Ram Kalpatthi

Hydroxycarbamide in very young children with sickle-cell anaemia: a multicentre, randomised, controlled trial (BABY HUG)

BACKGROUND Sickle-cell anaemia is associated with substantial morbidity from acute complications and organ dysfunction beginning in the first year of life. Hydroxycarbamide substantially reduces episodes of pain and acute chest syndrome, admissions to hospital, and transfusions in adults with sickle-cell anaemia. We assessed the effect of hydroxycarbamide therapy on organ dysfunction and clinical complications, and examined laboratory findings and toxic effects. METHODS This randomised trial was undertaken in 13 centres in the USA between October, 2003, and September, 2009. Eligible participants had haemoglobin SS (HbSS) or haemoglobin Sβ(0)thalassaemia, were aged 9-18 months at randomisation, and were not selected for clinical severity. Participants received liquid hydroxycarbamide, 20 mg/kg per day, or placebo for 2 years. Randomisation assignments were generated by the medical coordinating centre by a pre-decided schedule. Identical appearing and tasting formulations were used for hydroxycarbamide and placebo. Patients, caregivers, and coordinating centre staff were masked to treatment allocation. Primary study endpoints were splenic function (qualitative uptake on (99)Tc spleen scan) and renal function (glomerular filtration rate by (99m)Tc-DTPA clearance). Additional assessments included blood counts, fetal haemoglobin concentration, chemistry profiles, spleen function biomarkers, urine osmolality, neurodevelopment, transcranial Doppler ultrasonography, growth, and mutagenicity. Study visits occurred every 2-4 weeks. Analysis was by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT00006400. FINDINGS 96 patients received hydroxycarbamide and 97 placebo, of whom 83 patients in the hydroxycarbamide group and 84 in the placebo group completed the study. Significant differences were not seen between groups for the primary endpoints (19 of 70 patients with decreased spleen function at exit in the hydroxycarbamide group vs 28 of 74 patients in the placebo group, p=0·21; and a difference in the mean increase in DTPA glomerular filtration rate in the hydroxycarbamide group versus the placebo group of 2 mL/min per 1·73 m(2), p=0·84). Hydroxycarbamide significantly decreased pain (177 events in 62 patients vs 375 events in 75 patients in the placebo group, p=0·002) and dactylitis (24 events in 14 patients vs 123 events in 42 patients in the placebo group, p<0·0001), with some evidence for decreased acute chest syndrome, hospitalisation rates, and transfusion. Hydroxyurea increased haemoglobin and fetal haemoglobin, and decreased white blood-cell count. Toxicity was limited to mild-to-moderate neutropenia. INTERPRETATION On the basis of the safety and efficacy data from this trial, hydroxycarbamide can now be considered for all very young children with sickle-cell anaemia. FUNDING The US National Heart, Lung, and Blood Institute; and the National Institute of Child Health and Human Development.

Impact of hydroxyurea on clinical events in the BABY HUG trial

The Pediatric Hydroxyurea Phase 3 Clinical Trial (BABY HUG) was a phase 3 multicenter, randomized, double-blind, placebo-controlled clinical trial of hydroxyurea in infants (beginning at 9-18 months of age) with sickle cell anemia. An important secondary objective of this study was to compare clinical events between the hydroxyurea and placebo groups. One hundred and ninety-three subjects were randomized to hydroxyurea (20 mg/kg/d) or placebo; there were 374 patient-years of on-study observation. Hydroxyurea was associated with statistically significantly lower rates of initial and recurrent episodes of pain, dactylitis, acute chest syndrome, and hospitalization; even infants who were asymptomatic at enrollment had less dactylitis as well as fewer hospitalizations and transfusions if treated with hydroxyurea. Despite expected mild myelosuppression, hydroxyurea was not associated with an increased risk of bacteremia or serious infection. These data provide important safety and efficacy information for clinicians considering hydroxyurea therapy for very young children with sickle cell anemia. This clinical trial is registered with the National Institutes of Health (NCT00006400, www.clinicaltrials.gov).

