The FDA has granted Breakthrough Therapy Designation to Avidity Biosciences’ antibody oligonucleotide conjugate (AOC) therapy delpacibart etedesiran (del-desiran; AOC 1001) for treating myotonic dystrophy type 1. This designation underscores the potential of del-desiran to be an effective treatment and the urgency of bringing this treatment to people living with DM1, a devastating rare muscle disease with no current treatment options addressing its underlying cause.
Delpacibart etedesiran consists of a proprietary monoclonal antibody that binds to the transferrin receptor 1 (TfR1) conjugated with a siRNA targeting DMPK mRNA, designed to address the root cause of DM1 by reducing DMPK mRNA. The therapy has also been granted Orphan Drug and Fast Track designations by the FDA, and Orphan designation by the European Medicines Agency.
Avidity Biosciences plans to initiate the global pivotal phase 3 HARBOR study of del-desiran in the second quarter of 2024. The study will evaluate the therapy's efficacy through primary and secondary endpoints, including video hand opening time (vHOT), muscle strength, and activities of daily living.
Positive long-term data from the phase 2 MARINA-OLE trial demonstrated the efficacy of AOC 1001, with treated patients showing improvements in myotonia, muscle strength, and patient-reported outcomes. The study included over 265 infusions of AOC 1001, with most adverse events being mild or moderate. The most common related adverse events were nausea and headache.
The long-term data from the MARINA-OLE study has been described as remarkable, showing that del-desiran improved measures of disease progression in DM1 patients compared to natural history data. The favorable long-term safety data and consistent, durable improvement in myotonia, muscle strength, and patient-reported outcomes measures highlight the potential of del-desiran to make a meaningful difference in the lives of DM1 patients.
