Today, Sarepta announced the FDA accepted Casimersen for DMD patients amenable to skipping exon 45. The US Food and Drug Administration (FDA) has granted Priority Review Status and sets regulatory action date for February 25, 2021
Sarepta submitted its New Drug Application (NDA) filing in June 2020 and requested priority review, which the FDA granted. The NDA included data from the casimersen arm of the ESSENCE study (also known as Study 4045-301), a global, randomized, double-blind, placebo-controlled Phase 3 study evaluating the efficacy and safety of casimersen in patients amenable to skipping exons 45. An interim analysis from ESSENCE demonstrated a statistically significant increase in dystrophin production as measured by western blot in patients who received casimersen compared to baseline and placebo. The study is ongoing and remains blinded to collect additional efficacy and safety data.
Casimersen uses Sarepta’s proprietary phosphorodiamidate morpholino oligomer (PMO) chemistry and exon-skipping technology to skip exon 45 of the Duchenne gene. Casimersen is designed to bind to exon 45 of dystrophin pre-mRNA, resulting in exclusion, or “skipping,” of this exon during mRNA processing in patients with genetic mutations that are amenable to exon 45 skipping. Exon skipping is intended to allow for production of an internally truncated dystrophin protein.
About the ESSENCE Study
The ESSENCE study is a double-blind, placebo-controlled, multi-center Phase 3 study evaluating the efficacy and safety of casimersen (SRP-4045) and golodirsen (SRP-4053, approved as VYONDYS 53™). Eligible patients with out-of-frame deletion mutations amenable to exon 45 or 53 skipping are randomized to receive once weekly intravenous (IV) infusions of 30 mg/kg of SRP-4045 or 30 mg/kg of SRP-4053, respectively (combined-active group) or placebo for up to 96 weeks. This is followed by an open-label extension period in which all patients will receive open-label active treatment for 48 weeks, up to week 144 of the study.