A Phase I/II Trial of JR-446 in Mucopolysaccharidosis Type IIIB (MPS IIIB) (NCT07640984) | Clinical Trial Compass
Not Yet RecruitingPhase 1/2
A Phase I/II Trial of JR-446 in Mucopolysaccharidosis Type IIIB (MPS IIIB)
United States, Germany, United Kingdom12 participantsStarted 2026-06-18
Plain-language summary
This is a global, open-label, Phase I/II, interventional trial in participants younger than 6 years of age with Mucopolysaccharidosis Type IIIB (MPS IIIB), designed to assess the safety and tolerability of JR-446, determine its pharmacodynamic effects, and explore its potential to demonstrate early clinical effects on disease-relevant outcomes.
Who can participate
Age range
5 Years
Sex
ALL
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Inclusion criteria
. Patients with confirmed MPS IIIB with a phenotype of MPS IIIB that is not classified as slowly progressive (i.e., not attenuated).
. A chronological age \<6 years.
. Ability to complete and achieve a Standard score ≥55, using either Bailey Scale of Infant Development-4 (BSID-4) Cognitive domain or Kaufman Assessment Battery for Children-II (KABC-II) Non-Verbal Index, whichever tool is most appropriate for the participant's chronological age.
Exclusion criteria
. Contraindication for lumbar puncture or MRI.
. A participant who has a medical condition or extenuating circumstance that, in the opinion of the principal investigator or sub-investigator, might compromise the participant's ability to comply with protocol requirements, the participant's well-being or safety, or the interpretability of the participant's clinical data.
Questions worth asking your doctor
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
Questions for the trial coordinator
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
What they're measuring
1
To establish the safety and tolerability of JR-446 in MPS IIIB patients following repeated dose administration
. A participant who has received any other investigational drug product (including but not limited to, tralesinidase alfa enzyme replacement therapy \[TA-ERT\], Genistein, KINERET \[anakinra\], ambroxol, miglustat) within 4 months (or 5 half-lives, whichever is longer) before the time of providing informed consent.
. A participant who has received gene therapy treatment or hematopoietic stem cell transplantation (HSCT) with successful engraftment.
. Serious drug allergy or hypersensitivity to any components of JR-446 or medications likely prescribed during the trial.
. A participant has a history of bleeding disorder or current use of medications that, in the opinion of the investigator, place them at risk of bleeding following lumbar puncture.
. A patient with recurrent epileptic seizures not adequately controlled with anti-seizure medication, and which, in the clinical judgment of the principal investigator, would preclude safe participation in the trial.
. Serology consistent with human immunodeficiency virus (HIV) exposure or consistent with active hepatitis B (HepB) or hepatitis C (HepC) infection.