Long-term, open-labeled extension study of idursulfase in the treatment of Hunter syndrome

Joseph Muenzer, Michael Beck, Christine M. Eng, Roberto Giugliani, Paul Harmatz, Rick Martin, Uma Ramaswami, Ashok Vellodi, James E. Wraith, Maureen Cleary, Muge Gucsavas-Calikoglu, Ana Cristina Puga, Marwan Shinawi, Birgit Ulbrich, Suresh Vijayaraghavan, Susanne Wendt, Anne Marie Conway, Alexandra Rossi, David A.H. Whiteman, Alan Kimura

Research output: Contribution to journalArticlepeer-review

179 Scopus citations


Purpose: This study evaluated the safety and effectiveness of long-term enzyme replacement therapy with idursulfase (recombinant human iduronate-2-sulfatase) in patients with Hunter syndrome. Methods: All 94 patients who completed a 53-week double-blinded study of idursulfase enrolled in this open-labeled extension study and received intravenous idursulfase at a dose of 0.5 mg/kg weekly for 2 years, and clinical outcomes and safety were assessed. Results: No change in percent predicted forced vital capacity was seen, but absolute forced vital capacity demonstrated sustained improvement and was increased 25.1% at the end of the study. Statistically significant increases in 6-minute walking test distance were observed at most time points. Mean liver and spleen volumes remained reduced throughout the 2-year extension study. Mean joint range of motion improved for the shoulder and remained stable in other joints. Both the parent- and child-assessed Child Health Assessment Questionnaire Disability Index Score demonstrated significant improvement. Infusion-related adverse events occurred in 53% of patients and peaked at Month 3 of treatment and declined thereafter. Neutralizing IgG antibodies were detected in 23% of patients and seemed to attenuate the improvement in pulmonary function. Conclusions: Weekly infusions of idursulfase result in sustained clinical improvement during 3 years of treatment.

Original languageEnglish
Pages (from-to)95-101
Number of pages7
JournalGenetics in Medicine
Issue number2
StatePublished - Feb 2011


  • Hunter syndrome
  • clinical trial
  • enzyme replacement therapy
  • idursulfase
  • lysosomal storage disease
  • mucopolysaccharidosis type II


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