argenx announces collaboration with Broteio Pharma

- Differentiated antibody to address complement target - - Represents latest collaboration to stem from the argenx Innovative Access Program - - argenx granted option to license program after preclinical proof-of-concept -

21 March 2017

Breda, the Netherlands/Ghent, Belgium - argenx (Euronext Brussels: ARGX), a clinical-stage biotechnology company developing a deep pipeline of differentiated antibody-based therapies for the treatment of severe autoimmune diseases and cancer, today announced that it has entered into a new collaboration with Broteio Pharma B.V. to develop an antibody against a novel target in the complement cascade with therapeutic potential in autoantibody- and complement-mediated indications including autoimmune haemolytic anaemia (AIHA) and antibody mediated rejection (AMR) following organ transplantation.

"This collaboration represents the latest success for our Innovative Access Program and aligns with our corporate mission to develop differentiated antibodies for cancer and severe autoimmune diseases. The novel antibody targets a component of the complement cascade with therapeutic potential in both orphan and large market indications like Ischemia/Reperfusion Injuries (IRI)," comments Tim Van Hauwermeiren, CEO of argenx. "This new therapeutic antibody has the potential to act alongside our lead product candidate ARGX-113 in a synergistic fashion. ARGX-113 targets FcRn in order to clear pathogenic IgG antibodies while our new complement-targeted antibody can also address IgM mediated autoimmune diseases. This transaction positions us to further build out the depth and breadth of our autoimmune disease pipeline."

Under the terms of the agreement, argenx and Broteio will jointly develop the complement-targeted antibody to establish preclinical proof-of-concept using argenx's proprietary suite of technologies. Upon successful completion of these studies, argenx may exercise an exclusive option to license the program and assume responsibility for further development and commercialization.  

About the Innovative Access Program Through our Innovative Access Program (IAP) argenx is able to serially collaborate closely with academic experts and small biotech companies, bringing antibody discovery technologies to the heart of novel target research. The IAP allows our partners use of our technologies for the development of antibodies to help validate novel targets. In return argenx is granted early access to these targets. The diversity of argenx's SIMPLE Antibody ^TM immune repertoires help streamline target validation, with the potential to transform novel proteins into next generation therapeutic antibody programs.

Role of complement in auto-immune diseases The classical pathway of the complement system is composed of a series of proteins that are activated when IgG or IgM (auto)antibodies bind to their targets. This mechanism contributes to tissue damage and organ dysfunction in a number of (auto)immune inflammatory diseases. The novel complement target is key in the lysis of antibody-decorated cells and is active when an immune reaction is taking place. The novel antibody has therapeutic potential in orphan and large population autoimmune indications including autoimmune haemolytic anaemia (AIHA) and antibody mediated rejection (AMR). 

About Broteio Based in Utrecht, the Netherlands, Broteio Pharma B.V. ("Broteio") is a joint venture between Prothix B.V. and Bioceros Holding B.V. established to develop anti-complement monoclonal antibodies.  

About argenx argenx a clinical-stage biotechnology company developing a deep pipeline of differentiated antibody-based therapies for the treatment of severe auto-immune diseases and cancer. We are focused on developing product candidates with the potential to be either first-in-class against novel targets or best-in-class against known, but complex, targets in order to treat diseases with a significant unmet medical need. Our ability to execute on this focus is enabled by our suite of differentiated technologies. Our SIMPLE Antibody ^TM Platform, based on the powerful llama immune system, allows us to exploit novel and complex targets, and our three antibody engineering technologies are designed to enable us to expand the therapeutic index of our product candidates.   www.argenx.com

For further information, please contact:

Joke Comijn, Corporate Communications and Investor Relations Manager +32 (0)477 77 29 44 +32 (0)9 310 34 19 info@argenx.com

Beth DelGiacco (US IR) Stern Investor Relations +1 212 362 1200 beth@sternir.com

Forward-looking Statements The contents of this announcement include statements that are, or may be deemed to be, "forward-looking statements." These forward-looking statements can be identified by the use of forward-looking terminology, including the terms "believes," "estimates," "anticipates," "expects," "intends," "may," "will," or "should," and include statements argenx makes concerning the intended results of its strategy; its financial condition, results of operation and business outlook; the sufficiency of its cash, cash equivalents and current financial assets; and the momentum of its product candidate pipeline as well as the advancement of, and anticipated clinical development and regulatory milestones and plans related to, argenx's product candidates and clinical trials. By their nature, forward-looking statements involve risks and uncertainties and readers are cautioned that any such forward-looking statements are not guarantees of future performance. argenx's actual results may differ materially from those predicted by the forward-looking statements. argenx undertakes no obligation to publicly update or revise the information in this press release, including any forward-looking statements, except as may be required by law.