Stroke With Transfusions Changing to Hydroxyurea

BACKGROUND: Stroke occurs in 10% of children with SCA and has a very high risk of recurrence without therapy. Affected children receive chronic erythrocyte transfusions to prevent a secondary stroke, which are effective but have limited long-term utility due to transmission of infectious agents, erythrocyte alloantibody and autoantibody formation, and iron overload. Transfusion acquired iron overload can cause chronic organ damage with hepatic fibrosis and cirrhosis, poor growth and development, cardiac arrhythmias, and early sudden death in young patients with SCA and stroke. An alternative to transfusions for secondary stroke prevention that also addresses the issue of transfusion acquired iron overload is clearly needed. Hydroxyurea can prevent acute vaso-occlusive events in SCA, but its utility for cerebrovascular disease and for the prevention of secondary stroke in SCA is not proven. Pilot data indicate hydroxyurea can prevent stroke recurrence in children with SCA; after transfusions are discontinued, serial phlebotomy reduces iron burden. DESIGN NARRATIVE: This is a Phase III randomized clinical trial for children with SCA. The hypothesis is that hydroxyurea and phlebotomy can maintain an acceptable stroke recurrence rate and significantly reduce the hepatic iron burden. The primary aim is to compare standard therapy (transfusions and chelation) with alternative therapy (hydroxyurea and phlebotomy) for the prevention of secondary stroke and management of iron overload. Additional aims include comparisons of growth and development, frequency of non-stroke neurological and other sickle-related events, and quality of life. The use of hydroxyurea for secondary stroke prevention, coupled with removal of excess iron by phlebotomy, would represent a significant improvement in the management of individuals with SCA and stroke. If hydroxyurea is effective for the prevention of secondary stroke, it may also be beneficial for other children with SCA and cerebrovascular disease, including those at risk for primary stroke. The trial includes approximately 130 children (5.0-18.9 years of age with 65 subjects per treatment arm) with SCA who have had symptomatic cerebral infarctions and have been treated with red cell transfusions for at least 18 months. After completing baseline screening studies, half the participants will be switched to a therapeutic program of hydroxyurea and phlebotomy. Half of the participants will remain on transfusion and chelation. The composite primary endpoint in this study is to compare two modalities of treatment for the prevention of secondary stroke and management of iron overload. The impetus for this trial is the fact that long-term transfusion and chelation therapy in children is difficult, is frequently unsuccessful, and is often complicated by severe symptomatic iron overload, particularly of the heart, lungs, and liver.