JR-141 clinical trials
JR-141 is named as an intervention in 4 current clinical trials in our Brazil, USA, Germany, France, Spain, Italy, Poland, UK, Turkey, Israel and Japan registers. None are recruiting at the moment. The most common phase is Phase 3. The lead sponsor is JCR Pharmaceuticals Co., Ltd. The most-studied condition is Mucopolysaccharidosis II.
How JR-141 works
All drug targets →- Transferrin receptor binding agent Binding agentTarget: Transferrin receptor✓ In ChEMBL and the Guide to Pharmacology
Mechanisms and diseases from ChEMBL via the Open Targets Platform (release 26.09), ChEMBL record CHEMBL4594565, CC BY-SA 3.0. Targets checked against the IUPHAR/BPS Guide to PHARMACOLOGY (2026.3.1), ligand 11772, CC BY-SA 4.0. Trial phases are not approvals: approved uses are shown from the regulators' own records where we hold them.
Patient leaflets for JR-141
The package leaflet is the official guide for patients that comes with every medicine. These links go to the regulators that publish it.
- UKUnited Kingdom: Search MHRA ProductsPatient information leaflets and SmPCs for UK-licensed products.
- USUnited States: Search DailyMedFDA-approved labels, including patient and medication guides.
Leaflets differ between brands and countries; always read the one that comes with your own medicine. This is regulatory information, not medical advice.
Trials by status
Trials by phase
Clinical trials of JR-141
4 trials| Study | Phase | Status | Lead sponsor | Registers |
|---|---|---|---|---|
|
An Extension Study of JR-141 to Evaluate the Long-term Safety and Efficacy in MPS II (Hunter Syndrome) Subjects
NCT05594992 · ClinicalTrials.gov ↗ · Mucopolysaccharidosis II
|
Phase 3 | By invitation | JCR Pharmaceuticals Co., Ltd | USA, Germany, France, Spain, Italy, Poland, Brazil |
|
A Phase III Study of JR-141 in Patients With Mucopolysaccharidosis II (STARLIGHT)
NCT04573023 · Mucopolysaccharidosis II
|
Phase 3 | Active, closed | JCR Pharmaceuticals Co., Ltd | UK, USA, Germany, France, Spain, Italy, Poland, Turkey, Brazil, Israel |
|
An Extension Study of JR-141 in Patients With Mucopolysaccharidosis Type II
NCT04348136 · ClinicalTrials.gov ↗ · Mucopolysaccharidosis II
|
Phase 2/3 | Active, closed | JCR Pharmaceuticals Co., Ltd | Japan |
|
An Extension Study of JR-141-BR21 in Patients With Mucopolysaccharidosis II
NCT03708965 · ClinicalTrials.gov ↗ · Mucopolysaccharidosis II
|
Phase 2 | Active, closed | JCR Pharmaceuticals Co., Ltd | Brazil |
Registers list studies that are recruiting, about to open, active but closed to enrolment, or enrolling by invitation. The UK and USA registers cover industry-sponsored studies only. Trial titles and statuses are copied from the registry as published.
Conditions studied with JR-141
1 conditionSponsors
lead sponsor per trial| Lead sponsor | Trials |
|---|---|
| JCR Pharmaceuticals Co., Ltd | 4 |
By country register
A trial with sites in more than one country appears in each of those registers.
Related compounds
Questions about JR-141 trials
How many clinical trials are testing JR-141?
4 current trials in our Brazil, USA, Germany, France, Spain, Italy, Poland, UK, Turkey, Israel and Japan registers name JR-141 as a drug or biological intervention, as of the registry sync on 10 November 2026. Completed and withdrawn studies are not counted.
Are JR-141 trials recruiting patients?
Not at the moment. None of the 4 trials in our registers is recruiting; they are active but closed to enrolment, not yet open, or enrolling by invitation. Only the study team can confirm whether a patient is eligible.
Who sponsors JR-141 clinical trials?
The lead sponsor is JCR Pharmaceuticals Co., Ltd. The number in brackets is how many trials each organisation leads.
Where does this information come from?
Every trial, status, phase and sponsor on this page is copied from public ClinicalTrials.gov records by a daily sync. Nothing here describes how JR-141 works or whether it is effective, and it is not medical advice.
How this page is built
Everything on this page is copied from public ClinicalTrials.gov registry records — it is not written from memory, and nothing here describes how JR-141 works or whether it is effective. Each trial links to its own record so you can check it yourself.
- ClinicalTrials.gov (U.S. National Library of Medicine) ↗ Trial IDs, titles, intervention names and synonyms, phase, overall status, lead sponsor and conditions for every trial on this page
This page is built automatically: a daily sync job reads the registry records behind our country trial registers, collects every trial that lists JR-141 (or a registered synonym) as a drug or biological intervention, and tabulates the registry fields directly. Placebos and generic comparators are excluded. There is no AI drafting and no per-compound editorial pass, and the page has not been clinically reviewed. The “last verified” date above is the timestamp of that sync, not a review date. Our general editorial approach is described in our editorial standards and corrections policy. The ClinicalTrials.gov data on this page was last retrieved on 10 Nov 2026. How every register is built: methodology · fixes we have made: corrections log.