New therapy helps boy with rare disease

By Julie Steenhuysen

CHICAGO (Reuters) - A drug used to suppress the immune system in cancer and rheumatoid arthritis has helped extend the life of a Minnesota boy struggling with a rare and deadly form of the genetic disorder Pompe disease.

A team of researchers led by Dr. Nancy Mendelsohn of Children's Hospitals and Clinics of Minnesota used a novel treatment plan using Rituxan, or rituximab, a drug used for non-Hodgkin's lymphoma and rheumatoid arthritis made by Genentech Inc and Biogen Idec.

Rituxan is a monoclonal antibody, a genetically engineered immune system molecule. The team used Rituxan in combination with the rheumatoid arthritis drug methotrexate and intravenous gamma globulin, in a bid to damp down the child's immune response.

"It seems to have worked," said Mendelsohn, who chronicled the child's case in the New England Journal of Medicine on Wednesday.

Pompe is an enzyme disease, and many of its youngest victims lack a gene that makes alpha-glucosidase or GAA, which is needed to break down glycogen, a stored form of sugar.

The resulting build up of glycogen damages the muscles, especially the heart and skeletal muscles.

Older Pompe patients often respond to enzyme replacement therapy, but many infants with the "CRIM negative" form of the disease quickly make antibodies to the enzyme and rarely see their first birthday.

Not so for Ira Brown of Minneapolis, whose symptoms first appeared at around five weeks of age.