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Study on the Effectiveness and Safety of DNL310 vs Idursulfase for Children and Young Adults with Mucopolysaccharidosis Type II

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying a rare genetic condition called Mucopolysaccharidosis Type II, also known as MPS II or Hunter syndrome. This condition affects the body's ability to break down certain sugars, leading to various health issues. The study involves two treatments: Tividenofusp Alfa (DNL310) and Idursulfase. Tividenofusp Alfa is a new treatment being tested, while Idursulfase is an existing treatment used for MPS II. Both treatments are given as a solution through a vein, known as an infusion.

The purpose of the study is to compare the effectiveness and safety of Tividenofusp Alfa with Idursulfase in children and young adults with MPS II. The study will look at how these treatments affect the brain and behavior, as well as other health aspects. Participants will receive one of the treatments and will be monitored over a period of time to see how their condition changes. The study will include regular check-ups and assessments to track progress and any side effects.

Participants in the study will be divided into two groups based on their age and specific type of MPS II. The study will last for up to 96 weeks, during which various health measurements will be taken, such as changes in certain substances in the body and improvements in daily activities. The goal is to gather information that could lead to better treatment options for those living with MPS II.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, participants are divided into two groups based on age: Cohort A (ages 2 to <6 years) and Cohort B (ages 6 to <26 years).

    Participants must have a confirmed diagnosis of Mucopolysaccharidosis Type II (MPS II).

  2. Step 2

    Initial treatment phase

    Participants receive treatment with either Tividenofusp Alfa (DNL310) or Idursulfase.

    Both medications are administered as a solution for infusion through intravenous use.

  3. Step 3

    Treatment schedule

    The treatment is administered regularly over a period of time, with specific intervals determined by the study protocol.

    Participants in Cohort A are monitored for changes in cerebrospinal fluid (CSF) concentration of heparan sulfate (HS) at Week 24.

  4. Step 4

    Monitoring and assessments

    Participants undergo various assessments to evaluate the effectiveness of the treatment.

    For Cohort A, assessments include changes in adaptive behavior using the Vineland-3 scale at Week 96.

    For Cohort B, assessments include changes in distance walked in the 6-minute walk test (6MWT) at Week 48.

  5. Step 5

    Additional evaluations

    Both cohorts are evaluated for changes in urine concentrations of HS and dermatan sulfate (DS) at Weeks 24 and 48.

    Liver and spleen volumes are measured using MRI at Week 48 to ensure they are within normal ranges.

  6. Step 6

    Completion of the study

    The study is estimated to conclude by December 30, 2025.

    Final assessments are conducted to determine the overall impact of the treatment on MPS II symptoms.

Who can join the trial?

3 criteria

  • Participants must be aged **2 to less than 6 years** for Cohort A or **6 to less than 26 years** for Cohort B.
  • Participants must have a **confirmed diagnosis** of Mucopolysaccharidosis Type II, also known as **MPS II**. For Cohort A, this is referred to as **nMPS II**, and for Cohort B, as **nnMPS II**.
  • For those in non-run-in Cohort A and Cohort B, participants must be on **maintenance ERT** (Enzyme Replacement Therapy) and have tolerated at least **4 months** (or 16 weeks) of **idursulfase therapy** before the screening period.

Who cannot join the trial?

5 criteria

  • Patients who have a medical condition other than **Mucopolysaccharidosis Type II (MPS II)**.
  • Patients who are not within the specified age range for the study.
  • Patients who are not part of the specified clinical trial group.
  • Patients who are not male or female, as both genders are included in the study.
  • Patients who are not considered part of a vulnerable population, as the study includes vulnerable groups.
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Investigated drugs

  • DNL310

    is an investigational medication being studied for its potential effects on the central nervous system (CNS) in children with Mucopolysaccharidosis Type II (MPS II), also known as Hunter syndrome. This medication is being evaluated to see if it can reduce the concentration of harmful substances in the cerebrospinal fluid (CSF) and improve adaptive behavior in affected children.

  • Idursulfase

    is an approved enzyme replacement therapy used to treat Mucopolysaccharidosis Type II (MPS II). It works by providing the enzyme that people with this condition lack, helping to break down certain substances in the body. In this study, it is being compared to DNL310 to assess its effectiveness and safety in treating the CNS symptoms of the disease.

What is already known about the treatment

  • DNL310

    DNL310 is administered intravenously and is currently being studied in clinical trials for its effectiveness and safety in treating Mucopolysaccharidosis Type II (MPS II), a rare genetic disorder. The medication is designed to address central nervous system symptoms by reducing harmful substances in the brain. It works by targeting and breaking down specific molecules that accumulate in patients with MPS II. DNL310 is classified as an enzyme replacement therapy, aiming to improve adaptive behavior and overall quality of life for affected individuals.

  • Idursulfase

    Idursulfase is also administered intravenously and is an established treatment for Mucopolysaccharidosis Type II (MPS II). It is approved for use and has been widely documented in medical literature. The primary therapeutic indication is to replace the deficient enzyme in patients, helping to break down complex sugars that accumulate in the body. Idursulfase functions by supplementing the missing enzyme, thereby reducing symptoms and improving physical function. It is classified as an enzyme replacement therapy and is a standard treatment option for managing MPS II.

Investigated diseases

Mucopolysaccharidosis Type II (MPS II) – This is a rare genetic disorder caused by a deficiency of the enzyme iduronate-2-sulfatase. This enzyme deficiency leads to the accumulation of glycosaminoglycans (GAGs) in the body's cells, which can cause a variety of symptoms. The disease primarily affects males and can lead to progressive damage to the heart, bones, joints, respiratory system, and central nervous system. Symptoms may include developmental delays, distinctive facial features, and joint stiffness. Over time, individuals with MPS II may experience worsening of physical and cognitive abilities. The severity and progression of symptoms can vary widely among those affected.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IVTrial ID2024-510990-21-00Protocol codeDNLI-E-0007Estimated enrolment64 patientsSponsorDenali Therapeutics Inc.

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

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