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Hunter disease/mucopolysaccharidosis type II/iduronate sulfatase deficiency
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
Specific treatment for this disease continues to be explored. Enzyme replacement therapy with human idursulfatase produced by recombinant DNA technology has been administered intravenously [81–84]. Urinary levels of GAG were reduced. Splenic volume was decreased [81]. Mental decline has not been arrested. Treatment was approved by the FDA in 2006. In a double-blind placebo-controlled trial [82] urinary GA6 were reduced in two weeks and liver and spleen value decreased by 24 weeks. In a trial, forced vital capacity and the 6-minute walk test were significantly reported [83]. Currently idursulfase is given in weekly, 3-hour infusions at 0.5 mg/kg. Bone marrow transplantation has been performed in this disease [85]. It may improve respiratory problems or the size of liver and spleen. It does not improve cerebral function.
Enzyme replacement combinational therapy: effective treatments for mucopolysaccharidoses
Published in Expert Opinion on Biological Therapy, 2021
Azam Safary, Hakimeh Moghaddas-Sani, Mostafa Akbarzadeh-Khiavi, Alireza Khabbazzi, Mohammad A. Rafi, Yadollah Omidi
Idursulfase (I2S, IDS, Elaprase®, α-L-iduronate sulfate sulfatase, EC: 3.1.6.13), as a recombinant form of human iduronate-2-sulfatase, has received FDA approval in 2006 for the treatment of MPS II. This enzyme is produced using genetic engineering in a continuous human cell line and is being intravenously injected at a dose of 0.5 mg/kg per week [11]. The idursulfase is a glycoprotein composed of 525 amino acids, containing eight N-linked glycosylation sites that are occupied by 2 bis-M6P containing oligosaccharide chains. All members of the sulfatase family undergo PTMs in the endoplasmic reticulum (ER). Cα-formylglycine (Cα-FGly) is a catalytic residue in the active site of the sulfatase enzymes and plays an essential role in their catalytic activity. In eukaryotes, it is generated in the rough ER of a conserved cysteine residue by a formylglycine-generating enzyme (FGE). Idursulfase as a member of the sulfatase family catalyzes the removal of the sulfate group from the 2-position of L-iduronic acid in DS and HS in the lysosomes [75]. Idursulfase beta is another approved ERT for Hunter syndrome, which is produced in the CHO cell line. Based on the biochemical and physicochemical comparison of two recombinant enzymes, idursulfase beta has a higher content of formylglycine and exhibits significantly greater specific enzymatic activity compared to the idursulfase. However, further clinical evaluations should be conducted to demonstrate the long-term efficacy and differentiation between these enzymes [76].
Safety and efficacy of idursulfase in the treatment of mucopolysaccharidosis II (Hunter syndrome): a post-marketing study in Japan
Published in Expert Opinion on Drug Safety, 2020
A prior study of 34 untreated MPS II patients in Taiwan indicated that the mean age at death for patients with the severe phenotype was 13.2 years and for those with a milder phenotype was 22.6 years [38]. Data from the global Hunter Outcome Survey [29], which included 895 MPS II patients enrolled and followed up between 2005 and 2016, indicated that idursulfase treatment was able to increase median patient survival, from 21.2 years in untreated patients to 33.0 years in treated patients. It is not possible to directly compare the data obtained in this postmarketing study with those of previous idursulfase studies [29,39,40], as differences in study design and assessments preclude any relevant inferences. Comparisons of data are also limited by the small sample of patients analyzed in the present study. Nevertheless, the current analysis confirms the benefits of idursulfase treatment for Japanese MPS II patients. In the present study, the survival rate at 7 years was 82.7%; 91.2% in mild cases and 76.7% in severe cases. Thus, a relatively high survival rate was maintained even in severe cases. Idursulfase was able to slow other aspects of disease progression, such as features of skin, joint, and respiratory disorders, which affect the quality of life of the patient and their family, reducing the overall burden of the disease. Furthermore, from baseline to the final evaluation, a decrease in urinary UA was also confirmed.