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Background: Sickle cell anemia is associated with progressive compromise of neurocognitive function exacerbated by stroke or silent cerebral infarction. Despite decades of experience with chronic transfusion, hematopoietic stem cell transplantation, and HU, improvement in neurocognitive performance from these interventions has not been clearly demonstrated; only one study has reported improvement in global cognitive index from HU (Puffer, Child Neuropsychology, 2007). As part of a comprehensive prospective evaluation of the effects of HU treatment on the central nervous system, we evaluated neuropsychological performance in school-age children with sickle cell anemia. Methods: Subjects had HbSS/Sβ0 thalassemia and no history of previous central nervous system (CNS) events and were 7-18 years old. After informed consent, baseline evaluations included the Wechsler Intelligence Scale for Children, 4th edition (WISC-IV) and the Woodcock-Johnson Achievement Test Version III (WJ-III). Treated patients received HU beginning at 20 mg/kg/d with gradual escalation to maximum tolerated dose (MTD) within one year. They were evaluated with the same CNS studies after 12 months. A control group who declined HU treatment was matched by diagnosis and age and was also evaluated at baseline and after one year. Summary statistics of WISC and WJ-III scores were reported for each time point and for their change between two time points in each group and were compared using the Wilcoxon rank sum and Wilcoxon signed rank tests, respectively. Results: Age and gender distributions in HU-treated (n=21) and untreated control patients (n=11) were comparable. In HU-treated patients, but not in controls, there was significant improvement in mean full scale IQ (FSIQ) after one year (Table 1). In treated subjects, mean WISC subscale scores were all higher after one year, although none were statistically significant. Among controls, FSIQ and all subscales, except working memory, showed a numerical decrease in mean scores, with the greatest decline in perceptual reasoning. Subtest scores from the WJ-III Achievement test in HU-treated patients showed significant improvement in comprehension of word passages. Among controls, WJ-III Achievement subtest scores showed no significant changes. When mean changes in WISC scores from baseline to one-year follow-up were compared (Table 2), treated patients showed greater positive changes than controls, but differences were not significant. Changes in WJ-III scores for treated and control subjects also were not significant. Conclusions: In children with sickle cell anemia, HU treatment over a one year period was associated with a significant improvement in the Wechsler Full Scale IQ; subscales showed small to medium positive changes although the differences were not statistically significant. By contrast, in the untreated control group, most scores were lower after one year and mean changes in scores from baseline were less positive than those in the HU group. In measures of achievement, the treated group demonstrated improved passage (reading) comprehension, a skill related to executive function. Overall, these results suggest that HU may improve cognitive function or prevent decline. Correlation of standard and functional MR neuroimaging in these subjects with neurocognitive performance is pending. Future trials are needed to examine the impact of other interventions (e.g., memory training, multisensory reading intervention), possibly in conjunction with HU. Disclosures No relevant conflicts of interest to declare.

Transcranial Doppler (TCD) screening in children with sickle cell anemia (SCA) identifies abnormally elevated cerebral artery flow velocities that confer an elevated risk for primary stroke. Chronic transfusions offer effective stroke prophylaxis in this setting, but must be continued indefinitely and lead to transfusional iron overload. An alternative treatment strategy that offers similar effective protection against primary stroke, and provides control of iron overload, is needed. TCD With Transfusions Changing to Hydroxyurea (TWiTCH, NCT01425307) was an NHLBI-funded Phase III multicenter randomized clinical trial comparing 24-months of standard treatment (transfusions) to alternative treatment (hydroxyurea) in children with SCA and abnormal TCD velocities. All eligible children had received at least 12 months of transfusions. TWiTCH had a non-inferiority trial design; the primary study endpoint was the 24-month TCD velocity obtained from a linear mixed model, controlling for baseline (enrollment) values, with a non-inferiority margin of 15 cm/sec. The transfusion arm maintained children at HbS 240 cm/sec. Exit brain MRI/MRA exams documented no new parenchymal abnormalities but one child (transfusion arm) developed new vasculopathy. Sickle cell related serious adverse events were more common in the hydroxyurea arm than the transfusion arm (23 to 15), but none was related to study treatment or study procedures. Iron overload improved more in the hydroxyurea arm than in the transfusion arm, with a greater average change in serum ferritin (-1085 compared to -38 ng/mL, p Disclosures Ware: Eli Lilly: Other: DSMB membership; Bayer Pharmaceuticals: Consultancy; Bristol Myers Squibb: Research Funding; Biomedomics: Research Funding. Off Label Use: Hydroxyurea for children with SCA. Owen:Novartis: Speakers Bureau. Rogers:BioRad Labs: Consultancy; Apopharma: Consultancy; Baxter: Consultancy; Glaxo Smith Kline: Consultancy. Kwiatkowski:Shire Pharmaceuticals and Sideris Pharmaceuticals: Consultancy; Sideris Pharmaceuticals: Consultancy; Novartis: Research Funding; ISIS: Membership on an entity's Board of Directors or advisory committees. Heeney:Sancillio: Consultancy; Eli Lilly: Research Funding. Nottage:Janssen Pharmaceuticals: Employment. Cohen:Novartis: Consultancy; ApoPharma: Other: DSMB member.

