Is hydroxyurea an effective treatment for children with sickle cell disease (SCD)?

Updated: May 12, 2021
  • Author: Joseph E Maakaron, MD; Chief Editor: Emmanuel C Besa, MD  more...
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In a meta-analysis of the literature through 2007, Strouse et al studied the efficacy, effectiveness, and toxicity of hydroxyurea in children with SCD and found that fetal hemoglobin levels increased from 5-10% to 15-20%; hemoglobin concentration increased modestly (approximately 1 g/L) but significantly; hospitalizations decreased by 56-87%; and the frequency of pain crisis decreased. [72]

A phase III multicenter international clinical trial in 38 children with SCD found that hydroxyurea treatment can lower elevated cerebral blood flow velocities, which have been linked to stroke risk. After a mean of 10.1 months, transcranial Doppler (TCD) ultrasound showed that mean velocity had decreased 15.5 cm/sec in patients receiving hydroxyurea but had increased 10.2 cm/sec in those receiving observation only (P=0.02). Post hoc analysis according to treatment received showed that after 15 months, conversion from conditional to abnormal cerebral blood flow velocities occurred in 50% of patients in the observation group but none of those in the hydroxyurea group. [73]  

In December 2017, the FDA approved Siklos (hydroxyurea) to reduce the frequency of painful crises and the need for blood transfusions in children 2 years of age and older and adolescents with sickle cell anemia who have recurrent moderate to severe painful crises. Siklos is the first hydroxyurea formulation to be FDA-approved for pediatric SCD. The approval was based on data from the ESCORT (European Sickle Cell Disease Cohort), an open-label single-arm trial that enrolled 405 pediatric patients with sickle cell disease from 2-18 years of age (274 children, ages 2-11 y; 108 adolescents, ages 12-16 y). The median change in fetal hemoglobin levels was 0.5 g/dL in 63 patients at 6 months and 0.7 g/dL in 83 patients at12 months after initiation of  treatment. After 12 months of treatment, the drug exhibited an ability to increase fetal hemoglobin in all patients, and decrease the percentage of patients who experienced at least on vaso-occlusive episode, one episode of acute chest syndrome, one hospitalization due to SCD, or one blood transfusion. [74]

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