Efgartigimod Alfa

Study met primary endpoint (p-value=0.0068) First global phase 3 study to demonstrate clinically meaningful improvements in disease activity across all three subtypes – MuSK+, LRP4+, triple seronegative Supplemental Biologics License Application (sBLA) to be submitted to U.S. Food and Drug Administration (FDA) by end of 2025 August 25, 2025, 7:00 AM CET – argenx SE (Euronext & Nasdaq: ARGX), a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases, today announced positive topline data from the pivotal ADAPT SERON study of VYVGART® (IV: efgartigimod alfa-fcab). The study met its primary endpoint (p-value=0.0068), 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. Based on these results, argenx plans to submit an sBLA to the U.S. FDA seeking expansion of the VYVGART label to include adult AChR-Ab seronegative gMG patients across all three subtypes – MuSK+, LRP4+, triple seronegative. Detailed results from the ADAPT SERON study will be presented at an upcoming medical meeting. VYVGART was well tolerated and safe across AChR-Ab seronegative subtypes and consistent with the established safety profile in patients with AChR-Ab seropositive gMG and other indications. No new safety concerns were identified. “The results of the ADAPT SERON study, the largest study to date of AChR-Ab seronegative gMG, confirm that VYVGART now has the potential to be a targeted, effective, safe, and necessary treatment for patients living with gMG, regardless of autoantibody status,” said James F. Howard Jr., M.D., Professor of Neurology (Neuromuscular Disease), Medicine and Allied Health, Department of Neurology, The University of North Carolina at Chapel Hill School of Medicine and Principal Investigator for the ADAPT SERON trial. “Paired with our existing knowledge, these data demonstrate that pathogenic IgGs are underlying drivers of gMG across patient subtypes. This is a critical advancement in the management of this debilitating and unpredictable disease for patients with limited treatment options.” “The ADAPT SERON study represents our longstanding commitment to the MG community and our ambition to help all MG patients address this debilitating condition and reach as many MG patients as we can,” said Luc Truyen, M.D. Ph.D., Chief Medical Officer, argenx. “The positive outcome of the ADAPT SERON study clearly shows VYVGART’s ability to provide meaningful benefit across all AChR-ab seronegative gMG subtypes.” The Phase 3 ADAPT SERON study was a randomized, double-blind, placebo-controlled, multi-center study evaluating the safety and efficacy of efgartigimod in adults with AChR-Ab seronegative gMG (n=119) across North America, Europe, China, and the Middle East. Part A randomized participants (1:1) received 4 once-weekly infusions of efgartigimod IV or placebo, followed by a 5-week follow-up and primary analysis. Part B was an open-label extension: participants received 2 fixed cycles of 4 once-weekly efgartigimod infusions (4-week interval between cycles); from cycle 3 onward, additional cycles could be started ≥1 week after the last administration of the previous cycle, based on clinical status. The primary endpoint was the MG-ADL total score change from baseline to day 29 in part A. Enrolled participants had a confirmed MG diagnosis by an independent panel of experts, and an MG-ADL total score of 5 or greater. Participants were on a stable dose of at least one gMG treatment prior to randomization, including acetylcholinesterase inhibitors, corticosteroids or nonsteroidal immunosuppressive drugs. Participants were eligible to enroll in ADAPT SERON if they were AChR-Ab seronegative, which included participants who are MuSK-Ab seropositive, LRP4-Ab seropositive, or triple seronegative. MG-ADL is a validated measure of disease activity in patients living with myasthenia gravis, which evaluates the functional impact of symptoms on daily activities such as speaking, chewing, swallowing, breathing, and limb strength. gMG is a rare, chronic, neuromuscular autoimmune disease caused by pathogenic IgGs targeting the neuromuscular junction (NMJ), resulting in impaired neuromuscular transmission and debilitating and potentially life-threatening muscle weakness and chronic fatigue. Approx. 