Avidity Biosciences, Inc. announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to delpacibart etedesiran (AOC 1001), the company's lead clinical development program, for the treatment of myotonic dystrophy type 1 (DM1). Delpacibart etedesiran, abbreviated as del-desiran, is an investigational treatment designed to address the root cause of DM1, an underrecognized, progressive and often fatal neuromuscular disease with no approved therapies. Avidity is initiating the global pivotal HARBOR?

study of del-desiran this quarter. The primary endpoint in the Phase 3 HARBOR trial is video hand opening time (vHOT) and key secondary endpoints include muscle strength as measured by hand grip strength and quantitative muscle testing (QMT) total score, and activities of daily living as measured by DM1-Activ. Avidity recently reported positive long-term MARINA-OLE?

data demonstrating reversal of disease progression in adults living with DM1 across multiple endpoints including vHOT, muscle strength and DM1-Activ when compared to natural history data. In addition to receiving FDA Breakthrough Therapy designation, del-desiran has previously been granted Orphan Drug and Fast Track designations by the FDA and Orphan designation by the European Medicines Agency (EMA) for the treatment of DM1.