Argenx SE (NASDAQ:ARGX) stock is trading higher on continued upward momentum after the company released topline data on Monday from the pivotal Phase 3 ADAPT SERON study of Vyvgart (IV: efgartigimod alfa-fcab).
The study met its primary endpoint, demonstrating that AChR-Ab seronegative gMG patients treated with Vyvgart achieved a statistically significant and clinically meaningful improvement in MG-ADL (Myasthenia Gravis Activities of Daily Living) total score compared to placebo.
Argenx plans to submit a supplemental marketing application to the U.S. Food and Drug Administration (FDA) by the end of 2025, seeking expansion of the Vyvgart label to include adult AChR-Ab seronegative gMG patients across all three subtypes.
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Positive clinical data from the ADAPT SERON trial provide key evidence that purging of IgG auto-antibodies via FcRN inhibition may be sufficient to reduce disease progression in seronegative gMG patients despite their lack of AchR autoantibody production.
Analyst Myles Minter of William Blair says strong trial results for efgartigimod in seronegative gMG and CIDP support its FcRN inhibition's potential across IgG-driven diseases, reinforcing William Blair's bullish view on Argenx.
Positive ADAPT SERON data and anticipated approval in seronegative gMG could expand Argenx's estimated 60,000-patient Vyvgart TAM by 18% by 2030. Vyvgart's gMG sales are projected at $2.93 billion in 2025, up 39% year-over-year.
Further upside could come from additional indications. Data from the ADAPT-OCULAR study are expected in the first half of 2026, potentially adding another 12% to Vyvgart's market. Meanwhile, late-stage trials in immune thrombocytopenia, thyroid eye disease, myositis, Sjögren's syndrome, and other autoinflammatory disorders are underway, highlighting Argenx's "pipeline-in-a-product" approach.
Reflecting the momentum, William Blair reiterated an Outperform rating, while Piper Sandler raised its price target on the stock from $750 to $820 and maintained an Overweight rating.
Price Action: ARGX stock is trading higher by 3.18% to $698.83 at last check Tuesday.
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