Mucopolysaccharidosis IIPhase 3NCT04573023
A Phase III Study of JR-141 in Patients With Mucopolysaccharidosis II (STARLIGHT)
A Phase 3 study testing JR-141, Idursulfase and JR-141 or Idursulfase in people with Mucopolysaccharidosis II, run by JCR Pharmaceuticals Co., Ltd. at 26 sites in 12 countries.
Trial summary
A Global Phase III multicenter, randomized, assessor-blinded, active-controlled designed to evaluate safety and efficacy of study drug for the treatment of the MPS II. Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Mucopolysaccharidosis II
- What is being tested?
- JR-141, Idursulfase and JR-141 or Idursulfase
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 86 participants
- Where
- 26 sitesin 12 countries
- Study dates
- 14 Feb 2022to 31 Oct 2027
- Phase
- Phase 3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- A patient who voluntarily signs an Institutional Review Board or Independent Ethics Committee-approved written informed consent form. If the patient 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 patient's legally acceptable representative (e.g., his/her parents or guardians) may sign the informed consent on behalf of the patient. Written informed assent should be obtained from the patient, wherever possible.
- Patients with confirmed diagnosis of MPS II
- Naïve patients or patients who are receiving stable enzyme replacement therapy with idursulfase for more than 12 weeks before starting administration of JR-141 or idursulfase for this study.
- Patients or patients whose partners are of child-bearing potential agree to use a medically accepted, highly effective method of contraception being use of condoms from the time of informed consent.
- <Cohort A>
- Patients aged 36-42 months old at the time of ICF signing: patients must have a standard score measured by the BSID-III of 85 or less at screening.
Show all 14Show fewer
- Patients aged 43-71 months old at the time of ICF signing: patients must EITHER have (1) A DQ measured by BSID-III of 20 to 85 at screening OR (2) A composite standard score on NVI measured by KABC-II of 85 or less at screening (only who can perform KABC-II)
- Patients aged 30-35 months old at the time of randomization and who are judged as having the severe phenotype by the Expert Board.
- <Cohort B>
- Patients 6 years of age or older at the time of ICF signing and whose IQ are 70 and higher.
- Enrollment of subjects in Cohort B is contingent on the availability in that country of a validated country-specific version of the test (either WISC-V, WAIS-IV, or T.O.V.A.).
- Attenuated patients with 1 SD deficiency in the omission errors or variability domains of the T.O.V.A..
- Patients or patients whose female partners are of child-bearing potential i.e., fertile, following menarche and until becoming post-menopausal unless permanently sterile, agree to use a medically accepted, highly effective method of contraception, from the time of informed consent. 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 intervention administration.
- For subjects with hearing impairment requiring hearing aid(s), every effort has been made to encourage compliance with the use of functioning hearing aid(s) before baseline neurocognitive assessments, and parent/legally acceptable representative or subject agrees to encourage wearing them during the study and on neurocognitive testing days.
Who cannot join
- A patient with a history of HSCT with successful engraftment.
- A patient who has received gene therapy treatment at any point.
- A patient who is judged by the principal investigator or sub-investigator as being unable to undergo lumbar puncture, including those who have difficulties in taking position for lumbar puncture due to joint contracture or those who are likely to experience breathing difficulties during the lumbar puncture process.
- A patient who is enrolled in another clinical study that involves clinical investigations or use of any investigational product (drug or device) within 4 months before obtaining informed consent.
- Unable to comply with the protocol as determined by the principal investigator or subinvestigator.
- Judged by the principal investigator or subinvestigator to be ineligible to participate in the study due to a history of serious drug allergy or sensitivity including anesthesia or hypersensitivity to any component of JR-141.
Show all 15Show fewer
- A patient who has a known or suspected local or general infection or is at risk of abnormal bleeding due to medical conditions or therapies.
- A patient who has documented mutation of other genes, including loci adjacent to the IDS gene that are known to be associated with developmental delay, seizures, or other significant CNS disorders.
- A patient who has documented loss of activity of sulfatases other than IDS.
- A patient who has had a ventriculoperitoneal shunt placed or any other brain surgery, or has a clinically significant ventriculoperitoneal shunt malfunction within 30 days of screening.
- A patient who is full time employee of the sponsor or research site personnel directly affiliated with this study or their immediate family members.
- A patient who otherwise is judged by the principle investigator or sub-investigator to be ineligible to participate in the study.
- The subject has a positive pregnancy test or is breastfeeding at screening or randomization.
- [Only in France]
- Persons deprived of their liberty by a judicial or administrative decision, according to article L.1121-6 the Public Health Code (Code de la santé publique), 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 Code de la santé publique)
Trial locations and contacts
26 sites in 12 countries.
