arGEN-X to Host Conference Call & Webcast to Report Half-Year Results on 26 August 2015

Breda, the Netherlands / Ghent, Belgium– arGEN-X N.V. (Euronext Brussels: ARGX), a clinical-stage biopharmaceutical company focused on creating and developing differentiated therapeutic antibodies for the treatment of cancer and severe autoimmune diseases, today announces it will report its business update and financial results for the first half of 2015 on Wednesday, August 26, 2015.

The arGEN-X management team will host a conference call and audio webcast at 3:00pm CET (9:00am EDT) to discuss the financial results, as well as provide a half-year business update.

To participate in the conference call, please select your phone numberhere, and use the confirmation code 89351549. The webcast may be accessed on the homepage of the arGEN-X website atwww.argen-x.comor by clicking here.

A replay of the webcast will also be available at the arGEN-X