The Food and Drug Administration (FDA) has granted Fast Track designation to AOC 1020 for the treatment of facioscapulohumeral muscular dystrophy.

Facioscapulohumeral muscular dystrophy is a rare, genetic muscle disorder caused by an abnormal expression of DUX4 (double homeobox 4) leading to skeletal muscle wasting and progressive muscle function loss. AOC 1020 is designed to reduce the expression of DUX4 mRNA and DUX4 protein in muscles. The investigational treatment consists of a monoclonal antibody that binds to the transferrin receptor 1 (TfR1) conjugated with a small interfering RNA targeting DUX4 mRNA.

The Company is currently investigating AOC 1020 in the phase 1/2 FORTITUDE study in adults with facioscapulohumeral muscular dystrophy. The double-blind, placebo-controlled study is evaluating the safety, tolerability, pharmacokinetics, and pharmacodynamics of AOC 1020 administered intravenously. Though the study is not powered to assess functional benefit, assessments of efficacy will be made using key biomarkers, including magnetic resonance imaging measures of muscle volume and composition. Mobility, muscle strength, patient reported outcomes, and quality of life measures will also be analyzed.

“The FDA Fast Track designation for AOC 1020 reinforces the importance of finding an effective treatment to help people living with FSHD, a devastating and debilitating muscular dystrophy disorder with no treatment options,” said Steve Hughes, MD, chief medical officer at Avidity. “AOC 1020 is designed to directly target the disease-causing gene, DUX4, to address the underlying cause of FSHD. We look forward to working collaboratively with the FDA to bring the first RNA therapy directly targeting DUX4 to patients as quickly as possible.”


Avidity Biosciences granted FDA Fast Track designation for AOC 1020 for the treatment of facioscapulohumeral muscular dystrophy. News release. Avidity Biosciences. Accessed January 18, 2023.