Duchenne Muscular Dystrophy (DMD)Phase 2NCT07573631
An Open-Label Extension Study to Evaluate the Long-term Safety and Efficacy of BMN 351 in Participants With Duchenne Muscular Dystrophy
A Phase 2 study testing BMN 351 in people with Duchenne Muscular Dystrophy (DMD), run by BioMarin Pharmaceutical at 6 sites in 5 countries.
Trial summary
This open-label extension study aims to evaluate the long-term safety and tolerability of weekly BMN 351 infusions, as well as to assess the effect of BMN 351 on physical function, in participants with DMD who participated in the 351-201 study. Read more about this study
- Who is it for?
- Ages 4 years and older, men only
- Conditions the study is for
- Duchenne Muscular Dystrophy (DMD)
- What is being tested?
- BMN 351
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 18 participants
- Where
- 6 sitesin 5 countries
- Study dates
- 20 Apr 2026to Dec 2031
- Phase
- Phase 2
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 4 years and older
- Men only
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- Participants must have completed 351-201 without permanent discontinuation of the investigational medicinal product (IMP) or withdrawal from the study
- Currently receiving treatment with oral corticosteroids, on a stable dose regimen during 351-201, and must remain on a consistent dose regimen throughout 351-202 or 351-203 except for modifications to accommodate changes in weight
- Transition to the equivalent dose of vamorolone is permitted in 351-202 where approved in participating countries.
- Willing and able to adhere to the study visit schedule and other protocol requirements
- Willing to use contraception (sexually mature males) throughout the study and for 90 days after the final dose, if sexually active
- Contraceptive use by males should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.
- Willing and able to provide written assent (if required by local regulations or the IRB/IEC) after the nature of the study has been explained and prior to performance of any research-related procedure
- Willing and able to provide written, signed informed consent as parent or guardian after the nature of the study has been explained and prior to performance of any research-related procedure
Who cannot join
- Have known coagulation disorder
- Are taking any prohibited medications
- any approved exon skipping therapy within 12 weeks prior to baseline or with any gene therapy for the treatment of DMD at any time
- anti-coagulants, anti-thrombotics, or anti-platelet agents
- immunosuppressants
Trial locations and contacts
6 sites in 5 countries. Contact the study team or a site near you to ask about taking part.
6 sites in 5 countries
Italy2 sites
Fondazione Serena ETS - Centro Clinico NeMO Milano
Milan, Italy
UOC Fase I - Fondazione Policlinico Universitario A. Gemelli IRCCS - Universita Cattolica del Sacro Cuore
Rome, Italy
Netherlands1 site
Leids Universitair Medisch Centrum
Leiden, Netherlands, 2333 ZA
Turkey (Türkiye)1 site
Yeditepe University Kosuyolu Hospital
Istanbul, Turkey
United Kingdom1 site
Great Ormond Street Hospital NHS Foundation Trust
London, United Kingdom, WC1N 3JH
About this study
Official title: An Open-Label Extension Study to Evaluate the Long-term Safety and Efficacy of Weekly Intravenous Infusions of BMN 351 in Participants With Duchenne Muscular Dystrophy Amenable to Exon 51 Skipping
This open-label extension study aims to evaluate the long-term safety and tolerability of weekly BMN 351 infusions, as well as to assess the effect of BMN 351 on physical function, in participants with DMD who participated in the 351-201 study.
Read the detailed description
This Phase 2, multi-center, open-label extension study is designed to assess the long-term safety, tolerability, and functional efficacy of weekly intravenous doses of BMN 351 administered to participants with Duchenne muscular dystrophy (DMD) amenable to exon 51 skipping in the Phase 1/2 study, 351-201. Up to 18 participants ages 4 through 23 at baseline will enroll in the trial after completing 351-201.
The first visit for this study is the same as the final visit of 351-201. To be eligible for this study, potential participants must satisfy the eligibility criteria described in the protocol.
- Conditions
- Duchenne Muscular Dystrophy (DMD)
- Being tested
- BMN 351
- Medical subject headings
- Muscular Dystrophy, Duchenne
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
BMN 351Drug
Anti-sense Oligonucleotide BMN 351 will be administered intravenously
| Study group | Role | What they receive |
|---|---|---|
| BMN 351 | Experimental | Participants from 351-201 enrolling in 351-202 will initially receive BMN 351 at the dose level at which they completed 351-201. Once all 351-201 participants have completed their Week 25 visit in 351-202, available safety and PD data will be analyzed and a single optimal dose level will be selected for 351-202. All participants from 351-201 will transition to that dose level at their next applicable visit. Receives: Drug: BMN 351 |
What is being measured
The primary outcome is the main question the study is designed to answer.
To assess the long-term safety and tolerability of BMN 351 in participants with DMD
The safety and tolerability of BMN 351 will be assessed based on the incidence of adverse and serious adverse events.
