Novartis reported that its Phase III HARBOR study of del-desiran (delpacibart etedesiran) in myotonic dystrophy type 1 did not meet the primary endpoint of video hand opening time (vHOT) improvement versus placebo through week 54. The company said del-desiran showed signals of clinical activity in secondary endpoints and exploratory analyses, while safety remained generally consistent with prior data. Novartis said it is evaluating the full HARBOR dataset and will engage health authorities to determine the next development path. In parallel, it reiterated continued progress in its antibody oligonucleotide conjugate (AOC) pipeline. The update raises immediate decision points for RNA therapeutics strategy and resource allocation, especially after del-desiran was added to the neuromuscular portfolio through the Avidity Biosciences acquisition and positioned against a high-unmet-need disease area.