Skip to main content
OpenTrials
Enrolling by Invitation

NCT Number: NCT05594992

An Extension Study of JR-141 to Evaluate the Long-term Safety and Efficacy in MPS II (Hunter Syndrome) Subjects

An extension of Global Phase III open-label, multicenter designed to evaluate the Long-term safety and efficacy of study drug for the treatment of the MPS II.

Enrolling by Invitation

Interested in participating?

Request Info

Key information

Conditions

Mucopolysaccharidosis II Carbohydrate Metabolism, Inborn Errors Congenital, Hereditary, and Neonatal Diseases and Abnormalities Connective Tissue Diseases Genetic Diseases, Inborn Genetic Diseases, X-Linked Heredodegenerative Disorders, Nervous System Intellectual Disability Lysosomal Storage Diseases Metabolic Diseases Metabolism, Inborn Errors Mucinoses Mucopolysaccharidoses Nervous System Diseases Neurobehavioral Manifestations Neurologic Manifestations Nutritional and Metabolic Diseases Skin and Connective Tissue Diseases X-Linked Intellectual Disability

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 3

Primary location

Hospital Universitario Austral, Buenos Aires, Argentina

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • A subject who participated in the Parent Study (JR-141-GS31) and completed the assessments at Week 105 in Cohort A or Week 53 in Cohort B before being administered the study medication of that respective visit, and in the opinion of the principal investigator there are no safety concerns.
  • A subject from whom an IRB or IEC-approved written informed consent can be obtained, which is voluntarily signed. If the subject is aged under 18 years (aged under 16 years in the UK) at the time of enrollment or willingness to participate in the study cannot be confirmed due to MPS II-related intellectual disability, the subject's legally acceptable representative (e.g., his parents or guardians) may sign the ICF on behalf of the subject. Written informed assent should be obtained from the subject, wherever possible.
  • Female subject of child bearing potential or male subject whose female partner is of child-bearing potential, i.e., fertile, following menarche and until becoming post-menopausal unless permanently sterile, agrees to use a medically accepted, highly effective method of contraception from the time of signing the ICF. The method of contraception must be used during the study until 90 days for male subjects, and 30 days for female subjects after the final study drug administration.

Exclusion criteria

  • A subject who changed treatment from JR-141 to idursulfase during the treatment period in the Parent Study (JR-141-GS31).
  • A subject who is unable to comply with the protocol (e.g., is unable to return for safety evaluations or is otherwise unlikely to complete the study) as determined by the principal investigator or sub-investigator.
  • [Only in France] Persons deprived of their liberty by a judicial or administrative decision, according to article L. 1121-6 of the Public Health Code (Code de la santé publique, CSP) adults who are the subject of a measure of legal protection or unable to express their consent according to article L. 1121-8 of the CSP.

Treatment and study plan

JR-141

Drug

IV infusion, 2.0 mg/kg/week

Primary outcomes

  1. Change in heparan sulfate concentrations in cerebrospinal fluid from each subject's first administration of JR-141 throughout the Parent Study (JR-141-GS31) or this study to each time point

    Time frame: [A-1, A-2, A-3: Week 157, 209, 261] [A-4: Week 131, 183, 235, 287]

    Assessment will be mandatory for the first two years after starting JR-141 administration through the parent study or the extension study.

  2. Change in neurocognitive testing, calculated by the BSID-III or KABC-II, from each subject's first administration of JR-141 throughout the Parent Study (JR-141-GS31) or this study

    Time frame: [A-1: Week 157, 209, 261] [A-2: Week 131, 157, 183, 209, 261] [A-3: Week 131, 157, 209, 261 ] [A-4: Week 131, 157, 183, 235, 287]

  3. Change in neurocognitive testing, calculated by the VABS-II from each subject's first administration of JR-141 throughout the Parent Study (JR-141-GS31) or this study

    Time frame: [A-1: Week 157, 209, 261] [A-2: Week 131, 157, 183, 209, 261] [A-3: Week 131, 157, 209, 261 ] [A-4: Week 131, 157, 183, 235, 287][B-1: Week 78, 105, 157, 209, 261] [B-2: Week 78, 105, 131, 157, 209, 261]

  4. Change in neurocognitive testing, calculated by the Wechsler, from each subject's first administration of JR-141 throughout the Parent Study (JR-141-GS31) or this study

    Time frame: [B-1: Week 78, 105, 157, 209, 261] [B-2: Week 78, 105, 131, 157, 209, 261]

Secondary outcomes

  1. Change in liver and spleen volume from each subject's first administration of JR-141 throughout the Parent Study (JR-141-GS31) or this study

    Time frame: [A-1, A-3: Week 157, 209, 261] [A-2: Week 131, 157, 209, 261] [A-4: Week 131, 183, 235, 287] [B-1: Week 105, 157, 209, 261] [B-2: Week 78, 105, 157, 209, 261]

  2. Change in 6-minute walk distance from each subject's first administration of JR-141 throughout the Parent Study (JR-141-GS31) or this study

    Time frame: [B-1: Week 105, 157, 209, 261] [B-2: Week 78, 105, 157, 209, 261]

Sponsors and collaborators

Lead sponsor

JCR Pharmaceuticals Co., Ltd.

Industry

Registry information

Official study title

An Extension Study of JR-141 to Evaluate the Long-term Safety and Efficacy in Mucopolysaccharidosis Type II (Hunter Syndrome) Subjects

Important dates

Study start
2023
Primary completion
2028
Study completion
2028
First posted
Oct 26, 2022
Registry last updated
Jan 21, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.