William H. Schultz

Hydroxycarbamide versus chronic transfusion for maintenance of transcranial doppler flow velocities in children with sickle cell anaemia - TCD with Transfusions Changing to Hydroxyurea (TWiTCH): A multicentre, open-label, phase 3, non-inferiority trial

Background For children with sickle cell anaemia and elevated transcranial Doppler (TCD) flow velocities, regular blood transfusions effectively prevent primary stroke, but must be continued indefinitely. The efficacy of hydroxyurea in this setting is unknown. Methods TWiTCH was a multicentre Phase III randomised open label, non-inferiority trial comparing standard treatment (transfusions) to alternative treatment (hydroxyurea) in children with abnormal TCD velocities but no severe vasculopathy. Iron overload was managed with chelation (Standard Arm) and serial phlebotomy (Alternative Arm). The primary study endpoint was the 24-month TCD velocity calculated from a general linear mixed model, with non-inferiority margin = 15 cm/sec. Findings Among 121 randomised participants (61 transfusions, 60 hydroxyurea), children on transfusions maintained <30% sickle haemoglobin, while those taking hydroxyurea (mean 27 mg/kg/day) averaged 25% fetal haemoglobin. The first scheduled interim analysis demonstrated non-inferiority, and the sponsor terminated the study. Final model-based TCD velocities (mean ± standard error) on Standard versus Alternative Arm were 143 ± 1.6 and 138 ± 1.6 cm/sec, respectively, with difference (95% CI) = 4.54 (0.10, 8.98), non-inferiority p=8.82 × 10−16 and post-hoc superiority p=0.023. Among 29 new neurological events adjudicated centrally by masked reviewers, no strokes occurred but there were 3 transient ischaemic attacks per arm. Exit brain MRI/MRA revealed no new cerebral infarcts in either arm, but worse vasculopathy in one participant (Standard Arm). Iron burden decreased more in the Alternative Arm, with ferritin difference −1047 ng/mL (−1524, −570), p<0.001 and liver iron difference −4.3 mg Fe/gm dry weight (−6.1, −2.5), p=0.001. Interpretation For high-risk children with sickle cell anaemia and abnormal TCD velocities, after four years of transfusions and without severe MRA vasculopathy, hydroxyurea therapy can substitute for chronic transfusions to maintain TCD velocities and help prevent primary stroke.BACKGROUND For children with sickle cell anaemia and high transcranial doppler (TCD) flow velocities, regular blood transfusions can effectively prevent primary stroke, but must be continued indefinitely. The efficacy of hydroxycarbamide (hydroxyurea) in this setting is unknown; we performed the TWiTCH trial to compare hydroxyurea with standard transfusions. METHODS TWiTCH was a multicentre, phase 3, randomised, open-label, non-inferiority trial done at 26 paediatric hospitals and health centres in the USA and Canada. We enrolled children with sickle cell anaemia who were aged 4-16 years and had abnormal TCD flow velocities (≥ 200 cm/s) but no severe vasculopathy. After screening, eligible participants were randomly assigned 1:1 to continue standard transfusions (standard group) or hydroxycarbamide (alternative group). Randomisation was done at a central site, stratified by site with a block size of four, and an adaptive randomisation scheme was used to balance the covariates of baseline age and TCD velocity. The study was open-label, but TCD examinations were read centrally by observers masked to treatment assignment and previous TCD results. Participants assigned to standard treatment continued to receive monthly transfusions to maintain 30% sickle haemoglobin or lower, while those assigned to the alternative treatment started oral hydroxycarbamide at 20 mg/kg per day, which was escalated to each participants maximum tolerated dose. The treatment period lasted 24 months from randomisation. The primary study endpoint was the 24 month TCD velocity calculated from a general linear mixed model, with the non-inferiority margin set at 15 cm/s. The primary analysis was done in the intention-to-treat population and safety was assessed in all patients who received at least one dose of assigned treatment. This study is registered with ClinicalTrials.gov, number NCT01425307. FINDINGS Between Sept 20, 2011, and April 17, 2013, 159 patients consented and enrolled in TWiTCH. 121 participants passed screening and were then randomly assigned to treatment (61 to transfusions and 60 to hydroxycarbamide). At the first scheduled interim analysis, non-inferiority was shown and the sponsor terminated the study. Final model-based TCD velocities were 143 cm/s (95% CI 140-146) in children who received standard transfusions and 138 cm/s (135-142) in those who received hydroxycarbamide, with a difference of 4·54 (0·10-8·98). Non-inferiority (p=8·82 × 10(-16)) and post-hoc superiority (p=0·023) were met. Of 29 new neurological events adjudicated centrally by masked reviewers, no strokes were identified, but three transient ischaemic attacks occurred in each group. Magnetic resonance brain imaging and angiography (MRI and MRA) at exit showed no new cerebral infarcts in either treatment group, but worsened vasculopathy in one participant who received standard transfusions. 23 severe adverse events in nine (15%) patients were reported for hydroxycarbamide and ten serious adverse events in six (10%) patients were reported for standard transfusions. The most common serious adverse event in both groups was vaso-occlusive pain (11 events in five [8%] patients with hydroxycarbamide and three events in one [2%] patient for transfusions). INTERPRETATION For high-risk children with sickle cell anaemia and abnormal TCD velocities who have received at least 1 year of transfusions, and have no MRA-defined severe vasculopathy, hydroxycarbamide treatment can substitute for chronic transfusions to maintain TCD velocities and help to prevent primary stroke. FUNDING National Heart, Lung, and Blood Institute, National Institutes of Health.

