Argenx's Vyvgart Shows Promise in Seronegative Myasthenia Gravis Patients, Expanding Treatment Options

Argenx, a leading pharmaceutical company in the field of autoimmune diseases, has unveiled promising results from its ADAPT SERON trial, demonstrating the efficacy of its blockbuster drug Vyvgart (efgartigimod) in seronegative generalized myasthenia gravis (gMG) patients. This development marks a significant step forward in addressing the unmet needs of a subset of gMG patients who have long been overlooked in the treatment paradigm.

Breakthrough in Seronegative gMG Treatment

The ADAPT SERON trial, which enrolled 119 patients across three seronegative gMG subtypes, met its primary endpoint with Vyvgart-treated patients showing a statistically significant improvement over placebo on the Myasthenia Gravis Activities of Daily Living (MG-ADL) test. Patients receiving Vyvgart demonstrated an average positive change from baseline of 3.35 points on the MG-ADL scale at four weeks, compared to a 1.9 point improvement in the placebo group.

Dr. Luc Truyen, Chief Medical Officer at Argenx, emphasized the company's mission to ensure "no MG patient is left behind." The trial results support Argenx's hypothesis that pathogenic immunoglobulin G is an underlying driver of myasthenia gravis across various subtypes, regardless of autoantibody status.

Expanding Vyvgart's Reach and Potential

Argenx plans to seek regulatory approval for both the intravenous and subcutaneous formulations of Vyvgart in the seronegative population. This expansion could potentially add approximately 11,000 new patients to Vyvgart's current U.S. prescribing pool, according to analysts at William Blair.

The company also presented additional data at the 2025 American Association of Neuromuscular & Electrodiagnostic Medicine Annual Meeting (AANEM) and the Myasthenia Gravis Foundation of America (MGFA) scientific sessions. These included results on Vyvgart's efficacy in adolescents with gMG, long-term data extending to nearly 170 weeks, and the drug's ability to help patients reduce steroid use.

Competitive Landscape and Future Outlook

Vyvgart's success in seronegative gMG patients could potentially give Argenx an edge over competitors in the rapidly evolving gMG treatment market. Since Vyvgart's initial approval in late 2021, several other novel gMG treatments have entered the market, including Alexion's Ultomiris, UCB's Rystiggo, and Johnson & Johnson's Imaavy.

Argenx is not resting on its laurels, with ongoing trials of efgartigimod in various other autoimmune conditions, including ocular myasthenia gravis, thyroid eye disease, myositis, Sjogren's disease, and lupus nephropathy. The company's commitment to expanding treatment options across multiple indications underscores its position as a key player in the pharmaceutical industry's efforts to address rare and challenging autoimmune disorders.