Novartis (NYSE: NVS) announced that its experimental treatment del-brax met primary and key secondary endpoints in the biomarker cohort of the FORTITUDE Phase I/II study for facioscapulohumeral muscular dystrophy (FSHD).

The study showed reductions in KHDC1L and creatine kinase biomarker levels, indicating target engagement and reduced muscle damage in FSHD patients. Del-brax is an investigational antibody oligonucleotide conjugate designed to suppress DUX4 expression in muscle cells.

"The FORTITUDE biomarker cohort data importantly replicate the target engagement and downstream muscle protection seen with del-brax in earlier dose-escalation cohorts," said Nazem Atassi, Global Head, Neuroscience and Gene Therapy Development at Novartis.

FSHD is a rare neuromuscular disease characterized by progressive muscle function loss and disability. Del-brax has received FDA Orphan Drug and Fast Track designations, plus EMA Orphan Drug designation, and is currently in Phase III development.

The treatment was acquired through Novartis' purchase of Avidity Biosciences, completed in February 2026. The acquisition included two other experimental treatments: delpacibart-etedesiran for myotonic dystrophy type 1, currently in Phase III development, and delpacibart-zotadirsen for Duchenne muscular dystrophy, in Phase II development.

The company stated it will evaluate the biomarker and clinical data and engage with global regulatory agencies regarding del-brax development.