Enzyme replacement therapy with idursulfase for mucopolysaccharidosis type II (Hunter syndrome).Cochrane Database Syst Rev. 2011 Nov 09CD
Mucopolysaccharidosis II, also known as Hunter syndrome, is a rare, X-linked disease caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase, which catalyses a step in the catabolism of glycosaminoglycans. The glycosaminoglycans accumulate within tissues affecting multiple organs and physiologic systems. The clinical manifestations include neurologic involvement, severe airways obstruction, skeletal deformities and cardiomyopathy. The disease has a variable age of onset and variable rate of progression. In those with severe disease, death usually occurs in the second decade of life, whereas those patients with less severe disease may survive into adulthood. Enzyme replacement therapy with intravenous infusions of idursulfase has emerged as a new treatment for mucopolysaccharidosis type II.
To evaluate the effectiveness and safety of enzyme replacement therapy with idursulfase compared to other interventions, placebo or no intervention, for treating mucopolysaccharidosis type II.
We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register (date of last search 01 September 2011).We also searched EMBASE, PubMed and the Literature Latino-Americana e do Caribe em Ciências da Saúde (LILACS) (date of last search October 2009).
Randomised and quasi-randomised controlled trials of enzyme replacement therapy with idursulfase compared to no intervention, placebo or other options (e.g. behavioral strategies, transplantation).
DATA COLLECTION AND ANALYSIS
Two authors independently screened the trials identified, appraised quality of papers and extracted data.
One study (96 patients) met the inclusion criteria, although the primary outcome of this review - z score for height and weight, was not assessed in the study. Following 53 weeks of treatment, patients in the weekly idursulfase 0.5 mg/kg group demonstrated a significant improvement rate compared with placebo for the primary outcome: distance walked in six minutes on the basis of the sum of ranks of change from baseline, mean difference 37.00 (95% confidence interval 6.52 to 67.48). The every-other-week idursulfase 0.5 mg/kg group also showed an improvement, which was not significant compared with placebo, mean difference 23.00 (95% confidence interval -4.49 to 50.49). After 53 weeks, there was no statistical significance difference in per cent predicted forced vital capacity between the three groups and absolute forced vital capacity was significantly increased from baseline in the weekly dosing group compared to placebo, mean difference 0.16 (95% confidence interval CI 0.05 to 0.27). No difference was observed between the every-other-week idursulfase 0.5 mg/kg group and placebo.In addition, liver and spleen volumes and urine glycosaminoglycan excretion were significantly reduced from baseline by both idursulfase dosing regimens. Idursulfase was generally well tolerated, but infusion reactions did occur. Idursulfase antibodies were detected in 31.7% of patients at the end of the study and they were related to a smaller reduction in urine glycosaminoglycan levels.