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A study to evaluate the efficacy and safety of DYNE-101 in patients with Myotonic Dystrophy Type 1

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What is this study about?

This study focuses on Myotonic Dystrophy Type 1, a condition that affects the muscles. The purpose of the study is to evaluate the efficacy of DYNE-101 compared with a placebo. DYNE-101 is an investigational medicine that uses an antibody, which is a type of protein that can target specific parts of the body, attached to an oligonucleotide, a small piece of genetic material. This medication is delivered through intravenous use, meaning it is administered directly into a vein via an infusion.

During the study, participants will receive either the active medication or a placebo. The treatment lasts for 48 weeks. While receiving the treatment, various observations will be made to monitor how the body responds and to check for any adverse events, which are unwanted or harmful medical occurrences. Monitoring includes checking vital signs, such as heart rate and blood pressure, and performing an electrocardiogram to check the electrical activity of the heart.

Who Can Join the Study?

  • You must be between 16 and 65 years old at the time of joining the study.
  • If you take testosterone (a hormone used in certain treatments), your dose must have remained the same for at least 30 days before the study begins.
  • You must agree to use highly effective contraception (methods used to prevent pregnancy) as directed by the study rules.
  • You must be able to provide informed consent, which means you understand the study and officially agree to participate while allowing the use of your private health information.
  • You must be willing and able to attend all scheduled study visits, take the medication as planned, and complete all required health checks.
  • You must have a confirmed diagnosis of Myotonic Dystrophy Type 1 (DM1) through molecular genetics (a test that looks at your DNA) showing a specific genetic marker called a trinucleotide repeat size greater than 100.
  • You must show signs of myotonia, which is a condition where muscles are slow to relax after a contraction, specifically measured by taking at least 3 seconds to open your hand.
  • Your hand grip strength must be between 15% and 85% of what is considered normal for a healthy person.
  • You must be able to complete the 5×STS test (a test where you stand up from a chair five times) in 8 seconds or more without using walking aids like canes or walkers.
  • You must be able to complete the 10-MWRT (a walking test) and the 5×STS (the chair stand test) without using walking aids, though small supports like ankle braces that do not go above the ankle bone are allowed.
  • Your Body Mass Index (BMI), which is a measure of your weight relative to your height, must be less than 35kg/m2.

Who Cannot Join the Study?

  • Any medical condition, medical history, physical findings, or laboratory abnormalities (unusual results from medical tests) that the study doctor believes could affect your safety, make it difficult to follow the study schedule, or make it hard to understand the results of the study.
  • Any medical condition other than Myotonic Dystrophy Type 1 (DM1) that would significantly affect your ability to walk or participate in tests that measure how your body functions.
  • Uncontrolled diabetes mellitus (blood sugar that is not being managed properly) or any other serious illness that could make it difficult to see if the study treatment is safe or working.
  • Use of GLP-1 agonist/incretin medications, such as semaglutide, dulaglutide, liraglutide, exenatide, or tirzepatide, within 5 half-lives (the time it takes for the amount of medicine in your body to reduce by half) of your screening tests.
  • A history or presence of certain heart rhythm problems, such as second- or third-degree heart block, ventricular arrhythmias (irregular heartbeats starting in the lower chambers of the heart), or specific ECG (an electrical test of the heart) results like a QTcF or PR interval that is too long, or a left bundle-branch block (a delay in the heart’s electrical signal), unless you have a pacemaker or defibrillator (devices implanted to control heart rhythm) that was put in more than 2 weeks ago.
  • Known structural heart disease (physical changes to the heart’s shape or parts), evidence of noncompaction cardiomyopathy (a condition where the heart muscle is abnormally shaped), or a left ventricular ejection fraction (a measurement of how much blood the heart pumps out with each beat) of less than 40%.
  • A history of suicide attempts, suicidal behavior, or suicidal ideation (thoughts about wanting to die) within the last 6 months that meets specific severity levels or if the doctor believes there is a significant risk.
  • Treatment with medications that can improve myotonia (muscle stiffness) or muscle function, such as mexiletine, phenytoin, carbamazepine, procainamide, disopyramide, ranolazine, flecainide, lamotrigine, nifedipine, acetazolamide, clomipramine, imipramine, amitriptyline, taurine, or quinine, within 5 half-lives of those medicines.
  • Current treatment with systemic immunosuppressive therapy (medicines that lower your body’s ability to fight infections).
  • A known diagnosis of congenital DM1 (a form of the disease present from birth).
  • A history of major surgical procedure within the last 12 weeks, unless it was for a pacemaker or defibrillator, or if you are expected to have a major surgery during the study period.
  • Persistent systolic blood pressure (the pressure in your arteries when your heart beats) lower than 90 mm Hg, or signs of hypotension (low blood pressure) or volume depletion/dehydration (not having enough fluid in your body).
  • A history of DVT (blood clots in the deep veins, usually the legs) or PE (blood clots in the lungs) within the last 5 years.
  • A history of significant liver disease, ongoing treatment for liver disease, or confirmed high ALT (a type of liver enzyme measured in blood tests) levels.
  • A history of significant hematologic disease (disorders of the blood) or blood test results showing low platelets (cells that help blood clot) or low hemoglobin (a protein in red blood cells that carries oxygen) for your age and sex.
  • A history of significant kidney disease, ongoing treatment for kidney disease, or an eGFR (a calculation of how well your kidneys filter blood) of less than 60 mL/min.
  • Acute kidney injury (sudden damage to the kidneys) within 12 weeks of screening, shown by an increase in serum creatinine (a waste product measured in the blood to check kidney function).
  • Hematuria (blood in the urine) greater than 5 red blood cells per high power field during a urinalysis (urine test) at screening.
  • The inability to follow physical activity rules, such as abstaining from strenuous exercise (avoiding very hard physical activity), from screening until the end of the study period.
  • Being pregnant, breastfeeding, or planning to become pregnant during the study.
  • Use of nephrotoxic medications (medicines that can damage the kidneys), such as NSAIDs (common pain relievers), aminoglycosides (certain antibiotics), bisphosphonates (bone medications), or antiviral agents, within 5 half-lives of those medicines, or needing medical procedures that use contrast (a special dye used in imaging).
  • Any active malignancy (cancer) or a history of cancer within the last 5 years, except for certain types of skin cancer that were successfully removed and cured at least 1 year ago.
  • Having received gene therapy, another investigational drug (a drug being tested in studies), or a biologic agent within 5 half-lives of that agent or within 4 months of screening, unless it was an oligonucleotide therapy (a type of genetic medicine) received at least 3 years ago.
  • A forced vital capacity (FVC) (the total amount of air you can exhale) of less than 50% while sitting.
  • Recent physical inactivity, such as being unable to move for 3 or more days, if the doctor believes this would make it hard to follow study rules.
  • The inability to undergo venipuncture (the process of using a needle to draw blood) successfully or tolerate having access to your veins.
  • The inability or impaired ability to finish the study procedures or complete the study due to physical or cognitive impairment (problems with body movement or thinking/understanding) or illicit drug or alcohol abuse.

