argenx reports fourth quarter business update and full year 2015 financial results

• Clinical programs in severe auto-immune diseases and oncology
• Supported by strong financial position
• Management to host conference call today at 3 pm CET / 9 am EDT

Breda, the Netherlands / Ghent, Belgium– argenx (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 announced its fourth quarter business update and full year results for 2015, in accordance with IFRS as adopted by the European Union.

The full year results will be discussed during a conference call and webcast presentation today at 3 pm CET / 9 am EDT. To participate in the conference call, please select your phone number below, and use the confirmation code 61559035. The webcast may be accessed on the homepage of the argenx website atwww.argenx.comor byclicking here.

FOURTH QUARTER 2015 AND RECENT HIGHLIGHTS

• Announced initial results from Phase 1 single ascending dose (SAD) study of ARGX-113, a potential breakthrough therapy for severe autoimmune diseases. Results showed compound to be safe and well-tolerated across all doses in healthy volunteers. Promising pharmacodynamic (PD) effects were seen relating to speed, depth and duration of IgG reduction.
• Presented topline Phase 1 clinical data of ARGX-110 in patients with T-cell lymphoma (TCL) showing compelling evidence of early biologic activity, and presented further preclinical evidence on the potential of the compound in acute myeloid leukemia (AML).
• Opened three clinical trial sites in South Korea for recruitment of MET-amplified cancer patients for Phase 1 safety expansion cohort of ARGX-111.
• Received milestone payment from LEO Pharma collaboration, initiated in May 2015 to develop antibody-based treatments for skin conditions.
• Received EUR 16 million investment by U.S. funds advised by subsidiaries of Federated Investors. They entered into a subscription agreement with argenx to purchase 1,480,420 shares at a price of EUR 10.79 per share.
• Appointed Nicolas Leupin, MD, MBA, as Chief Medical Officer (CMO), who will lead the Company’s global clinical development activities.
• Received notification of 13 new patent grants.

FINANCIAL HIGHLIGHTS (as of 31 December, 2015) (compared to financial highlights as of 31 December 2014)

• Operating income of EUR 10 million (31 Dec 2014: EUR 5.4 million).
• Net loss of EUR 15.3 million (31 Dec 2014: EUR 10.3 million).
• Net cash burn of EUR 13.6 million, resulting in a cash position of EUR 42.3 million (cash, cash-equivalents and financial assets) allowing Company to pursue development of its product portfolio as planned.

We are very proud of our recent progress in our ongoing clinical programs and through expansion of our antibody pipeline. In 2015 we began development of ARGX-115, a cancer immunotherapy asset and the first preclinical program out of our Innovative Access Program. We also achieved important milestones across all of our programs, driven by our lead autoimmune candidate, ARGX-113, which entered the clinic in the fourth quarter of 2015, the fourth development program from our SIMPLE AntibodyTM platform to have reached clinical stages in just six years. Looking forward we expect the multiple ascending dose portion of our Phase 1 study will read out in mid-2016, said Tim Van Hauwermeiren, Chief Executive Officer of argenx.

We also made significant progress on the corporate side of our business. Our business development activities continued strong in 2015 with the announcement of our new partnership with LEO Pharma to develop antibody-based treatments for skin conditions. And on the financial front, we announced an investment from a well-established U.S-based investment fund. With a strong cash position, a well-balanced pipeline of wholly-owned and partnered clinical assets and several innovative early stage programs in oncology and auto-immune diseases, we feel we have positioned the Company for future success.