Influence of bilirubin uridine diphosphate-glucuronosyltransferase 1A promoter polymorphisms on serum bilirubin levels and cholelithiasis in children with sickle cell anemia

Purpose Genetic mutations in the uridine diphosphate (UDP)–glucuronosyltransferase 1A (UGT1A) enzyme promoter have been associated with unconjugated hyperbilirubinemia and Gilbert syndrome. The effects of UGT1A promoter polymorphisms on serum bilirubin levels and symptomatic gallstone formation were studied in a cohort of children with sickle cell anemia (SCA). Methods The UGT1A promoter genotype was determined for 115 consecutive children with SCA. Steady-state laboratory parameters and previous cholecystectomy for symptomatic gallstones were recorded retrospectively, then analyzed according to UGT1A genotype. Results Children with SCA had a lower frequency of the normal (TA) 6 UGT1A promoter allele (0.413) than the abnormal (TA) 7 allele (0.461). A previously described shorter (TA) 5 allele (frequency 0.074) and longer (TA) 8 allele (frequency 0.052) were also observed. Children with the 7/7 UGT1A genotype had a significantly higher mean bilirubin level (5.8 ± 3.1 mg/dL) than those with the 6/6 (2.4 ± 0.8 mg/dL) or 6/7 genotype (3.0 ± 1.1 mg/dL;P < 0.001 by analysis of variance). Patients with the 7/7 genotype were more likely to have previous cholecystectomy (87.5%) than those with the 6/6 (35.7%) or the 6/7 genotype (36.1%;P = 0.002 by &khgr; 2 ). Conclusions Genetic variation in the UGT1A promoter significantly influences serum bilirubin levels and the development of symptomatic cholelithiasis in children with SCA. The UGT1A promoter polymorphisms represent an important nonglobin genetic modifier of clinical disease expression in SCA.

Elective cholecystectomy in children with sickle hemoglobinopathies. Successful outcome using a preoperative transfusion regimen.

Twenty-seven children with major sickle hemoglobinopathies underwent elective cholecystectomy for cholelithiasis. All were managed with a preoperative transfusion regimen to achieve a hemoglobin concentration of 11-14 g/dl with greater than 65% hemoglobin A. Intraoperative cholangiography revealed common bile duct stones in five patients, although only one case was diagnosed by preoperative ultrasonographic examination. Twenty-four children underwent incidental appendectomy by total intussusception. There were no vaso-occlusive events nor any other perioperative morbidity or mortality. Four months after cholecystectomy, one boy had a small bowel obstruction requiring surgical re-exploration. No patients had transfusion-acquired infection, although one boy had erythrocyte allosensitization to Lewis A antigen. This preoperative transfusion regimen and careful perioperative management permits safe elective cholecystectomy in children with sickle cell disease.

Genetic predictors for stroke in children with sickle cell anemia.

Stroke is a devastating complication of sickle cell anemia (SCA), affecting 5% to 10% of patients before adulthood. Several candidate genetic polymorphisms have been proposed to affect stroke risk, but few have been validated, mainly because previous studies were hampered by relatively small sample sizes and the absence of additional patient cohorts for validation testing. To verify the accuracy of proposed genetic modifiers influencing stroke risk in SCA, we performed genotyping for 38 published single nucleotide polymorphisms (SNPs), as well as α-thalassemia, G6PD A(-) variant deficiency, and β-globin haplotype in 2 cohorts of children with well-defined stroke phenotypes (130 stroke, 103 nonstroke). Five polymorphisms had significant influence (P < .05): SNPs in the ANXA2, TGFBR3, and TEK genes were associated with increased stroke risk, whereas α-thalassemia and a SNP in the ADCY9 gene were linked with decreased stroke risk. Further investigation at these genetic regions may help define mutations that confer stroke risk or protection in children with SCA.

A pilot study of hydroxyurea to prevent chronic organ damage in young children with sickle cell anemia.

Hydroxyurea improves laboratory parameters and prevents acute clinical complications of sickle cell anemia (SCA) in children and adults, but its effects on organ function remain incompletely defined.