Background: Up to 40% of children with sickle cell anemia (SCA) will have abnormalities on brain imaging due to their hematologic disorder, much of which is subclinical. Common abnormalities on brain magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) include leukoencephalopathy from microvascular ischemic insult and vascular stenosis from endothelial damage. Silent cerebral ischemic insults are progressive; further neurologic abnormalities, including overt stroke, are more common among children with ischemic findings on MRI compared to children without them. Furthermore, poor performance on neuropsychological testing, lower IQ, and higher rates of grade retention are common in children with SCA and cerebral ischemic disease. The effect of hydroxyurea treatment on the development and progression of vascular stenosis and leukoencephalopathy is unclear. This study aimed to longitudinally evaluate the development of intracerebral abnormalities through serial MRI/MRA in children with SCA (HbSS and HbSβ0-thalassemia) who receive long-term therapy with hydroxyurea. Methods: Children with SCA and no prior history of overt stroke enrolled in the Hydroxyurea Study of Long-Term Effects (HUSTLE NCT00305175) underwent brain MRI/MRA, transcranial doppler (TCD) examinations, and laboratory evaluations immediately before hydroxyurea initiation and after 3 and 6 years of treatment to maximum tolerated dose. MRI/MRAs were reviewed for the presence or absence of vascular stenosis and leukoencephalopathy. Leukoencephalopathy was defined as white matter T2 hyperintensity. Proportions of abnormal MRI/MRA findings were compared between baseline and 3 years and baseline and 6 years using McNemar’s test and the Wilcoxon-Mann-Whitney exact test was used to explore associations with laboratory parameters. Results: Forty-six children with SCA, mean age 9.4 years (range 1-17.3), had an MRI/MRA at baseline and 3 years post-initiation of hydroxyurea. Ten children had an additional MRI/MRA after 6-years of hydroxyurea therapy. Frequencies of leukoencephalopathy and vascular stenosis are shown in the table. Prevalence of leukoencephalopathy before hydroxyurea therapy was higher than that reported in the literature for untreated children with SCA of similar age. There were no significant differences between baseline imaging findings and those at 3 and 6 years. Table: Prevalence of leukoencephalopathy and vascular stenosis at baseline, 3 and 6 years Baseline (n=47) Median age 9.6 years (range 1.0 to 17.3) 3 years (n=46) Median age 13.1 years (range 4.4 to 21.1) 6 years (n=10) Median age 14.5 years (range 8.3 to 18.3) Leukoencephalopathy 27 (57.4%) 28 (60.9%)* 5 (50%)* Stenosis 3 (6.4%) 1 (2.2%)* 0 *all p>0.05 Children with leukoencephalopathy at baseline and 3 years were older than those without (mean 10.7 vs. 7.7 years, p=0.01; 10.5 vs. 7.5 years, p=0.02 respectively). Lower HbF at baseline was associated with the presence of leukoencephalopathy at year 3 (median HbF 4.6% vs. 12.4%, p=0.008), but there was no association between HbF at 3-years and the presence of leukoencephalopathy at 3-years (median HbF 16.4% vs. 13.2%, p=0.55). When stratified by age, these findings were similar. TCD velocities and other hematologic parameters were not associated with MRI/MRA abnormalities. The small number of vascular stenosis cases precluded further analyses of this outcome. Conclusions: In this longitudinal study, children treated with hydroxyurea for 3-6 years did not demonstrate an increased frequency of vascular stenosis or leukoencephalopathy on brain MRI/MRA during treatment. Older age at hydroxyurea initiation and lower pre-hydroxyurea HbF percentage were associated with the presence of leukoencephalopathy at baseline and 3-years. These findings suggest that hydroxyurea may mitigate the expected progression of vascular stenosis and leukoencephalopathy in children with SCA, and that this therapy should be initiated early on, before the development of cerebrovascular disease, particularly among those with a low HbF percentage. Disclosures Off Label Use: hydroxyurea for children with sickle cell disease.

