Stroke Prevention Trial in Children With Sickle Cell Disease and Iron Overload Halted

Susan Jeffrey

June 09, 2010

June 9, 2010 — The National Heart, Lung and Blood Institute (NHLBI) announced it has stopped a clinical trial in children with sickle cell disease and iron overload because the newer treatment being evaluated, hydroxyurea with regular phlebotomy, was found to be unlikely to prevent recurrent strokes better than standard therapy combining blood transfusion with deferasirox.

The trial, called Stroke With Transfusions Changing to Hydroxyurea (SWiTCH), had enrolled 133 children from 26 US sites and was comparing the 2 treatment regimens.

"Protecting our participants is an important factor in determining whether to stop a trial," Susan B. Shurin, MD, acting director of the NHBLI, said in a statement from the National Institutes of Health (NIH) dated June 3. About one third of participants had completed the study, during which they were treated and monitored for about 30 months.

The study's Data and Safety Monitoring Board reviewed interim results from the trial and recommended halting the trial; the NHLBI accepted the recommendation and stopped the trial May 6, the statement notes. The board pointed out that no strokes occurred in 66 participants treated with blood transfusions and deferasirox, whereas 7 strokes occurred in the 67 children receiving hydroxyurea and phlebotomy.

Study participants and their families have been contacted and will discuss their future options with their healthcare providers, the NIH release notes.

Previous research has shown that hydroxyurea helps prevent pain crises and some lung complications in adults, and it is the only US Food and Drug Administration–approved drug for treating sickle cell anemia. Preliminary studies had suggested hydroxyurea may also reduce the risk for stroke recurrence in children.

The SWiTCH trial included children between 5 and 18 years of age, all of whom had had a previous stroke. All had been receiving standard therapy with blood transfusions for at least 18 months before enrolment, and all had high levels of iron. The study compared hydroxyurea with standard transfusion therapy and also compared 2 approaches to reduce the iron overload that results from transfusion therapy: phlebotomy, simple regular blood removal, and deferasirox, an iron chelation agent.

Preliminary findings showed phlebotomy did not reduce liver iron better than deferasirox, and analysis of the data available suggested continuing the trial was unlikely to show that phlebotomy would provide a greater benefit in controlling iron accumulation. "Without the ability to provide benefits for the management of liver iron, the potential risks of continuing study treatments were no longer warranted," the NIH statement notes.

The study was scheduled to run until 2012. Rho Inc, of Chapel Hill, North Carolina, served as the SWiTCH statistics and data management center. "Researchers will analyze and publish the final data in the coming months," the statement concludes.

The study was funded by the NHLBI. Novartis US donated the deferasirox (Exjade). Bristol-Myers Squibb and UPM Pharmaceuticals Inc provided the hydroxyurea for the trial.

See the full announcement from NHLBI on the NIH Web site.

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