Hunter syndrome drug JR-141 tested for Long-Term safety

NCT ID NCT05594992

ENROLLING_BY_INVITATION Disease control Sponsor: JCR Pharmaceuticals Co., Ltd. Source: ClinicalTrials.gov ↗

First seen Jun 24, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This study is an extension of a previous trial testing JR-141, a drug given weekly by IV, for people with Hunter syndrome (a rare genetic disorder). It aims to see if the drug remains safe and effective over a longer period. About 80 participants who completed the earlier study will continue receiving JR-141, and researchers will track changes in spinal fluid markers, thinking skills, and physical abilities.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: JR-141 (a drug given by IV infusion weekly)
What this could lead to: If successful, this could confirm that JR-141 safely controls Hunter syndrome symptoms long-term, offering a continued treatment option for patients.
What could go wrong: This is an extension study, so it builds on earlier results but is still open-label (no placebo). Long-term benefits are not guaranteed, and side effects may emerge over time.

This is an AI summary of the original study and may miss details. Read our disclaimer.

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Conditions

The condition(s) this trial relates to.

mucopolysaccharidosis type 2

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

MUCOPOLYSACCHARIDOSIS II

Contacts and locations

Locations

Children's Hospital of Philadelphia

Philadelphia, Pennsylvania, 19104, United States
Hospital Sant Joan de Déu

Barcelona, Spain
Hospital Universitario Austral

Buenos Aires, Argentina
Hospital de Clínicas de Porto Alegre

Porto Alegre, Brazil
Hôpital Femme Mère Enfant

Bron, France
Instituto de Genética e Erros Inatos do Metabolismo

São Paulo, Brazil
Osp. Pediatrico Bambino Gesù, IRCCS

Rome, Italy
UCSF Benioff Children's Hospital Oakland

Oakland, California, 94609, United States
Universitätsklinikum Hamburg-Eppendorf

Hamburg, Germany
Uniwersytecki Szpital Dziecięcy

Krakow, Poland

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