Avidity Biosciences’ AOC 1020, newly dubbed del-brax, demonstrated a safe profile and was tied to functional improvement among people with facioscapulohumeral muscular dystrophy (FSHD) in a phase 1/2 trial.
The initial data drop assesses del-brax, a novel RNA therapeutic Avidity has dubbed an “antibody oligonucleotide conjugate,” among people with FSHD. The rare genetic disease progressively weakens muscles and causes significant pain, fatigue and disability. Currently, no approved treatments for the condition exist.
The double-blind trial tested single and multiple doses of del-brax among 39 participants with FSHD. The therapy demonstrated a favorable safety and tolerability profile—the primary objective of the study—with no serious adverse events reported and zero discontinuations.
The investigational therapy, which is designed to treat the abnormal expression of a gene called double homeobox 4 (DUX4), was also tied to a greater than 50% mean reduction across multiple DUX4 regulated gene panels for 12 patients receiving 2 mg/kg at four months.
While specific data among patients receiving a 4 mg/kg dose level were not shared, Avidity said all participants treated with del-brax showed 20% or higher reductions in DUX4 regulated genes. Patients in the 4 mg/kg cohort were included in the safety and tolerability assessment.
Though the phase 1/2 trial isn’t designed to assess functional benefit, Avidity is exploring measures such as mobility and patient reported outcomes. The early data show trends that del-brax improves muscle strength and function.
“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,” Jeffrey Statland, M.D., neurology professor at the University of Kansas Medical Center and trial investigator, said in a June 12 Avidity release. “These early data would support the notion that del-brax has the potential to change the course of disease for people living with FSHD,”
The trial has a primary readout date set for September 2025, according to ClinicalTrials.gov.
Avidity intends to accelerate initiation of registrational cohorts for del-brax, which has snagged both FDA orphan and fast track designation in the indication.
“FSHD is one of the most prevalent forms of muscular dystrophy and currently, there are no treatment options,” Mark Stone, president and CEO of the FSHD Society, said in the release. “The initial del-brax data offers real hope for those living with the disease, their families and their caregivers, who are desperately waiting for a treatment.”
The data will be presented at the Annual FSHD Society International Research Congress, which is being held later this week in Colorado.