Enzyme replacement therapy
Information about Enzyme replacement therapy
Enzyme replacement therapy refers to treatment of congenital enzyme deficiencies using purified human, animal or recombinant enzyme preparations. The enzymes are given parenterally, usually by intravenous infusion.
Liver toxicity of Enzyme replacement therapy
The diseases treated are generally rare genetic disorders which lead to severe disability and premature death.
Mechanism of action of Enzyme replacement therapy
Enzyme replacement therapy is typically used to replace a missing or deficient enzyme in a person with an inherited enzyme deficiency syndrome. The missing enzyme is replaced by infusions of an enzyme that is purified from human or animal tissue or blood or produced by novel recombinant techniques. Typically, the enzyme is modified to allow for a longer half-life, more potent activity, resistance to degradation or targeting to a specific organ, tissue or cell type.
Enzyme replacement therapy for alpha-1-antitrypsin (A1AT) deficiency
The first successful enzyme replacement therapies were for alpha-1-antitrypsin (A1AT) deficiency using plasma derived purified human A1AT. A1AT deficiency is associated with early onset emphysema attributed to the lack of leukocyte elastase inhibitor which leads to progressive pulmonary damage. Small prospective studies suggested a benefit from augmentation therapy, raising the levels of A1AT in serum by infusing the enzyme purified from human serum. This therapy was eventually shown to be beneficial, particularly in patients with early or intermediate pulmonary dysfunction and was quite safe, without the occurrence of viral hepatitis, despite being prepared from human plasma.
Enzyme replacement therapy in Gaucher disease
A second form of successful enzyme replacement therapy was established for Gaucher disease, an inherited deficiency of lysosomal acid β-glucocerebrosidase that leads to accumulation of the substrate (glucocerebroside and its other breakdown products such as ceramide) in lysosomes. The major tissues affected are liver, spleen and bone. The glucocerebrosidase was initially prepared from placental tissue and was modified to allow its specific uptake by macrophages and delivery into lysosomes. Subsequently, recombinant forms of glucocerebrosidase have been developed and now constitute the standard of care for type 1 Gaucher disease.
Genetic diseases treated with enzyme replacement therapy
Subsequently, similar or related approaches have been taken to treat other enzyme deficiency syndromes such as adenosine deaminase deficiency, lysosomal acid lipase deficiency, Fabry disease, Pompe disease, Hurler and Hunter syndrome and several of the rarer forms of mucopolysaccharidoses. A list of enzymes approved for use in enzyme replacement therapy in the United States, the year of first approval, the generic and brand names of the product and the disease for which they are used are given in the Table.
Side effects of Enzyme replacement therapy
Natural purified and recombinant enzymes are generally well tolerated with minimal systemic adverse reactions. The usual major reactions to enzyme replacement therapy are local infusion reactions and hypersensitivity reactions. Hypersensitivity can be a difficult problem, not just in causing allergic symptoms but also in causing inactivity of the enzyme by cross reacting antibodies. Hypersensitivity reactions are generally more common and more severe in patients with total absence of the enzyme, rather than a deficiency or minor amino acid mutation that inactivates the protein. Hypersensitivity reactions can be severe with rash, fever, hypotension, angioneurotic edema, bronchospasm, anaphylaxis and cardio-pulmonary collapse. Most reactions, however, are mild and transient and may be prevented by premedication with antihistamines, antipyretics or corticosteroids.
List of Enzyme replacement therapy
|Generic Name||Brand Name||Enzyme||Year||Disease|
|Alpha1-Proteinase inhibitor||Prolastin-C Glassia||Alpha1-Antitrypsin||2009/2010||A1AT Deficiency|
|Pegademase||Adagen||Adenosine Deaminase||2000||ADA Deficiency|
|Agalsidase beta||Fabrazyme||Alpha-Galactosidase A||2003||Fabry|
|Alglucosidase alfa||Lumizyme||Acid alpha-Glucosidase||2010||Pompe|
|Laronidase||Aldurazyme||α-L-Iduronidase||2003||Hurler, MPS I|
|Idursulfase||Elaprase||Iduronate-2-Sulfatase||2006||Hunter, MPS II|
|Elosulfase alfa||Vimizim||N-Acetylgalactosamine-6 Sulfatase||2014||Morquio Snydrome A, MPS IVA|
|Galsulfase||Naglazyme||N-Acetylgalactosamine-4 Sulfatase||2005||Maroteaux-Lamy, MPS VI|
|Sebelipase alfa||Kanuma||Lysosomal Acid Lipase||2015||Wolman, LAL Deficiency|
* Withdrawn from market. MPS=Mucopolysaccharidosis.
genetic disorder agents
- gaucher disease agents
glucosylceramide synthase inhibitors (substrate restriction therapy)
lysosomal acid lipase deficiency agents
- agalsidase beta, alglucosidase alfa, alpha1-proteinase inhibitor, elosulfase alfa, galsulfase, idursulfase, laronidase, pegademase
Huntington disease agents
Urea Cycle Disorder Agents
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