An Observational LTFU Study for Patients Previously Treated With Autologous ex Vivo Gene Therapy for ADA-SCID

December 10, 2025 updated by: Donald B. Kohn, M.D., University of California, Los Angeles

An Observational Long-term Follow-up Study for Patients Previously Treated With Autologous ex Vivo Gene Therapy for Severe Combined Immunodeficiency Due to Adenosine Deaminase Deficiency (ADA-SCID)

This observational long-term follow-up study is designed to collect safety and efficacy data from ADA-SCID patients previously treated with autologous ex vivo gene therapy products based on the EFS-ADA LV encoding for human adenosine deaminase (ADA) gene (EFS-ADA LV), as part of the OTL-101 clinical development program. No investigational medicinal product will be administered to these patients as part of the OTL-101-6 study.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Enrolling by invitation

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 overall aim of this study is to record and evaluate long-term safety and efficacy data from ADA-SCID patients previously treated with autologous ex vivo gene therapy products based on the EFS-ADA vector, as part of the UCL/A- ADA clinical development program. This will fulfil the requirements for the monitoring of delayed adverse events set by regulatory agencies for subjects treated with gene therapies.

The study will have the following specific objectives:

  • To characterize the long-term safety of the gene therapy treatment;
  • To characterize the long-term clinical efficacy of the gene therapy treatment. Patients who were treated as part of the UCL/A-ADA clinical development program but did not complete the expected follow- up period (e.g. as a consequence of early withdrawal due to safety events) will be included in the LTFU study, subject to their consent and compliance with inclusion and exclusion criteria.

For any patients who completed their expected follow-up period before this study became available, outcome data will be retrospectively collected for the intervening period. From the first LTFU assessment onwards, prospective data will be gathered from the annual standard of care evaluations the patients will receive from the PI or their local healthcare professionals (HCPs).

Each patient, or their legal guardian, will be required to provide informed consent, which will define the objectives of this study, the expected duration of the patient's participation, as well as the data to be collected and the schedule of collection. It is anticipated that data will be collected annually to coincide with standard of care visits.

The study outcomes will be:

  • Overall survival (OS) at 15 years of follow-up post treatment with gene therapy;
  • Event-free survival (EvFS) at 15 years of follow-up post treatment with gene therapy. An "event" will be defined as enzyme replacement therapy (ERT) reinstitution, need for a rescue allogeneic hematopoietic stem cell transplant (HSCT) or further gene therapy treatment;
  • Use of immunoglobulin replacement therapy (IgRT);
  • Adverse events (AEs), serious adverse events (SAEs) and safety concerns
  • Other physical and laboratory parameters

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.
Observational

Enrollment (Estimated)

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.
70

Contacts and Locations

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

Study Locations

  • United Kingdom
      • London, United Kingdom, WC1N 1EH
        • UCL Great Ormond Street Institute of Child Health
  • United States
    • California
      • Los Angeles, California, United States, 90095
        • Mattel Children's Hospital UCLA/Ronald Reagan UCLA Medical Center

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
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

This observational LTFU study is open for enrollment to ADA-SCID patients previously treated with autologous ex vivo gene therapy products based on the EFS-ADA lentiviral vector as part of the OTL-101 clinical development program. Patients treated in clinical trials as part of IND #15440, study OTL-101-5 (EudraCT No 2017-001275-23) or study 10-MI-29 (EudraCT No 2010-024253-36), as well as in Expanded Access or Compassionate Use Programs, will be eligible for enrollment.

Description

Inclusion Criteria:

A patient is eligible for enrollment in the study if all of the following criteria are met:

  1. the patient has been treated with an autologous ex vivo gene therapy product based on the EFS-ADA LV, as part of the OTL-101 clinical development program;
  2. the patient displays persistent detectable gene marking, as determined by the Investigator;
  3. the patient or, if applicable, the patient's parent(s)/legal guardian(s), are able and willing to provide informed consent.

Exclusion Criteria:

  • There are no exclusion criteria for participation in this observational LTFU study.

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

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
Overall Survival
Time Frame: 15 years post-treatment
Establishing efficacy through overall survival
15 years post-treatment
Event-Free Survival
Time Frame: 15 years post-treatment
Establishing efficacy through event-free survival
15 years post-treatment
Incidence of Adverse Events
Time Frame: 15 years post-treatment
Long-Term Safety incidence of AEs and SAEs
15 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.
University of California, Los Angeles

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Great Ormond Street Hospital for Children NHS Foundation Trust

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Donald B. Kohn, M.D., University of Califorina, Los Angeles

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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.
September 26, 2019

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.
August 1, 2040

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.
August 1, 2040

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).
August 6, 2019

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.
August 6, 2019

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.
August 7, 2019

Study Record Updates

Last Update Posted (Estimated)

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 18, 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 10, 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-101-6

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

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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