80% of patients with gMG have detectable antibodies against the AChR in sera, and these patients are diagnosed as AChR-Ab seropositive gMG. Approximately 20% of patients with gMG do not have detectable serum antibodies directed against AChR and are referred to as AChR-Ab seronegative gMG. These patients may have detectable autoantibodies targeting other NMJ proteins, such as muscle-specific tyrosine kinase (MuSK) and low-density lipoprotein receptor-related protein 4 (LRP4), or others. Anti-MuSK antibodies are detected in approximately 1-10% of patients with gMG, while anti-LRP4 antibodies are detected in approximately 1-5% of patients with gMG. About 10% of patients do not have any detectable autoantibodies against AChR, MuSK or LRP4. These triple seronegative patients have historically been excluded from studies and have a higher disease burden and unmet medical need compared to patients with detectable autoantibodies. Currently, there are no approved treatments available for patients with anti-LRP4 antibodies or for triple seronegative patients. VYVGART is a human IgG1 antibody fragment that binds to the neonatal Fc receptor (FcRn), resulting in the reduction of circulating IgG autoantibodies. It is the first approved FcRn blocker in the United States, EU, China and Canada for the treatment of adults with generalized myasthenia gravis (gMG) who are anti-acetylcholine receptor (AChR) antibody positive and in Japan for the treatment of adults with gMG who do not have sufficient response to steroids or non-steroidal immunosuppressive therapies (ISTs). argenx is a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases. Partnering with leading academic researchers through its Immunology Innovation Program (IIP), argenx aims to translate immunology breakthroughs into a world-class portfolio of novel antibody-based medicines. argenx developed and is commercializing the first approved neonatal Fc receptor (FcRn) blocker and is evaluating its broad potential in multiple serious autoimmune diseases while advancing several earlier stage experimental medicines within its therapeutic franchises. 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iStock, Deagreez Based on new data, argenx expects to the expansion of Vyvgart’s label into patients with generalized myasthenia gravis who are negative for antibodies against the AChR marker—an indication William Blair analysts called the broadest option in this disease space. Argenx’s Vyvgart significantly improved disease activity and daily life in certain patients with generalized myasthenia gravis in a Phase III study, setting the FcRn inhibitor up for a potential label expansion. Writing to investors on Monday, William Blair analysts said that with these new data, Vyvgart “represents the first FcRN inhibitor to demonstrate statistically significant clinical efficacy in AChR seronegative gMG [generalized myasthenia gravis] patients”—the specific population that the Phase III ADAPT SERON trial focused on. If cleared for this specific indication, Vyvgart would have “the broadest label of all FcRn antagonists approved in gMG,” they added. Argenx did not reveal specific data in its news release on Monday , noting only that Vyvgart elicited a “statistically significant and clinically meaningful improvement” in disease activity in patients with gMG who are seronegative for antibodies against the AChR marker. According to the biotech, this particular subpopulation represents about 20% of all gMG patients, a group that often experiences a heavier disease burden. With these findings, argenx is gearing up for a supplemental application to expand Vyvgart into patients negative for antibodies against AChR, covering all three subtypes: MuSK-positive, LRP4-positive and triple seronegative patients, as per its Monday release. The company expects to make its submission by the end of the year. If approved, Vyvgart would gain access to roughly 11,000 additional gMG patients beyond its current market, according to William Blair. Breaking into this patient population would also give Vyvgart an edge over its current competitors, including Johnson & Johnson’s Imaavy and UCB’s Rystiggo, both of which “are approved only in gMG patients with AChR-positive or MuSK-positive” disease, according to the analysts. Infused intravenously, Vyvgart is a human IgG1 antibody fragment that treats gMG by lowering the circulating levels of IgG. The therapy was first approved in 2021 but is currently only indicated for patients who are positive for antibodies against AChR. In June 2023, argenx secured an approval for a subcutaneous formulation of Vyvgart, called Vyvgart Hytrulo, for gMG. The under-the-skin injection has also been approved for chronic inflammatory demyelinating polyneuropathy . Last year, argenx reached more than 10,000 patients and brought in nearly $2.2 billion in sales from its Vygart line alone.