Global Study of Del-desiran for the Treatment of DM1 (HARBOR)

January 20, 2026 updated by: Avidity Biosciences, Inc.

A Phase 3 Randomized, Double-Blind, Placebo-Controlled, Global Study to Evaluate the Efficacy and Safety of Intravenous AOC 1001 for the Treatment of Myotonic Dystrophy Type 1

A Phase 3 Randomized, Double-Blind, Placebo-Controlled, Global Study to Evaluate the Efficacy and Safety of Intravenous Delpacibart Etedesiran (abbreviated del-desiran, formerly AOC 1001) for the Treatment of Myotonic Dystrophy Type 1

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

The study consists of a Screening Period of up to 6 weeks and 54-week Treatment Period. The anticipated duration is approximately 60 weeks.

Participants will be randomized to receive an intravenous infusion of either del-desiran or placebo at the clinical study site every 8 weeks for a total of 7 doses. The final dose will occur at Week 48, followed by a final assessment at Week 54.

After completion of Week 54 assessments, eligible participants will have the option to enroll into an open label extension (OLE) study, pending regulatory approval.

An Independent Data Monitoring Committee (IDMC) comprised of members independent and external to the Sponsor will review safety, tolerability, and efficacy (as needed) data of this study at regular intervals.

Study Type

Interventional

Enrollment (Actual)

159

Phase

  • 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 Locations

  • Canada
    • Ontario
      • Ottawa, Ontario, Canada, K1Y 4E9
        • The Ottawa Hospital
    • Quebec
      • Montreal, Quebec, Canada, H3A 2B4
        • Montreal Neurological Institute
  • Denmark
      • Aarhus N, Denmark, 8200
        • Aarhus University Hospital
      • Copenhagen, Denmark, 2100
        • Rigshospitalet
  • France
      • Paris, France, 75013
        • AP-HP Hopital Pitie-Salpetriere
  • Germany
      • Munich, Germany, 80336
        • Klinikum der Ludwig-Maximilians-Universitaet Muenchen
  • Italy
      • Milan, Italy, 20162
        • Fondazione Serena Onlus - Centro Clinico NeMO Milano
  • Japan
      • Osaka, Japan, 565-0871
        • Osaka University Hospital
      • Osaka, Japan, 560-8552
        • National Hospital Organization Osaka Toneyama Medical Center
      • Tokyo, Japan, 187-8551
        • National Center of Neurology and Psychiatry
    • Aomori
      • Aomori, Aomori, Japan, 038-1331
        • Aomori Hospital
  • Netherlands
      • Maastricht, Netherlands, 6229 HX
        • Maastricht University Medical Center
      • Nijmegen, Netherlands, 6525 GA
        • Stichting Radboud Universitair Medisch Centrum
  • Spain
      • Donostia / San Sebastian, Spain, 20014
        • Hospital Universitario Donostia
  • United Kingdom
      • London, United Kingdom, NW1 2BU
        • University College London Hospital
      • London, United Kingdom, SW17 0QT
        • St. Georges University Hospitals NHS Foundation Trust
  • United States
    • California
      • Stanford, California, United States, 94305
        • Stanford University
    • Colorado
      • Denver, Colorado, United States, 80045
        • University of Colorado
    • Florida
      • Gainesville, Florida, United States, 32608
        • University of Florida
      • Tampa, Florida, United States, 33612
        • University Research Center of South Florida
    • Indiana
      • Indianapolis, Indiana, United States, 46202
        • Indiana University (IU)
    • Kansas
      • Kansas City, Kansas, United States, 66205
        • Kansas University Medical Center
    • Maryland
      • Baltimore, Maryland, United States, 21205
        • Kennedy Krieger Institute
    • Massachusetts
      • Boston, Massachusetts, United States, 02215
        • Beth Israel Deaconess Medical Center
    • Minnesota
      • Minneapolis, Minnesota, United States, 55455
        • University of Minnesota
    • New York
      • Rochester, New York, United States, 14642
        • University of Rochester Medical Center
    • North Carolina
      • Durham, North Carolina, United States, 27708
        • Duke University Medical Center
      • Winston-Salem, North Carolina, United States, 27157
        • Wake Forest
    • Ohio
      • Cincinnati, Ohio, United States, 45219
        • University of Cincinnati Gardner Neuroscience Institute
      • Columbus, Ohio, United States, 43221
        • Ohio State University
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19104
        • University of Pennsylvania
    • Texas
      • Houston, Texas, United States, 77030
        • Houston Methodist Neurological Institute
    • Virginia
      • Richmond, Virginia, United States, 23298
        • Virginia Commonwealth University
    • Washington
      • Seattle, Washington, United States, 98104
        • University of Washington

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
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Key Inclusion Criteria:

  • Clinical and genetic diagnosis (CTG repeat ≥ 100) of DM1
  • Ability to walk independently (orthoses and ankle braces allowed) for at least 10 meters at screening

Key Exclusion Criteria:

  • Breastfeeding, pregnancy, or intent to become pregnant during the study
  • Unwilling or unable to comply with contraceptive requirements
  • Abnormal lab values, conditions or diseases that would make the participant unsuitable for the study
  • Diabetes that is not adequately controlled
  • History of decompensated heart failure within 3 months of screening. Participants with preexisting pacemaker/ICD are not excluded.
  • Body Mass Index > 35 kg/m2 at Screening
  • Recently treated with an investigational drug or biological agent
  • Treatment with anti-myotonic medication within 5 half-lives or 14 days of baseline, whichever is longer, prior to baseline.

Note: Additional protocol defined Inclusion and Exclusion criteria 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: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Del-desiran
Del-desiran (AOC 1001) will be administered seven times
Drug: AOC 1001 (del-desiran)
Del-desiran will be administered by intravenous (IV) infusion.
Placebo Comparator: Placebo
Saline will be administered seven times
Drug: Placebo
Placebo will be administered by intravenous (IV) infusion.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Hand function
Time Frame: Through Week 54
video Hand Opening Time (vHOT)
Through Week 54

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Hand grip strength
Time Frame: Through Week 54
by dynamometer
Through Week 54
Quantitative Muscle Testing composite score
Time Frame: Through Week 54
by dynamometer
Through Week 54
Myotonic Dystrophy Type 1 activity and participation scale c
Time Frame: Through Week 54
Through Week 54
10-Meter Walk/Run Test
Time Frame: Through Week 54
Time (in seconds) to walk or run 10 meters
Through Week 54

Collaborators and Investigators

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

Sponsor

Avidity Biosciences, Inc.

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.

Helpful Links

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)

May 30, 2024

Primary Completion (Estimated)

August 1, 2026

Study Completion (Estimated)

September 1, 2026

Study Registration Dates

First Submitted

May 8, 2024

First Submitted That Met QC Criteria

May 8, 2024

First Posted (Actual)

May 13, 2024

Study Record Updates

Last Update Posted (Actual)

January 22, 2026

Last Update Submitted That Met QC Criteria

January 20, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • AOC 1001-CS3

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

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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