Erythrocytapheresis can reduce iron overload and prevent the need for chelation therapy in chronically transfused pediatric patients

Purpose This research was undertaken to determine the advantages, complications, costs, and efficacy of erythrocytapheresis in young pediatric patients who receive chronic erythrocyte transfusion therapy. Patients and Methods We retrospectively analyzed data for 10 children who received erythrocytapheresis for an average of 16 months. Erythrocytapheresis was compared to simple transfusion therapy with respect to annual blood unit exposure, occurrence of alloimmunization, and costs. Serum ferritin levels were compared before and after the period of erythrocytapheresis. Results Erythrocytapheresis was well tolerated, even in children as young as 5 years or as small as 20 kg. It required a greater annual unit exposure than simple transfusions, but did not increase alloimmunization. Ferritin levels decreased significantly in children receiving concurrent deferoxamine, and decreased or stablized in those not on chelation therapy. Children started on erythrocytapheresis soon after stroke have not developed iron overload. Although the costs of erythorocytapheresis exceed that of simple transfusion, the substantial costs of deferoxamine therapy should be considered; one child on erythrocytapheresis has been able to discontinue chelation therapy following normalization of his ferritin level. Conclusion Erythrocytapheresis is a safe and effective method for young patients receiving chronic erythrocyte transfusions. Erythrocytapheresis can reduce total iron burden and may obviate the need for expensive chelation therapy.

Stroke with transfusions changing to hydroxyurea (SWiTCH): A phase III randomized clinical trial for treatment of children with sickle cell anemia, stroke, and iron overload†

Stroke occurs in 5–10% of children with sickle cell anemia (SCA) and has a high (>50%) risk of recurrence without therapy. Chronic monthly erythrocyte transfusions effectively prevent recurrent stroke, but their long‐term use is limited by serious side effects, including iron overload. An alternative to transfusion for secondary stroke prevention in SCA is needed, especially one that also improves the management of iron overload.

Coping strategies and laboratory pain in children with sickle cell disease

Studies have found that coping strategies are significant predictors of pain report, health care use, and psychosocial adjustment in children with sickle cell disease (SCD); however, the mechanisms of the relationship are not clear. In this study, 41 children with SCD completed a laboratory pain task to analyze their pain perception under standardized conditions. Sensory decision theory analyses were used to analyze the pain perception data. Children and their parents also completed measures of coping strategies and adjustment. Hierarchical regression analyses controlling for the child’s age indicated that children who reported using active cognitive and behavioral coping strategies had a lower tendency to report pain during the laboratory pain task. Results are discussed in terms of the utility of using laboratory pain models with children and the need for future intervention studies to target coping strategies in children with SCD pain.

Diagnosis and management of common bile duct stones in patients with sickle hemoglobinopathies

Nine of 35 patients with sickle hemoglobinopathies and cholelithiasis were found to have concomitant common bile duct (CBD) stones. We describe the diagnosis and management of these patients with CBD stones. Historical information, physical examination, and routine laboratory tests were unable to identify accurately the patients with CBD stones. Similarly, ultrasonography of the hepatobiliary system was an insensitive method for detecting CBD stones, as only 3 of 8 patients were correctly identified. In contrast, both an intraoperative cholangiogram and endoscopic retrograde cholangiopancreatography were sensitive procedures for detection of CBD stones. We conclude that CBD stones are relatively common in patients with sickle cell disease and cholelithiasis, and clinicians should have a high index of suspicion for their presence.

Magnetic resonance imaging/angiography and transcranial Doppler velocities in sickle cell anemia: results from the SWiTCH trial

The Stroke With Transfusions Changing to Hydroxyurea (SWiTCH) trial compared standard (transfusions/chelation) to alternative (hydroxyurea/phlebotomy) treatment to prevent recurrent stroke and manage iron overload in children chronically transfused over 7 years before enrollment. Standardized brain magnetic resonance imaging/magnetic resonance angiography (MRA) and transcranial Doppler (TCD) exams were performed at entry and exit, with a central blinded review. A novel MRA vasculopathy grading scale demonstrated frequent severe baseline left/right vessel stenosis (53%/41% ≥Grade 4); 31% had no vessel stenosis on either side. Baseline parenchymal injury was prevalent (85%/79% subcortical, 53%/37% cortical, 50%/35% subcortical and cortical). Most children had low or uninterpretable baseline middle cerebral artery TCD velocities, which were associated with worse stenoses (incidence risk ratio [IRR] = 5.1, P ≤ .0001 and IRR = 4.1, P < .0001) than normal velocities; only 2% to 12% had any conditional/abnormal velocity. Patients with adjudicated stroke (7) and transient ischemic attacks (19 in 11 standard/8 alternative arm subjects) had substantial parenchymal injury/vessel stenosis. At exit, 1 child (alternative arm) had a new silent infarct, and another had worse stenosis. SWiTCH neuroimaging data document severe parenchymal and vascular abnormalities in children with SCA and stroke and support concerns about chronic transfusions lacking effectiveness for preventing progressive cerebrovascular injury. The novel SWiTCH vasculopathy grading scale warrants validation testing and consideration for use in future clinical trials. This trial was registered at www.clinicaltrials.gov as #NCT00122980.