Argenx reported positive late-stage results for Vyvgart Hytrulo (subcutaneous efgartigimod) in a Phase 3 program across adults with myositis, aiming to broaden use of the Vyvgart franchise. The company said the under-the-skin therapy met its primary endpoint in a combined analysis and showed improvements on the Total Improvement Score (TIS), a composite scale used to track muscle strength and physical function. The data indicated rapid and sustained benefit starting as early as week four, with effects maintained for up to a year alongside steroid tapering. Argenx said efficacy was driven particularly by the immune-mediated necrotising myopathy (IMNM) subgroup, where there are no approved targeted therapies. Improvements in the dermatomyositis (DM) subgroup were described as meaningful but did not reach statistical significance. Safety was reported as consistent with prior Vyvgart studies. The readout comes as Argenx seeks to extend blockbuster momentum in a rare autoimmune disease market estimated around 20,000 patients, reinforcing investor focus on additional indications beyond current labeling.