The pediatric hydroxyurea phase III clinical trial (BABY HUG): Challenges of study design

Evidence of the laboratory benefits of hydroxyurea and its clinical efficacy in reducing acute vaso‐occlusive events in adults and children with sickle cell anemia has accumulated for more than 15 years. A definitive clinical trial showing that hydroxyurea can also prevent organ damage might support widespread use of the drug at an early age. BABY HUG is a randomized, double‐blind placebo‐controlled trial to test whether treating young children ages 9–17 months at entry with a liquid preparation of hydroxyurea (20 mg/kg/day for 2 years) can decrease organ damage in the kidneys and spleen by at least 50%. Creation of BABY HUG entailed unique challenges and opportunities. Although protection of brain function might be considered a more compelling endpoint, preservation of spleen and renal function has clinical relevance, and significant treatment effects might be discernable within the mandated sample size of 200. Concerns about unanticipated severe toxicity and burdensome testing and monitoring requirements were addressed in part by an internal Feasibility and Safety Pilot Study, the successful completion of which was required prior to enrolling a larger number of children on the protocol. Concerns over recruitment of potentially vulnerable subjects were allayed by inclusion of a research subject advocate, or ombudsman. Finally, maintenance of blinding of research personnel was aided by inclusion of an unblinded primary endpoint person, charged with transmitting endpoint data and monitoring blood work locally for toxicity (ClinicalTrials.gov number, NCT00006400). Pediatr Blood Cancer 2010;54:250–255.

Transcranial Doppler Ultrasonography (TCD) in Infants with Sickle Cell Anemia: Baseline Data from the BABY HUG Trial

Transcranial Doppler ultrasonography (TCD) is used to predict stroke risk in children with sickle cell anemia (SCA), but has not been adequately studied in children under age 2 years.

Diagnosis, pathophysiology and management of children with refractory immune thrombocytopenic purpura.

Purpose of review Refractory immune thrombocytopenic purpura is infrequent in children, but carries substantial morbidity and even mortality. Management of these children is controversial despite the availability of several treatment options as these strategies have not been directly compared and there are many definitions for refractory immune thrombocytopenic purpura. This review will provide an update on the pathogenesis, diagnosis and treatment options for children with severe, acute and chronic refractory immune thrombocytopenic purpura. Recent findings Recent studies have demonstrated a number of immunologic alterations (dominant proinflammatory state, inadequate thrombopoiesis, and various B and T lymphocyte disturbances) in the pathogenesis of chronic immune thrombocytopenic purpura. New agents that target certain of these mechanisms (e.g. anti-CD20 monoclonal antibody, thrombopoietic agents) have shown promising results in recent clinical trials, primarily but not solely in adults. Summary Management of refractory immune thrombocytopenic purpura often requires multiple agents that may provide only short-term benefit. Lack of clear views about the use of these medications, their unwanted side effects and an inability to specifically target a particular patients disease all lead to frustration among patients, family and the physicians. Better understanding of pathogenesis with the availability of newer therapies with different mechanisms of effect should, however, allow improved management of these patients.

Long-Term Use of the Thrombopoietin-Mimetic Romiplostim in Children With Severe Chronic Immune Thrombocytopenia (ITP)

Treatment of chronic severe pediatric ITP is not well studied. In a phase 1/2 12–16‐week study, 15/17 romiplostim‐treated patients achieved platelet counts ≥50 × 109/L, and romiplostim treatment was well tolerated. In a subsequent open‐label extension (≤109 weeks), 20/22 patients received romiplostim; all achieved platelet counts >50 × 109/L. Twelve patients continued in a second extension (≤127 weeks). Longitudinal data from start of romiplostim treatment through the two extensions were evaluated to investigate the safety and efficacy of long‐term romiplostim treatment in chronic severe pediatric ITP.

Pulmonary function abnormalities and asthma are prevalent in children with sickle cell disease and are associated with acute chest syndrome.

Pulmonary diseases form major sources of morbidity and mortality in children with sickle cell disease (SCD). The objective of the study was to determine the prevalence of lung function abnormalities and asthma and their association with acute chest syndrome (ACS) in children with SCD. This was a cross-sectional retrospective study of 127 children with SCD; we collected information regarding ACS and asthma and pulmonary function test (PFT) data. Based on PFT results, the patients were assigned to one pattern of lung function [normal, obstructive lung disease (OLD), restrictive lung disease (RLD)]. Statistical analyses included Pearson correlation, prevalence odds ratio (POR), cross-tabulation, and multiple binary logistic regression. OLD was noted in 35% and RLD in 23% of the patients, with the remainder exhibiting a normal PFT pattern. Forty-six percent of patients had asthma, 64% of whom had a history of ACS. OLD (r = .244, P = .008, POR = 2.8) and asthma (r = .395, P < .001, POR = 5.4) were significantly associated with a history of ACS. There was a negative correlation between having normal PFT data and a history of ACS (r = −.289, P = .002, POR = .3). Asthma and pulmonary function abnormalities are prevalent in children with SCD, with OLD being more common than RLD. There is an association between asthma, OLD, and ACS, however causality cannot be proven due to the study design. We stress the importance of actively investigating for a clinical diagnosis of asthma in all patients with SCD and suggest that PFT data may help detect patients at lower risk for ACS.

