Breakthrough Status for Myotonic Dystrophy Therapy
FDA has granted Avidity Biosciences a breakthrough therapy designation for delpacibart etedesiran (AOC 1001) and its use in treating myotonic dystrophy Type 1 (DM1). The investigational treatment is “designed to address the root cause of DM1, an underrecognized, progressive and often fatal neuromuscular disease with no approved therapies,” the company says.
Avidity is beginning a global Phase 3 pivotal study (HARBOR) of the therapy this quarter, with a primary endpoint of video hand opening time (vHOT) and key secondary endpoints including muscle strength as measured by hand grip strength and quantitative muscle testing (QMT) total score, and measured daily living activities, the company says. Avidity notes it recently reported positive long-term MARINA-OLE data demonstrating reversal of disease progression in adults living with DM1 across multiple endpoints including vHOT and muscle strength when compared to natural history data.
Delpacibart etedesiran works by reducing levels of a disease-related mRNA called DMPK, according to the company. It comprises a proprietary monoclonal antibody that binds to the transferrin receptor 1 conjugated with a siRNA targeting DMPK mRNA. In preclinical studies, the therapy successfully delivered siRNAs to muscle cells, “resulting in durable, dose-dependent reductions of DMPK RNA across a broad range of muscles including skeletal, cardiac, and smooth muscles,” it says.