Background and aims Symptoms of Hunter syndrome typically become apparent at 2–4 years of age. Previous analyses have demonstrated improvements in certain clinical measures in young patients receiving idursulfase (Shire); however, data on long-term idursulfase use in these patients remain limited. This analysis used data available in the Hunter Outcome Survey (HOS), a global, observational registry sponsored by Shire, to investigate long-term effectiveness of idursulfase in boys with Hunter syndrome aged 0–5 years.
Methods As of January 2014, 260/564 males followed prospectively in HOS had received ≥1 idursulfase infusion (excluding those who had received a bone marrow transplant or were enrolled in the TKT018/TKT024 clinical trials), were aged 0–5 years at treatment initiation and were included in the analysis. Median age at first treatment was 3.5 years; median treatment duration was 41.6 months. Clinical measures recorded in HOS at annual timepoints over 3 years were compared with baseline values.
Results Median urinary glycosaminoglycan (uGAG) levels, liver size and left ventricular mass index had improved at all yearly timepoints compared with baseline (median uGAG, –64.6% versus baseline after 3 years, n = 32). However, the number of patients with baseline and post-treatment data available was relatively low in some instances (n = 7–56), especially at 3 years.
Conclusions This analysis of data from HOS suggests that a positive trend in the clinical effectiveness of idursulfase was generally maintained over 3 years of treatment in these boys aged 0–5 years with Hunter syndrome, supporting the results of previous analyses.