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 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 participant's 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.

Transcranial doppler ultrasonography (TCD) in infants with sickle cell anemia: baseline data from the BABY HUG trial.

BACKGROUND: 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. PROCEDURE: TCD was performed on infants with SCA enrolled in the BABY HUG trial. Subjects were 7-17 months of age (mean 12.6 months). TCD examinations were successfully performed in 94% of subjects (n = 192). RESULTS: No patient had an abnormal TCD as defined in the older child (time averaged maximum mean TAMM velocity > or =200 cm/sec) and only four subjects (2%) had velocities in the conditional range (170-199 cm/sec). TCD velocities were inversely related to hemoglobin (Hb) concentration and directly related to increasing age. CONCLUSION: Determination of whether the TCD values in this very young cohort of infants with SCA can be used to predict stroke risk later in childhood will require analysis of exit TCD's and long-term follow-up, which is ongoing (ClinicalTrials.gov number, NCT00006400).

Stroke Avoidance for Children in REpública Dominicana (SACRED): Protocol for a Prospective Study of Stroke Risk and Hydroxyurea Treatment in Sickle Cell Anemia.

BACKGROUND: In the Dominican Republic, where the burden of sickle cell anemia (SCA) is high, many children lack access to routine screening and preventative care. Children with SCA are at risk for stroke, an event that leads to significant morbidity and mortality. In the United States, screening via transcranial Doppler (TCD) identifies children with SCA at highest stroke risk, allowing early intervention with blood transfusions. The need for indefinite transfusions for primary stroke prevention limits their practicality in limited-resource countries. Hydroxyurea has been shown to lower TCD velocities and to prevent conversion from conditional (170 to 199 cm/sec) to abnormal (greater than or equal to 200 cm/sec) velocities. In resource-limited settings, implementation of a TCD screening program, coupled with hydroxyurea therapy, could reduce the burden of SCA and stroke. OBJECTIVE: The aims of the Stroke Avoidance for Children in REpública Dominicana (SACRED) trial are (1) to screen children with SCA for stroke risk using TCD and to determine the prevalence of elevated velocities in a cross-sectional sample; (2) to identify clinical and laboratory correlates of elevated velocities; and (3) to obtain longitudinal data on the natural history of TCD velocities and to measure therapeutic effects of hydroxyurea. METHODS: This prospective trial, designed and conducted by Cincinnati Children's Hospital Medical Center (CCHMC) and Hospital Infantil Robert Reid Cabral (HIRRC) with Centro de Obstetricia y Ginecología, includes a baseline cross-sectional epidemiological survey of the distribution of TCD velocities across a large cohort of children with SCA in the Dominican Republic. Children with conditional velocities are eligible to begin protocol-directed hydroxyurea if laboratory criteria are met. The treatment schedule begins with a fixed-dose of approximately 20 mg/kg/day for 6 months, after which it escalates to maximum tolerated dose (MTD). All participants undergo longitudinal annual TCD evaluation, while those on hydroxyurea have semi-annual evaluations during the 3-year study period. Data are collected using an Internet-based Research Electronic Data Capture (REDCap) system with forms translated into Spanish; both remote and on-site monitoring are used. RESULTS: To date, 122 children with SCA have enrolled in SACRED including 85 (69.7%, 85/122) with normal, 29 (23.8%, 29/122) with conditional, 5 (4.1%, 5/122) with abnormal, and 3 (2.5%, 3/122) with inadequate TCD velocities. Of the 29 children with conditional TCD velocities, 17 (59%, 17/29) have initiated hydroxyurea per protocol, with plans for escalation to MTD. CONCLUSIONS: The SACRED trial will provide novel epidemiologic data about the prevalence of children with SCA and increased stroke risk in the Dominican Republic. The study also includes an investigation of the impact of hydroxyurea at MTD on elevated TCD velocities, as well as clinical and laboratory parameters. The design and implementation of SACRED reflect a successful international institutional partnership, one that features local capacity building and training in research methods and clinical care. The trial's results have important implications for screening and prevention of primary stroke in children with SCA living in resource-limited settings. TRIAL REGISTRATION: ClinicalTrials.gov NCT02769845; https://www.clinicaltrials.gov/ct2/show/NCT02769845 (Archived by WebCite at http://www.webcitation.org/6qf6n0Egh).