The US Food and Drug Administration (FDA) granted AOC 1044, a potential new treatment for Duchenne muscular dystrophy (DMD), Orphan Drug Designation. 

“We are pleased that the FDA has granted both Orphan Drug and Fast Track designation to AOC 1044, highlighting the importance of advancing new treatments for people living with DMD”, said Steve Hughes, MD, chief medical officer at Avidity Biosciences, the developers of the treatment.

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“There are currently no treatment options that target the underlying cause of DMD44. We look forward to advancing AOC 1044 in clinical development and bringing this very important treatment to patients as quickly and safely as possible,” he added.

AOC 1044 is an investigational antibody oligonucleotide conjugate for patients with DMD with a mutation in the DMD gene amenable to exon 44 skipping. It is designed to deliver phosphorodiamidate morpholino oligomers to skeletal and heart muscles to skip exon 44 so that the reading frame of the DMD gene is restored and a shorter but still functional dystrophin protein can be made. 

The experimental treatment is currently being tested in a placebo-controlled, randomized, double-blind, phase 1/2 clinical trial to investigate its tolerability, safety, pharmacodynamics, and pharmacokinetics in healthy volunteers and patients with DMD.

The trial is currently recruiting healthy volunteers who are 18 to 55 years of age in San Antonio, Texas. Its estimated completion date is March 2025.

DMD is a rare genetic disease caused by a mutation in the DMD gene. This gene contains the information necessary to make dystrophin protein, which is essential for the health of muscle cells. In its absence, muscle tissue becomes damaged at each contraction and, over time, is replaced with scar tissue.

Symptoms of the disease include muscle weakness and wasting that also affects the diaphragm and heart tissue. Patients eventually succumb to death, usually due to respiratory failure and cardiomyopathy. 

There is currently no effective treatment available for patients with DMD targeting exon 44.


Avidity Biosciences receives FDA Orphan Drug Designation for AOC 1044 for treatment of Duchenne muscular dystrophy in people with mutations amenable to exon 44 skipping. News release. Avidity Biosciences;  August 15, 2023

Study of AOC 1044 in healthy adult volunteers and participants with Duchenne muscular dystrophy (DMD) mutations amenable to exon 44 skipping (EXPLORE44). US National Library of Medicine. Updated April 4, 2023. Accessed August 17, 2023.