Avidity Biosciences Announces New Positive AOC 1001 Data Demonstrating Improvement in Multiple Additional Functional Endpoints and Favorable Long-term Safety and Tolerability in People with Myotonic Dystrophy Type 1

Avidity Biosciences, Inc. (Nasdaq: RNA), a biopharmaceutical company committed to delivering a new class of RNA therapeutics called Antibody Oligonucleotide Conjugates (AOCs^™), today announced new positive AOC 1001 data demonstrating improvement in multiple additional functional endpoints and favorable long-term safety and tolerability in people living with myotonic dystrophy type 1 (DM1). AOC 1001, Avidity’s lead clinical program utilizing its AOC platform, is designed to address the root cause of DM1, an underrecognized, progressive and often fatal neuromuscular disease with no approved therapies. The AOC 1001 data from the Phase 1/2 MARINA^® trial and MARINA open-label extension (MARINA-OLE^™) study will be highlighted in an oral presentation at the 28th Annual Congress of the World Muscle Society (WMS) in Charleston, South Carolina and can be found on Avidity’s website on the Publications page.

“The new AOC 1001 data presented today demonstrating improvements in muscle strength and patient reported outcomes add to the previously reported positive topline data showing improvements in myotonia and mobility. The AOC 1001 data continues to be quite remarkable with consistent improvements across multiple functional endpoints,” said Nicholas E. Johnson, M.D., M.Sci., FAAN, associate professor and vice chair of research in the Department of Neurology at Virginia Commonwealth University, lead investigator of the MARINA trial and study presenter. “The AOC 1001 functional data coupled with the long-term favorable tolerability and safety data provide us with hope that AOC 1001 has the potential to help patients with DM1, who are in desperate need of treatments.”

The new AOC 1001 data demonstrate improvement in additional functional measures including hand grip, muscle strength and patient reported outcomes, augmenting previously reported positive data showing improvements in myotonia, muscle strength and mobility. With new long-term safety data from over 200 infusions totaling 46.2 patient-years of exposure, AOC 1001 continues to demonstrate favorable safety and tolerability with most adverse events (AEs) mild to moderate.

“Data from MARINA and MARINA-OLE reinforce our belief in the potential of AOC 1001 to become an effective treatment option for people living with DM1, a devastating rare disease for which there are no treatment options available. With this robust data package, we are finalizing the Phase 3 study design and global regulatory path for AOC 1001 and look forward to sharing a first look at efficacy data from the MARINA-OLE study in the first half of 2024,” said Sarah Boyce, president and chief executive officer at Avidity. “In addition to our DM1 program, we continue to advance our DMD and FSHD clinical development programs and plan to report data from all three of our programs by mid-2024 while continuing to expand our discovery and development pipeline.”

In May 2023, the U.S. Food and Drug Administration (FDA) eased the partial clinical hold on AOC 1001, allowing Avidity to double the number of participants in the MARINA-OLE study receiving 4 mg/kg of AOC 1001 from 12 to 24 participants. Data from the 12 participants dose-escalated from 2 mg/kg to 4 mg/kg of AOC 1001 as part of the easement of the partial clinical hold showed no neurological events and no MRI changes following dosing. The company continues to work as quickly as possible to resolve the partial clinical hold.