Positive results from phase III ESSENCE study in the casimersen arm to treat Duchenne Muscular dystrophy

Sarepta Therapeutics, Inc .announced results from its interim analysis of muscle biopsy endpoints comparing casimersen treatment to placebo in the ESSENCE study, also known as study 4045-301. ESSENCE is a global, randomized double-blind, placebo-controlled Phase III study evaluating the efficacy and safety of casimersen and golodirsen in patients amenable to skipping exons 45 or 53, respectively.

Patients amenable to exon 45 skipping were randomized to receive a once-weekly intravenous (IV) infusion of casimersen dosed at 30mg/kg (N=27) or placebo (N=16) for 96 weeks. The interim analysis was performed on data from biopsies of the bicep muscle at baseline and on-treatment at Week 48.

Key findings from the interim analysis include : In the casimersen arm, mean dystrophin protein (% normal dystrophin as measured by western blot) increased to 1.736% of normal compared to a mean baseline of 0.925% of normal (p<0.001). A statistically significant difference in the mean change from baseline to week 48 in dystrophin protein was observed between the casimersen-treated arm compared to the placebo arm (p=0.009). Of the 22 patients receiving casimersen who have been tested for increased exon-skipping mRNA using reverse transcription polymerase chain reaction (RT-PCR), all have displayed an increase in skipping exon 45 (p<0.001) over their baseline levels, representing a 100% response rate. A statistically significant positive correlation between exon 45 skipping and dystrophin production was observed (Spearman rank correlation = 0.635, p<0.001). The study is ongoing and remains blinded to collect additional efficacy and safety data.