argenx to Highlight Key Data and Breadth of Immunology Innovation at 2025 AANEM Annual Meeting and MGFA Scientific Session

Amsterdam, the Netherlands– argenx SE (Euronext & Nasdaq: ARGX), a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases, will present data for VYVGART® (IV: efgartigimod alfa-fcab and SC or Hytrulo: efgartigimod alfa and hyaluronidase-qvfc) and pipeline candidate empasiprubart at the 2025 American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) Annual Meeting and Myasthenia Gravis Foundation of America (MGFA) Scientific Session in San Francisco from October 29-November 1, 2025.

“We’re proud to have a robust presence at this year’s AANEM Annual Meeting and MGFA Scientific Session, where we are sharing pivotal data and meaningful evidence across a broad spectrum of serious neuromuscular diseases, including MG, CIDP, MMN and IIM,” said Luc Truyen, M.D., Ph.D., Chief Medical Officer, argenx. “The breadth of studies reflect the strength and momentum of our clinical development programs, from the continued expansion of VYVGART into new patient populations, to our fast-approaching growth opportunity with empasiprubart. These presentations also underscore our commitment to generating evidence that propels innovation and positively impacts people living with these debilitating diseases.”

Abstracts at AANEM and MGFA will highlight real-world and clinical data demonstrating the potential of argenx’s innovative therapies to help more people living with autoimmune and neuromuscular diseases.

Details for oral and poster presentations at AANEM and MGFA are as follows:

*Session Times:

More information on the data presented at the 2025 AANEM Annual Meeting and MGFA Scientific Session can be foundhere.

What is VYVGART®(efgartigimod alfa-fcab)?VYVGART is a prescription medicine used to treat a condition called generalized myasthenia gravis, which causes muscles to tire and weaken easily throughout the body, in adults who are positive for antibodies directed toward a protein called acetylcholine receptor (anti-AChR antibody positive).IMPORTANT SAFETY INFORMATIONDo not use VYVGART if you have a serious allergy to efgartigimod alfa or any of the other ingredients in VYVGART. VYVGART can cause serious allergic reactions and a decrease in blood pressure leading to fainting.VYVGART may cause serious side effects, including:

Tell your doctor if you have signs or symptoms of an infection, allergic reaction, or infusion-related reaction. These can happen while you are receiving your VYVGART treatment or afterward. Your doctor may need to pause or stop your treatment. Contact your doctor immediately if you have signs or symptoms of a serious allergic reaction.Before taking VYVGART, tell your doctor if you:

What are the common side effects of VYVGART?The most common side effects of VYVGART are respiratory tract infection, headache, and urinary tract infection.

These are not all the possible side effects of VYVGART. Call your doctor for medical advice about side effects. You may report side effects to the US Food and Drug Administration at 1-800-FDA-1088.

IMPORTANT SAFETY INFORMATIONDo not take VYVGART HYTRULO if you are allergic to efgartigimod alfa, hyaluronidase, or any of the ingredients in VYVGART HYTRULO. VYVGART HYTRULO can cause serious allergic reactions and a decrease in blood pressure leading to fainting.Before taking VYVGART HYTRULO, tell your healthcare provider about all of your medical conditions, including if you:

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

These are not all the possible side effects of VYVGART HYTRULO. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

About VYVGART and VYVGART HytruloVYVGART® (efgartigimod alfa fcab) is a first-in-class human IgG1 antibody fragment that binds to the neonatal Fc receptor (FcRn), resulting in the reduction of circulating IgG autoantibodies. VYVGART® Hytrulo is a subcutaneous combination of efgartigimod alfa (VYVGART) and recombinant human hyaluronidase PH20 (rHuPH20), Halozyme’s ENHANZE® drug delivery technology to facilitate subcutaneous injection delivery of biologics. VYVGART is approved for generalized myasthenia gravis (gMG) and immune thrombocytopenia (Japan only). VYVGART Hytrulo is approved for gMG and chronic inflammatory demyelinating polyneuropathy (CIDP). VYVGART Hytrulo may be marketed under different proprietary names in other regions.

About EmpasiprubartEmpasiprubart (ARGX-117) is a novel humanized monoclonal antibody that binds C2 and blocks activation of both the classical and lectin pathways of the complement cascade. By blocking complement activity upstream of C3 and C5, empasiprubart has the potential to reduce tissue inflammation and cellular damage, representing a broad pipeline opportunity across multiple severe autoimmune indications. In addition to multifocal motor neuropathy, argenx is evaluating empasiprubart in delayed graft function following kidney transplant, and chronic inflammatory demyelinating polyneuropathy (CIDP).

About Generalized Myasthenia Gravis (gMG)Generalized myasthenia gravis (gMG) is a rare and chronic autoimmune disease where IgG autoantibodies disrupt communication between nerves and muscles, causing debilitating and potentially life-threatening muscle weakness. Approximately 85% of people with MG progress to gMG within 24 months¹, where muscles throughout the body may be affected. Patients with confirmed AChR antibodies account for approximately 85% of the total gMG population.

