Avidity Biosciences, Inc. announced that the U.S. Food and Drug Administration (FDA) has granted Rare Pediatric Disease designation to AOC 1044, the company's investigational therapy for the treatment of Duchenne muscular dystrophy (DMD) in people living with mutations amenable to exon 44 skipping (DMD44). AOC 1044 is being assessed in the Phase 1/2 EXPLORE44? trial for people living with DMD44 and is the first of multiple AOCs the company is developing for DMD.

In addition to receiving Rare Pediatric Disease Designation, AOC 1044 has been granted Orphan Designation by the FDA and the European Medicines Agency (EMA), and Fast Track Designation by the FDA. DMD is a rare genetic condition that is characterized by progressive muscle damage and weakness due to the loss of dystrophin protein that typically starts at a very young age. Currently, there are no therapies approved targeting exon 44.

In December 2023, Avidity reported positive AOC 1044 data in healthy volunteers from the EXPLORE44 trial. AOC 1044 is designed to deliver phosphorodiamidate morpholino oligomers (PMO) to skeletal muscle and heart tissue to specifically skip exon 44 of the dystrophin gene to enable dystrophin production. AOC 1044 delivered unprecedented concentrations of PMO in skeletal muscle with up to 50-times greater concentrations of PMO in skeletal muscle following a single dose compared to peptide conjugated PMOs in healthy volunteers.

AOC 1044 was well tolerated, demonstrated statistically significant exon 44 skipping compared to placebo of up to 1.5% in healthy volunteers after a single dose of 10 mg/kg AOC 1044 and increased exon skipping in all participants. Avidity plans to provide a first look at AOC 1044 data in people living with DMD44 in 2H 2024. The FDA defines a "rare pediatric disease" as a serious or life-threatening disease in which the serious or life-threatening manifestations primarily affect individuals aged from birth to 18 years.

Under the FDA's Rare Pediatric Disease Priority Review Voucher program, a sponsor who receives an approval for a drug or biologic for a rare pediatric disease may qualify for a voucher that can be redeemed to receive a priority review of a subsequent marketing application for a different product.