BioMarin Pharmaceutical has officially launched a new Phase 2 extension study (NCT07573631) evaluating BMN 351, an investigational exon 51 skipping therapy designed for people living with Duchenne muscular dystrophy (DMD). The study will focus on long-term safety, tolerability, and physical function outcomes in participants who previously completed the earlier 351-201 clinical trial.
What Is the BMN 351 Exon 51 Skipping Therapy Phase 2 Clinical Trial?
The BMN 351 exon 51 skipping therapy phase 2 clinical trial is a multi-center, open-label extension study for individuals with Duchenne muscular dystrophy who are amenable to exon 51 skipping. Researchers will evaluate how safe and effective weekly intravenous BMN 351 infusions remain over a longer treatment period.
The trial plans to enroll up to 18 participants between the ages of 4 and 23 who previously completed the Phase 1/2 study known as 351-201.
Understanding Duchenne Muscular Dystrophy and Exon 51 Skipping
What Is Duchenne Muscular Dystrophy?
Duchenne Muscular Dystrophy is a rare genetic disease that causes progressive muscle weakness and muscle degeneration. It is caused by mutations in the dystrophin gene, which is essential for maintaining healthy muscle cells.
What Is Exon 51 Skipping?
Exon skipping therapies are designed to help the body produce a shorter but functional version of the dystrophin protein. Exon 51 skipping specifically targets patients whose mutations can potentially benefit from skipping exon 51 during the protein production process.
BMN 351 is being investigated as a next-generation exon skipping therapy that may help slow disease progression in eligible patients.
Key Details About the Phase 2 Study
Study Design
The trial is:
- Multi-center
- Open-label
- Long-term extension study
- Focused on weekly intravenous dosing
The first visit in this study will also serve as the final visit of the earlier 351-201 trial.
Estimated Timeline
- Study Start: April 2026
- Primary Completion: December 2031
- Estimated Study Completion: December 2031
Countries Participating in the Study
The study includes clinical trial locations in:
- Italy
- Netherlands
- Spain
- Türkiye
- United Kingdom
Who Can Participate?
Main Inclusion Criteria
Participants must:
- Have completed the 351-201 study
- Continue stable corticosteroid treatment
- Follow study visit requirements
- Provide informed consent or assent when applicable
- Use contraception if required by protocol guidelines
Main Exclusion Criteria
Participants cannot join if they:
- Have known coagulation disorders
- Use prohibited medications
- Received another approved exon skipping therapy within 12 weeks before baseline
- Previously received gene therapy for DMD
- Use anti-coagulants or immunosuppressants
Why This Trial Matters for the Duchenne Community
The launch of the BMN 351 exon 51 skipping therapy phase 2 clinical trial represents another important step in the development of targeted genetic therapies for Duchenne muscular dystrophy.
Long-term extension studies are especially important because they help researchers understand:
- Whether treatment benefits can be maintained over time
- Long-term safety profiles
- Effects on daily physical function
- Potential impact on disease progression
For families affected by Duchenne, continued progress in exon skipping research provides renewed hope for future treatment options.
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