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

NCT07573631 | Enrolling By Invitation Phase 2 DMC

• 2 other identifiers: 351-2022024-511656-41-00
• Study Type: interventional
• Target: 18
• Locations: 5 countries
• Sites: 7

Brief 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.

Conditions

Duchene Muscular Dystrophy

Outcome Measures

Primary Outcomes (1)

• 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.

  Through study completion, at least 1 year

Secondary Outcomes (4)

• To evaluate the effect of BMN 351 on physical function

  Change from baseline and subsequent 24-week incremental visits

• To evaluate the effect of BMN 351 on physical function

  Change from baseline and subsequent 24-week incremental visits

• To evaluate the effect of BMN 351 on physical function

  Change from baseline and subsequent 24-week incremental visits

• To evaluate the effect of BMN 351 on physical function

  Change from baseline and subsequent 24-week incremental visits

Other Outcomes (7)

• To evaluate the trough plasma concentration of BMN 351

  Baseline, Week 13, Week 25, Week 37, Week 49

• To evaluate the immune response to BMN 351

  Change from baseline and subsequent 24-week incremental visits

• To evaluate lung function longitudinally for participants ages 7 and above

  Change from baseline to subsequent 24-week incremental visits

Study Arms (1)

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.

Drug: BMN 351

Interventions

BMN 351 DRUG

Anti-sense Oligonucleotide BMN 351 will be administered intravenously

BMN 351

Eligibility Criteria

• Age: 4 Years+
• Sex: male
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• BioMarin Pharmaceutical: lead

Study Sites (7)

Fondazione Serena ETS - Centro Clinico NeMO Milano

Milan, Italy

Location

UOC Fase I - Fondazione Policlinico Universitario A. Gemelli IRCCS - Universita Cattolica del Sacro Cuore

Rome, Italy

Location

Leids Universitair Medisch Centrum

Leiden, 2333 ZA, Netherlands

Location

Hospital Sant Joan de Deu

Barcelona, 08950, Spain

Location

Hospital Viamed Santa Angela De la Cruz

Seville, 41013, Spain

Location

Yeditepe University Kosuyolu Hospital

Istanbul, Turkey, Turkey (Türkiye)

Location

Great Ormond Street Hospital NHS Foundation Trust

London, WC1N 3JH, United Kingdom

Location

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: Open-Label Extension study available to eligible participants from the 351-201 study

Study Record Dates

• First Submitted: April 17, 2026
• First Posted: May 7, 2026
• Study Start: April 1, 2026
• Primary Completion (Estimated): December 1, 2031
• Study Completion (Estimated): December 1, 2031
• Last Updated: May 7, 2026

Record last verified: 2026-05

Locations

TU (1); GB (1); NL (1); ES (2); IT (2)