26 sites in 12 countries
United States7 sites
University of North Carolina at Chapel Hill Medical School Wing E
Chapel Hill, North Carolina, 27514
Ann & Robert H. Lurie Children's Hospital of Chicago
Chicago, Illinois, 60611
University of Minnesota
Minneapolis, Minnesota, 55455
Columbia University Irving Medical Center
New York, New York, 10032
UCSF Benioff Children's Hospital Oakland
Oakland, California, 94609
Children's Hospital of Philadelphia
Philadelphia, Pennsylvania, 19104
Phoenix Children's Hospital
Phoenix, Arizona, 85016
Germany4 sites
Universitätsklinikum Giessen
Giessen
Universitätsklinikum Hamburg-Eppendorf
Hamburg
SphinCS GmbH
Höchheim
Universitätsmedizin Mainz
Mainz
France3 sites
Hôpital Femme Mère Enfant
Lyon
Chu De Montpellier Hopital Gui De Chauliac
Montpellier
Hôpital Armand Trousseau
Paris
Brazil2 sites
Hospital de Clínicas de Porto Alegre
Porto Alegre
Instituto de Genética e Erros Inatos do Metabolismo
São Paulo
Israel2 sites
Clalit Health Services Ha'Emek Medical Center
Afula, 1834111
Sheba Medical Center
Ramat Gan, 6265601
Turkey (Türkiye)2 sites
Gazi University Medicine Faculty Hospital
Ankara
Ege University Children Hospital
Izmir
United Kingdom1 site
Great Ormond Street Hospital for Children NHS Trust - Metabolic Medicine
London
About this study
A Global Phase III multicenter, randomized, assessor-blinded, active-controlled designed to evaluate safety and efficacy of study drug for the treatment of the MPS II.
- Conditions
- Mucopolysaccharidosis II
- Being tested
- JR-141, Idursulfase, JR-141 or Idursulfase
- Medical subject headings
- Mucopolysaccharidosis II
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
JR-141Drug
IV infusion, 2.0 mg/kg/week
IdursulfaseDrug
IV infusion
JR-141 or IdursulfaseDrug
The subjects who have achieved the pre-specified criteria* are able to change the drug.
*If a subject in Idursulfase group shows decline in their neurocognitive outcome, idursulfase can be switched to JR-141.
If a subject in JR-141 group shows decline in their peripheral outcome, JR-141 will be switched to idursulfase.
| Study group | Role | What they receive |
|---|---|---|
| JR-141 2.0 mg/kg/week | Experimental | Not described Receives: Drug: JR-141 |
| administered as the standard of care: idursulfase (ELAPRASE®) | Other | standard of care-controlled study Receives: Drug: Idursulfase |
| Rescue arm | Other | Not described Receives: Drug: JR-141 or Idursulfase |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in levels of cerebrospinal fluid heparan sulfate from baseline (Cohort A)
Measured: Baseline to Week 53
Change in the raw scores of cognitive testing measured from baseline (BSID-III) (Cohort A)
Measured: Baseline to Week 105
Secondary outcomes (5)
For regions other than US: Change in the age equivalent scores of cognitive testing measured from baseline (BSID-III or KABC-II) (Cohort A)
Measured: Baseline to Week 105
For regions other than US: Change in the age equivalent scores of adaptive behavior measured from baseline (VABS-II) (Cohort A)
Measured: Baseline to Week 105
For the US: Change in the raw scores of adaptive behavior measured from baseline (VABS-II) (Cohort A)
Measured: Baseline to Week 105
For all regions: Relative change in liver volume relative to body weight from baseline (Cohort A and Cohort B)
Measured: Baseline to Week 53
For all regions: Relative change in spleen volume relative to body weight from baseline (Cohort A and Cohort B)
Measured: Baseline to Week 53
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 Oct 2020
- Study start14 Feb 2022
- Primary completion31 Oct 2027 (estimated)
- Study completion31 Oct 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Mucopolysaccharidosis IIStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 86 participants (actual)
Sponsor and investigators
- Lead sponsor
- JCR Pharmaceuticals Co., Ltd.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04573023
- Sponsor's protocol ID
- JR-141-GS31
- Status last verified
- Jun 2026
- First submitted
- 17 Sep 2020
- Last updated
- 2 Oct 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 2 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase III Study of JR-141 in Patients With Mucopolysaccharidosis II (STARLIGHT)
- ClinicalTrials.gov ID
- NCT04573023
- Acronym / sponsor ID
- JR-141-GS31
- Conditions
- Mucopolysaccharidosis II
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 86 participants (actual)
- Lead sponsor
- JCR Pharmaceuticals Co., Ltd.Industry (pharma, biotech, devices)
- Study start
- 14 Feb 2022 (actual)
- Primary completion
- 31 Oct 2027 (estimated)
- Study completion
- 31 Oct 2027 (estimated)
- First posted
- 5 Oct 2020 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
A Global Phase III multicenter, randomized, assessor-blinded, active-controlled designed to evaluate safety and efficacy of study drug for the treatment of the MPS II.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| JR-141 2.0 mg/kg/week | Experimental | Drug: JR-141 |
| administered as the standard of care: idursulfase (ELAPRASE®) | Other | Drug: Idursulfasestandard of care-controlled study |
| Rescue arm | Other | Drug: JR-141 or Idursulfase |
Who may qualify
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (14 listed)
- A patient who voluntarily signs an Institutional Review Board or Independent Ethics Committee-approved written informed consent form. If the patient 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 patient's legally acceptable representative (e.g., his/her parents or guardians) may sign the informed consent on behalf of the patient. Written informed assent should be obtained from the patient, wherever possible.
