argenx reported that its pivotal Phase 3 ADAPT SERON trial showed VYVGART achieved a statistically significant improvement in daily living activities for adults with acetylcholine-receptor-antibody (AChR-Ab) seronegative generalized myasthenia gravis. Patients receiving four weekly infusions of the FcRn blocker recorded better MG-ADL scores than placebo at Day 29 (p = 0.0068). The 119-patient, double-blind study is the first late-stage trial to demonstrate efficacy across all three seronegative gMG subtypes—MuSK-positive, LRP4-positive and triple seronegative—populations that currently lack approved targeted therapies. Investigators reported no new safety concerns, with a profile consistent with previous VYVGART studies. argenx plans to submit a supplemental Biologics License Application to the U.S. Food and Drug Administration by year-end 2025 to extend VYVGART’s U.S. label beyond its existing indication for AChR-Ab seropositive gMG. Roughly one-fifth of gMG patients are seronegative, representing a material expansion opportunity for the drug. The announcement lifted argenx shares about 3 % in pre-market trading. RBC Capital initiated coverage at Outperform with an $850 price target, while Wedbush reiterated its $800 target, citing the drug’s broadened potential patient base.