1 United States site
2 to 24 Years
1. Diagnosis of SCA (Hb SS or Sβ0 thalassemia).
2. On simple chronic transfusion therapy for stroke prevention (primary or secondary
prevention) for ≥1 year with no plans to stop simple chronic transfusion in the next
1. Poor adherence to simple transfusion regimen as defined by having an HbS >45% at any
time in the last year AND a transfusion interval >5 weeks.
2. Treatment with hydroxyurea in the 12 months prior to study enrollment.
3. Abnormal initial laboratory values (temporary exclusions):
1. Absolute neutrophil count <1.5 x 10^9/L 2. Platelet count <100 x 10^9/L 3. Serum creatinine more than twice upper limit for age 4. Pregnancy or unwillingness to use a medically acceptable form of contraception if sexually active.