- Patients with confirmed diagnosis of MPS II
- Naïve patients or patients who are receiving stable enzyme replacement therapy with idursulfase for more than 12 weeks before starting administration of JR-141 or idursulfase for this study.
- Patients or patients whose partners are of child-bearing potential agree to use a medically accepted, highly effective method of contraception being use of condoms from the time of informed consent.
- <Cohort A>
Key exclusion criteria (15 listed)
- A patient with a history of HSCT with successful engraftment.
- A patient who has received gene therapy treatment at any point.
- A patient who is judged by the principal investigator or sub-investigator as being unable to undergo lumbar puncture, including those who have difficulties in taking position for lumbar puncture due to joint contracture or those who are likely to experience breathing difficulties during the lumbar puncture process.
- A patient who is enrolled in another clinical study that involves clinical investigations or use of any investigational product (drug or device) within 4 months before obtaining informed consent.
- Unable to comply with the protocol as determined by the principal investigator or subinvestigator.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| JR-141IV infusion, 2.0 mg/kg/week | Drug | JR-141 2.0 mg/kg/week |
| IdursulfaseIV infusion | Drug | administered as the standard of care: idursulfase (ELAPRASE®) |
| JR-141 or IdursulfaseThe subjects who have achieved the pre-specified criteria* are able to change the drug. *If a subject in Idursulfase group shows decline in their neurocognitive outcome, idursulfase can be switched to JR-141. If a subject in JR-141 group shows decline in their peripheral outcome, JR-141 will be switched to idursulfase. | Drug | Rescue arm |
Primary outcome
Change in levels of cerebrospinal fluid heparan sulfate from baseline (Cohort A)
Time frame: Baseline to Week 53
Change in the raw scores of cognitive testing measured from baseline (BSID-III) (Cohort A)
Time frame: Baseline to Week 105
5 secondary outcomes
For regions other than US: Change in the age equivalent scores of cognitive testing measured from baseline (BSID-III or KABC-II) (Cohort A)
Time frame: Baseline to Week 105
For regions other than US: Change in the age equivalent scores of adaptive behavior measured from baseline (VABS-II) (Cohort A)
Time frame: Baseline to Week 105
For the US: Change in the raw scores of adaptive behavior measured from baseline (VABS-II) (Cohort A)
Time frame: Baseline to Week 105
For all regions: Relative change in liver volume relative to body weight from baseline (Cohort A and Cohort B)
Time frame: Baseline to Week 53
For all regions: Relative change in spleen volume relative to body weight from baseline (Cohort A and Cohort B)
Time frame: Baseline to Week 53
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 2 Oct 2026.
Related trials for Mucopolysaccharidosis II
Active, not recruitingPhase 2
MT2013-31: Allo HCT for Metabolic Disorders and Severe Osteopetrosis
Mucopolysaccharidosis Disorders, Hurler Syndrome
Enrolling by invitationPhase 2/3
An Extension Study of the Long-Term Safety, Tolerability, and Efficacy of Tividenofusp Alfa (DNL310) in Participants With Mucopolysaccharidosis Type II (MPS II) From Study DNLI-E-0002 or Study DNLI-E-0007
Mucopolysaccharidosis II
Active, not recruitingPhase 2/3
A Multi-cohort Study of Safety, Efficacy, PK and PD of GNR-055 in Patients With Mucopolysaccharidosis Type II
Mucopolysaccharidosis Type II, Metabolic Diseases
Active, not recruitingPhase 2/3
A Study to Determine the Efficacy and Safety of Tividenofusp Alfa (DNL310) vs Idursulfase in Pediatric and Young Adult Participants With Neuronopathic (nMPS II) or Non-Neuronopathic Mucopolysaccharidosis Type II (nnMPS II)
Mucopolysaccharidosis II
Active, not recruitingPhase 2
An Extension Study of JR-141-BR21 in Patients With Mucopolysaccharidosis II
Mucopolysaccharidosis II
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
26 sites in 12 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing JR-141, Idursulfase and JR-141 or Idursulfase in people with Mucopolysaccharidosis II, run by JCR Pharmaceuticals Co., Ltd. at 26 sites in 12 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 14 inclusion and 15 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 2 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 26 sites in United States, Germany, France, Brazil, Israel and 7 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in levels of cerebrospinal fluid heparan sulfate from baseline (Cohort A) (time frame: Baseline to Week 53). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 2 Oct 2026; AzTrials last refreshed its copy on 7 Nov 2026.