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Enrolling by Invitation

NCT Number: NCT07573631

An Open-Label Extension Study to Evaluate the Long-term Safety and Efficacy of BMN 351 in Participants With Duchenne Muscular Dystrophy

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.

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Key information

Conditions

Duchenne Muscular Dystrophy (DMD) Congenital, Hereditary, and Neonatal Diseases and Abnormalities Genetic Diseases, Inborn Genetic Diseases, X-Linked Muscular Diseases Muscular Disorders, Atrophic Muscular Dystrophies Muscular Dystrophy, Duchenne Musculoskeletal Diseases Nervous System Diseases Neuromuscular Diseases

Age range

4 year and older

Sex eligibility

Male

Study type

Interventional

Phase

Phase 2

Primary location

Fondazione Serena ETS - Centro Clinico NeMO Milano, Milan, Italy

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About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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

Exclusion criteria

  • 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

Treatment and study plan

BMN 351

Drug

Anti-sense Oligonucleotide BMN 351 will be administered intravenously

Primary outcomes

  1. 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.

Secondary outcomes

  1. To evaluate the effect of BMN 351 on physical function

    Time frame: Change from baseline and subsequent 24-week incremental visits

    North Star Ambulatory Assessment (NSAA) will be assessed at the specific visits and compared to individual baseline and external controls

  2. To evaluate the effect of BMN 351 on physical function

    Time frame: Change from baseline and subsequent 24-week incremental visits

    Timed 4 stair climb (4SC) will be assessed at the specified visits and compared to individual baseline and external controls

  3. To evaluate the effect of BMN 351 on physical function

    Time frame: Change from baseline and subsequent 24-week incremental visits

    SV95C will be assessed at the specified visits and compared to individual baseline and external controls

  4. To evaluate the effect of BMN 351 on physical function

    Time frame: Change from baseline and subsequent 24-week incremental visits

    PUL 2.0 will be assessed at the specified visits and compared to individual baseline and external controls

Sponsors and collaborators

Lead sponsor

BioMarin Pharmaceutical

Industry

Registry information

Official study 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

Important dates

Study start
2026
Primary completion
2031
Study completion
2031
First posted
May 7, 2026
Registry last updated
Jul 24, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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