Atrium Therapeutics launched as a spinout carrying Avidity Biosciences’ cardiac RNA programs and the public listing formerly held by Avidity after Novartis completed its $12 billion acquisition. The San Diego‑based startup emerged with roughly $270 million in cash and two preclinical candidates targeting PRKAG2 syndrome and PLN cardiomyopathy. Atrium’s leadership includes former Avidity executives Kathleen Gallagher (CEO) and Sarah Boyce (chair). The company emphasized its use of Avidity’s delivery technology to reach heart muscle — a long‑standing hurdle for RNA therapeutics beyond the liver and skeletal muscle. Atrium plans to advance its two disclosed candidates toward IND‑enabling work while retaining additional preclinical programs. The spinout highlights how large pharma M&A can seed new, focused biotech ventures that pursue niche indications outside the buyer’s strategic remit.