Editor's note 2/2/12:This story was updated to reflect the award of a new MDA grant to Eric Sjoberg at Amicus Therapeutics.
Drugs that suppress the immune system can successfully prevent or reverse rejection of enzyme replacement therapy in Pompe disease (acid maltase deficiency),a new study has shown.
Pompe disease results from a deficiency of the enzyme acid maltase, also called acid alpha-glucosidase, or GAA. The disease can be treated with Myozyme or Lumizyme, which are both laboratory-modified forms of GAA. Enzyme replacement therapy (ERT) can be lifesaving in the infantile-onset form of Pompe disease.
However, in some individuals, particularly those who are not making any GAA at all, the immune system regards the replacement enzyme as foreign and develops immune system proteins called antibodies that limit the treatment's effectiveness.
In the January 2012 issue of Genetics in Medicine, Yoav Messinger at Children's Hospitals and Clinics of Minnesota, and colleagues, show that two immunosuppressant drugs — rituximab and methotrexate— prevented formation of anti-GAA antibodies in two children who were not making any GAA themselves and who were being treated with Myozyme.
The investigators also showed that these two drugs, in combination with intravenous immunoglobulins (IVIG), which modify the behavior of the immune system, were effective in reversing an established immune response to Myozyme in two other children whose cells were not producing any GAA.
All four children who received the immunosuppression regimen benefited from Myozyme treatment.
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Genzyme, the company that developed Myozyme and Lumizyme, is studying the best way to bring about immunologic tolerance to Myozyme.
MDA grantee studying immune response to ERT
Eric Sjoberg at Amicus Therapeutics received an MDA grant in early 2012 to study the immune response some people have to ERT. Sjoberg and colleagues also will determine whether an experimental drug called AT2220, in development at Amicus, can dampen an ERT-related immune response.