Hunterase® is an enzyme replacement therapy for the treatment of Hunter syndrome (mucopolysaccharidosis type II, MPS II). Since 2012, Hunterase® has been made available in more than ten countries worldwide. The established efficacy and safety of Hunterase® provide a unique treatment option to patients with MPS II.

Mucopolysaccharidosis type II (MPS II, Hunter syndrome)

Mucopolysaccharidosis type II (MPS II) or Hunter syndrome, is a rare, disabling, and often fatal genetic disease, which has been listed on the First National List of Rare Diseases (CRDL) published by the Chinese government¹.

The syndrome is caused by the absence or deficiency of a lysosomal enzyme, iduronate-2-sulfatase (IDS), which is required for the degradation of two glycosaminoglycans (GAGs), heparan sulfate and dermatan sulfate. In MPS II, GAGs progressively accumulate throughout the body, causing a variety of disease manifestations and leading to tissue dysfunction, organ failure, and reduced life expectancy. The clinical spectrum of MPS II ranges from a severe form with onset in late infancy to early childhood, manifesting severe somatic disease and central nervous system degeneration, to an attenuated form with onset in mid to late childhood, manifesting less severe somatic disease with mild or no central nervous system involvement.

The main clinical manifestations of MPS II are developmental delay, short stature, coarse facies, multiple skeletal deformities (osteogenesis multiplex), joint contractures, hernias, hepatosplenomegaly, hearing loss, valvular heart disease, hypertrophic cardiomyopathy, obstructive sleep apnea, restrictive lung disease, and frequent respiratory infections. Patients with the severe form may live for up to 10 years to 20 years², whereas those with the attenuated form often live into mid-adulthood. Enzyme replacement therapy is the standard treatment of MPS II and treatment of symptoms is also required.

MPS II is an X-linked disorder that affects males almost exclusively. The incidence of MPS II is estimated to be higher in East Asian countries (1/51,000-1/93,000 live births in Taiwan^3,4) than in predominantly Caucasian countries (1/149,000-1/162,000 live births^5,6).

References:

1. The list of 121 rare diseases jointly released by the five departments of the national health commission in May 2018.
2. Guillen-Navarro E, et al. Orphanet J Rare Dis. 2013; 8: 92.
3. Lin HY, et al. Am J Med Genet 2009; 149A: 960-964.
4. Chuang CK, et al. Orphanet J Rare Dis. 2018; 13: 84.
5. Meikle PJ, et al. JAMA. 1999; 281: 249-54.
6. Poorthuis BJ, et al. Hum Genet. 1999; 105: 151-156.