The life of a Minnesota boy suffering with a rare and serious form of the genetic disorder Pompe disease has been extended after treatment with a drug typically used to suppress the immune system of those with cancer and rheumatoid arthritis.
Rituxan, or rituximab, is a monoclonal antibody made by Genentech Inc and Biogen Idec. It consists of genetically engineered immune system molecules, and is used to treat non-Hodgkin’s lymphoma, rheumatoid arthritis and other conditions.
Dr. Nancy Mendelsohn of Children’s Hospitals and Clinics of Minnesota led a team of researchers that devised a novel treatment plan for the boy using Rituxan in combination with the rheumatoid arthritis drug methotrexate and intravenous gamma globulin. The researchers’ goal was to dampen the boy’s immune response.
“It seems to have worked,” Dr. Mendelsohn told Reuters.
Pompe is an enzyme disease that robs many of its youngest victims of a gene that makes GAA, or alpha-glucosidase, which is required to break down glycogen. If not broken down, the glycogen, a stored form of sugar, builds up and damages the muscles. The condition is particularly damaging to the heart and skeletal muscles.
While older patients with Pompe usually respond to enzyme replacement therapy, many infants with the “CRIM negative” form of the disease quickly produce antibodies to the enzyme and rarely live even one year.
However, that has not been the case for Ira Brown of Minneapolis, whose symptoms first appeared at five weeks of age.
Dismayed by the poor prognosis of infants who develop the disorder, Mendelsohn and her team wanted to try to suppress the child’s immune system, hoping that would allow him to better respond to the enzyme replacement treatment.
At 2-1/2, Brown is now the oldest survivor of the CRIM negative form of Pompe disease after receiving the new treatment.
Mendelsohn is optimistic the treatment will produce a tolerance to enzyme-replacement therapy, so that the Rituxan could ultimately be discontinued. The treatment is being tried on other children, she said, and may work for other diseases such as hemophilia A and B, Gaucher’s disease and Fabry’s disease.
Mendelsohn’s report about Brown’s case was published Wednesday in the New England Journal of Medicine on Wednesday. A summary can be viewed here.
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