Avidity Biosciences Receives FDA Breakthrough Therapy Designation for Delpacibart Etedesiran for Treatment of Myotonic Dystrophy Type 1

Avidity Biosciences, Inc. recently announced the US 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.

“We are pleased the FDA has granted Breakthrough Therapy designation to del-desiran for myotonic dystrophy type 1, underscoring the potential of del-desiran to be an effective treatment and the urgency of bringing this treatment to people living with DM1,” said Sarah Boyce, President and Chief Executive Officer at Avidity. “Initiation is underway for our global Phase 3 HARBOR study as we focus on rapidly advancing del-desiran for people living with DM1, who currently have no treatment options to address the underlying cause of this devastating rare muscle disease.”

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.

MARINA-OLE is an open-label, multi-center trial designed to evaluate the long-term safety and tolerability of del-desiran (AOC 1001) in participants with DM1 who were previously enrolled in the MARINA Phase 1/2 trial. This trial will continue to evaluate the safety, tolerability, PK, PD, and efficacy of del-desiran in participants enrolled in the randomized, placebo-controlled, Phase 1/2 MARINA clinical trial. Participants enrolled in the MARINA-OLE study receive quarterly doses of del-desiran regardless of whether they received active treatment or placebo in the MARINA study. The total duration of active treatment with del-desiran in the MARINA-OLE study is approximately 24 months. Once patients have completed active treatment, there will be a nine-month safety follow-up period. Avidity may extend active treatment beyond 24 months at a future timepoint. For more information on this study click here or visit http://www.clinicaltrials.gov and search for NCT05479981.

Del-desiran (AOC 1001), Avidity’s lead product candidate utilizing its AOC platform, is designed to address the root cause of DM1 by reducing levels of a disease-related mRNA called DMPK. Del-desiran consists of a proprietary monoclonal antibody that binds to the transferrin receptor 1 (TfR1) conjugated with a siRNA targeting DMPK mRNA. In preclinical studies, del-desiran 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. Del-desiran is currently in Phase 1/2 development with the completed MARINA trial and the ongoing MARINA-OLE trial in adults with DM1. The U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) have granted Orphan Designation for del-desiran and the FDA has granted del-desiran Fast Track Designation.

Myotonic dystrophy type 1 (DM1) is an underrecognized, progressive and often fatal disease caused by a triplet-repeat in the DMPK gene, resulting in a toxic gain of function mRNA. The disease is highly variable with respect to severity, presentation and age of onset, however all forms of DM1 are associated with high levels of disease burden and may cause premature mortality. DM1 primarily affects skeletal and cardiac muscle, however patients can suffer from a constellation of manifestations including myotonia and muscle weakness, respiratory problems, fatigue, hypersomnia, cardiac abnormalities, severe gastrointestinal complications, and cognitive and behavioral impairment. Currently, there are no approved treatments for people living with DM1.

Avidity Biosciences, Inc.’s mission is to profoundly improve people’s lives by delivering a new class of RNA therapeutics – Antibody Oligonucleotide Conjugates (AOCs™). Avidity is revolutionizing the field of RNA with its proprietary AOCs, which are designed to combine the specificity of monoclonal antibodies with the precision of oligonucleotide therapies to address targets and diseases previously unreachable with existing RNA therapies. Utilizing its proprietary AOC platform, Avidity demonstrated the first-ever successful targeted delivery of RNA into muscle and is leading the field with clinical development programs for three rare muscle diseases: myotonic dystrophy type 1 (DM1), Duchenne muscular dystrophy (DMD) and facioscapulohumeral muscular dystrophy (FSHD). Avidity is broadening the reach of AOCs with its advancing and expanding pipeline including programs in cardiology and immunology through internal discovery efforts and key partnerships. Avidity is headquartered in San Diego, CA. For more information, visit www.aviditybiosciences.com.