Phase II Doubleblind Exploratory Study of GSK2402968 in Ambulant Subjects With Duchenne Muscular Dystrophy

Inclusion Criteria: * Ambulant subjects with Duchenne muscular dystrophy resulting from a mutation in 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) or H-RMCA (High-Resolution Melting Curve Analysis), and correctable by GSK2402968-induced DMD exon 51 skipping, * Males, at least 5 years of age and with a life expectancy of at least 1 year * Able to rise from floor in ≤7 seconds (without aids/orthoses), * Able to complete the 6MWD test with a distance of at least 75m * Receiving 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 duration of the study * QTc \<450msec * On adequate contraception * Able to comply with and complete all protocol requirements Exclusion Criteria: * any additional missing exon for DMD * Current of history of liver or renal disease or impairment * Acute illness within 4 weeks of the first dose * Use of prohibited meds within 6 months of fist dose * Current participation in any other investigational clinical trial * Positive hepatitis B surface antigen, hepatitis C antibody test, or human immunodeficiency virus (HIV) test at screening * Symptomatic cardiomyopathy * Children in Care