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CompletedNCT03359213Updated Jul 24, 2025

A Study of JR-141 in Patients With Mucopolysaccharidosis II (BR21)

A Phase 2 interventional study of JR-141 and JR-141 in Mucopolysaccharidosis II, sponsored by JCR Pharmaceuticals Co., Ltd.. Completed at 2 sites in Brazil. Open to male participants aged 0 Years and older. Per ClinicalTrials.gov, last updated 2025-07-24.

Sponsored by JCR Pharmaceuticals Co., Ltd. · Phase 2, Interventional, and Treatment

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Phase
Phase 2
Study type
Interventional
Enrollment
18
Allocation
Randomized
Ages
0 Years and older
Sex
Male
01

Where this study stands

Counted across the records on this site · 2026-11-14

Among 13 studies in Mucopolysaccharidosis II with a site in Brazil — 2 open to participants now, 7 under way, 5 of them phase 3. Mucopolysaccharidosis II · Brazil.

Enrollment
10th of 10
18 · median 73
Started
2018
with 1 other
Phase 2
2 of 13
none open now
Registered
5th of 13
by date
Lead sponsor
4 of 13
JCR Pharmaceuticals Co., Ltd.

Among the 13 studies in Mucopolysaccharidosis II with a site in Brazil, this one is the 10th largest by enrollment of the 10 interventional ones that give a count, is one of 2 that started in 2018, is one of 2 in phase 2, and was the 5th registered.

Mucopolysaccharidosis II

77 studies on the registry are indexed under Mucopolysaccharidosis II; 8 are open to participants now.

Browse Mucopolysaccharidosis II studies →

Open to participants now

2 of the 13 studies in Mucopolysaccharidosis II with a site in Brazil are open now. Recruiting first, the newest first:

All 2 open studies →

A study can be open while its sites in Brazil have not opened yet or have stopped. Only those recruiting at a site in Brazil →

Who these studies take

Of the 4 Mucopolysaccharidosis II studies recruiting now, 1 sets no upper age limit and 3 stop at 75 or younger; 4 take children under 18; none take healthy volunteers.

This study: 0 Years and older · male · no healthy volunteers.

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02

Study summary

A Phase II open-label, randomized, parallel group, 2 sites (Brazil), designed to evaluate the safety and efficacy of 3 doses of study drug for the treatment of the MPS II.

03

Conditions studied

  • Mucopolysaccharidosis II
04

Who can participate

Ages eligible
0 Years and older
Sexes eligible
Male
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  • Males with confirmed diagnosis of MPS II, based on deficient activity of IDS in leucocytes or fibroblasts and/or pathogenic mutations identified in the IDS gene (if enzyme diagnosis was in dried blood spots or plasma, molecular genetics confirmation is mandatory).

  • One of the following age groups:

    1. 0 to 3 years and 11 months old (6 patients, 2 in each dose)
    2. 4 years to 7 years and 11 months old (6 patients, 2 in each dose)
    3. 8 years or older (6 patients, 2 in each dose)
  • Capable of providing written consent by himself, unless the patient is under the age of 18 years at the time of process, or it is not possible to obtain consent from the patient himself due to his intellectual disabilities associated with MPS II.
  • In the case of a patient who is under the age of 18 years or from whom it is not possible to obtain consent due to his intellectual disabilities associated with MSP II, he may be included if written consent can be provided by legal representative; however written consent should be obtained from the patient himself too, wherever possible.
  • Naïve patients or patients who are receiving enzyme replacement therapy with idursulfase could be included if provided treatment has been stable in the last 6 months and agree to interrupt the treatment at least one week before the first study drug infusion, and agree in suspending this treatment for the duration of the trial.