Measured: Through study completion, at least 1 year
Secondary outcomes (4)
To evaluate the effect of BMN 351 on physical function
North Star Ambulatory Assessment (NSAA) will be assessed at the specific visits and compared to individual baseline and external controls
Measured: Change from baseline and subsequent 24-week incremental visits
To evaluate the effect of BMN 351 on physical function
Timed 4 stair climb (4SC) will be assessed at the specified visits and compared to individual baseline and external controls
Measured: Change from baseline and subsequent 24-week incremental visits
To evaluate the effect of BMN 351 on physical function
SV95C will be assessed at the specified visits and compared to individual baseline and external controls
Measured: Change from baseline and subsequent 24-week incremental visits
To evaluate the effect of BMN 351 on physical function
PUL 2.0 will be assessed at the specified visits and compared to individual baseline and external controls
Measured: Change from baseline and subsequent 24-week incremental visits
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 May 2026
- Study start20 Apr 2026
- Primary completionDec 2031 (estimated)
- Study completionDec 2031 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Duchenne Muscular Dystrophy (DMD)Studies of the same condition, open and under way.
- More trials run by BioMarin PharmaceuticalThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Open-Label Extension study available to eligible participants from the 351-201 study
- Masking
- None (open label)
- Enrolment
- 18 participants (estimated)
Sponsor and investigators
- Lead sponsor
- BioMarin Pharmaceutical
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07573631
- Sponsor's protocol ID
- 351-202
- Other IDs
- 2024-511656-41-00
- Status last verified
- Jul 2026
- First submitted
- 17 Apr 2026
- Last updated
- 24 Jul 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 24 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- An Open-Label Extension Study to Evaluate the Long-term Safety and Efficacy of Weekly Intravenous Infusions of BMN 351 in Participants With Duchenne Muscular Dystrophy Amenable to Exon 51 Skipping
- ClinicalTrials.gov ID
- NCT07573631
- Acronym / sponsor ID
- 351-202
- Conditions
- Duchenne Muscular Dystrophy (DMD)
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Enrolling by invitation
- Enrolment
- 18 participants (estimated)
- Lead sponsor
- BioMarin PharmaceuticalIndustry (pharma, biotech, devices)
- Study start
- 20 Apr 2026 (actual)
- Primary completion
- Dec 2031 (estimated)
- Study completion
- Dec 2031 (estimated)
- First posted
- 7 May 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This open-label extension study aims to evaluate the long-term safety and tolerability of weekly BMN 351 infusions, as well as to assess the effect of BMN 351 on physical function, in participants with DMD who participated in the 351-201 study.
Detailed description
This Phase 2, multi-center, open-label extension study is designed to assess the long-term safety, tolerability, and functional efficacy of weekly intravenous doses of BMN 351 administered to participants with Duchenne muscular dystrophy (DMD) amenable to exon 51 skipping in the Phase 1/2 study, 351-201. Up to 18 participants ages 4 through 23 at baseline will enroll in the trial after completing 351-201.
The first visit for this study is the same as the final visit of 351-201. To be eligible for this study, potential participants must satisfy the eligibility criteria described in the protocol.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Open-Label Extension study available to eligible participants from the 351-201 study
| Arm | Type | Receives |
|---|---|---|
| BMN 351 | Experimental | Drug: BMN 351Participants from 351-201 enrolling in 351-202 will initially receive BMN 351 at the dose level at which they completed 351-201. Once all 351-201 participants have completed their Week 25 visit in 351-202, available safety and PD data will be analyzed and a single optimal dose level will be selected for 351-202. All participants from 351-201 will transition to that dose level at their next applicable visit. |
Who may qualify
- Ages
- 4 years and older
- Sex
- Male only
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (8 listed)
- Participants must have completed 351-201 without permanent discontinuation of the investigational medicinal product (IMP) or withdrawal from the study
- Currently receiving treatment with oral corticosteroids, on a stable dose regimen during 351-201, and must remain on a consistent dose regimen throughout 351-202 or 351-203 except for modifications to accommodate changes in weight
- Willing and able to adhere to the study visit schedule and other protocol requirements
- Willing to use contraception (sexually mature males) throughout the study and for 90 days after the final dose, if sexually active
- Willing and able to provide written assent (if required by local regulations or the IRB/IEC) after the nature of the study has been explained and prior to performance of any research-related procedure
Key exclusion criteria (5 listed)
- Have known coagulation disorder
- Are taking any prohibited medications
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| BMN 351Anti-sense Oligonucleotide BMN 351 will be administered intravenously | Drug | BMN 351 |
Primary outcome
To assess the long-term safety and tolerability of BMN 351 in participants with DMD
Time frame: Through study completion, at least 1 year
The safety and tolerability of BMN 351 will be assessed based on the incidence of adverse and serious adverse events.
4 secondary outcomes
To evaluate the effect of BMN 351 on physical function
Time frame: Change from baseline and subsequent 24-week incremental visits
To evaluate the effect of BMN 351 on physical function
Time frame: Change from baseline and subsequent 24-week incremental visits
To evaluate the effect of BMN 351 on physical function
Time frame: Change from baseline and subsequent 24-week incremental visits
To evaluate the effect of BMN 351 on physical function
Time frame: Change from baseline and subsequent 24-week incremental visits
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Jul 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
The record lists no contact. Use the official record to reach the sponsor.
6 sites in 5 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing BMN 351 in people with Duchenne Muscular Dystrophy (DMD), run by BioMarin Pharmaceutical at 6 sites in 5 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 8 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: enrolling by invitation, as of the sponsor's last update on 24 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 6 sites in Italy, Netherlands, Spain, Turkey (Türkiye), United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
To assess the long-term safety and tolerability of BMN 351 in participants with DMD (time frame: Through study completion, at least 1 year). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 24 Jul 2026.