Treatment with enzyme replacement therapy reverses symptoms in patients with Type I
Gaucher's disease, according to a study published in the May 23 issue of the New
England Journal of Medicine* and conducted by scientists at the National Institute of
Neurological Disorders and Stroke (NINDS). A rare metabolic disorder, Type I Gaucher's
disease affects an estimated 10,000 to 12,000 Americans.
"As the first effective drug treatment for Gaucher's disease, this therapy offers
patients who have been saddled with chronic and debilitating symptoms the chance to break
free from disease," said Dr. Norman Barton, M.D., Ph.D., the NINDS scientist who
directed the study. "Patients treated in the study not only experienced a dramatic
reduction in objective disease signs, they also reported impressive gains in energy,
self-confidence and quality of life."
In Type I Gaucher's disease, the body lacks sufficient levels of an enzyme called
glucocerebrosidase needed for breakdown of a fatty material, or lipid. The deficiency
causes lipid to accumulate, swelling the spleen and liver, crowding out the marrow in the
bones, and triggering anemia and low blood platelet counts. These patients often suffer
from fatigue, grossly distended abdomens, joint and bone pain, repeated bone fractures,
and increased bruising and bleeding. Enzyme replacement therapy replenishes the lacking
glucocerebrosidase with a modified version of the enzyme, known generically as alglucerase
and sold under the trade name Ceredase.
In the recent study, 12 patients with symptomatic Type I Gaucher's disease were treated
every two weeks with intravenous infusions of the drug for periods ranging from 9-12
months. Therapy increased levels of hemoglobin in all patients. It also boosted platelet
counts in seven patients, produced bone improvement in three patients, reduced liver size
in five patients, and decreased spleen enlargement among all patients by an average of
one-third. No adverse effects were observed. "Enzyme replacement is remarkably safe,
and it appears to benefit all patients with Type I Gaucher's disease," Dr. Barton
said.
In addition, all of the treated patients reported increased energy, improved
self-esteem and self-image, and greater ease and self-confidence in daily activities.
While patients in this study received high doses of enzyme, NINDS scientists are now
working to determine the lowest dose needed to reverse symptoms. They have also begun
studies to define how much enzyme patients need in order to stay healthy once their blood
counts have recovered to normal, since lipid buildup would resume in patients without
continued therapy.
Most traditional treatments for Gaucher's disease, such as removal of an enlarged
spleen, relieve some symptoms but do not slow disease progression. Although bone marrow
transplantation can sometimes reverse the disease, it is a relatively risky procedure.
Ceredase is derived from human tissues, purified, then chemically altered in order to
target the cells with lipid buildup. This technique for altering the natural enzyme could
suggest treatments for other metabolic diseases, said NINDS scientist Roscoe Brady, M.D.,
who pioneered enzyme replacement therapy for Gaucher's disease through more than 30 years
of research.
"The targeting strategy we've developed to deliver enzyme in this disorder is a
prototype," said Dr. Brady, chief of the NINDS Developmental and Metabolic Neurology
Branch. "It can be applied to an entire class of inherited diseases where the body
lacks vital proteins, including other lipid storage disorders. We plan to investigate this
possibility," he said.
Gaucher's disease has three forms and affects all racial and ethnic groups. Type I is
the most common genetic disorder among people of Eastern European Jewish descent -- as
many as one in 10 of this group is estimated to carry one copy of the defective gene. In
the rarer and more severe Types II and III, the abnormal lipid storage also affects the
nervous system. NINDS scientists are working to determine the effects of enzyme
replacement therapy in Gaucher's patients with neurological complications.
Ceredase is manufactured by the Genzyme Corporation of Cambridge, Massachusetts, and
was approved by the FDA in early April for treatment of Type I Gaucher's disease.
The National Institute of Neurological Disorders and Stroke, one of the 13 National
Institutes of Health in Bethesda, Maryland, is the primary supporter of brain and nervous
system research in the United States.
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*Barton NW, Brady RO, Dambrosia JM., et. al. Replacement therapy for enzyme deficiency:
Macrophage-targeted Glucocerebrosidase for Gaucher's Disease. The New England Journal of
Medicine, May 23, 1991.