A Phase 1/2 interventional study of SAR446268 in Myotonic Dystrophy, sponsored by Sanofi. Recruiting at 10 sites in 6 countries. Open to participants aged 10 Years to 55 Years. Per ClinicalTrials.gov, last updated 2026-09-21.
Sponsored by Sanofi · Phase 1/2, Interventional, and Treatment
This is a Phase 1/Phase 2 open-label single arm, multicenter, and multinational study with SAR446268 for treatment of male and female participants 10 to 55 years old with non-congenital myotonic dystrophy (DM) type 1 (DM1).
The purpose of this study is to evaluate the safety and efficacy of SAR446268 in knocking down dystrophia myotonica protein kinase (DMPK) messenger ribonucleic acid (mRNA) levels and improving neuromuscular function in DM1 participants receiving a single intravenous (IV) administration of SAR446268. The study consists of a dose escalation part (Part A) during which single ascending doses of SAR446268 will be evaluated in 3 distinct cohorts and an optional fourth dose cohort. Once a safe and effective dose is identified, additional participants will be treated in Part B, the dose expansion phase of the study.
The study duration will be 112 weeks (approximately 2 years) for each participant in Parts A and B respectively and includes an optional pre-screening period, approximately 8-week screening phase and a 104-week follow-up period post-SAR446268 administration.
Each participant meeting the eligibility criteria for each of the study parts will receive a single dose administration of SAR446268.
126 studies on the registry are indexed under Myotonic Dystrophy; 50 are open to participants now.
This study's planned enrollment of 32 is below the median of 40 across 67 interventional studies indexed under Myotonic Dystrophy.
Browse Myotonic Dystrophy studies →Sanofi is the lead sponsor of 1,557 studies on the registry; 91 are open to participants now.
Of its 205 completed or terminated interventional studies of FDA-regulated products, 123 (60%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Participants are eligible to be included in the study only if all of the following criteria apply:
For Part B, participants must be as follows:
Exclusion Criteria:
Participants are excluded from the study if any of the following criteria apply:
Participants with liver or biliary disease defined as having at least one of the following:
Participants with renal disease defined as:
The above information is not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.
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.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
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.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
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.
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.
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.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
LVEF (left ventricular ejection fraction)
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
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.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
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.
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.
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.
Participants will receive a single dose of SAR446268 on Day 1
Biological: SAR446268
Pharmaceutical form: Solution for infusion; Route of administration: IV infusion
Part A and Part B: Incidence of treatment-emergent adverse events (TEAEs) following SAR446268 administration
Number of TEAEs post-SAR446268 administration
Time frame: Baseline to Week 52
Part B: Proportion of participants with at least 40% DMPK mRNA knockdown in muscle biopsy at Weeks 12 and 52 following SAR446268 administration
Time frame: Weeks 12 and 52
Part A: Change in 10-meter walk-run test from baseline to Weeks 26 and 52 following SAR446268 administration
The 10-meter walk-run test is a mobility test that measures how fast a participant can traverse 10 meters with or without assisted devices.
Time frame: Baseline to Week 26 and 52
Part A: Change in myotonia from baseline to Weeks 26 and 52 following SAR446268 administration as measured by the hand opening time (middle finger)
This test for myotonia measures how quickly a participant can open his/her hand after making a tight fist.
Time frame: Baseline to Week 26 and 52
Part A: Change in bilateral hand grip test from baseline to Weeks 26 and 52 following SAR446268 administration
This test for strength of the hand muscles measures the maximum force generated by a participant's hand grip using a dynamometer.
Time frame: Baseline to Week 26 and 52
Part A: Proportion of participants with at least 40% DMPK mRNA knockdown in muscle biopsy at Weeks 12 and 52 following SAR446268 administration
Time frame: Weeks 12 and 52
Part A: Change in DMPK mRNA levels in muscle biopsy from baseline to Weeks 12 and 52 following SAR446268 administration
Time frame: Baseline to Week 12 and 52
Part A: Change in RNA splicing index in muscle biopsy from baseline to Weeks 12 and 52 following SAR446268 administration
Time frame: Baseline to Week 12 and 52
Part A: Assessment of the duration of AAV vector shedding of SAR446268 in sampling of urine, saliva, and semen at 4-week intervals following SAR446268 administration
Time frame: Baseline, Weeks 4, 8, and 12
Part B: Change in 10-meter walk-run test from baseline to Weeks 26 and 52 following SAR446268 administration
The 10-meter walk-run test is a mobility test that measures how fast a participant can traverse 10 meters with or without assisted devices.
Time frame: Baseline to Week 26 and 52
Part B: Change in myotonia from baseline to Weeks 26 and 52 following SAR446268 administration as measured by the hand opening time (middle finger)
This test for myotonia measures how quickly a participant can open his/her hand after making a tight fist.
Time frame: Baseline to Week 26 and 52
Part B: Change in bilateral hand grip test from baseline to Weeks 26 and 52 following SAR446268 administration
This test for strength of the hand muscles measures the maximum force generated by a participant's hand grip using a dynamometer.
Time frame: Baseline to Week 26 and 52
Part B: Change in DMPK mRNA knockdown in muscle biopsy from baseline to Weeks 12 and 52 following SAR446268 administration
Time frame: Baseline to Week 12 and 52
Part B: Change in RNA splicing index in muscle biopsy from baseline to Weeks 12 and 52 following SAR446268 administration
Time frame: Baseline to Week 12 and 52
Part B: Assessment of the duration of AAV shedding of SAR446268 in sampling of urine, saliva, and semen at 4-week intervals following SAR446268 administration
Time frame: Baseline, Weeks 4, 8, and 12
Plan to share: Yes — Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org
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