Previously Banned Drug May Be Useful in Treating Rare Disorder

A morning sickness drug, banned for causing birth defects in the 1960s, is being studied as a treatment option for a rare immune system disease in children.

"Thalidomide in clinical trials has been coming back for the past five or 10 years," said Dr. Kenneth McClain, associate professor of pediatrics at Baylor College of Medicine. "Researchers are realizing that it has some good effects and can be useful in carefully controlled situations."

Dr. McClain is studying the use of thalidomide in young children with Langerhans Cell Histiocytosis, a disease caused by an abnormal growth of white blood cells. In the two-year clinical trial, he is evaluating patients at Texas Children's Cancer Center.

LCH affects between two and five children per million in the United States. Patients with LCH have high concentrations of a protein called tumor necrosis factor alpha in the lesions associated with the disease. Thalidomide has been shown to decrease the production of this protein.

In LCH, collections of tissue cells known as histiocytes cause a range of symptoms, including bone lesions, skin rashes, mouth ulcers and problems with the spleen, liver and central nervous system. Older children and adults usually have one or two of these symptoms. Children under 12 months of age frequently have most of these symptoms, Dr. McClain said.

The standard treatment has been chemotherapy.

"The reason it's such a serious disease in young children is that it involves so many systems of the body," Dr. McClain said. "Fifty percent of the time when we use chemotherapy, it's not successful."

Half of the children under age 2 who have involvement of the liver, lungs or bone marrow do not survive.

The study is tightly controlled, with a very stringent consent process.

The National Organization of Rare Diseases provided a funding grant to conduct the study.

Though the drug has a history of causing birth defects when administered to pregnant women, the side effects for the young LCH patients appear minor, Dr. McClain said. The major side effect observed for children in the study has been a disruption in the normal sleep cycle.

Dr. McClain's Phase 2 clinical trial is the only non-chemotherapy trial available for children with histiocytosis.

"We're hopeful that this will offer us a new treatment option. We've really exhausted the common therapies we use," said Dr. McClain, who serves as president of the Histiocyte Society.

Thalidomide is also being investigated for use in adults with some skin diseases, cancers and AIDS.

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©2006 Texas Medical Center

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