Avidity Biosciences, Inc. announced that the U.S. Food and Drug Administration (FDA) has placed a partial clinical hold on new participant enrollment in the Phase 1/2 MARINA™ clinical trial of AOC 1001 in adults with myotonic dystrophy type 1 (DM1). Close to 40 participants are currently enrolled in the MARINA and MARINA open label extension (MARINA-OLE™) trials. All participants, whether they are on AOC 1001 or placebo, may continue in their current dosing cohort although no additional participants may be enrolled until the partial clinical hold is resolved.

All participants in MARINA may roll over into the MARINA-OLE where they will receive AOC 1001 as planned. DM1 is an underrecognized, progressive and often fatal neuromuscular disease with no approved treatment options. The partial clinical hold is in response to a serious adverse event reported in a single participant in the 4mg/kg cohort of the MARINA study.

Avidity is working closely with the FDA and the trial investigator to assess the cause of this event. The company is taking all necessary steps to resolve the partial clinical hold on new participant enrollment as quickly as possible. Avidity remains on track to conduct a preliminary assessment of safety, tolerability and key biomarkers in approximately half of the study participants in the MARINA trial in the fourth quarter of 2022.

Avidity received IND clearance from the FDA to proceed with the clinical trial of AOC 1020 for the treatment of facioscapulohumeral muscular dystrophy (FSHD) and AOC 1044 for the treatment of Duchenne muscular dystrophy (DMD) with mutations amenable to exon 44 skipping. These programs are now advancing into the clinic.