A Study to Investigate the Efficacy and Safety of OTL-203 in Subjects With MPS-IH Compared With Standard of Care With Allogeneic HSCT (HURCULES)

December 18, 2025 updated by: Orchard Therapeutics

A Multi-center, Randomized, Active Controlled Clinical Trial to Evaluate the Efficacy and Safety of OTL-203 in Subjects With Mucopolysaccharidosis Type I, Hurler Syndrome (MPS-IH) Compared to Standard of Care With Allogeneic Hematopoietic Stem Cell Transplantation (Allo-HSCT)

A multi-center randomized clinical trial to compare OTL-203 (gene therapy) with stem cell transplant (standard of care) in patients with MPS-IH (Hurler syndrome).

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The study is a multi-center, randomized, active controlled clinical trial designed to evaluate the efficacy and safety of OTL-203 in patients with mucopolysaccharidosis type I, Hurler syndrome (MPS-IH) compared to standard of care with allogeneic hematopoietic stem cell transplantation (allo-HSCT). A total of 40 patients with a confirmed diagnosis of MPS-IH who meet the study inclusion criteria will be randomized to receive either OTL-203 or allo-HSCT. The trial will comprise of a screening, baseline, and treatment period, with a follow-up period of 5 years post-treatment, and primary analysis performed at 2 years follow-up of the last treated subject.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
41

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Italy
      • Milan, Italy, 20131
        • Ospedale San Raffaele
  • Netherlands
      • Utrecht, Netherlands, 3584 CX
        • UMC Utrecht
      • Utrecht, Netherlands, 3584 CS
        • Princess Máxima Center
  • United Kingdom
      • Manchester, United Kingdom, M13 9WL
        • Manchester University NHS Foundation Trust Blood and Marrow Transplant Programme, Royal Manchester Children's Hospital
  • United States
    • Minnesota
      • Minneapolis, Minnesota, United States, 55455
        • University of Minnesota, Pediatrics

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Norm-referenced cognitive standard score of ≥70 measured by age-appropriate cognitive domains of either Bayley Scale of Infant Development (BSID)-III or Wechsler Preschool and Primary Scale of Intelligence (WPPSI)-IV.
  2. Confirmed laboratory diagnosis of MPS-IH as demonstrated by biallelic mutation(s) in the gene coding for IDUA enzyme
  3. Final confirmation of MPS-IH diagnosis by a Diagnostic Review Committee (DRC).

Exclusion Criteria:

  1. Previous allo-HSCT or gene therapy
  2. Current enrollment or past treatment in any other interventional study/trial using a novel investigational agent and/or treated with prohibited medications listed in the protocol
  3. Positivity to serological testing for Human Immunodeficiency Virus (HIV)-1 or HIV-2, Human T Lymphotropic Virus (HTLV)-1 or HTLV-2, Hepatitis B Virus (HBV) core, Hepatitis C Virus (HCV), mycoplasma, active tuberculosis (TB) and not meeting the microbiology biological screening requirements.
  4. Malignant neoplasia (except local skin cancer).
  5. Myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML)
  6. History of uncontrolled seizures
  7. Subjects with an active infection not responsive to treatment, end-organ damage, or any other disease that contraindicates performance of any of the procedures detailed in the protocol, or medical conditions or extenuating circumstances that, in the opinion of the Investigator, might compromise the subject's well-being or safety, or the interpretability of the subject's clinical data.
  8. Subjects, who in the opinion of the Investigator, may not be able to comply with protocol requirements or cooperate fully with the study procedures and necessary long-term follow up

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: OTL-203
Eligible subjects randomized to Arm 1 will receive an intravenous (IV) infusion of OTL-203 gene therapy. Subjects will receive conditioning regimen with busulfan and fludarabine prior to OTL-203 infusion.
Genetic: Experimental: OTL-203
Experimental: OTL-203: Autologous CD34+ enriched cell fraction that contains hematopoietic stem and progenitor cells transduced ex vivo using lentiviral vector encoding the human IDUA gene
Active Comparator: Allo-HSCT
Eligible subjects randomized to Arm 2 will receive allogeneic hematopoietic stem cell transplantation. Subjects will receive conditioning regimen with busulfan and fludarabine prior to allo-HSCT.
Genetic: Active Comparator: Allo-HSCT
Active Comparator: Allogeneic hematopoietic stem cell transplantation

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Event-free survival
Time Frame: 2 years
Defined by events of death, rescue transplant, treatment failure, immunological complications, severe cognitive and/or growth impairment.
2 years

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change from baseline to Year 2 in α-L-iduronidase (IDUA) activity in leukocytes
Time Frame: Day 30 and multiple visits up to 5 years post-treatment
IDUA activity in leukocytes will be used to measure post-treatment systemic correction of the biochemical defect that causes the disease
Day 30 and multiple visits up to 5 years post-treatment
Safety of OTL-203 compared to allo-HSCT procedure
Time Frame: Up to 5 years post-treatment
Measured by Overall incidence of adverse events (AEs) whether or not considered related to the study treatment, including conditioning regimen-related AEs, Study Procedure-related AEs, Disease-related AEs, Treatment related AEs, Serious adverse events (SAEs)
Up to 5 years post-treatment
Malignancy or abnormal clonal proliferation (ACP) using different tests and procedures (e.g., general clinical evaluation, blood counts, and specialized assessments such as integration site analysis).
Time Frame: Up to 5 years post-treatment
Malignancy or ACP due to insertional oncogenesis will be evaluated in subjects treated with OTL-203.
Up to 5 years post-treatment
Replication Competent Lentivirus (RCL)
Time Frame: Up to 5 years post-treatment
Presence of RCL will be evaluated in subjects treated with OTL-203
Up to 5 years post-treatment
Immune response against IDUA enzyme
Time Frame: Up to 5 years post-treatment
Anti-IDUA antibodies analysis will be evaluated in all subjects.
Up to 5 years post-treatment
Change from baseline to Year 2 in the ratio to the upper limit of normal (ULN) of urinary heparan sulfate levels
Time Frame: Day 30 and multiple visits up to 5 years post-treatment
Urinary heparan sulfate levels will be used to measure post-treatment clearance of glycosaminoglycans accumulated within tissues and organs due to IDUA enzymatic deficiency
Day 30 and multiple visits up to 5 years post-treatment

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Orchard Therapeutics

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 11, 2023

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
March 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 1, 2031

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 17, 2023

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 27, 2023

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 29, 2023

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
December 22, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 18, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
December 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • OTL-203-02

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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Conditions

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Dietary Supplements

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