A Clinical Study to Assess Two Doses of GSK2402968 in Subjects With Duchenne Muscular Dystrophy (DMD)

Inclusion Criteria:

   - Ambulant subjects with Duchenne muscular dystrophy (DMD) resulting from a
   mutation/deletion within the DMD gene, confirmed by a state-of-the-art DNA diagnostic
   technique covering all DMD gene exons, including but not limited to MLPA (Multiplex
   Ligation-dependent Probe Amplification), CGH (Comparative Genomic Hybridisation),
   SCAIP (Single Condition Amplification/Internal Primer) or H-RMCA (High-Resolution
   Melting Curve Analysis), and correctable by GSK2402968-induced DMD exon 51 skipping

   - Males, aged at least 5 years,

   - Life expectancy of at least 1 year,

   - Able to rise from floor in < or =15 seconds (without aids/orthoses) at Screening Visit
   1 and Screening Visit 2,

   - Able to complete 6 Minute Walk Distance (6MWD) test with minimal distance of at least
   75 meters, with reproducible results (within 20% of each other) at Screening Visit 1,
   Screening Visit 2 and at the baseline visit prior to randomization,

   - Receiving oral glucocorticoids for a minimum of 6 months immediately prior to
   screening, with no significant change in total daily dosage or dosing regimen for a
   minimum of 3 months immediately prior to screening and a reasonable expectation that
   total daily dosage and dosing regimen will not change significantly for the 48 week
   duration of the study (Dose adjustments that are based on weight changes are
   permitted),

   - QTc <450msec (based on single or average QTc value of triplicate ECGs obtained over a
   brief recording period), or <480 msec for subjects with Bundle Branch Block. Note: QTc
   may be either QTcB or QTcF, and machine read or manual overread

   - Willing and able to comply with all protocol requirements and procedures,

   - Able to give informed assent and/or consent in writing signed by the subject and/or
   parent(s)/legal guardian (according to local regulations).

Exclusion Criteria:

   - Any additional missing exon for DMD that cannot be treated with GSK2402968,

   - Current or history of liver disease or impairment including :

      1. an INR vaue above 1.5 is in and of itself exclusionary

      2. a total bilirubin greater than 2 times the Upper Limit of Normal is in and of
      itself exclusionary

      3. a GGT greater than 2 times the Upper Limit of Normal is in and of itself
      exclusionary

   - Current or history of renal disease or impairment,

   - Baseline platelet count below the Lower Limit of Normal,

   - aPPT above the Upper Limit of Normal,

   - History of significant medical disorder which may confound the interpretation of
   either efficacy or safety data e.g. inflammatory disease

   - Acute illness within 4 weeks of the first anticipated administration of study
   medication which may interfere with study assessments,

   - Use of anticoagulants, antithrombotics or antiplatelet agents, previous treatment with
   investigational drugs, idebenone or other forms of Coenzyme Q10 within 1 month of the
   first administration of study medication,

   - Current or anticipated participation in any investigational clinical studies,

   - Positive hepatitis B surface antigen, hepatitis C antibody test (if verified via RIBA
   or PCA testing), or human immunodeficiency virus (HIV) test at screening,

   - Symptomatic cardiomyopathy. If subject has a left ventricular ejection fraction <45%
   at Screening, the investigator should discuss inclusion of subject in the study with
   the medical monitor,

   - Children in Care. The definition of a Child in Care is a child who has been placed
   under the control or protection of an agency, organisation, institution or entity by
   the courts, the government or a government body, acting in accordance with powers
   conferred on them by law or regulation. The definition of a child in care can include
   a child cared for by foster parents or living in a care home or institution, provided
   that the arrangement falls within the definition above. The definition of a child in
   care does not include a child who is adopted or has an appointed legal guardian