CompletedNCT07344376Updated Jan 15, 2026

An Extension Study to Assess the Long-term Safety and Efficacy of Hunterase (Idursulfase Beta)

A Phase 3 interventional study of Hunterase in MPS II, Hunter Syndrome (MPS II) and Hunter Syndrome, sponsored by GC Biopharma Corp. Completed at 1 site in South Korea. Open to male participants. Per ClinicalTrials.gov, last updated 2026-01-15.

Sponsored by GC Biopharma Corp · Phase 3, Interventional, and Treatment

From the registry’s dates

Registered 7 years 5 months after the study started (first participant enrolled May 2018, registered Nov 2025).

Phase: Phase 3
Study type: Interventional
Enrollment: 30
Allocation: Not applicable
Sex: Male

Study summary

The objective of this study is to assess the long-term safety and efficacy of Hunterase for approximately 1 year in subjects who completed the end of study (EOS) visit (Visit 54) tests in the Phase 3 Hunterase study and patients who received Hunterase for more than 6 months

Conditions studied

MPS II
Hunter Syndrome (MPS II)
Hunter Syndrome
Hunterase
GC1111

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Keywords

Hunterase
GC1111
GC Biopharma
Long-term study
extension study

In context

Sudden Infant Death

45 studies on the registry are indexed under Sudden Infant Death; 13 are open to participants now.

This study's enrollment of 30 is below the median of 100 across 30 interventional studies indexed under Sudden Infant Death.

Browse Sudden Infant Death studies →

Lead sponsor

GC Biopharma Corp is the lead sponsor of 14 studies on the registry; 4 are open to participants now.

Counted across the registry records on this site, refreshed daily.

Who can participate

Ages eligible: Child (0–17), Adult (18–64), Older adult (65+)
Sexes eligible: Male
Accepts healthy volunteers: No

Inclusion criteria

Subject diagnosed with Hunter syndrome (MPS II) who completed activities at the EOS visit (Visit 54) in the GC1111_P3 study
(Subject who did not participate in the GC1111_P3 study) Subject diagnosed with Hunter syndrome (MPS II) who received Hunterase for more than 6 months
(Subjects who did not participate in the GC1111_P3 study) Males aged ≥ 5
Informed consent form voluntarily signed by the subject or by a legally acceptable representative
Subject who agrees to use contraception

Exclusion criteria

Exclusion Criteria:

Subject with hypersensitivity to any of the ingredients of the investigational product
Subject impossible to perform follow-up observation of the safety
Subject who received the treatment with another investigational product within 14 days prior to the start of study drug
Subject who plans to be treated with another investigational product during the study period
Subject who has history of tracheostomy, bone marrow transplant, or cord blood transplant
Any other inappropriate conditions for study participation at the investigator's discretion

Study design

Phase: Phase 3
Primary purpose: Treatment
Allocation: Not applicable
Intervention model: Single group
Masking: None (open label)
Enrollment: 30 participants (actual)

Study arms

Other
Hunterase
Single arm
Drug: Hunterase

Interventions

DrugHunterase
0.5mg/kg weekly IV administration
Also known as: GC1111

What researchers measure

Primary outcomes

Laboratory tests (CBC, Chemistry, Urinanalysis)
Abnormality of Laboratory tests results
Time frame: Every visit until 12months
Physical examination
Abnormality of physical examination
Time frame: Every visit until 12months
Adverse Event
occurence, grade
Time frame: Every visit until 12months
Electrocardiography
Abnormality of ECG results
Time frame: Every 6 months until 12months

Secondary outcomes

6-minute walk test
Mean, Change and percent change of 6-minute walk test
Time frame: Every 4months until 12months
Urine GAG (Heparan sulfate, Dermatan sulfate)
Mean, Change and percent change of Urine HS/DS
Time frame: Every visit until 12months

Study locations

1 site

Samsung Medical Center
Seoul, South Korea

References and documents

Publications

Im M, Song A, Park H, Kim J, Kim C, Noh ES, Bae GY, Sung J, Hwang J, Ahn YJ, Kim H, Oh Y, Kim B, Cho SY. Sustained clinical benefit of idursulfase beta in mucopolysaccharidosis II: two-year experience from a phase 3 extension study including patients switched from idursulfase. Orphanet J Rare Dis. 2026 Jul 9. doi: 10.1186/s13023-026-04492-2. Online ahead of print. PubMed 42421116 ↗

Individual participant data

Plan to share: No

Updates

Tracking since Sep 25, 2026

No changes since tracking began. The registry record was last updated on Jan 15, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗

Registry details

Key details

Study ID: NCT07344376
Lead sponsor: GC Biopharma Corp
Collaborators: Samsung Medical Center
Responsible party: Sponsor
First posted: Jan 15, 2026
Start date: May 23, 2018
Primary completion: Dec 30, 2022
Completion: Dec 30, 2022
Last update: Jan 15, 2026

Oversight

Data monitoring committee: No
FDA-regulated drug: No
FDA-regulated device: No

View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Nov 2025. You cannot join it, but the record below documents what was studied.

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Discussion

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