JR-141 for Hunter Syndrome

Not currently recruiting at 34 trial locations

Overseen By JCR Pharmaceuticals Co., Ltd.

Age: Any Age

Sex: Any

Trial Phase: Phase 3

Sponsor: JCR Pharmaceuticals Co., Ltd.

Must be taking: Enzyme replacement

Disqualifiers: Gene therapy, HSCT, Brain surgery, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Pivotal Trial (Near Approval) This treatment is in the last trial phase before FDA approval

Prior Safety Data This treatment has passed at least one previous human trial

Approved in 1 Jurisdiction This treatment is already approved in other countries

Compensation: Varies

Number of Visits: 26

Duration: 105 weeks

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial tests the safety and effectiveness of a new treatment called JR-141 (pabinafusp alfa) for individuals with Hunter Syndrome, a rare genetic disorder affecting many parts of the body. Participants will receive either JR-141, a standard treatment called idursulfase, or another supportive treatment. Eligible participants must have a confirmed diagnosis of Hunter Syndrome and may have been on stable enzyme replacement therapy for at least 12 weeks. As a Phase 3 trial, this study is the final step before FDA approval, offering participants the opportunity to contribute to potentially bringing a new treatment to market.

Will I have to stop taking my current medications?

The trial does not specify if you need to stop taking your current medications. However, if you are on stable enzyme replacement therapy with idursulfase, you can continue it during the study.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research shows that JR-141, also known as pabinafusp alfa, is generally safe for humans. Studies over the past five years have shown ongoing benefits for both brain and body symptoms in people with Hunter Syndrome, a rare genetic disorder. Previous trials reported no major safety concerns, indicating it is safe to use. This treatment is designed to pass through the blood-brain barrier, a protective layer around the brain, marking a significant advancement. The trial's progression to a later phase further suggests that JR-141 demonstrated a good safety record in earlier research. ^{1 2 3 4 5}

Why are researchers excited about this study treatment for Hunter Syndrome?

JR-141 is unique because it offers a novel approach to treating Hunter Syndrome by crossing the blood-brain barrier, a feat that current treatments like idursulfase (ELAPRASE®) struggle to achieve. This ability means JR-141 can potentially address both the physical and neurological symptoms of the condition, offering a more comprehensive treatment option. Researchers are excited about JR-141 because it represents a significant advancement, potentially improving quality of life for patients with Hunter Syndrome by targeting areas that existing treatments cannot effectively reach.

What evidence suggests that this trial's treatments could be effective for Hunter Syndrome?

Research has shown that JR-141, one of the treatments studied in this trial, is promising for Hunter syndrome. Previous patients experienced positive results, with JR-141 effectively addressing both body-related and brain-related symptoms. This treatment can reach the brain, addressing symptoms that other treatments might miss. Long-term data indicates that patients using JR-141 for five years have continued to benefit both mentally and physically. The unique mechanism of JR-141 offers hope for managing the challenging symptoms of Hunter syndrome. Participants in this trial may receive either JR-141 or the standard of care treatment, idursulfase (Elaprase). ^{1 2 3 4 6}

Are You a Good Fit for This Trial?

This trial is for patients with Hunter Syndrome (MPS II). Eligible participants include those diagnosed with MPS II, either treatment-naïve or on stable enzyme therapy. They must agree to use effective contraception and sign consent forms. There are specific age-related cognitive criteria for two separate cohorts: Cohort A includes children aged 36-71 months with certain developmental scores, while Cohort B includes individuals aged 6 years or older with an IQ of 70 or higher.

Inclusion Criteria

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

For children 36-42 months old, their measured development score must be 85 or less. For children 43-71 months old, either their development quotient should be between 20 to 85, or their composite standard score on a specific test should be 85 or less. Children 30-35 months old must be assessed as having a severe condition by an Expert Board.

I am 6 or older with an IQ of 70 or more and fit the specific test criteria for Cohort B.

Exclusion Criteria

I have had a successful stem cell transplant.

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

I have a genetic mutation linked to developmental delays or seizures.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive JR-141 2.0 mg/kg/week or standard of care idursulfase (ELAPRASE®) for the treatment of MPS II

105 weeks

Weekly visits for treatment administration

Follow-up

Participants are monitored for safety and effectiveness after treatment, including assessments of antibodies and cognitive testing

4 weeks

Visits at Week 26, 53, 78, and 105

What Are the Treatments Tested in This Trial?

Interventions

• Idursulfase
• JR-141

Trial Overview The STARLIGHT Phase III trial is testing the safety and effectiveness of a drug called JR-141 compared to Idursulfase in treating MPS II. Participants will be randomly assigned to receive either JR-141 alone, JR-141 combined with Idursulfase, or only Idursulfase in a blinded manner where assessors do not know which treatment each participant receives.

How Is the Trial Designed?

Group I: administered as the standard of care: idursulfase (ELAPRASE®) Experimental Treatment 1 Intervention

standard of care-controlled study

Group II: Rescue arm Experimental Treatment 1 Intervention

Group III: JR-141 2.0 mg/kg/week Experimental Treatment 1 Intervention

JR-141 is already approved in Japan for the following indications:

Approved in Japan as IZCARGO for:

• Mucopolysaccharidosis type II (MPS II)
• Hunter syndrome

Who Is Running the Clinical Trial?

JCR Pharmaceuticals Co., Ltd.

Lead Sponsor

Trials

13

Recruited

320+

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC7854283/

A Phase 2/3 Trial of Pabinafusp Alfa, IDS Fused with Anti ... Pabinafusp alfa (JR-141) is a novel enzyme drug that crosses the blood-brain barrier by transcytosis via transferrin receptors.

2. biospace.com biospace.com/press-releases/jcr-pharmaceuticals-presents-long-term-clinical-data-on-pabinafusp-alfa-for-the-treatment-of-mucopolysaccharidosis-type-ii-mps-ii-at-iciem-2025

JCR Pharmaceuticals Presents Long-Term Clinical Data ... Key findings included five-year clinical data demonstrating sustained neurocognitive and somatic benefits of pabinafusp alfa (JR-141) in ...

3. clinicaltrials.gov clinicaltrials.gov/study/NCT04573023

NCT04573023 | A Phase III Study of JR-141 in Patients ... A Global Phase III multicenter, randomized, assessor-blinded, active-controlled designed to evaluate safety and efficacy of study drug for the treatment of ...

4. firstwordpharma.com firstwordpharma.com/story/5977574

JCR Pharmaceuticals Announces the Achievement of ... This novel mechanism of action is expected to make JR-141 effective against the central nervous system (CNS) symptoms of Hunter syndrome. In non ...

5. checkrare.com checkrare.com/efficacy-and-safety-of-pabinafusp-alfa-in-mps-ii-hunter-syndrome/

Efficacy and Safety of Pabinafusp-Alfa in MPS-II (Hunter ... Previous clinical trials have provided positive results suggesting pabinafusp alfa is efficacious against both somatic and neurological symptoms.

6. finance.yahoo.com finance.yahoo.com/news/jcr-pharmaceuticals-presents-long-term-170300633.html

JCR Pharmaceuticals Presents Long-Term Clinical Data ... Key findings included five-year clinical data demonstrating sustained neurocognitive and somatic benefits of pabinafusp alfa (JR-141) in ...