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Study on the Effectiveness and Safety of OTL-203 for Patients with Hurler Syndrome (MPS-IH) Compared to Standard Treatment with Stem Cell Transplantation

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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 disorder called Mucopolysaccharidosis type I, Hurler Syndrome (MPS-IH). This condition affects the body's ability to break down certain sugars, leading to various health problems. The study is comparing a new treatment called OTL-203 with the current standard treatment, which is a type of stem cell transplant known as allogeneic hematopoietic stem cell transplantation (allo-HSCT). OTL-203 is a gene therapy that involves using a patient's own stem cells, which are modified to help produce an enzyme that people with MPS-IH lack.

The purpose of the study is to evaluate the safety and effectiveness of OTL-203 compared to the standard treatment. Participants in the study will receive either the new gene therapy or the standard stem cell transplant. The study will monitor participants over time to see how well they do with each treatment. This includes looking at survival without major health events, changes in enzyme activity, and other health measures like cognitive function, joint movement, and quality of life.

The study will also track any side effects or complications that may arise from the treatments. This includes monitoring for immune responses, infections, or other serious health issues. The goal is to determine if OTL-203 can provide a safer and more effective treatment option for people with Mucopolysaccharidosis type I, Hurler Syndrome.

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

    Enrollment

    Upon joining the study, the patient is enrolled after meeting specific criteria, including age and a confirmed diagnosis of Mucopolysaccharidosis type I, Hurler Syndrome.

  2. Step 2

    Initial assessment

    The patient undergoes an initial assessment to evaluate cognitive function, physical health, and other baseline measurements. This includes tests like the Bayley Scale of Infant Development or the Wechsler Preschool and Primary Scale of Intelligence.

  3. Step 3

    Treatment initiation

    The patient begins treatment with OTL-203, which involves the use of genetically modified stem cells. This is administered through an intravenous infusion.

  4. Step 4

    Medication administration

    The patient receives several medications as part of the treatment protocol:

    Laronidase is administered intravenously.

    Plerixafor is given subcutaneously.

    Busulfan is administered intravenously.

    Fludarabine is given intravenously.

    Rituximab is administered intravenously.

  5. Step 5

    Monitoring and follow-up

    The patient is monitored regularly to assess the effectiveness and safety of the treatment. This includes checking enzyme activity, urinary heparan sulfate levels, and other health indicators.

    Regular assessments are conducted to evaluate cognitive function, joint movement, hearing, vision, and overall quality of life.

  6. Step 6

    End of study evaluation

    At the end of the study period, a comprehensive evaluation is conducted to determine the long-term effects of the treatment, including event-free survival and any adverse events experienced during the trial.

Who can join the trial?

5 criteria

  • Written informed consent must be provided by the parent or legal guardian.
  • The participant can be a boy or girl aged between 28 days and 30 months. In some cases, children older than 30 months may be considered if they meet all the requirements and there is an agreement with the Medical Monitor.
  • The child must have a cognitive standard score of 70 or higher. This score is measured using tests that check the child's thinking and understanding abilities.
  • The child must have a confirmed laboratory diagnosis of **MPS-IH**. This means there are specific changes (mutations) in the gene responsible for the **IDUA enzyme**. The diagnosis can be confirmed if the child has two severe gene changes or if there are other signs of the disease, like frequent ear infections, hernias, or certain bone and eye problems.
  • The diagnosis of **MPS-IH** must be confirmed by a special committee after reviewing gene mutation analysis, evidence of low **IDUA enzyme** activity, changes in **GAG metabolism**, and physical signs of the disease.

Who cannot join the trial?

10 criteria

  • Patients who have a different condition than Mucopolysaccharidosis type I, Hurler Syndrome cannot participate.
  • Patients who are not within the specified age range for the study cannot participate.
  • Patients who are not able to follow the study procedures or comply with the study requirements cannot participate.
  • Patients who have other medical conditions that might interfere with the study cannot participate.
  • Patients who are pregnant or breastfeeding cannot participate.
  • Patients who have participated in another clinical trial recently may not be eligible.
  • Patients who have a history of certain medical treatments that could affect the study results cannot participate.
  • Patients who have allergies or reactions to the study medication or similar medications cannot participate.
  • Patients who have a history of substance abuse or other behaviors that might interfere with the study cannot participate.
  • Patients who have a family history of certain genetic conditions that might affect the study cannot participate.
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Investigated drugs

  • OTL-203

    is an investigational therapy being studied for its effectiveness and safety in treating patients with mucopolysaccharidosis type I, Hurler syndrome (MPS-IH). This therapy is being compared to the standard treatment to see if it can improve outcomes for patients with this condition.

  • Allogeneic Hematopoietic Stem Cell Transplantation (allo-HSCT)

    is the current standard of care for treating mucopolysaccharidosis type I, Hurler syndrome. This procedure involves transplanting stem cells from a donor to help the patient's body produce healthy blood cells and improve their condition. The trial is comparing this standard treatment to the investigational therapy, OTL-203, to determine which is more effective.

What is already known about the treatment

OTL-203 – This medication is administered through intravenous infusion and is currently being evaluated in clinical trials for its effectiveness and safety in treating Mucopolysaccharidosis type I, specifically Hurler Syndrome. It is not yet widely available in medical practice as it is still under investigation. The main therapeutic indication for OTL-203 is to improve outcomes in patients with this rare genetic disorder, which affects the body's ability to break down certain sugars. At the molecular level, OTL-203 works by delivering a functional copy of the gene responsible for producing the enzyme that is deficient in patients with this condition. It is classified pharmacologically as a gene therapy product.

Investigated diseases

Mucopolysaccharidosis type I, Hurler Syndrome – This is a rare genetic disorder caused by a deficiency of the enzyme alpha-L-iduronidase. This enzyme deficiency leads to the accumulation of glycosaminoglycans in various body tissues, causing progressive damage. Symptoms often appear in early childhood and may include developmental delay, coarse facial features, and enlarged organs. As the disease progresses, individuals may experience joint stiffness, heart problems, and vision and hearing impairments. The condition can also lead to skeletal abnormalities and short stature. Over time, the accumulation of these substances can affect the function of multiple organs and systems.
Trial detailsLast updated 2 Oct 2026
Age0-17PhasePhase IIITrial ID2022-500306-17-00Protocol codeOTL-203-02Estimated enrolment40 patientsSponsorOrchard Therapeutics (Europe) Limited

sourced from the EU Clinical Trials Register and site verification

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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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