Aspinout from Avidity’s portfolio, Atrium Therapeutics launched with approximately $270 million in cash and equivalents to advance RNA therapeutics for rare genetic cardiomyopathies. The company took programs including siRNA and Antibody‑Oligonucleotide Conjugate (AOC) candidates—ATR‑1072 for PRKAG2 syndrome and ATR‑1086 for PLN cardiomyopathy—and plans an IND filing for ATR‑1072 in the second half of the year. Atrium will leverage AOC delivery technology to target cardiac tissue and plans clinical development in rare, life‑threatening cardiomyopathies with high unmet medical need. The sizable capitalization and near‑term IND timeline position Atrium as a focused RNA cardiology player and reflect pharma’s willingness to fund specialty spinouts when assets fall outside acquirers’ strategic priorities.