argenx’s Partner Bird Rock Bio Demonstrates Potential for Gerilimzumab, A Novel SIMPLE Antibody™ Against IL-6 to Treat Rheumatoid Arthritis

Breda, the Netherlands / Ghent, Belgium – argenx 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 reported that its partner Bird Rock Bio (formerly RuiYi), a company focused on the discovery and development of novel biologic therapies, has announced that gerilimzumab, a novel SIMPLE AntibodyTM neutralizing the IL-6 cytokine, has demonstrated safety and pharmacokinetics that support low, infrequent dosing and the potential for favorable pricing.

Bird Rock Bio initiated two clinical trials in healthy adult volunteers focused on the pharmacokinetics of gerilimzumab in single and multiple ascending dose studies where the compound was administered by subcutaneous injection. A total of 50 subjects were included in both studies, which assessed the safety and tolerability of gerilimzumab compared with placebo. Gerilimzumab was well tolerated and no serious adverse events were reported. Positive results from this study support advancing the compound into trials in patients with autoimmune disorders. Bird Rock Bio plans to complete submission for a pivotal trial for rheumatoid arthritis by the first half of 2016.

Tim Van Hauwermeiren, CEO at argenx commented: The favorable outcomes of the two studies for gerilimzumab represent an exciting step forward for this exceptional antibody. Gerilimzumab was originally discovered using our SIMPLE Antibody™ platform and was further differentiated with our proprietary NHance® technology in order to prolong the circulation time and improve tissue distribution of antibodies. We are very pleased with how rapidly Bird Rock Bio has successfully progressed gerilimzumab.

About gerilimzumab

Gerilimzumab is the result of a unique collaborative model, involving Bird Rock Bio, argenx (Euronext Brussels: ARGX), and Genor Biopharma. In late 2012, Bird Rock Bio entered into a collaboration for the worldwide rights to gerilimzumab from argenx, a biopharmaceutical company focused on creating and developing differentiated antibodies for the treatment of cancer and severe autoimmune diseases. Early in 2013, Bird Rock Bio partnered gerilimzumab with Genor Biopharma for IND enablement, manufacturing process development and commercialization for China. Bird Rock Bio has retained all other commercial rights of gerilimzumab for the rest of the world.

About argenx

argenx combines the diversity of the llama immune system with antibody engineering to advance a clinical pipeline to treat patients with cancer and autoimmune diseases. Our platforms allow us to unlock novel and complex targets and develop antibody-based drugs designed for greater efficacy and longer duration of effect. The strength of our team, our deep understanding of the biology, and our committed collaborations with industry leaders contribute to the success of our journey.

argenx is listed on the Euronext Brussels exchange under the symbol ARGX.

SIMPLE Antibody™ and NHance® are trademarks of arGEN-X NV