Abstract
Mucopolysaccharidosis type II (MPS II; Hunter syndrome; OMIM 309900) is a life-limiting, multisystemic disease with varying presentation and severity. Enzyme replacement therapy with intravenous idursulfase (EC 3.1.6.13) has been available since 2006. Data from the Hunter Outcome Survey (July 2016) were used to compare survival in idursulfase-treated (n = 800) and untreated (n = 95) male patients followed prospectively in this multinational, observational registry. Median age at symptom onset was similar for the treated and untreated groups (1.6 and 1.5 years, respectively), as was median age at diagnosis (3.3 and 3.2 years) and the proportion of patients with cognitive impairment (58.0%; 57.9%). The proportion of idursulfase-treated patients differed according to geographical region. Overall, 124/800 (15.5%) treated and 28/95 (29.5%) untreated patients had died. Respiratory failure was the most common cause of death (treated, 43/124 [34.7%]; untreated, 10/28 [35.7%]). Median survival (95% confidence interval [CI]) was 33.0 (30.4, 38.4) years in treated patients and 21.2 (16.1, 31.5) years in untreated patients; median follow-up time from birth to death or last visit was 13.0 and 15.1 years, respectively. A Cox model adjusted for treatment status, cognitive impairment, region and age at diagnosis indicated a 54% lower risk of death in treated compared with untreated patients: hazard ratio (HR), 0.46 (95% CI: 0.29, 0.72). Patients with cognitive impairment had nearly a fivefold higher risk of death than those without (HR, 4.84 [3.13, 7.47]). This analysis in a large population of patients with MPS II indicates for the first time that idursulfase treatment is associated with increased survival.
Highlights
Mucopolysaccharidosis type II (MPS II; Hunter syndrome; OMIM 309900) is a rare, life-limiting, multisystemic, X-linked lysosomal storage disease
A Cox model adjusted for treatment status, cognitive impairment, region and age at diagnosis indicated a 54% lower risk of death in treated compared with untreated patients: hazard ratio (HR), 0.46
The proportion of idursulfase-treated patients differed according to geographical region (Table 1); overall, most patients were from Europe and North America irrespective of treatment status
Summary
Mucopolysaccharidosis type II (MPS II; Hunter syndrome; OMIM 309900) is a rare, life-limiting, multisystemic, X-linked lysosomal storage disease. The resulting signs and symptoms can include both somatic and neurological involvement and are progressive in nature (Neufeld and Muenzer 2001; Wraith et al 2008a; b). Those affected by MPS II are almost always males (Neufeld and Muenzer 2001), with an estimated incidence of 0.6–1.3 per 100,000 live male births (Meikle et al 1999; Poorthuis et al 1999; Baehner et al 2005; Tylki-Szymanska 2014). Patients are generally considered to be in one of two categories
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