The purpose of this study is to evaluate the safety and efficacy of GC1111 (recombinant human iduronate-w-sulfatase) in Hunter Syndrome (Mucopolysaccharidosis II) patients

Inclusion Criteria:

1. Patients with diagnosis of MPS II based on both clinical and biochemical criteria
2. Male, ages 6 to 35 years old
3. Patients who are able to comply with the study requirements
4. Patients who have given voluntary written consent to participate in the study
5. Patients who is acceptable for using an appropriate method of contraception

Exclusion Criteria:

1. History of a tracheostomy or a bone marrow transplant
2. Known hypersensitivity to idursulfase
3. Known shock to idursulfase
4. History of receiving treatment with another investigational therapy within the past 30 days
5. History of a stem cell transplant
6. Known hypersensitivity to any of the components of idursulfase
7. Female