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Highlights

  • ADAPT SERON met its primary endpoint with statistical significance (p=0.0068).
  • First global Phase 3 to show benefit across MuSK+, LRP4+, and triple seronegative subtypes.
  • Company intends to file an sBLA with the FDA by the end of 2025.

argenx reported positive topline results from the Phase 3 ADAPT SERON study evaluating VYVGART® (efgartigimod) in patients with AChR-Ab seronegative generalized myasthenia gravis (gMG). The trial achieved its primary endpoint, with a reported p-value of 0.0068 for improvement on the Myasthenia Gravis Activities of Daily Living (MG-ADL) total score versus placebo, indicating a statistically significant difference in favour of treatment.

Notably, argenx said ADAPT SERON is the first global Phase 3 to demonstrate clinical benefits across the three main seronegative subgroups — MuSK+, LRP4+, and triple seronegative patients — a result that, if confirmed in full dataset analyses, could expand the evidence base for treating these historically under-studied populations. The trial’s design and subgroup composition were described in earlier protocol materials and scientific posters.

The company confirmed there were no new safety signals identified in the topline review and that the safety profile observed was consistent with previous VYVGART studies. argenx plans to submit a Supplemental Biologics License Application (sBLA) to the U.S. Food and Drug Administration seeking label expansion to include seronegative gMG patients by the end of 2025. Regulatory timelines and the FDA review process will determine the next steps for any label change.

Market and clinical observers will await the full dataset and peer-reviewed analyses to assess effect sizes, durability of response, and detailed safety findings across subgroups. The topline announcement provides an initial readout, but granular information — including secondary endpoints, responder rates, and adverse-event breakdowns — will be key for clinicians, regulators and investors seeking to evaluate the clinical and regulatory implications.

Separately, recent regulatory scrutiny tied to VYVGART Hytrulo in other indications has drawn attention to safety monitoring; any sBLA review is likely to include a careful assessment of post-marketing and trial safety data. argenx’s forthcoming full data release and regulatory filings should clarify benefit-risk considerations for the seronegative gMG population.