Avidity Biosciences is a clinical-stage biopharmaceutical company developing Antibody Oligonucleotide Conjugates (AOCs), a drug class that combines monoclonal antibodies with RNA-targeting oligonucleotides. The core innovation is using an antibody targeting the transferrin receptor 1 (TfR1) on muscle cells to deliver oligonucleotides directly into muscle tissue — solving a fundamental delivery limitation that previously prevented RNA therapeutics from reaching muscle. All three of Avidity's clinical programs target rare neuromuscular diseases with no currently approved disease-modifying treatments: del-zota for Duchenne muscular dystrophy (exon 44 mutation), del-desiran for myotonic dystrophy type 1, and del-brax for facioscapulohumeral muscular dystrophy. Avidity plans to commercialize these neuromuscular programs independently, targeting small, well-defined patient populations with high-priced, recurring chronic treatments administered via intravenous infusion. Avidity also has two external collaborations — with Eli Lilly (immunology) and Bristol-Myers Squibb (cardiology) — where partners fund development and commercialization in exchange for milestones and royalties. Key near-term value inflection points include a BLA submission for del-zota in 2026 and Phase 3 data for del-desiran in the second half of 2026. In October 2025, Novartis agreed to acquire Avidity, with the deal expected to close in the first half of 2026; prior to closing, Avidity will spin off its early-stage cardiology programs into a separate public company called Atrium Therapeutics.