Exclusion criteria

Exclusion Criteria:

  • Refusal to sign the form.
  • Unable to perform the study procedures, except for neurocognitive testing.
  • Previous engrafted BMT/.
  • Surgical or other major medical intervention planned to occur before week 26.
  • Participation in a clinical trial with an drug in the last 12 months.
  • Judged by the investigator or subinvestigator as being unable to undergo lumbar puncture, including those who have difficulties in taking a position for lumber puncture due to joint contracture or those who are likely to experience difficulty breathing during the lumbar puncture process.
  • Judged by the investigator or subinvestigator to be ineligible to participate in the study due to a history of a serious drug allergy or sensitivity.
  • Otherwise judged by the investigator or subinvestigator to be ineligible to participate in the study out of consideration for the subject safety.
Terms in these criteria, in plain language(3)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Allogeneic and autologous transplant

Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

05

Study design

Phase
Phase 2
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
None (open label)
Enrollment
18 participants (actual)

Study arms

  • Experimental
    JR-141 1.0 mg/kg/week

    Drug: JR-141

  • Experimental
    JR-141 2.0 mg/kg/week

    Drug: JR-141

  • Experimental
    JR-141 4.0 mg/kg/week

    Drug: JR-141

Interventions

  • DrugJR-141

    IV infusion (lyophilized powder), 1.0 mg/kg/week

  • DrugJR-141

    IV infusion (lyophilized powder), 2.0 mg/kg/week

  • DrugJR-141

    IV infusion (lyophilized powder), 4.0 mg/kg/week

06

What researchers measure

Primary outcomes

  1. Number of participants with Adverse Events

    * Adverse events * Antidrug antibodies * Blood pressures in mmHg * Heart rate in beats/minute * Respiratory rate in breaths/minute * Temperature in °C * Presence or absence of abnormalities for physical examination * Presence or absence of abnormalities for 12-lead electrocardiogram * Routine laboratory tests in blood (hematology, liver function, renal function, iron-related levels) and urine (urinalysis)

    Time frame: 26 weeks

Secondary outcomes

  1. Plasma Pharmacokinetic parameter [Maximum Plasma Concentration [Cmax]]

    Plasma concentration of JR-141

    Time frame: 21 hours after dosing at the first and last infusions

  2. Plasma Pharmacokinetic parameter [Area Under the Curve [AUC]]

    Plasma concentration of JR-141

    Time frame: 21 hours after dosing at the first and last infusions

  3. Liver and spleen volumes (MRI)

    Time frame: 26 weeks

  4. Left ventricular mass by a standard 2-dimensional Doppler echocardiogram

    Time frame: 26 weeks

  5. Urinary heparan sulfate concentrations

    Time frame: 26 weeks

  6. Urinary dermatan sulfate concentrations

    Time frame: 26 weeks

  7. Serum heparan sulfate concentrations

    Time frame: 26 weeks

  8. Serum dermatan sulfate concentrations

    Time frame: 26 weeks

07

Study locations

2 sites
  • Grupo de Pesquisa Clínica em Genética Médica - HCPA
    Porto Alegre, Brazil
  • Igeim - Unifesp
    São Paulo, Brazil
08

References and documents

Individual participant data

Plan to share: No

No publications or documents are linked to this record.

09

Timeline

Tracking since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reached

Ran from Jul 2018 to primary completion in Oct 2019, 14 months.

How these figures are worked out, and which studies are left out of them.

Registered
Nov 17, 2017
First posted
Dec 2, 2017
StartActual
Jul 26, 2018
Primary completionActual
Oct 4, 2019
CompletionActual
Oct 4, 2019
Last update
Jul 24, 2025
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
No changes since tracking began. The registry record was last updated on Jul 24, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT03359213
Lead sponsor
JCR Pharmaceuticals Co., Ltd.
Responsible party
Sponsor
First posted
Dec 2, 2017
Start date
Jul 26, 2018
Primary completion
Oct 4, 2019
Completion
Oct 4, 2019
Last update
Jul 24, 2025

Oversight

Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Jul 2025. You cannot join it, but the record below documents what was studied.

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Discussion

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Studies of the drug tested here: Pabinafusp alfa

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JCR Pharmaceuticals Co., Ltd.

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