A January 2023 news release from biopharmaceutical company Avidity Biosciences, Inc. (“Avidity”) shares that the company’s therapy, AOC 1020, earned Fast Track designation from the FDA for the treatment of people with facioscapulohumeral muscular dystrophy (FSHD). Currently, there is no cure for FSHD. Treatment options are mostly designed to help manage symptoms. Therefore, there is an urgent need to develop therapies that target the underlying genetic cause of the condition.
Fast Track designation is granted by the FDA to facilitate and expedite the development and review of therapies. To earn this designation, therapies must fill an unmet medical need or must be designed for rare or life-threatening conditions. Incentives that come along with this designation include Priority Review and Accelerated Approval eligibility, Rolling Review, and more frequent meetings and communication with the FDA.
So what is AOC 1020? Avidity explains that this intravenously administered monoclonal antibody (mAB) treatment focuses on DUX4; mutated DUX4 is the main cause of FSHD. These mutations cause abnormal DUX4 protein expression, leading to muscle function and wasting. With AOC 1020, Avidity hopes to reduce DUX4 protein expression, reducing the burden of FSHD. In murine (mouse/rat) models of FSHD, just one dose of AOC 1020 helped prevent muscle weakness.
Avidity is evaluating AOC 1020 within the Phase 1/2 MARINA study for myotonic dystrophy type 1, the Phase 1/2 EXPLORE44 study for Duchenne muscular dystrophy, and the Phase 1/2 FORTITUDE study for FSHD. Around 70 participants will enroll in the FORTITUDE study. Within this study, researchers hope to learn more about the treatment’s safety, efficacy, pharmacodynamic and pharmacokinetics, and tolerability.
What is Facioscapulohumeral Muscular Dystrophy (FSHD)?
As described above, DUX4 gene mutations typically cause FSHD, though SMCHD1 mutations have also been implicated. While facioscapulohumeral muscular dystrophy, one of the nine forms of muscular dystrophy, is inherited in an autosomal dominant pattern, the condition sometimes arises from spontaneous gene mutations. This genetic muscle disorder causes progressive muscle weakness and wasting, most commonly in the upper arms, shoulder blades, and face. In a majority of patients, symptoms manifest before 20 years old. Symptoms can, but do not always, include:
- Scapular winging
- Assymetrical muscle weakness and atrophy that begins in the eyes, mouth, abdominal muscles, lower legs, upper arms, and shoulders
- Dry mouth
- Foot drop
- Chronic fatigue
- Sunken breast bone
- High-tone hearing loss