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name City Country Status
Fondazione Policlinico Universitario Agostino Gemelli IRCCS Rome Italy
Universitaetsmedizin Goettingen Goettingen Germany
University Hospital Maastricht Maastricht The Netherlands
Oncopole Claudius Regaud Toulouse France
Katholieke Universiteit te Leuven Leuven Belgium

Other Sites

Site Name City Country Status
Azienda Ospedaliero-Universitaria Sant Andre Rome Italy
Hospital Universitario Infanta Sofía San Sebastian De Los Reyes Spain
Charite Universitaetsmedizin Berlin KöR Berlin Germany
Stichting Radboud University Medical Center Nijmegen The Netherlands
Rheinische Friedrich-Wilhelms-Universitaet Bonn Bonn Germany
Centre Hospitalier Universitaire De Nantes Nantes France
Region Midtjylland Aarhus Denmark
Rigshospitalet Copenhagen Denmark
Hopital Beaujon Clichy France
Hospital Universitario 12 De Octubre Madrid Spain
Cctetl Ckjlxem Nnsx Milan Italy
Azupzununf Pqcydswe Hqrhzblh Dh Mzlnzznvj Marseille France
Azrjhqd Obwqqbyuaab Uxvoeycisgyua Cnyfnsslnqqi Dfuua Skucuz E Dtklk Ssshrpo Ds Tnznnm Turin Italy
Hlhqjkqr Uacmhxgpnhsft Dhjbqpde Donostia / San Sebastian Spain
Kiveldtm dcx Uaumhnmrpdzo Mjwhqcsn Aro Munich Germany
Uhdcwlbdzw Oq Advnvap Edegem Belgium
Hfgyjcur Vjri dxrkfrsm Barcelona Spain

Want to learn more about this study or check if you can participate? Contact us.

Trial status

Country Status Recruitment Start
Belgium Belgium
Not yet recruiting
30.04.2026
Denmark Denmark
Not yet recruiting
30.04.2026
France France
Not yet recruiting
30.04.2026
Germany Germany
Not yet recruiting
30.04.2026
Italy Italy
Not yet recruiting
30.04.2026
Spain Spain
Recruiting
30.04.2026
The Netherlands The Netherlands
Not yet recruiting
30.04.2026

Trial locations

Investigated drugs:

DYNE-101 is an experimental treatment given through an IV infusion. It is designed to target a specific protein to help deliver genetic material into cells, with the goal of treating the underlying causes of Myotonic Dystrophy Type 1 and improving muscle function.

Investigated diseases:

Myotonic Dystrophy Type 1 – This is a genetic disorder that primarily affects the muscles. It is characterized by myotonia, which is the inability of muscles to relax quickly after a contraction. Over time, the condition leads to progressive muscle weakness and wasting in various parts of the body. It can also involve other systems, such as the nervous system and the heart. The symptoms typically worsen as the disease advances.

Trial ID:
2025-522957-20-00
Protocol code:
DYNE101-DM1-301
Trial Phase:
Therapeutic confirmatory (Phase III)

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