Developmental Function in Toddlers With Sickle Cell Anemia

BACKGROUND: Neurocognitive impairment occurs in children and adults with sickle cell anemia, but little is known about neurodevelopment in very young children. We examined the neurodevelopmental status of infants participating in the Pediatric Hydroxyurea Phase III Clinical Trial (Baby Hug) to determine relationships with age, cerebral blood flow velocity, and hemoglobin concentration. METHODS: Standardized measures of infant neurodevelopment were administered to 193 infants with hemoglobin SS or hemoglobin S-β0 thalassemia between 7 and 18 months of age at the time of their baseline evaluation. Associations between neurodevelopmental scores and age, family income, parent education, hemoglobin concentration, and transcranial Doppler velocity were examined. RESULTS: Mean functioning on the baseline neurodevelopment scales was in the average range. There were no mental development scores <70 (impaired); 22 children had scores in the clinically significant range, 11 with impaired psychomotor scores and 11 with problematic behavior rating scores. Significantly poorer performance was observed with older age at baseline. Behavior rating scores were an average of 2.82 percentile points lower per month of age, with similar patterns observed with parent report using adaptive behavior scales. Parent-reported functional abilities and hemoglobin were negatively associated with higher transcranial Doppler velocities. CONCLUSIONS: Whereas overall functioning was in the normal range, behavioral and adaptive function was poorer with older age, even in this very young group of children. Explanatory mechanisms for this association between poorer developmental function and older age need to be identified.

Effect of chronic transfusion therapy on progression of neurovascular pathology in pediatric patients with sickle cell anemia

BACKGROUND Chronic blood transfusion (CBT) is currently the standard of care for primary and secondary stroke prevention in children with sickle cell anemia (SCA). However, the effect of CBT on cerebrovascular pathology is not well known. METHODS We reviewed children with SCA receiving CBT for abnormal transcranial Doppler (TCD) [n=12] or cerebrovascular accident (CVA) [n=22]. Baseline cerebral magnetic resonance imaging (MRI) and magnetic resonance angiogram (MRA) were compared with the most recent scans available for each patient and independently scored by a neuroradiologist. RESULTS Thirty-four patients with a mean age of 6.5years at the time of baseline MRI/MRA were studied. Average elapsed time from baseline to most recent scans was 7.3years. Overall, patients experienced worsening vasculopathy, as measured by mean increases in their baseline MRI and MRA scores of +0.76 and +1.03. There was a significant difference in the mean change of MRI/MRA scores between patients who had CVA and abnormal TCD (MRI; +1.23 vs. -0.08, p=0.001 and MRA; +1.54 vs. +0.08, p=0.02). Patients with abnormal baseline MRA had worsening scores compared to those with normal baseline MRA (54% vs. 9.5%, p=0.01). Also, patients who had CVA were more likely to have an abnormal baseline MRA and worsening scores compared to abnormal TCD patients. CONCLUSION We show that children with CVA experience progression of cerebral vasculopathy despite CBT. In contrast, CBT for abnormal TCD confers protection against the development and/or progression of cerebral vasculopathy. This effect appears to be real given our large cohort of patients with longer follow up as compared to previous studies.

Immunologic Effects of Hydroxyurea in Sickle Cell Anemia

BACKGROUND AND OBJECTIVE: Susceptibility to encapsulated bacteria is well known in sickle cell disease (SCD). Hydroxyurea use is common in adults and children with SCD, but little is known about hydroxyurea’s effects on immune function in SCD. Because hydroxyurea inhibits ribonucleotide reductase, causing cell cycle arrest at the G1–S interface, we postulated that hydroxyurea might delay transition from naive to memory T cells, with inhibition of immunologic maturation and vaccine responses. METHODS: T-cell subsets, naive and memory T cells, and antibody responses to pneumococcal and measles, mumps, and rubella vaccines were measured among participants in a multicenter, randomized, double-blind, placebo-controlled trial of hydroxyurea in infants and young children with SCD (BABY HUG). RESULTS: Compared with placebo, hydroxyurea treatment resulted in significantly lower total lymphocyte, CD4, and memory T-cell counts; however, these numbers were still within the range of historical healthy controls. Antibody responses to pneumococcal vaccination were not affected, but a delay in achieving protective measles antibody levels occurred in the hydroxyurea group. Antibody levels to measles, mumps, and rubella showed no differences between groups at exit, indicating that effective immunization can be achieved despite hydroxyurea use. CONCLUSIONS: Hydroxyurea does not appear to have significant deleterious effects on the immune function of infants and children with SCD. Additional assessments of lymphocyte parameters of hydroxyurea-treated children may be warranted. No changes in current immunization schedules are recommended; however, for endemic disease or epidemics, adherence to accelerated immunization schedules for the measles, mumps, and rubella vaccine should be reinforced.