What is the mechanism of action of this treatment?

Hunter Syndrome, or Mucopolysaccharidosis II (MPS II), is treated primarily through Enzyme Replacement Therapy (ERT) and Gene Therapy. ERT involves infusing a synthetic version of the deficient enzyme iduronate-2-sulfatase (I2S) to help break down glycosaminoglycans (GAGs) and reduce their harmful accumulation in tissues. Gene Therapy, on the other hand, introduces a functional I2S gene into the patient's cells, potentially enabling the body to produce the enzyme naturally. These treatments are vital as they address the underlying enzyme deficiency, thereby alleviating symptoms, slowing disease progression, and significantly improving the quality of life for patients.

What side effects are associated with this type of intervention?

Hunter Syndrome, also known as Mucopolysaccharidosis II (MPS II), is commonly treated with Enzyme Replacement Therapy (ERT) or Gene Therapy. ERT, such as idursulfase, aims to replace the deficient enzyme iduronate-2-sulfatase. Common side effects of ERT include infusion-related reactions like fever, headache, rash, and hypertension. More severe reactions can include anaphylaxis. Gene therapy, which targets the underlying genetic cause, is still under investigation but may present risks such as immune responses to the viral vector used for gene delivery, potential insertional mutagenesis, and long-term effects that are not yet fully understood.

What prior FDA approvals exist?

Hunter Syndrome, or Mucopolysaccharidosis II (MPS II), has seen FDA approval for enzyme replacement therapies (ERT) such as idursulfase (brand name Elaprase). Elaprase is designed to replace the deficient iduronate-2-sulfatase enzyme in patients with MPS II, helping to reduce the accumulation of glycosaminoglycans. Gene therapy approaches are also being explored, but as of now, ERT remains the primary FDA-approved treatment for managing the symptoms and progression of Hunter Syndrome.

What other types of research exist?

Promising novel alternatives for Hunter Syndrome (MPS II) patients in 2024 include gene editing technologies such as CRISPR/Cas9, which aim to correct the genetic mutations causing the enzyme deficiency. Additionally, substrate reduction therapies (SRTs) that decrease the accumulation of glycosaminoglycans (GAGs) and small molecule chaperones that stabilize the defective enzyme are also being explored. These approaches offer potential improvements in targeting the root cause of the disease and enhancing patient outcomes.

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Enzyme Replacement Therapy

JR-141 for Hunter Syndrome

Phase 3

Recruiting

Research Sponsored by JCR Pharmaceuticals Co., Ltd.

Eligibility Criteria Checklist

Specific guidelines that determine who can or cannot participate in a clinical trial

Must have

Patients with confirmed diagnosis of MPS II

Must not have

A patient with a history of HSCT with successful engraftment

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

Timeline

Screening 3 weeks

Treatment Varies

Follow Up baseline to week 26, 53, 78, 105

Awards & highlights

Pivotal Trial

No Placebo-Only Group

Summary

This trial is testing a new medicine for patients with MPS II to see if it is safe and effective. Previous research in animals helped design this trial to evaluate the new medicine for MPS II patients.

Who is the study for?

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.

What is being tested?

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.

What are the potential side effects?

While the specific side effects of JR-141 are not listed here, similar treatments often cause reactions at injection sites, allergic responses, headaches, fever and chills. Side effects can vary from person to person based on individual health conditions.

Eligibility Criteria

Inclusion Criteria

You may be eligible if you check “Yes” for the criteria below

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I have been diagnosed with MPS II.

Exclusion Criteria

You may be eligible for the trial if you check “No” for criteria below:

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I have had a successful stem cell transplant.

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

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I have had brain surgery or a shunt placed in the last 30 days, or my shunt isn't working well.

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I have received gene therapy treatment before.

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I have a documented loss of sulfatase activity, not including IDS.

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I cannot have a lumbar puncture procedure.

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I may have an infection or a higher risk of bleeding due to my health condition or treatments.

Timeline

Screening ~ 3 weeks3 visits

Treatment ~ Varies

Follow Up ~ baseline, week 26, 53

Screening ~ 3 weeks

Treatment ~ Varies

Follow Up ~baseline, week 26, 53

This trial's timeline: 3 weeks for screening, Varies for treatment, and baseline, week 26, 53 for reporting.

Treatment Details

Study Objectives

Study objectives can provide a clearer picture of what you can expect from a treatment.

Other study objectives

Antibodies

Change in adaptive behavioral testing measured from baseline

Change in cognitive testing measured from baseline

+1 more

Awards & Highlights

Pivotal Trial

The final step before approval, pivotal trials feature drugs that have already shown basic safety & efficacy.

No Placebo-Only Group

All patients enrolled in this study will receive some form of active treatment.

Trial Design

3Treatment groups

Experimental Treatment

Group I: administered as the standard of care: idursulfase (ELAPRASE®)Experimental Treatment1 Intervention

standard of care-controlled study

Group II: Rescue armExperimental Treatment1 Intervention

Group III: JR-141 2.0 mg/kg/weekExperimental Treatment1 Intervention

Treatment

First Studied

Drug Approval Stage

How many patients have taken this drug

JR-141

2018

Completed Phase 3

~60

Idursulfase

2012

Completed Phase 4

~160

0 / 8Eligibility criteria met

Research Highlights

Information in this section is not a recommendation. We encourage patients to speak with their healthcare team when evaluating any treatment decision.

Mechanism Of Action

Side Effect Profile

Prior Approvals

Other Research

Hunter Syndrome, or Mucopolysaccharidosis II (MPS II), is treated primarily through Enzyme Replacement Therapy (ERT) and Gene Therapy. ERT involves infusing a synthetic version of the deficient enzyme iduronate-2-sulfatase (I2S) to help break down glycosaminoglycans (GAGs) and reduce their harmful accumulation in tissues. Gene Therapy, on the other hand, introduces a functional I2S gene into the patient's cells, potentially enabling the body to produce the enzyme naturally. These treatments are vital as they address the underlying enzyme deficiency, thereby alleviating symptoms, slowing disease progression, and significantly improving the quality of life for patients.