiation Project (Q-SHIP) session. A Q-SHIP session includes a hematologist-led discussion on hydroxyurea, a video of patients talking about hydroxyurea, and a direct offer to start hydroxyurea. RESULTS:Over 64 weeks, 112 eligible patients presented to the ED and 59% (n?=?66) participated in a Q-SHIP session a median of 6 days (IQR 2, 20 days) after ED or hospital discharge; 55% of participants (n?=?36) started hydroxyurea. After a median follow-up of 49 weeks, 83% (n?=?30) of these participants continued hydroxyurea. Laboratory markers of hydroxyurea adherence were significantly increased from baseline: median mean corpuscular volume +8.6?fL (IQR 5.0, 17.7, P?<?.0001) and median hemoglobin F +5.7% (IQR 2.5, 9.8, P?=?.0001). Comparing Q-SHIP participants to nonparticipants, 12 weeks after ED visit, participants were more likely to have started hydroxyurea than nonparticipants (53% vs 20%, P?=?.0004) and to be taking hydroxyurea at last follow-up (50% vs 20%, P?=?.001). Two years after the implementation of Q-SHIP the overall proportion of eligible patients on hydroxyurea presenting to our ED increased from 56% to 80%, P?=?.0069. CONCLUSIONS:Participation in a clinic to specifically address starting hydroxyurea after a SCA complication increases hydroxyurea use.
| S-EPMC6159227 | biostudies-literature
Project description:BACKGROUND:Hydroxyurea is a disease-modifying medication for patients with sickle cell disease (SCD). Despite demonstrated efficacy, hydroxyurea nonadherence in clinical practice is common and results in worse health outcomes for nonadherent patients. Mobile Directly Observed Therapy (Mobile DOT) is a pilot-tested, electronic, multidimensional hydroxyurea adherence intervention for children with SCD. Mobile DOT includes sending daily text message reminders to patients to take hydroxyurea, patients recording and sending daily videos that capture their hydroxyurea administrations for the research team to review and track adherence, providing personalized feedback to patients about their adherence, and providing small monetary incentives to patients if they achieve high hydroxyurea adherence. OBJECTIVE:This study aimed to determine if Mobile DOT increases hydroxyurea adherence in children with SCD and to explore its impact on hematologic and clinical outcomes. METHODS:This was a single-arm, 6-month intervention study of patients with SCD on hydroxyurea who were aged ?19 years and reported having access to an electronic device. Participants' hydroxyurea adherence when they received Mobile DOT was compared with their adherence 6 months before and after receiving Mobile DOT. Participants' medication possession ratio (MPR) was calculated from their pharmacy dispensing records and was used to measure adherence. Laboratory and clinical outcomes were abstracted from participants' electronic medical records. Infrequently hospitalized patients who received at least 160 days of the intervention were considered to be engaged participants. RESULTS:Of 91 patients who were approached, 55 enrolled and 34 engaged with Mobile DOT. The median age of the engaged participants was 10 years (range 2-18.8 years), and 21 (62%, 21/34) participants were male, 28 (82%, 21/34) had hemoglobin SS SCD, and 19 (56%, 19/34) were prescribed hydroxyurea for at least a year before enrollment. With Mobile DOT, engaged participants' median MPR increased from 61.7% to 84.4% (P<.001) and significantly more (67% vs 30%; P=.002) achieved ?80% hydroxyurea adherence compared with baseline values. Engaged participants' mean fetal hemoglobin (HgbF) levels and mean corpuscular volumes (MCV) improved significantly after 6 months of Mobile DOT (P=.04 and P=.001, respectively), but their adherence, HgbF levels, and MCV returned to baseline values during the 6 months after the intervention. Hospitalizations and the clinical outcomes that were measured occurred infrequently during the study. Nonengagement was associated with being female and having a recent SCD complication. In addition, having insufficient electronic data, being unable to quickly complete Mobile DOT each day, and not perceiving that Mobile DOT was beneficial may have further decreased engagement. CONCLUSIONS:Mobile DOT shows promise as an effective intervention for some children with SCD. Modifications that may improve recruitment, reduce attrition, and increase engagement were identified and could increase the impact that Mobile DOT has on children with SCD. TRIAL REGISTRATION:ClinicalTrials.gov NCT02578017; https://clinicaltrials.gov/ct2/show/NCT02578017.
| S-EPMC6705009 | biostudies-literature
Project description:Early identification of infants with sickle cell disease (SCD) by newborn screening, now universal in all 50 states in the US, has improved survival, mainly by preventing overwhelming sepsis with the early use of prophylactic penicillin. Routine transcranial Doppler screening with the institution of chronic transfusion decreases the risk of stroke from 10% to 1% in paediatric SCD patients. Hydroxyurea decreases the number and frequency of painful crises, acute chest syndromes and number of blood transfusions in children with SCD. Genetic research continues to be driven toward the prevention and ultimate cure of SCD before adulthood. This review focuses on clinical manifestations and therapeutic strategies for paediatric SCD as well as the evolving topic of gene-focused prevention and therapy.
| S-EPMC3899685 | biostudies-other
Project description:Sickle cell anemia (SCA) is a severe, inherited hemoglobin disorder affecting 100,000 persons in the US and millions worldwide. Hydroxyurea, a once daily oral medication, has emerged as the primary disease-modifying therapy for SCA. The accumulated body of evidence over 30 years demonstrates that hydroxyurea is a safe and effective therapy for SCA, but hydroxyurea remains underutilized for a variety of reasons.In this review, we summarize the available evidence regarding the pharmacology, clinical, and laboratory benefits, and safety of hydroxyurea therapy for the treatment of SCA. The purpose of this review is to provide the reader a comprehensive understanding of hydroxyurea and to reinforce the fact that hydroxyurea is a safe and effective medication for the treatment of SCA.In our opinion, hydroxyurea therapy should be considered standard-of-care for SCA, representing an essential component of patient management. Early initiation and broader use of hydroxyurea will alter the natural history of SCA, so affected children can live longer and healthier lives. In addition, hydroxyurea use should be extended to low-resource settings such as sub-Saharan Africa, where the burden of SCA and the need for hydroxyurea is arguably the greatest.
| S-EPMC5868345 | biostudies-literature
Project description:BACKGROUND:Hydroxyurea (HU) is a FDA- and EMA-approved drug that earned an important place in the treatment of patients with severe sickle cell anemia (SCA) by showing its efficacy in many studies. This medication is still underused due to fears of physicians and families and must be optimized. METHODS:We analyzed our population and identified HU pharmacokinetic (PK) parameters in order to adapt treatment in the future. Working with a pediatric population, we searched for the most indicative sampling time to reduce the number of samples needed. RESULTS:Nine children treated by HU for severe SCA were included for this PK study. HU quantification was made using a validated gas chromatography/mass spectrometry (GC/MS) method. Biological parameters (of effectiveness and compliance) and clinical data were collected. None of the nine children reached the therapeutic target defined by Dong et al. as an area under the curve (AUC) = 115 h.mg/L; four patients were suspected to be non-compliant. Only two patients had an HbF over 20%. The 2 h sample was predictive of the medication exposure (r2 = 0.887). CONCLUSIONS:It is urgent to be more efficient in the treatment of SCA, and pharmacokinetics can be an important asset in SCA patients.
| S-EPMC6833033 | biostudies-literature