Avidity Biosciences, Inc. (Nasdaq: RNA), a US-based biopharmaceutical company involved in delivering a new class of RNA therapeutics called Antibody Oligonucleotide Conjugates (AOCs), announced on Wednesday positive initial AOC 1020 data from the Phase 1/2 FORTITUDE trial.

The company says that the trial demonstrated unprecedented and consistent reductions of greater than 50% in DUX4 regulated genes, trends of functional improvement, and favourable safety and tolerability in people living with facioscapulohumeral muscular dystrophy (FSHD). Avidity plans to accelerate initiation of registrational cohorts in the FORTITUDE study. Avidity also announced delpacibart braxlosiran as the approved international nonproprietary name of AOC 1020, abbreviated as del-brax.

Del-brax is the first investigational therapy designed to treat the underlying cause of FSHD, which is caused by the abnormal expression of a gene called double homeobox 4 or DUX4. FSHD is a rare, hereditary disorder marked by life-long, relentless loss of muscle function, significant pain, fatigue, and progressive disability. Currently, there are no approved therapies for the treatment of FSHD.

'As the first therapy to directly target DUX4, it is very encouraging to see that the del-brax data demonstrate consistent reductions in DUX4 regulated genes and provided trends of functional improvement in patients with FSHD at the four-month timepoint. These early data would support the notion that del-brax has the potential to change the course of disease for people living with FSHD,' said Jeffrey M. Statland, M.D., professor of Neurology, University of Kansas Medical Center, and FORTITUDE trial investigator. 'Early data showing trends in del-brax to improve muscle strength and function are very encouraging for patients with FSHD who are in need of treatments to prevent the muscle weakness and disability that is associated with this relentlessly, progressive disease.'

The AOC 1020 initial data will be highlighted in an oral presentation at the 31st Annual FSHD Society International Research Congress, being held 13-14 June 2024, in Denver, Colorado.