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

NCT05594992 | Enrolling By Invitation Phase 3 DMC FDA Drug

• 1 other identifier: JR-141-GS32
• Study Type: interventional
• Target: 80
• Locations: 8 countries
• Sites: 10

Brief Summary

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.

Conditions

Mucopolysaccharidosis II

Outcome Measures

Primary Outcomes (4)

• 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

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

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

• 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

  [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]

• 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

  [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]

• 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

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

Secondary Outcomes (2)

• 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

  [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]

• 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

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

Study Arms (1)

JR-141 2.0 mg/kg/week

EXPERIMENTAL

Drug: JR-141

Interventions

JR-141 DRUG

IV infusion, 2.0 mg/kg/week

JR-141 2.0 mg/kg/week

Eligibility Criteria

• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

• 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.

You may not qualify if:

• 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.

Sponsors & Collaborators

• JCR Pharmaceuticals Co., Ltd.: lead

Study Sites (10)

UCSF Benioff Children's Hospital Oakland

Oakland, California, 94609, United States

Location

Children's Hospital of Philadelphia

Philadelphia, Pennsylvania, 19104, United States

Location

Hospital Universitario Austral

Buenos Aires, Argentina

Location

Hospital de Clínicas de Porto Alegre

Porto Alegre, Brazil

Location

Instituto de Genética e Erros Inatos do Metabolismo

São Paulo, Brazil

Location

Hôpital Femme Mère Enfant

Bron, France

Location

Universitätsklinikum Hamburg-Eppendorf

Hamburg, Germany

Location

Osp. Pediatrico Bambino Gesù, IRCCS

Rome, Italy

Location

Uniwersytecki Szpital Dziecięcy

Krakow, Poland

Location

Hospital Sant Joan de Déu

Barcelona, Spain

Location

MeSH Terms

Conditions

Mucopolysaccharidosis II

Condition Hierarchy (Ancestors)

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

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: October 6, 2022
• First Posted: October 26, 2022
• Study Start: February 22, 2023
• Primary Completion (Estimated): February 28, 2028
• Study Completion (Estimated): February 28, 2028
• Last Updated: January 21, 2026

Record last verified: 2026-01

Locations

DE (1); IT (1); BR (2); US (2); PL (1); AR (1); FR (1); ES (1)