Novartis' RNA drug del-brax hits primary endpoint in early-stage FSHD trial

Novartis reported that its antisense oligonucleotide conjugate, del-brax, achieved the primary biomarker endpoint in a Phase 1/2 study of patients with facioscapulohumeral muscular dystrophy (FSHD). The trial showed the drug lowered two key biomarkers linked to the disease, indicating strong target engagement and reduced muscle damage.

The experimental therapy, also known as delpacibart braxlosiran, is designed to silence the DUX4 gene, which is abnormally active in FSHD patients and drives muscle degeneration. By delivering an antisense sequence directly to muscle tissue, the drug aims to restore normal muscle function and slow disease progression.

The study enrolled 90 participants across three cohorts, testing two dose levels of del-brax against placebo. Researchers measured changes in the DUX4‑regulated biomarker KHDC1L and creatine kinase, a marker of muscle injury, and observed meaningful reductions in both.

The positive readout follows Novartis' $12 billion acquisition of Avidity Biosciences, underscoring the company's bet on RNA‑based therapeutics for rare neuromuscular disorders.