argenx announces extension of therapeutic antibody alliance with Shire

Breda, the Netherlands / Ghent, Belgium – argenx (Euronext Brussels: 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 the extension of its strategic partnership with Shire plc (NASDAQ: SHPG) to advance the discovery and development of novel human therapeutic antibodies for diverse rare and unmet diseases for a further year until May 30, 2018.

The productivity of our collaboration with Shire has presented exciting product development opportunities in previously untapped target territory, said Debbie Allen, Senior VP Business Development of argenx. Extension of this partnership provides both parties the potential to treat the pathophysiology of rare genetic diseases with potentially first-in-class antibody products.

About the strategic alliance with Shire

Under the terms of the agreement extension announced today, the parties will continue to progress preclinical development of the most promising programs to have arisen from the collaboration to date. Upon attainment of specified development criteria, Shire may exercise options – accompanied by a milestone payment to argenx on a per program basis - to take over product development and commercialization. argenx will thereafter receive milestone payments as programs proceed through clinical development and royalties on eventual product sales. argenx shall have the right to in-license any products falling outside Shire’s areas of focus on pre-agreed financial terms. Further details of the extension agreement were not disclosed.

The initial agreement between Shire and argenx commenced in 2012 and was expanded into a strategic alliance in 2014 granting Shire licenses to the entire suite of argenx discovery technologies. argenx has received licensing fees, research funding, and milestone payments from this collaboration.

About argenx

argenx is a clinical-stage biotechnology company with a deep pipeline of differentiated antibody-based therapies intended for the treatment of severe autoimmune diseases and cancer. We are focused on developing product candidates that are either first-in-class against novel targets or best-in-class against known, but complex, targets to treat diseases with a significant unmet medical need. Our ability to execute on this focus is enabled by our suite of differentiated technologies. Our SIMPLE AntibodyTM Platform, based on the powerful llama immune system, allows us to exploit novel and complex targets, and our three antibody engineering technologies enable us to expand the therapeutic index of our product candidates.

For further information, please contact:

Joke Comijn, Corporate Communications and Investor Relations Manager

+32 (0)477 77 29 44

+32 (0)9 310 34 19

Beth DelGiacco (US IR)

Stern Investor Relations

+1 212 362 1200

Forward-looking Statements

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 the intended results of its strategy. 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. argenx undertakes no obligation to publicly update or revise forward-looking statements, except as may be required by law.