argenx SE

Regulatory Filings • May 15, 2019

argenx to Host R&D Day on May 22, 2019

May 15, 2019

Breda, the Netherlands / Ghent, Belgium – argenx (Euronext & Nasdaq: ARGX), a clinical-stage biotechnology company developing a deep pipeline of differentiated antibody-based therapies for the treatment of severe autoimmune diseases and cancer, today announced that it will host an R&D Day for analysts and investors on May 22, 2019 at 8 a.m. ET in New York City.

argenx management will showcase two new product candidates, ARGX-117 and ARGX-118, and provide updates on the cusatuzumab (ARGX-110) development plan and argenx's preparation for the potential commercialization of efgartigimod (ARGX-113). Additionally, the event will feature presentations from several key opinion leaders:

• Erik Hack, M.D. Ph.D., Professor of Immunology at UMC Utrecht
• Bart Lambrecht, M.D., Ph.D., Director, VIB Center for Inflammation Research at Ghent University
• W. Ludo van der Pol, M.D., Ph.D., Associate Professor of Neurology at UMC Utrecht
• Rafael Villicana, M.D., Associate Professor of Medicine, Medical Director of Kidney Transplantaion at Loma Linda University Medical Center

A live webcast of the event will be available on the Company's website at www.argenx.com. A replay of the event will be available for 90 days following the presentation.

About argenx

argenx is a clinical-stage biotechnology company developing a deep pipeline of differentiated antibody-based therapies for the treatment of severe auto-immune diseases and cancer. The company is focused on developing product candidates with the potential to be either first-inclass against novel targets or best-in-class against known, but complex, targets in order to treat diseases with a significant unmet medical

need. argenx's ability to execute on this focus is enabled by its suite of differentiated technologies. The SIMPLE AntibodyTM Platform, based on the powerful llama immune system, allows argenx to exploit novel and complex targets, and its three complementary Fc engineering technologies are designed to expand the therapeutic index of its product candidates.

www.argenx.com

For further information, please contact:

Joke Comijn, Director Corporate Communications & Investor Relations (EU) +32 (0)477 77 29 44 +32 (0)9 310 34 19 info@argenx.com

Beth DelGiacco, VP Investor Relations (US) +1 518 424 4980 bdelgiacco@argenx.com

Forward-looking Statements

The contents of this announcement include statements that are, or may be deemed to be, "forward-looking statements." These forwardlooking 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 the intended results of its strategy and the momentum of its product candidate pipeline. 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 argenx's expectations regarding its the inherent uncertainties associated with competitive developments, 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.