Avidity Biosciences Announces Completion of Enrollment for HARBOR™, the First Global Phase 3 Trial of Delpacibart Etedesiran (del-desiran) for Treatment of DM1 and Provides Guidance on Regulatory Submission

Core Insights - Avidity Biosciences has completed enrollment in the Phase 3 HARBOR clinical trial for del-desiran, targeting myotonic dystrophy type 1 (DM1), with topline data expected in Q2 2026 [1][3] - The company plans to submit marketing applications for del-desiran in the U.S., EU, and Japan starting in H2 2026, aiming to be the first approved drug for DM1 globally [1][2] - Del-desiran has received multiple designations from the FDA and EMA, including Breakthrough Therapy and Orphan Drug status, indicating its potential significance in treating DM1 [4][7] Company Overview - Avidity Biosciences focuses on developing a new class of RNA therapeutics known as Antibody Oligonucleotide Conjugates (AOCs™), which aim to combine the specificity of monoclonal antibodies with the precision of oligonucleotide therapies [8] - The company is advancing clinical programs for rare muscle diseases, including DM1, Duchenne muscular dystrophy (DMD), and facioscapulohumeral muscular dystrophy (FSHD) [8] Clinical Trial Details - The HARBOR trial is a randomized, placebo-controlled study involving approximately 150 participants aged 16 and older, assessing the efficacy of del-desiran every eight weeks [5] - Primary and secondary endpoints include video hand opening time (vHOT), muscle strength, and activities of daily living, with an open-label extension trial expected to begin in Q3 2025 [5] Disease Context - Myotonic dystrophy type 1 (DM1) is a rare, hereditary neuromuscular disease characterized by multisystemic manifestations and a significant disease burden, with no approved treatments currently available [6][7]