Promising findings from Avidity’s myotonic dystrophy trial

A major breakthrough for the field of RNA therapeutics

Avidity Biosciences announced today that its investigational treatment for myotonic dystrophy type 1 (DM1), called AOC 1001, can be delivered into the muscle of human patients to target the gene responsible for the disease. DM1 is a genetic, muscle-damaging disease that affects children and adults. Like FSHD, myotonic dystrophy weakens muscles in the face, hands, feet, and other areas of the body. Avidity is also working on a similar drug called AOC 1020, for FSHD.

Both AOC 1001 and AOC 1020 are based on a new technology using “small interfering RNA” (siRNA), which acts like a heat-seeking missile to precisely identify and block the activity of the genes that cause disease. In the DM1 trial, the siRNA targets the DMPK gene which causes the disease. For DM1 and FSHD alike, a major challenge is to get the siRNA inside billions of muscle cells where it can do its work. To this end, Avidity attached the siRNA to an antibody that latches onto a protein on the surface of muscle cells and then delivers the siRNA to the inside of the cell.

AOC 1001 worked beautifully in lab experiments with monkeys. But delivering the drug into human patients who are 3,000 times larger than mice was a huge question mark. Based on today’s news, early results from a preliminary assessment of the clinical trial demonstrated successful delivery of siRNA to muscle and reductions of DMPK levels by 45% on average in the patients who volunteered for the trial. AOC 1001 was generally well tolerated with most adverse events mild or moderate. The study continues to be ongoing with additional results expected next year in 2023.

“Utilizing our AOC platform technology, we have demonstrated for the first time ever the successful targeted delivery of siRNA to muscle in humans, a major breakthrough for the field of RNA therapeutics,” said Art Levin, Ph.D., chief scientific officer at Avidity. “These unprecedented data open up the RNA field and underscore the potential of our AOC platform to expand the possibilities of how we can treat diseases and target a range of different cells and tissues beyond the liver, which up until now have been inaccessible with existing RNA-based therapeutics.”

For AOC 1020, Avidity uses a different siRNA aimed at the DUX4 gene that causes FSHD. But technology to deliver AOC 1020 into muscles is the same. So the news today provides great hope that AOC 1020 will be able to deliver the anti-DUX4 siRNA where it needs to go. We will soon have a chance to find out, because Avidity has announced plans to start its Phase 1 / 2 clinical trial for FSHD early in 2023 and plans to share data from a preliminary assessment of AOC 1020 in the first half of 2024.

Learn more

• Tune in to our FSHD University webinar on January 19, 2023.
• Avidity Biosciences announces Phase 1/2 trial for FSHD
• Read the full press release