About AChR-Ab seronegative gMGgMG 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.

About Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)CIDP is a rare and serious autoimmune disease of the peripheral nervous system. There is increasing evidence that IgG antibodies play a key role in the damage to the peripheral nerves. People with CIDP experience fatigue, muscle weakness and a loss of feeling in their arms and legs that can worsen over time or may come and go. These symptoms can significantly impair a person's ability to function in their daily lives. Without treatment, one-third of people living with CIDP will need a wheelchair.

About Multifocal Motor NeuropathyMultifocal motor neuropathy (MMN) is a rare, severe, chronic autoimmune disease of the peripheral nervous system. The disease is characterized by slowly progressive, asymmetric muscle weakness mainly of the hands, forearms and lower legs. MMN is often associated with the presence of anti-GM1 IgM autoantibodies, leading to activation of the classical complement pathway, driving subsequent axon damage. High-dose IVIg is the only approved treatment for MMN and patients typically experience disease progression despite therapy, indicating an unmet need for efficacious and better tolerated therapeutic options.

About Idiopathic Inflammatory MyopathiesIdiopathic inflammatory myopathies (myositis) are a rare group of autoimmune diseases that can be muscle specific or affect multiple organs including the skin, joints, lungs, gastrointestinal tract and heart. Myositis can be very severe and disabling and have a material impact on quality of life. Initially, myositis was classified as either DM or polymyositis, but as the underlying pathophysiology of myositis has become better understood, including through the identification of characteristic autoantibodies, new polymyositis subtypes have emerged. Two of these subtypes are IMNM and ASyS. Proximal muscle weakness is a unifying feature of each subtype. IMNM is characterized by skeletal muscle weakness due to muscle cell necrosis. ASyS is characterized by muscle inflammation, inflammatory arthritis, interstitial lung disease, thickening and cracking of the hands (“mechanic’s hands”) and Raynaud’s phenomenon. DM is characterized by muscle inflammation and degeneration and skin abnormalities, including heliotrope rash, Gottron’s papules, erythematous, calcinosis and edema.

About argenxargenx 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. For more information, visitwww.argenx.comand follow us onLinkedIn,Instagram,Facebook, andYouTube.

FORWARD LOOKING STATEMENTSThe contents of this announcement include statements that are, or may be deemed to be, “forward-looking statements.” These forward-looking statements can be identified by the use of forward-looking terminology, including the terms “aim,” “believe,” “can,” “continue,” “evaluate,” “may,” “progress,” and “will” and include statements argenx makes concerning the ADAPT SERON results and interim ADAPT Jr data, including VYVGART’s potential to treat a broad set of MG patients; the continued expansion of VYVGART into new patient populations; its potential growth opportunity with empasiprubart, including the timing thereof; its commitment to generating evidence through its various studies and positively impact patients living with serious neuromuscular diseases; the data for VYVGART, VYVGART Hytrulo and empasiprubart that will be presented at the upcoming AANEM Annual Meeting and MGFA Scientific Session, including the agenda for such meetings; its commitment to advancing innovative therapies and transforming outcomes for patients, including with the EMVIGORATE and EMNERGIZE studies; its goal of (i) advancing VYVGART in treating additional gMG patient populations, (ii) driving CIDP innovation with VYVGART Hytrulo and empasiprubart and (iii) progressing the development of empasiprubart in MMN; its evaluation of emprasiprubart in delayed graft function following kidney transplant and chronic CIDP; and its goal of translating immunology breakthroughs into a world-class portfolio of novel antibody-based medicines. By their nature, forward-looking statements involve risks and uncertainties and readers are cautioned that any such forward-looking statements are not guarantees of future performance. argenx’s actual results may differ materially from those predicted by the forward-looking statements as a result of various important factors, including but not limited to, the results of argenx’s clinical trials; expectations regarding the inherent uncertainties associated with the development of novel drug therapies; preclinical and clinical trial and product development activities and regulatory approval requirements; the acceptance of its products and product candidates by its patients as safe, effective and cost-effective; the impact of governmental laws and regulations, including tariffs, export controls, sanctions and other regulations on its business; its reliance on third-party suppliers, service providers and manufacturers; inflation and deflation and the corresponding fluctuations in interest rates; and regional instability and conflicts. A further list and description of these risks, uncertainties and other risks can be found in argenx’s U.S. Securities and Exchange Commission (SEC) filings and reports, including in argenx’s most recent annual report on Form 20-F filed with the SEC as well as subsequent filings and reports filed by argenx with the SEC. Given these uncertainties, the reader is advised not to place any undue reliance on such forward-looking statements. These forward-looking statements speak only as of the date of publication of this document. argenx undertakes no obligation to publicly update or revise the information in this press release, including any forward-looking statements, except as may be required by law.