Profile of idursulfase for the treatment of Hunter syndrome

: Mucopolysaccharidosis type II (MPS II; Hunter syndrome) is a rare X-linked lysosomal storage disorder caused by deficiency of the enzyme iduronate-2-sulfatase (IDS). Enzyme replacement therapy (ERT) with recombinant human IDS, available since 2005, is currently the most appropriate treatment for this progressive, multisystemic, chronic, and life-threatening disease. Efficacy and safety of therapy with idursulfase have been assessed in several clinical trials, and confirmed in many clinical reports. Long-term follow-up of patients receiving ERT has demonstrated the importance of an early onset of treatment with idursulfase, before irreversible pathological changes occur. Intravenously administered idursulfase is not able to cross the blood–brain barrier, so neurological signs and symptoms cannot benefit from ERT, still remaining a major challenge in the treatment of MPS II.