Avidity Biosciences, Inc. announced that it has commenced enrolling patients from the Phase 1/2 MARINA(TM) study into a Phase 2 open-label extension study (MARINA-OLE(TM)) of AOC 1001 in adults with myotonic dystrophy type 1 (DM1). All patients enrolled in the randomized, placebo-controlled MARINA(TM) clinical trial with AOC 1001 are eligible to enroll in MARINA-OLE. DM1 is an underrecognized, progressive and often fatal neuromuscular disease.

It primarily affects skeletal and cardiac muscle with multiple organ involvement and can be highly variable with respect to severity, presentation, and age of onset. There are currently no disease-modifying treatments for people living with DM1. AOC 1001, Avidity's lead program utilizing its AOC platform, is designed to address the root cause of DM1 by reducing levels of DMPK, the disease-related mRNA.

AOC 1001 consists of a proprietary monoclonal antibody that binds to the transferrin receptor 1 (TfR1) conjugated with a small interfering RNA (siRNA). The U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) have granted Orphan Designation for AOC 1001 and the FDA has granted AOC 1001 Fast Track Designation. About the Phase 2 MARINA-OLE(TM) Study MARINA-OLE(TM) is an open-label, multi-center study designed to evaluate the long-term safety and tolerability of AOC 1001 in DM1 patients who were previously enrolled in the MARINA Phase 1/2 study.

This study will continue to evaluate the safety, tolerability, PK, PD, and efficacy of AOC 1001 in patients that enrolled in the randomized, placebo-controlled, Phase 1/2 MARINA clinical study. Patients who enroll in the MARINA-OLE study will receive quarterly doses of AOC 1001 regardless of whether they received active treatment or placebo in the MARINA study. The total duration of active treatment with AOC 1001 in the MARINA-OLE is approximately 24 months.

Once patients have completed active treatment, there will be a 9-month safety follow-up period. Avidity may extend active treatment beyond 24 months at a future timepoint.