arGEN-X – Third Quarter Business Update

November 14, 2014

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 provides a business update for the third quarter 2014 and financial highlights for the nine months ended 30 September 2014.

RECENT PIPELINE HIGHLIGHTS

  • Submitted Investigational New Drug application (IND) to evaluate lead candidate ARGX-110, a novel anti-CD70 therapeutic antibody, in the United States for the treatment of Waldenström’s macroglobulinemia (a rare, incurable B-cell lymphoma) in partnership with The Leukemia and Lymphoma Society (LLS)
  • Initiated the efficacy evaluation of ARGX-110 in patients with relapsed/refractory CD70-positive T-cell lymphomas as an expansion arm of the ongoing Phase 1b study
  • Completed enrolment of first cohort of patients with CD70-positive hematological malignancies into the ongoing Phase 1b expansion trial with ARGX-110
  • Completed enrolment of first cohort of patients with CD70-positive solid tumors into the Phase 1b expansion trial with ARGX-110
  • Announced positive preclinical data for ARGX-113 supporting its use as a potential breakthrough concept for the treatment of severe autoimmune diseases
  • Key patents granted in the US relating to ARGX-110 and ARGX-111, providing patent protection for both until 2031-2032 and allowing for up to an additional five years of patent term extension
  • Patent granted reinforcing protection for the SIMPLE Antibody™ platform and antibodies in arGEN-X’ pipeline

FINANCIAL HIGHLIGHTS

  • Completed successful Initial Public Offering (IPO) on Euronext Brussels (pricing on 8 July with overallotment option exercised on 11 August) raising total gross proceeds of EUR 41.8 million
  • Net loss for the nine-month period to 30 September 2014 was EUR 6.3 million compared to EUR 4.7 million for the same period in 2013
  • Cash position as at 30 September 2014 was EUR 59.9 million. Cash position at the end of June, before the receipt of the proceeds from the IPO, was EUR 20.6 million

Tim Van Hauwermeiren, Chief Executive Officer of arGEN-X, said: “We are well on track executing our IPO business plan, progressing the product pipeline through a series of clinical value inflection points and leveraging the power of our technology suite in the complex target space. We are encouraged by the highly favorable, cumulative safety profile of ARGX-110. The adaptive design of the Phase 1b study enabled us to select compelling orphan indications for further study including T-cell lymphomas and Waldenström’s macroglobulinemia, both characterized by high unmet medical need and lack of treatment options. In addition, we expect to select a safe starting dose for further clinical studies with ARGX-111 before year-end and we are thrilled by the promising preclinical data with ARGX-113 highlighting its potential to become a breakthrough treatment for severe autoimmune diseases based on its unique ability to deplete pathogenic auto-antibodies. With our strong cash position, highly competitive technology suite and diverse product pipeline we are well positioned to create substantial value for our shareholders.”