A Study to Investigate the Safety and Biodistribution of a Single Intrathecal (IT) Injection of INS1201 in Ambulatory Males With Duchenne Muscular Dystrophy (DMD) (ASCEND)

June 10, 2026 updated by: Insmed Gene Therapy LLC

A Phase 1, Multicenter, Open-label Study to Investigate the Safety and Biodistribution of a Single Intrathecal Injection of INS1201 in Ambulatory Males With Duchenne Muscular Dystrophy (The ASCEND Study)

The primary objective of this study is to evaluate the safety and tolerability of a single dose of INS1201 via IT administration in ambulatory male participants with DMD.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

12

Phase

  • Phase 1

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 Locations

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

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

No

Description

Inclusion Criteria

  • Participant must be male at birth, 3 to <5 years of age, inclusive (Part 1) and 2 to <3 years of age (Part 2), at the time of legally authorized representative (LAR) signing and dating the informed consent form.
  • Ambulatory -as defined as the ability to walk at least 10 meters unassisted (ie, without personal assistance or use of any assistive devices) Note: children who have not yet developed the ability to walk by the time of screening (for whatever reason) will not be eligible for the study.
  • Has a definitive diagnosis of DMD prior to Screening or as part of Screening based on genetic testing. Note that participants who rescreen do not have to repeat genetic testing for the diagnosis of DMD if one is already on file. Genetic reports must describe a frameshift deletion, frameshift duplication, premature stop ("nonsense"), canonical splice site mutation, or other pathogenic variant in the DMD gene fully contained between exons 18 to 58 (inclusive) that is expected to lead to absence of a functional dystrophin protein (mutations in exons 1-17 or 59-71 are therefore not permitted).
  • Able to cooperate with motor assessment testing.
  • Has received vaccinations recommended for the participant's age and DMD disease according to Centers for Disease Control and Prevention (CDC) Child and Adolescent Immunization Schedule by Age, World Health Organization, or local recommendation incorporating the Advisory Committee on Immunization Practices (ACIP) Vaccine Recommendations and Guidelines for Patients with Altered Immunocompetence.

Exception is made for seasonal influenza and coronavirus disease 2019 (COVID-19) vaccines, for which shared decision-making with the participant's physician is encouraged.

Exclusion Criteria

  • Prior treatment with gene or cell-based therapy at any time.
  • Oligonucleotide-based exon skipping or small molecule stop codon readthrough-promoting therapies for at least 6 months prior to enrolment.
  • Has left ventricular ejection fraction < 50% on the screening echocardiogram (ECHO) or clinical signs and/or symptoms of cardiomyopathy.
  • Has cardiac arrhythmia or significant electrocardiogram (ECG) interval abnormalities.
  • Major surgery within 3 months prior to Day 1 or planned surgery or procedures that would interfere with the conduct of the study at any time during this study.

  • The presence of any other clinically significant illness, including cardiac, pulmonary, hepatic, renal, hematologic, immunologic/allergic, behavioural disease, infection, unhealed injury, malignancy, concomitant illness, extenuating circumstance, or requirement for chronic drug treatment that, in the opinion of the Investigator:

    1. Creates unnecessary risks for undergoing gene transfer;
    2. Might compromise the participant's ability to comply with the protocol-required testing or procedures; or
    3. Might compromise the participant's well-being, safety, or clinical interpretability.
  • Has serological evidence of current, chronic, or active human immunodeficiency virus, hepatitis C, or hepatitis B infection.
  • Has signs of clinically significant symptomatic infection (eg, upper respiratory tract infection, pneumonia, pyelonephritis, meningitis) within 4 weeks prior to Day 1.
  • Has contraindications for IT administration of the product or for lumbar puncture, such as anatomical abnormalities, bleeding disorders or other medical conditions (eg, spina bifida, meningitis, or significant clotting abnormalities).
  • Demonstrates cognitive or developmental delay or impairment that could confound assessment of motor development in the opinion of the Investigator.
  • Total serum anti-AAV9 antibody titers of > 1:50 as determined by ELISA within 14 days of Day 1.

Note: Other inclusion/exclusion criteria may apply.

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: Non-Randomized
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Part 1: Cohort 1
Participants aged 3 to <5 years will receive a single dose level 1 of INS1201 by IT injection on Day 1.
Genetic: INS1201
Suspension for IT injection.
Experimental: Part 1: Cohort 2
Participants aged 3 to <5 years will receive a single dose level 2 of INS1201 by IT injection on Day 1.
Genetic: INS1201
Suspension for IT injection.
Experimental: Part 2: Cohort 3
Participants aged 2 to <3 years will receive a single dose level 1 of INS1201 by IT injection on Day 1.
Genetic: INS1201
Suspension for IT injection.
Experimental: Part 2: Cohort 4
Participants aged 2 to <3 years will receive a single dose level 2 of INS1201 by IT injection on Day 1.
Genetic: INS1201
Suspension for IT injection.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Parts 1 and 2: Incidence and Severity of Treatment Emergent Adverse Events (TEAEs)
Time Frame: Up to Week 96
Up to Week 96

Secondary Outcome Measures

Outcome Measure
Time Frame
Parts 1 and 2: Recommended Phase 2 Dose (RP2D) of INS1201
Time Frame: Week 16
Week 16
Parts 1 and 2: Change From Baseline in Quantity of Micro-Dystrophin Deoxyribonucleic Acid (DNA) as Measured by Droplet Digital Polymerase Chain Reaction (ddPCR) at Weeks 16 and 48
Time Frame: Baseline, Weeks 16 and 48
Baseline, Weeks 16 and 48
Parts 1 and 2: Change From Baseline in Micro-Dystrophin Protein Expression as Measured by Quantitative Protein Analysis at Weeks 16 and 48
Time Frame: Baseline, Weeks 16 and 48
Baseline, Weeks 16 and 48

Collaborators and Investigators

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

Sponsor

Insmed Gene Therapy LLC

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)

July 22, 2025

Primary Completion (Estimated)

January 31, 2028

Study Completion (Estimated)

March 31, 2028

Study Registration Dates

First Submitted

February 4, 2025

First Submitted That Met QC Criteria

February 4, 2025

First Posted (Actual)

February 10, 2025

Study Record Updates

Last Update Posted (Actual)

June 11, 2026

Last Update Submitted That Met QC Criteria

June 10, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • INS1201-101

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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