An Observational Study Evaluating Anti-Idursulfase Serum Antibody Response in Hunter Syndrome Patients

Completed

Brief Summary: The objective of this study is to evaluate the effect of anti-idursulfase antibodies on idursulfase safety (measured by infusion related adverse events) between patients who develop anti-idursulfase antibodies and patients who do not after long-term idursulfase enzyme replacement therapy (ERT).

Detailed Description: This study is being conducted to satisfy post-marketing commitments to monitor anti-idursulfase antibody development in Hunter syndrome patients after long-term idursulfase enzyme replacement therapy. The study will be conducted as a sub-study within the Hunter Outcome Survey (HOS). Hunter syndrome patients in the HOS who have previously received idursulfase as well as treatment-naive patients who will begin idursulfase treatment within 30 days of study enrollment will be included.

Recruitment & Eligibility

Inclusion Criteria

Patients must meet all of the following criteria to be considered eligible for enrollment:

The patient is male and enrolled in the HOS (i.e., meets the entry criteria of a documented diagnosis of Hunter syndrome)
The patient is ≥ 5 years-old
The patient is on idursulfase treatment or scheduled to begin idursulfase treatment within 30 days of study enrollment
The patient, patient's parent(s), or patient's legally authorized guardian must have voluntarily signed an Institutional Review Board (IRB)/Independent Ethics Committee (IEC)-approved informed consent form after all relevant aspects of the study have been explained and discussed with the patient, patient's parent(s), or patient's legally authorized guardian.

Exclusion Criteria

Patients who meet any of the following criteria are not eligible for this study:

The patient has received biologic/ERT products other than idursulfase, or other investigational product(s) for any reason within 30 days prior to study entry.
The patient has a life expectancy of < 2 years
The patient is unable to comply with the protocol, e.g., has a clinically relevant medical condition making implementation of the protocol difficult; has an uncooperative attitude; is unable to return for safety evaluations; or is otherwise unlikely to complete the study, as determined by the Investigator.

Arm && Interventions

Group	Intervention	Description
Elaprase	Idursulfase	Idursulfase 0.5 mg/kg Weekly

Primary Outcome Measures

Name	Time	Method
Infusion-Related Adverse Event (IRAE) Rates Between IgG Anti-idursulfase Antibody Positive (Ab+) and Anti-idursulfase IgG Antibody Negative (Ab-) Patients	Baseline to 109 Weeks	The primary analysis of how presence of antibodies affected IRAE rates was performed based on a negative binomial regression model. This was done to account for potentially differential follow-up time between antibody groups.

Secondary Outcome Measures

Name	Time	Method
Change From Baseline in uGAG Levels to 109 Weeks	Baseline to 109 Weeks	Urine GAG

Locations (6): Birmingham Children's Hospital
🇬🇧
Birmingham, United Kingdom
Hospital de Clinicas de Porto Alegre, Servico de Genetica Medica
🇧🇷
Porto Alegre, RS, Brazil
Children's Hospital & Research Center Oakland
🇺🇸
Oakland, California, United States
Great Ormond Street Hospital
🇬🇧
London, United Kingdom
Central Manchester University Hospitals, St. Mary's Hospital
🇬🇧
Manchester, United Kingdom
Children's Hospitals and Clinics of Minnesota, Division of Genetics
🇺🇸
Minneapolis, Minnesota, United States