Atrium Therapeutics launched as a spinout funded with roughly $270 million in cash to advance Avidity Biosciences’ preclinical cardiac RNA programs. The new company is advancing two lead candidates: ATR‑1072 (siRNA for PRKAG2 syndrome) and ATR‑1086 (PLN-targeting candidate), both built on Antibody‑Oligonucleotide Conjugate (AOC) delivery technology aimed at direct cardiac targeting. Atrium plans an IND for ATR‑1072 in the second half of the year and an IND for ATR‑1086 in 2027. Management emphasized the urgent unmet need in rare genetic cardiomyopathies and the potential to leverage established AOC delivery chemistry for heart‑selective RNA therapeutics. Investors and partners will watch early clinical tolerability and evidence of on‑target cardiac engagement closely; successful cardiac RNA delivery would unlock a large therapeutic opportunity that historically has been constrained by tissue targeting limitations.