Atrium Therapeutics debuted as a standalone company with approximately $270 million in cash, inheriting cardiac RNA delivery programs spun out of Avidity Biosciences after Novartis closed its acquisition. Atrium’s leadership includes former Avidity executives and the company said it will advance two preclinical candidates aimed at PRKAG2 syndrome and PLN cardiomyopathy, rare genetic cardiomyopathies lacking disease‑modifying options. Atrium’s launch repurposes assets Novartis did not acquire and retains Avidity’s public listing and RNA delivery know‑how. The spinout underscores continued investor and developer interest in expanding RNA therapeutics beyond liver and skeletal muscle delivery into cardiac tissue.