Adult Sickle Cell Drug May Benefit Kids, Too

SUNDAY Dec. 11, 2011 -- A drug called hydroxyurea that's approved for use in adults with severe sickle cell anemia can also help young children with the disease, new research suggests.

Children with sickle cell anemia younger than 4 years old who took the medication had fewer emergency department visits for pain crises, hospital admissions, illnesses with fever and need for transfusions, the study found.

"Hydroxyurea may be an option for all children with sickle cell anemia. If you're the parent of a child with sickle cell anemia, talk with your child's doctor about whether it might be right for your child," said study lead author Dr. Zora Rogers, a professor of pediatrics at the University of Texas Southwestern Medical Center, Dallas.

"We don't see a difference in toxicity; we don't see a big difference in growth," said Rogers, who's also clinical director of the bone marrow failure and general hematology program at Children's Medical Center in Dallas. "Hydroxyurea is not causing any obvious harm. We'll need to follow the children through adolescence, but right now the oldest is 9."

Rogers was scheduled to present the study's findings Sunday at the annual meeting of the American Society of Hematology in San Diego.

In sickle cell anemia, red blood cells become rigid and develop a crescent, or sickle, shape, often leading to pain, infection, organ damage, and even stroke. Hydroxyurea makes it less likely that red blood cells will bend abnormally, according to the U.S. National Institutes of Health. People taking the drug must get monthly blood counts to verify they're on the most effective dose, Rogers said.

The new study followed up on one done with babies and toddlers with sickle cell anemia. In that earlier study, nearly 200 babies between 9 and 18 months old were randomly selected to receive treatment with either hydroxyurea or a placebo. The study, called Baby Hug, found that children on hydroxyurea had fewer pain crises, acute chest syndrome events, blood transfusions and hospital admissions.

Parents of the 176 children who completed at least 18 months of the Baby Hug study were offered a chance to participate in the current follow-up study, sponsored by the U.S. National Heart, Lung, and Blood Institute. One hundred and sixty-three children continued in the study.

All the children had the chance to take hydroxyurea in the follow-up study. One hundred and thirty three parents chose the drug.

Researchers have seen each child every six months, and now have 36 months of follow-up data. Rogers said the researchers have almost 500 patient-years of follow-up information.

As with the initial study, the follow-up study saw fewer ER visits for pain crises, transfusions and hospital admissions. For each 100 patient-years, the study found 28.8 emergency room visits for pain crises for those children on hydroxyurea, compared to 53.6 for those on a placebo. For transfusions, there were 18.3 per 100 patient-years for kids on the medication, versus 35.9 for those on a placebo. There were 72.9 hospital admissions per 100 patient-years for those receiving treatment, and 131.7 for those taking a placebo.

The follow-up also found fewer illnesses with fever -- 28.5 per 100 patient years for kids on the drug and 61.5 for children not taking the drug.

"The benefits outweigh the risks for hydroxyurea when administered under supervision," said Dr. Lakshmanan Krishnamurti, director of hematology and hemoglobinopathy at Children's Hospital of Pittsburgh. "This study [offers] a ray of hope and shows us a way to move forward. I hope it leads to change in how physicians think about patients with sickle cell disease. Families can undertake medications and they will come for monitoring."

"We know what 30 years of sickle cell does to a body," Krishnamurti added. "This study shifts the paradigm from chronic palliation to an attempt to give the medication that now has a demonstrated track record of efficacy before damage is done."

A second study, also to be presented Sunday at the meeting, looked at the potential for a side effect from hydroxyurea called genotoxicity. A drug with genotoxic effects has the potential to damage DNA. Some laboratory tests had suggested that this could be possible with hydroxyurea.

Researchers from the Baylor College of Medicine in Houston and elsewhere looked for evidence of DNA damage in the babies and toddlers enrolled in the Baby Hug study. They found no significant differences in signs indicating DNA damage between kids on the drug and kids on a placebo, suggesting that any potential for genotoxicity is low.

Research presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.

More information

To learn more about hydroxyurea, visit the U.S. National Library of Medicine.

Posted: December 2011


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