arGEN-X Concludes EUR 12.5 Million Series A Financing Round

ROTTERDAM, The Netherlands, December 3 - arGEN-X BV, a biopharmaceutical company focused on the
discovery and development of human antibodies using its proprietary SIMPLE
Antibody(TM) platform, today announced the successful second closing of its
Series A equity financing round. The Company raised an additional EUR 3.0
million (~USD 4.5 million) from two leading life science investors, Credit
Agricole Private Equity and VIB (the prestigious Flemish research institute).

arGEN-X has raised a total of EUR 12.5million (~USD 18.7
million) from its completed Series A equity financing round, which was
heavily oversubscribed.

Philippe Guinot, a senior partner at Credit Agricole Private
Equity, joined the arGEN-X Supervisory Board.

The Series A round was co-led by Forbion Capital Partners (The
Netherlands) and LSP (Life Sciences Partners - The Netherlands). Other
members of the syndicate, which invested in the first closing of EUR 9.5
million, were KBC Private Equity (Belgium), BioGeneration Ventures (The
Netherlands) and existing shareholders Erasmus MC Biomedical Fund and Thuja
Capital Healthcare Funds.

arGEN-X will use the proceeds to further develop the Company's
proprietary, unencumbered SIMPLE Antibody(TM) engine and to continue to build
a proprietary pre-clinical antibody product portfolio. arGEN-X's SIMPLE
Antibody(TM) platform yields monoclonal antibodies which combine an
unparalleled functional diversity against human disease targets with best in
class human germline homology. arGEN-X's SIMPLE Antibodies(TM) are generated
in vivo, starting from active immunization, and exhibit ultra high starting
affinities and potencies without the need for further engineering.

The arGEN-X platform has the potential to rapidly create
exciting product candidates both against novel therapeutic targets and
against targets where standard antibody approaches fail to generate an
optimal lead diversity.

Philippe Guinot, PhD, Senior Partner at Credit Agricole
Private Equity commented: "We believe that arGEN-X has a truly innovative
technology and a management team with an impressive track record of building
a valuable business in the antibody area. It is no surprise to us that the
Company was able to attract such a high-quality syndicate of investors for
its Series A round and Credit Agricole Private Equity is delighted to have
had this opportunity to participate at this important early stage of the
arGEN-X' development."

Tim Van Hauwermeiren, Chief Executive Officer of arGEN-X
added: "We are very pleased to have raised this additional funding from two
experienced European life science investors. In addition, we are proud to
become VIB's first external investment and we view this as a real quality
stamp of approval. With substantial funding now in place, arGEN-X is well
positioned to execute its ambitious value-creating strategy over the next two
years."

Notes for the editor

About arGEN-X - www.arGEN-X.com

arGEN-X is a research stage biopharmaceutical company with a
broadly applicable, proprietary SIMPLE Antibody(TM) platform. The platform
allows arGEN-X to create an unparalleled diversity of in vivo generated
antibody leads against a broad range of human disease targets. This superior
choice of ultra-high affinity and highly potent leads, having best-in-class
human homology, allows for more stringent lead selection criteria, thereby
increasing the probability of success later in the drug development path. The
Company has validated its monoclonal antibody platform on two human disease
targets and has broad patent claims in place covering its technology.

arGEN-X(TM) and SIMPLE Antibody(TM) are deposited trademarks
of arGEN-X BV.

SIMPLE stands for Superior Immunodiversity with Minimal
Protein Lead Engineering.

About Credit Agricole Private Equity -
www.ca-privateequity.com

Credit Agricole Private Equity is an AMF-accredited
asset-management subsidiary of Credit Agricole S.A., specialising in direct
private-equity investment in non-listed companies. A multi-specialist player
in the private-equity market, it has a team of 80 professionals operating in
a variety of areas (LBO & Expansion, Venture Capital, Mezzanine,
Co-Investment, Renewable Energy, PPP Infrastructure, etc.), and manages
EUR2.8 billion in a variety of private-equity vehicles (FCPRs, SICARs, FCPIs
and SCRs). The 12-strong Venture Capital team manages EUR400 million through
FCPIs invested in young companies with high growth potential in the
technology and life-sciences sectors.

About VIB - www.vib.be

VIB is a non-profit research institute in life sciences. About
1200 scientists conduct strategic basic research on the molecular mechanisms
that are responsible for the functioning of the human body, plants, and
micro-organisms. Through a close partnership with four Flemish universities
- UGent, K.U.Leuven, University of Antwerp, and Vrije Universiteit Brussel
- and a solid funding program, VIB unites the forces of 70 research groups
in a single institute. The goal of the research is to extend the boundaries
of our knowledge profoundly. Through its technology transfer activities, VIB
strives to convert the research results into products for the benefit of
consumers and patients. VIB develops and disseminates a wide range of
scientifically substantiated information about all aspects of biotechnology.

For further information, please contact:

    Citigate Dewe Rogerson          arGEN-X
    David Dible                     Tim Van Hauwermeiren, MSc, eMBA
    Mark Swallow                    Chief Executive Officer
    Nina Enegren

    T: +44-207-282-2949/2948        T: +31-6-122-85-257
    E: David.Dible@citigatedr.co.uk E: tim.vh@arGEN-X.com

For further information, please contact: Citigate Dewe Rogerson, David Dible, Mark Swallow, Nina Enegren, T: +44-207-282-2949/2948, E: David.Dible at citigatedr.co.uk; arGEN-X, Tim Van Hauwermeiren, MSc, eMBA, Chief Executive Officer, T: +31-6-122-85-257