Argenx said its subcutaneous, prefilled-syringe FcRn antagonist Vyvgart Hytrulo (efgartigimod alfa) met primary endpoint results in immune-mediated necrotizing myopathy (IMNM) within a late-stage Phase 3 study, with rapid and sustained benefit and steroid tapering over time. The company also reported meaningful outcomes in myositis subsets, while one subgroup (dermatomyositis) did not achieve statistical significance. Investors and clinicians are likely to focus on the IMNM signal because the disease remains associated with limited targeted therapies and high unmet need. Argenx characterized safety as consistent with prior trials. A positive Phase 3 outcome supports potential label expansion and strengthens the Vyvgart franchise as Argenx aims to broaden delivery options beyond infusion settings.