ClinicalTrials.gov record NCT05594992
An Extension Study of JR-141 to Evaluate the Long-term Safety and Efficacy in MPS II (Hunter Syndrome) Subjects
An Extension Study of JR-141 to Evaluate the Long-term Safety and Efficacy in Mucopolysaccharidosis Type II (Hunter Syndrome) Subjects
AI summaryWhat this study is about, in plain languageShow ▾Hide ▴
AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.
Open-label Phase 3 extension testing long-term safety and efficacy of weekly IV JR-141 in people with Mucopolysaccharidosis II (Hunter syndrome). It continues JR-141 treatment for participants who completed the parent JR-141 trial and includes repeated clinical, neurological, and laboratory assessments.
What it is studying. The study is testing the long-term safety and effects of weekly IV JR-141 in people with MPS II. Key measures include cerebrospinal fluid heparan sulfate, neurocognitive testing, liver and spleen volume, and 6-minute walk distance over extended follow-up.
What the researchers hope to learn. To collect long-term safety data and measure JR-141's effects on biomarkers and clinical outcomes in MPS II, including CSF heparan sulfate levels, neurocognitive function, liver and spleen volume, and 6-minute walk distance.
What this study is about
The study's own summary, as published on ClinicalTrials.gov. Underlined terms have a short explanation.
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.
Interventions being studied
Being studied in this trial does not mean the treatment or procedure is approved or available for this condition.
- Drug
- JR-141
Eligibility
The criteria exactly as listed on ClinicalTrials.gov. Only the study team can say whether they apply to you.
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.
Study description and what participation involves
The registry record has no detailed description beyond the summary above.
AI summaryWhat participation may involve, in plain languageShow ▾Hide ▴
AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.
Participants continue receiving JR-141 as an intravenous infusion (2.0 mg/kg) given weekly and are followed long-term with scheduled study visits. Repeated assessments include collection of cerebrospinal fluid for heparan sulfate (CSF sampling, typically by spinal tap, is mandatory for the first two years), regular neurocognitive testing (for example BSID‑III, KABC‑II, VABS‑II, Wechsler), and measurements such as liver/spleen volume and 6‑minute walk distance. They must provide informed consent, follow contraception requirements if applicable, and be able to attend safety evaluations; the investigator can end participation if the person cannot comply or has safety concerns.
How the study is structured. An open-label, single-group Phase 3 extension where participants receive JR-141 by IV infusion (2.0 mg/kg weekly). There is no placebo or masking; people who completed the parent JR-141 study continue on study treatment and return for scheduled assessments including cerebrospinal fluid sampling, neurocognitive tests, imaging of organ size, and walking tests at defined time points.
Questions you could ask
These questions are suggestions for a conversation with the study team or your own clinician, not advice.
- The registry says participants are enrolled by invitation. Who decides who is invited, and how?
- The listed sites are in Argentina, Brazil, France, Germany, Italy, Poland, Spain, United States. Is any of them reachable for me, and does the study help with travel?
- Which of the eligibility criteria would need to be checked with tests before I could join?
More on Hunter syndrome
Important dates
- Study start
- Feb 22, 2023
- Primary completion
- Feb 28, 2028 (estimated)
- Study completion
- Feb 28, 2028 (estimated)
- Target enrollment
- 80 participants (estimated)
- Last updated on registry
- Jan 21, 2026
- Data verified
- Oct 10, 2026
Sponsor and research team
The lead sponsor funds and oversees the trial. A pharmaceutical or biotech company sponsor typically means the study is testing that company's drug or device; a hospital, university, or government agency usually indicates investigator-initiated or publicly funded research.
- Lead sponsor
- JCR Pharmaceuticals Co., Ltd.
Participating sites (10)
- UCSF Benioff Children's Hospital Oakland
Oakland, California, 94609 · United States
- Children's Hospital of Philadelphia
Philadelphia, Pennsylvania, 19104 · United States
- Hospital Universitario Austral
Buenos Aires · Argentina
- Hospital de Clínicas de Porto Alegre
Porto Alegre · Brazil
- Instituto de Genética e Erros Inatos do Metabolismo
São Paulo · Brazil
- Hôpital Femme Mère Enfant
Bron · France
- Universitätsklinikum Hamburg-Eppendorf
Hamburg · Germany
- Osp. Pediatrico Bambino Gesù, IRCCS
Rome · Italy
- Uniwersytecki Szpital Dziecięcy
Krakow · Poland
- Hospital Sant Joan de Déu
Barcelona · Spain
Terms used on this page · explanations by MedicalUpdates.ai
- open-label
- No masking is used, so the assigned intervention is not deliberately hidden from participants or study staff.
- study drug
- A treatment that is being tested and has not been approved for this use. It may be approved for a different condition. Being studied does not mean it works or is available outside the study.
- Cohort
- A group of people who share a characteristic, such as a diagnosis, and are studied together. 'Prospective' means they are followed forward from enrolment; 'retrospective' means existing records are reviewed.
- principal investigator
- The doctor or scientist responsible for running the study at a site or overall.
- written informed consent
- The process of explaining a study, including its risks and what participation involves, so that a person can decide freely whether to take part. Consent is usually documented in writing, and a participant can choose to leave the study later.
- enrollment
- The number of participants a study plans to include, or has included. 'Estimated' means the planned number; 'actual' means the number who joined.
- assent
- A child's or dependent adult's agreement to take part, given alongside the formal consent of a parent or legal representative.
- Inclusion Criteria
- The conditions a person must meet to be considered for the study, for example a confirmed diagnosis, an age range or a test result.
- Exclusion Criteria
- The conditions that rule a person out even if they meet the inclusion criteria, for example other illnesses, certain medicines or pregnancy.
The study record on this page is reproduced from ClinicalTrials.gov, a database of the U.S. National Library of Medicine, where it was submitted by the study sponsor. MedicalUpdates.ai does not own this content, is not affiliated with or endorsed by ClinicalTrials.gov, NIH, or the U.S. Government, and does not verify the record. Plain-language notes, the glossary and the questions above are added by this site; text in the boxes marked "AI summary" was written by an AI model and may contain errors. Registry records change over time. Check the original record for the current version and discuss eligibility or participation with a qualified healthcare professional.
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