A Phase 1/2 interventional study of SRP-1003 IV Infusion and Placebo IV Infusion in Myotonic Dystrophy 1, sponsored by Sarepta Therapeutics, Inc.. Enrolling by invitation at 35 sites in 11 countries. Open to participants aged 18 Years to 65 Years. Per ClinicalTrials.gov, last updated 2026-10-05.
Sponsored by Sarepta Therapeutics, Inc. · Phase 1/2, Interventional, and Treatment
This is a phase 1/2a double-blinded, placebo-controlled, dose-escalating study to evaluate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics of single and multiple ascending doses of SRP-1003 compared to placebo in male and female participants with type 1 myotonic dystrophy (DM1). Participants who have provided written informed consent and met all protocol eligibility requirements will be randomized to receive single (Part 1) or multiple (Part 2) doses of SRP-1003 or placebo.
126 studies on the registry are indexed under Myotonic Dystrophy; 50 are open to participants now.
This study's planned enrollment of 78 is above the median of 40 across 67 interventional studies indexed under Myotonic Dystrophy.
Browse Myotonic Dystrophy studies →Sarepta Therapeutics, Inc. is the lead sponsor of 52 studies on the registry; 8 are open to participants now.
Of its 21 completed or terminated interventional studies of FDA-regulated products, 12 (57%) have results posted.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
Key Exclusion Criteria:
Note: Additional inclusion/exclusion criteria may apply per protocol
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Biopsy and archival tissue
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
INR, PT and aPTT (clotting tests)
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Single or multiple doses of SRP-1003 by intravenous (IV) infusion
Drug: SRP-1003 IV Infusion
Single or multiple doses of placebo by IV infusion
Drug: Placebo IV Infusion
Single or multiple doses of SRP-1003 by subcutaneous (SC) injection
Drug: SRP-1003 SC Injection
Single or multiple doses of placebo by SC injection
Drug: Placebo SC Injection
SRP-1003 by IV infusion
Also known as: ARO-DM1 IV Infusion
0.9% sodium chloride (NaCl) calculated volume to match active treatment by IV infusion
SRP-1003 by SC injection(s)
Also known as: ARO-DM1 SC Injection
0.9% NaCl calculated volume to match active treatment by SC injection(s)
Number of Participants with Treatment-emergent Adverse Events Over Time Through End of Study (EOS)
Time frame: Single-dose phase (Part 1): Up to Day 90 (EOS); multiple-dose phase (Part 2): Up to Day 180 (EOS)
PK of SRP-1003: Maximum Observed Plasma Concentration (Cmax)
Time frame: Single-dose phase (Part 1): Up 24 hours post-dose; multiple-dose phase (Part 2): Through 24 hours post first and second dose
PK of SRP-1003: Area Under the Plasma Concentration Versus Time Curve from Zero to 24 Hours (AUC0-24)
Time frame: Single-dose phase (Part 1): Up 24 hours post-dose; multiple-dose phase (Part 2): Through 24 hours post first and second dose
PK of SRP-1003: Area Under the Plasma Concentration Versus Time Curve from Zero to the Last Quantifiable Plasma Concentration (AUClast)
Time frame: Single-dose phase (Part 1): Up 24 hours post-dose; multiple-dose phase (Part 2): Through 24 hours post first and second dose
PK of SRP-1003: Area Under the Plasma Concentration Versus Time Curve from Zero to Infinity (AUCinf)
Time frame: Single-dose phase (Part 1): Up 24 hours post-dose; multiple-dose phase (Part 2): Through 24 hours post first and second dose
Change from Baseline at Day 120 for Video Hand Opening Time (vHOT)
Time frame: (Part 2): Baseline, Day 120
Change from Baseline Over Time for the Timed Up and Go Test (TUG) Assessment
Time frame: (Part 2): Baseline through EOS (up to 180 days)
Change from Baseline Over Time for the 10-Meter Walk/Run Test (10MWT) Assessment
Time frame: (Part 2): Baseline through EOS (up to 180 days)
Change from Baseline Over Time for the Hand-held Quantitative Dynamometry Assessment
Time frame: (Part 2): Baseline through EOS (up to 180 days)
Change from Baseline Over Time for the Video Hand Opening Time (vHOT) Assessment
Time frame: (Part 2): Baseline through EOS (up to 180 days)
Change from Baseline Over Time for the Myotonic Dystrophy Type 1 Activity and Participation Scale (DM1-Activ-C) Assessment
Time frame: (Part 2): Baseline through EOS (up to 180 days)
Change from Baseline Over Time for the Myotonic Dystrophy Health Index (MDHI) Assessment
Time frame: (Part 2): Baseline through EOS (up to 180 days)
Plan to share: No
No publications or documents are linked to this record.
Started Mar 2024 (actual). Primary completion is estimated for Dec 2026, 33 months after the start.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
No contact was published for this record. The registry link below has the sponsor’s details.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.