The gene contains instructions for the production of alpha-galactosidase A, an enzyme responsible for breaking down a fatty molecule that cells produce — globotriaosylceramide, (Gb3 or GL-3).
Lack of the enzyme leads to a build-up of Gb3 in cells. The damage the build-up causes leads to the symptoms of Fabry disease, including kidney problems, heart attacks, and stroke.
How enzyme replacement therapy works
Enzyme replacement therapy generates the enzyme that is non-functional or missing in a disease.
It is a lifelong treatment, with the enzyme given continuously. Stopping it will lead to symptoms returning. A person receiving the treatment must be monitored closely for adverse effects. If there are any, the dose of the therapy must be adjusted.
Enzyme replacement therapy for Fabry disease
Patients with Fabry disease are unable to make sufficient amounts of alpha-galactosidase A. An enzyme replacement therapy provides them with the enzyme they need to break down the accumulation of Gb3. It is given by intravenous injection every few weeks.
Some researchers have questioned the therapy’s effectiveness. One review suggested it might provide less benefit than thought. Other researchers have noted that the results of enzyme replacement therapy vary greatly among patients. Its effectiveness depends on factors such as a person’s sex, differences in the mutation causing the disease, and the extent of organ damage before beginning the treatment, these scientists say.
A recent review concluded that enzyme replacement therapy is beneficial and should be started as early as possible, especially in men. Women generally have milder Fabry symptoms, so the treatment should be applied only if signs of organ damage appear, the review contended.
Fabry patients with kidney problems may need to add other therapies to their enzyme replacement regimen. These include angiotensin-converting enzyme (ACE) inhibitors and angiotensin 2 receptor blockers.
Types of enzyme replacement therapy for Fabry disease
There are two main enzyme replacement medications for Fabry disease — agalsidase alfa and agalsidase beta. Both mimic the actions of alpha-galactosidase A.
They are manufactured by various pharmaceutical companies and marketed in different parts of the world under different brand names. They include:
Fabrazyme is the first treatment developed specifically for Fabry disease. Its active ingredient is agalsidase beta, one version of the missing enzyme alpha-galactosidase A. The Sanofi Genzyme therapy is administered by intravenous injection once every two weeks.
Like Fabrazyme, PRX-102 is a copy of the human enzyme alpha-galactosidase A. While Fabrazyme is produced in cells from mammals, PRX-102 is produced in genetically modified plant cells. Its developer, Protalix Biopharmaceuticals, is testing it in a Phase 3 clinical trial.
Replagal’s active ingredient is agalsidase alfa, another version of the enzyme alpha-galactosidase A. Manufactured by Shire, it is approved for Fabry disease in the U.K., Canada, and many countries in Europe. It has yet to receive U.S. Food and Drug Administration approval.
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