Breda, the Netherlands ??August?25, 2021 ??argenx (Euronext & Nasdaq: ARGX), a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases and cancer, today announced that it has submitted, and the European Medicines Agency (EMA) has validated, the marketing authorization application (MAA) for the Company?s investigational FcRn antagonist, efgartigimod, for the treatment of generalized myasthenia gravis (gMG). Validation of the MAA confirms that the application is sufficiently complete to begin the formal review process.

The MAA is supported by results from the pivotal Phase 3 ADAPT trial evaluating the safety and efficacy of efgartigimod for the treatment of patients with gMG.

?gMG is a severe, chronic and debilitating disease that can be unpredictable and greatly impact a person?s quality of life. The EMA?s validation is an exciting step closer to our goal of helping people globally who are living with this disease in which there remains a significant unmet need.? said Tim Van Hauwermeiren, Chief Executive Officer of argenx. ?We have been building an experienced commercial team in Europe and look forward to our continued collaboration with European regulatory authorities through the review process.?

?There remains a significant unmet need for new gMG treatment options that are targeted to the underlying pathogenesis of the disease and supported by clinical data,? commented Prof. Dr. Andreas Meisel, Senior Physician of Neurology, Head of Myasthenia Gravis Outpatient Clinic at the Department of Neurology, Charit? ? Universit?tsmedizin Berlin, and Principal Investigator on the ADAPT study. ?Myasthenia gravis can severely impact a person?s quality of life and ability to carry out daily tasks, such as speaking, chewing and swallowing food, or brushing teeth and hair. In some cases, patients may also experience difficulty breathing. I am hopeful for continued research advancements for new options to treat this debilitating disease.?

Efgartigimod is currently under review with the U.S. Food and Drug Administration (FDA) for the treatment of gMG with a Prescription Drug User Fee Act (PDUFA) target action date of December 17, 2021. argenx also submitted and was notified of acceptance of an application for efgartigimod to Japan?s Pharmaceuticals and Medical Devices Agency (PMDA) earlier this year.

Phase 3 ADAPT Trial?

The Phase 3 ADAPT trial was a randomized, double-blind, placebo-controlled, multi-center, global trial evaluating the safety and efficacy of efgartigimod in patients with gMG. A total of 167 adult patients with gMG in North America, Europe and Japan enrolled in the trial and were treated. Patients were eligible to enroll in ADAPT regardless of antibody status, including patients with acetylcholine receptor (AChR) antibodies (AChR-Ab+) and patients where AChR antibodies were not detected. Patients were randomized in a 1:1 ratio to receive efgartigimod or placebo for a total of 26 weeks. ADAPT was designed to enable an individualized treatment approach with an initial treatment cycle followed by a variable number of subsequent treatment cycles. The primary endpoint was the number of AChR-Ab+ patients who achieved a response on the MG-ADL score defined by at least a two-point improvement for four or more consecutive weeks.

About Efgartigimod?

Efgartigimod is an investigational antibody fragment designed to reduce pathogenic immunoglobulin G (IgG) antibodies by binding to the neonatal Fc receptor and blocking the IgG recycling process. Efgartigimod is being investigated in several autoimmune diseases known to be mediated by disease-causing IgG antibodies, including neuromuscular disorders, blood disorders, and skin blistering diseases.

About Myasthenia Gravis

Myasthenia gravis (MG) is a rare and chronic autoimmune disease, often causing debilitating and potentially life-threatening muscle weakness. More than 85% of people with MG progress to generalized MG (gMG) within 18 months, where muscles throughout the body may be affected, resulting in extreme fatigue and difficulties with facial expression, speech, swallowing and mobility. In more life-threatening cases, MG can affect the muscles responsible for breathing.

About argenx?

argenx is a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases and cancer. 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 is evaluating efgartigimod in multiple serious autoimmune diseases. argenx is also advancing several earlier stage experimental medicines within its therapeutic franchises. argenx has offices in Belgium, the United States, Japan, and Switzerland. For more information, visit www.argenx.com and follow us on?LinkedIn.

Media: Kelsey Kirk kkirk@argenx.com Joke Comijn (EU) jcomijn@argenx.com Investors: Beth DelGiacco bdelgiacco@argenx.com Michelle Greenblatt mgreenblatt@argenx.com

The 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 believes, estimates, anticipates, expects, intends, may, will, or should, and include statements argenx makes concerning: its expected collaboration with European regulatory authorities; its statements regarding therapeutic potential of efgartigimod in patients; the commercial potential of efgartigimod; its clinical development and regulatory plans, including the timing and outcome of regulatory filings and approvals, including those with FDA,?PMDA and EMA?described in this announcement and the timing and progress of commercialization activities; and its statements regarding research advancements and number of treatment options. 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 the effects of the COVID-19 pandemic, the inherent uncertainties associated with preclinical and clinical trial and product development activities and regulatory approval requirements; argenx?s reliance on collaborations with third parties; estimating the commercial potential of argenx?s product candidates; argenx?s ability to obtain and maintain protection of intellectual property for its technologies and drugs; argenx?s limited operating history; and argenx?s ability to obtain additional funding for operations and to complete the development and commercialization of its product candidates. 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.