Avidity Biosciences Inc (Nasdaq:RNA), a biopharmaceutical company focused on developing a new class of RNA therapeutics called Antibody Oligonucleotide Conjugates (AOCs), announced on Monday the completion of enrolment in the ongoing global Phase 3 HARBOR clinical trial of delpacibart etedesiran (del-desiran) for people living with myotonic dystrophy type 1 (DM1).

Topline data from HARBOR, the first global Phase 3 clinical trial in DM1, are anticipated in the second quarter of 2026.

Prior to initiation of the HARBOR trial, Avidity aligned with global regulators, including FDA, on the registrational path for del-desiran. The company plans to submit marketing applications beginning in the second half of 2026 including in the United States, European Union and Japan.

Del-desiran is an investigational treatment designed to address the underlying genetic cause of DM1, a rare, hereditary, progressive neuromuscular disease that shortens life expectancy and requires life-long care.

Del-desiran has received Breakthrough Therapy, Orphan Drug and Fast Track designations from the US Food and Drug Administration (FDA) and Orphan designation from the European Medicines Agency (EMA). It was also the first investigational treatment for DM1 to receive Orphan Drug designation in Japan.

The global Phase 3 HARBOR trial is a randomised, placebo-controlled, double blind pivotal study designed to evaluate del-desiran in approximately 150 people (age 16 and older) living with DM1. The trial is being conducted at approximately 40 sites globally.