Introduction: Transcranial Doppler ultrasonography (TCD) is an established screening modality used to predict stroke in children with sickle cell anemia (SCA). Children with abnormal TCD velocities are at high risk for primary stroke. Based on STOP and STOP 2 data, indefinite chronic red cell transfusion therapy is recommended for children with SCA and abnormal TCD velocity, defined as a maximum time-averaged mean velocity (TAMV) ≥200 cm/sec. The aim of the current analysis was to evaluate the long term effects of transfusion therapy on TCD velocities, in a large cohort of children with SCA who received chronic red cell transfusion therapy for primary stroke prophylaxis. Methods: The TCD With Transfusions Changing to Hydroxyurea (TWiTCH) study is a phase III, randomized, controlled, multicenter non-inferiority trial comparing hydroxyurea to transfusions for primary stroke prevention in children with SCA and abnormal TCD velocities (ClinicalTrials.gov NCT01425307). Children with SCA and a history of abnormal TCD who received at least 12 months of transfusion therapy were eligible to participate. All subjects’ index TCD velocities (the TCD examination that prompted the start of chronic transfusion therapy) were reviewed centrally to confirm study eligibility. At enrollment, study TCD velocities were obtained using the SONARA/tek TCD Module by trained examiners and reviewed centrally. In addition, all children were evaluated with brain magnetic resonance angiography (MRA) scans, which were also reviewed centrally. Associations between demographic, clinical, radiological, and laboratory findings and index/enrollment TCD velocities were examined. Results: One hundred and thirty eight children with complete data were included in this analysis. Mean age for the entire cohort at enrollment was 9.8±2.8 years; 40% were male and 98.8% had HbSS. Mean age at the diagnosis of index TCD was 5.5±2 years. The mean duration of transfusion therapy was 4.3±2.4 years with 63% receiving simple transfusions, 30% receiving partial exchange transfusions, and 7% undergoing erythrocytapheresis. The mean pre-transfusion hemoglobin at study entry was 9.1±0.8 gm/dL and the mean pre-transfusion %HbS for the last 6 months prior to study entry was 29.5±8.3%. The average index TCD TAMV was 217±22 cm/sec (range 147-325). At study entry, the average TAMV was lower at 150±27cm/sec overall (142±27 cm/sec on the left and 140±29 cm/sec on the right). In 77% of the subjects, the TCD velocities had decreased to normal levels ( Conclusions: Most of the children with SCA at high risk for primary stroke enrolled in the TWiTCH study have normal TCD velocities at study entry, although 21% have conditional and 3% still have abnormal velocities. Longer duration of transfusion therapy was associated with lower TCD velocities, while the presence of severe vasculopathy on brain MRA and recent higher pre-transfusion %HbS values were associated with higher TCD velocities. The TWiTCH trial will serially perform TCD examinations to compare the effects of hydroxyurea versus transfusions. Disclosures Off Label Use: Use of hydroxyurea in children with sickle cell disease.

Introduction : Stroke is a major cause of morbidity and mortality in children with sickle cell anemia (SCA), and current efforts seek to prevent primary stroke in this high-risk population through transcranial Doppler (TCD) screening programs and prophylactic blood transfusions for children with abnormally high intracranial TCD velocities. During the SWITCH trial (ClinicalTrials.gov NCT00122980), a novel MRA vasculopathy grading (VOG) scale was developed, which documented baseline bilateral vessel stenosis and parenchymal injury in children receiving transfusions for secondary stroke prophylaxis, and provided a severity scale suitable for future clinical trials. We now describe the baseline brain magnetic resonance imaging/angiography (MRI/MRA) results and vasculopathy grading scores in children with SCA on primary stroke prophylaxis, and report correlations with intracranial TCD velocities and duration of transfusion. Methods: TCD With Transfusions Changing to Hydroxyurea (TWiTCH) is a Phase three randomized, controlled, multicenter clinical trial (ClinicalTrials.gov NCT01425307), comparing transfusions versus hydroxyurea for children with abnormal TCD velocities. Children were eligible for TWiTCH enrollment if they currently receive monthly transfusions for primary stroke prophylaxis, and had no known history of stroke, transient ischemic attack, or severe vasculopathy. All TWiTCH participants underwent baseline MRI/MRA examinations with central review after study enrollment. Baseline TCD examinations were also centrally reviewed and Time-Averaged Mean Velocities (TAMV) were recorded for the distal internal carotid artery (dICA), internal carotid bifurcation (BIF), first segment middle cerebral artery (MCA) = M1, mid MCA (MCA), and posterior cerebral artery (PCA). MRA vasculopathy grades were recorded bilaterally and compared to the TCD velocities and duration of transfusion. Results: Of 159 enrolled subjects, 143 had complete baseline MRI/MRA data. The mean age at study enrollment was 9.8 years, with a 2:3 male:female ratio, and mean age at the original abnormal (Index) TCD exam was 5.4 years. A total of 62 children had parenchymal abnormalities identified on baseline brain MRI, including 2 with infarcts, 54 with leukoencephalopathy, 5 with encephalomalacia, and 20 with lacunae lesions (not mutually exclusive). A total of 124 children had baseline MRA vasculopathy scores ≤3, while 19 had grades 4-6 (severe vasculopathy) that required removal from the study. There were significant positive associations between the baseline hemisphere vasculopathy grades and the corresponding TAMV velocities in the Left dICA (p=0.02), Left BIF (p˂.0001), Left MCA (p=.0002), Right BIF (p=.0003) and Right MCA (p=.0002). Likewise, when TCD velocities were categorized as low ( Conclusions: Since the TWiTCH study excluded the enrollment of children on chronic transfusion therapy for primary stroke prevention with a known history of stroke, TIA, or severe vasculopathy, the prevalence of baseline brain MRI and MRA abnormalities was relatively higher than expected and 19 participants failed screening due to unrecognized severe vessel stenosis. The recent published SWiTCH vasculopathy grading scale was validated in the TWiTCH population, with more severe stenosis found to be associated with higher ipsilateral TCD velocities. Exit brain MRI/MRA exams will be compared to entry studies, to provide longitudinal data including comparisons between the effects of continued transfusions and hydroxyurea. Disclosures No relevant conflicts of interest to declare.