Duchenne Muscular Dystrophy (DMD) is caused by mutations in the dystrophin gene leading to dystrophin deficiency, muscle fiber degeneration and progressive fibrotic replacement of muscles. Givinostat, a histone deacetylase (HDAC) inhibitor, significantly reduced fibrosis and promoted compensatory muscle regeneration in mdx mice. This study was conducted to evaluate whether the beneficial histological effects of Givinostat could be extended to DMD boys. Twenty ambulant DMD boys aged 7 to <11 years on stable corticosteroid treatment were enrolled in the study and treated for ≥12 months with Givinostat. A muscle biopsy was collected at the beginning and at the end of treatment to evaluate the amount of muscle and fibrotic tissue. Histological effects were the primary objectives of the study. Treatment with Givinostat significantly increased the fraction of muscle tissue in the biopsies and reduced the amount of fibrotic tissue. It also substantially reduced tissue necrosis and fatty replacement. Overall the drug was safe and tolerated. Improvement in functional tests was not observed in this study, but the sample size of the study was not sufficient to draw definitive conclusions. This study showed that treatment with Givinostat for more than 1 year significantly counteracted histological disease progression in ambulant DMD boys aged 7 to 10 years.

Muscle fat fraction calculation and mapping using the dual-echo dual-flip angle SPGR MRI technique are useful markers of disease severity and permit patterns of disease distribution to be identified in patients with DMD.

ObjectiveIn the last few years some of the therapeutical approaches for Duchenne muscular dystrophy (DMD) are specifically targeting distinct groups of mutations, such as deletions eligible for skipping of individual exons. The aim of this observational study was to establish whether patients with distinct groups of mutations have different profiles of changes on the 6 minute walk test (6MWT) over a 12 month period.MethodsThe 6MWT was performed in 191 ambulant DMD boys at baseline and 12 months later. The results were analysed using a test for heterogeneity in order to establish possible differences among different types of mutations (deletions, duplications, point mutations) and among subgroups of deletions eligible to skip individual exons.ResultsAt baseline the 6MWD ranged between 180 and 560,80 metres (mean 378,06, SD 74,13). The 12 month changes ranged between −325 and 175 (mean −10.8 meters, SD 69.2). Although boys with duplications had better results than those with the other types of mutations, the difference was not significant.Similarly, boys eligible for skipping of the exon 44 had better baseline results and less drastic changes than those eligible for skipping exon 45 or 53, but the difference was not significant.Conclusionseven if there are some differences among subgroups, the mean 12 month changes in each subgroup were all within a narrow Range: from the mean of the whole DMD cohort. This information will be of help at the time of designing clinical trials with small numbers of eligible patients.

This 48-week, randomized, placebo-controlled phase 3 study (DMD114044; NCT01254019) evaluated efficacy and safety of subcutaneous drisapersen 6 mg/kg/week in 186 ambulant boys aged ≥5 years, with Duchenne muscular dystrophy (DMD) resulting from an exon 51 skipping amenable mutation. Drisapersen was generally well tolerated, with injection-site reactions and renal events as most commonly reported adverse events. A nonsignificant treatment difference (P = 0.415) in the change from baseline in six-minute walk distance (6MWD; primary efficacy endpoint) of 10.3 meters in favor of drisapersen was observed at week 48. Key secondary efficacy endpoints (North Star Ambulatory Assessment, 4-stair climb ascent velocity, and 10-meter walk/run velocity) gave consistent findings. Lack of statistical significance was thought to be largely due to greater data variability and subgroup heterogeneity. The increased standard deviation alone, due to less stringent inclusion/exclusion criteria, reduced the statistical power from pre-specified 90% to actual 53%. Therefore, a post-hoc analysis was performed in 80 subjects with a baseline 6MWD 300-400 meters and ability to rise from floor. A statistically significant improvement in 6MWD of 35.4 meters (P = 0.039) in favor of drisapersen was observed in this subpopulation. Results suggest that drisapersen could have benefit in a less impaired population of DMD subjects.

Objective: Respiratory insufficiency is a major complication of Duchenne muscular dystrophy (DMD). Its progression shows considerable interindividual variability, which has been less thoroughly characterized and understood than in skeletal muscle. We collected pulmonary function testing (PFT) data from a large retrospective cohort followed at Centers collaborating in the Italian DMD Network. Furthermore, we analyzed PFT associations with different DMD mutation types, and with genetic variants in SPP1, LTBP4, CD40, and ACTN3, known to modify skeletal muscle weakness in DMD. Genetic association findings were independently validated in the Cooperative International Neuromuscular Research Group Duchenne Natural History Study (CINRG-DNHS). Methods and Results: Generalized estimating equation analysis of 1852 PFTs from 327 Italian DMD patients, over an average follow-up time of 4.5 years, 786 estimated that forced vital capacity (FVC) declined yearly by À4.2%, forced expiratory volume in 1 sec by À5.0%, and peak expiratory flow (PEF) by À2.9%. Glucocorticoid (GC) treatment was associated with higher values of all PFT measures (approximately + 15% across disease stages). Mutations situated 3' of DMD intron 44, thus predicted to alter the expression of short dystrophin isoforms, were associated with lower (approximately À6%) PFT values, a finding independently validated in the CINRG-DNHS. Deletions amenable to skipping of exon 51 and 53 were independently associated with worse PFT outcomes. A meta-analysis of the two cohorts identified detrimental effects of SPP1 rs28357094 and CD40 rs1883832 minor alleles on both FVC and PEF. Interpretation: These findings support GC efficacy in delaying respiratory insufficiency, and will be useful for the design and interpretation of clinical trials focused on respiratory endpoints in DMD.