On May 17, 2023, Avidity Biosciences, Inc. provided an update to the status of the partial clinical hold related to its AOC 1001 product candidate. The Company announced that the U.S. Food and Drug Administration (the "FDA") has eased the partial clinical hold related to AOC 1001, allowing Avidity to double the number of participants receiving 4 mg/kg of AOC 1001 in the MARINA Open-Label Extension (MARINA-OLE) study by dose escalating approximately 12 participants currently receiving the 2 mg/kg level to the 4 mg/kg level of AOC 1001. All other participants will remain on their current dosage level of either 2 mg/kg or 4 mg/kg of Aoc 1001.

This action by the FDA also allows the Company to enroll new participants at the 2 mg/kg dosage level. Data from the MARINA-OLE study will be used to finalize the AOC 1001 pivotal dose and Phase 3 study design for adults with myotonic dystrophy type 1 (DM1). Avidity remains on track to share a first look at data from theMARINA-OLE study at the end of 2023.