arGEN-X Granted Broad Patent Covering its Unique SIMPLE Antibody(TM) Platform

Novel Platform Set to Transform Human Therapeutic Antibody Discovery & Development

ROTTERDAM, The Netherlands, July 8, 2010 - arGEN-X, a biopharmaceutical company focused on the discovery
and development of human monoclonal antibodies using its proprietary SIMPLE
Antibody(TM) platform, announces that it has been granted the first patent
covering the platform. The patent GB2461546B, has been granted by the UK
Patent and Trademark Office (UKPTO).

The broad granted patent covers arGEN-X's SIMPLE Antibody(TM)
technology, which yields gold standard human therapeutic antibodies with an
unmatched functional diversity. It also covers arGEN-X's antibody products as
well as methods of generating them. arGEN-X is prosecuting additional patent
applications globally, which when granted will provide the company with an
unrivalled IP position in the human antibody space.

arGEN-X' SIMPLE Antibody(TM) platform utilizes the active immunization of
outbred Camelids with a target antigen to rapidly deliver highly diverse
antibodies whose variable regions are nearly identical to those of human
antibodies. arGEN-X then uses these to produce variable antibody regions with
96-99% human sequence homology via minimal germlining (humanization). This is
easily achieved without any loss in affinity and potency in just a matter of
weeks. These variable domains are then combined with human constant domains
to generate full size, fully human therapeutic antibodies.

A further key attraction of the SIMPLE Antibody(TM) platform
is its unique ability to generate incredibly diverse panels of ultra-potent
antibodies to a broad range of targets, including intractable and conserved
targets. These antibody panels effectively blanket the target of interest
providing pharma researchers with more choice in the drug discovery stage.
This allows them to use more stringent lead selection criteria, increasing
the probability of successful therapeutic antibody development.

arGEN-X has already demonstrated that human antibodies
generated using its SIMPLE Antibody(TM) platform routinely exhibit gold
standard potencies and affinities, without the need for additional
engineering. These properties combined with their excellent manufacturability
, make them an ideal starting point for a therapeutic antibody development
program.

Prof. Hans de Haard, CSO of arGEN-X commenting on today's
announcement said:

"The UKPTO's decision to grant the first patent for our SIMPLE
Antibody(TM) platform is a major value-enhancing milestone in arGEN-X'
corporate development. It is also a key step in our goal to achieve a broad
and unencumbered global IP position for our platform which will give us a
highly competitive position in the human antibody space".

"As we work with our SIMPLE Antibody(TM) platform, we are
increasingly convinced that it will transform the discovery and development
of human therapeutic antibodies. This is due to its ability to rapidly
produce incredibly diverse panels of ultra potent antibodies that address a
broad range of both intractable and conserved targets. These unique
properties are already generating considerable interest amongst potential
partners who are looking to access a platform around which they can build
broadly based therapeutic antibody discovery and development programs."

arGEN-X is currently using the power of the SIMPLE
Antibody(TM) platform to build its business by making this unique technology
and know-how available to biopharmaceutical companies through selective
strategic partnerships and by developing its own portfolio of exciting
therapeutic antibody candidates.

The power of the SIMPLE Antibody(TM) platform is enabling the
Company to rapidly build its own pipeline. arGEN-X' lead product, ARGX-109, a
fully human mAb targeting autoimmune, inflammation and oncology indications,
has already entered preclinical development in less than 12 months from start
of the discovery process. ARGX-109, which targets the cytokine IL-6, has
already shown very high potencies in a range of in vivo studies. arGEN-X
currently has a further three therapeutic antibody candidates in its own
development pipeline.

Note to Editors

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

arGEN-X is a preclinical 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 platform on four human disease targets to date. The
Company's first patent was granted by the UK Patent and Trademark Office in
July 2010. arGEN-X is globally prosecuting additional patent applications,
which will provide it with broad protection of its technology.

arGEN-X' SIMPLE Antibody(TM) Platform is based on the active
immunization of outbred Camelids with target antigens to deliver antibodies
whose variable regions are virtually identical to those of human antibodies.
The combination of those variable domains with the constant domains of human
antibodies, generates full size, human therapeutic antibodies.

The SIMPLE Antibody(TM) Platform enjoys an independent,
unencumbered patent position and is free of target gatekeeping restrictions.

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

SIMPLE stands for Superior Immunodiversity with Minimal
Protein Lead Engineering.

    For further information, please contact:

    Citigate Dewe Rogerson
    David Dible
    Mark Swallow
    Nina Enegren
    T: +44-207-282-2949/2948
    E: David.Dible@citigatedr.co.uk

    arGEN-X
    Tim Van Hauwermeiren, MSc, eMBA
    Chief Executive Officer
    T: +31-6-122-85-257
    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 , E: tim.vh at arGEN-X.com