argenx Announces 2021 Corporate Priorities and Highlights Recent Achievements Across Immunology Pipeline

• Submitted Biologics License Application (BLA) to U.S. Food and Drug Administration (FDA) for efgartigimod in generalized myasthenia gravis (gMG)
• Initiated 50-patient gMG bridging study of subcutaneous (SC) efgartigimod based on FDA feedback
• Enrolled first 30 patients, necessary for go/no-go decision, in ADHERE trial of SC efgartigimod for chronic inflammatory demyelinating polyneuropathy (CIDP)
• Announced interim data from Phase 2 CULMINATE trial of cusatuzumab in development with Janssen

Breda, the Netherlands – Jan. 8, 2021 – argenx (Euronext & Nasdaq: ARGX), a global immunology company committed to improving the lives of people suffering from severe autoimmune diseases and cancers, today announced its 2021 corporate priorities and highlighted recent achievements from its late-stage immunology pipeline driven by its FcRn antagonist, efgartigimod. Additionally, the Company announced interim data from the Phase 2 CULMINATE trial of cusatuzumab in development with Cilag GmbH International, an affiliate of Janssen, and provided financial guidance for 2021.

argenx previously announced an exclusive license agreement with Zai Lab Limited (“Zai Lab”) for the development and commercialization of efgartigimod in Greater China and the acceleration of efgartigimod development through Phase 2 proof-of-concept trials in new autoimmune indications. Zai Lab will also contribute Chinese patients to argenx’s global Phase 3 trials of efgartigimod. Under the terms of the agreement, argenx will receive $175 million in collaboration payments comprised of upfront Zai Lab equity, a guaranteed development cost-sharing payment, and a milestone payment upon U.S. efgartigimod approval. argenx will also be eligible for tiered royalties based on annual net sales of efgartigimod in Greater China.

“We are excited to enter a new chapter for argenx as we look toward commercialization and achieving our mission of reaching patients with debilitating rare diseases. We’ve submitted a BLA to the FDA for efgartigimod in gMG and expect to have global efgartigimod trials ongoing this year in six indications and two formulations. We hope to continue to demonstrate the broad opportunity of our FcRn antagonist within autoimmune diseases in 2021 and beyond,” said Tim Van Hauwermeiren, Chief Executive Officer of argenx. “In parallel, establishing global commercial infrastructure within the U.S. and Japan continues to be a top priority. Now through our collaboration with Zai Lab in China and with the appointment of a general manager in Europe, we’ve solidified and accelerated our capabilities to bring efgartigimod and our future immunology candidates to patients worldwide.”