Ablynx and Merck Serono Enter into Second Agreement To Co-Discover and Co-Develop Nanobodies (R)

GENEVA, Switzerland, October 11, 2010 - Merck Serono, a division of Merck KGaA, Darmstadt, Germany,
and Ablynx today announced that they have expanded their relationship and
entered into a second agreement, to co-discover and co-develop Nanobodies
against an inflammatory disease target.

Ablynx's Nanobodies are an innovative class of
antibody-derived therapeutic proteins that combine the advantages of
conventional antibodies with key properties of small molecule drugs such as
high affinity, small size allowing alternative delivery and enhanced tissue
penetration, and high stability.

In September 2008, Merck Serono and Ablynx entered into an
agreement to co-discover and co-develop Nanobodies against two targets in
oncology and immunology. This second agreement focuses on the discovery and
development of Nanobody-based therapeutics against an inflammatory disease
target. This new collaboration structure allows Ablynx to drive the process
up to the clinic, leveraging its strengths in Nanobody discovery and
preclinical development.

Under the terms of the agreement, Ablynx will receive up-front
payment of EUR10 million and be responsible for all activities and costs,
excluding manufacturing costs, up to the delivery of a preclinical package
that will form the basis for the filing of an IND or IND equivalent. Upon
acceptance of the package by Merck Serono, Ablynx will be eligible for a
EUR15 million milestone payment. Ablynx has the option to continue with Merck
Serono up to a 50:50 co-development basis and share the resulting profits, or
to convert this collaboration into an exclusive, worldwide licensing deal
with milestone payments and significant tiered royalties. Further details of
the agreement are undisclosed.

"We are very pleased with the progress made to date in our
existing collaboration with Ablynx in oncology and immunology and look
forward to expanding it to the area of rheumatology where our research
focuses on proteins that modulate key pathogenic mechanisms. We believe that
the specific features of Nanobodies have the potential to address some of the
challenges in treating autoimmune and inflammatory diseases in general, and
rheumatology in particular," said Dr Bernhard Kirschbaum, Executive Vice
President Research and Development at Merck Serono.

Dr Edwin Moses, CEO and Chairman of Ablynx added: "We are
delighted to broaden our relationship with Merck Serono. This second
collaboration and the novel deal structure underline the confidence that
Merck Serono has in our discovery and preclinical development capabilities."

About Ablynx

Founded in 2001 in Ghent, Belgium, Ablynx is a
biopharmaceutical company focused on the discovery and development of
Nanobodies, a novel class of therapeutic proteins based on single-domain
antibody fragments, for a range of serious and life-threatening human
diseases. The Company currently has over 240 employees. Ablynx completed a
successful IPO on Euronext Brussels [ABLX] on 7 November 2007 and raised
EUR50 million through an SPO in March 2010.

Ablynx is developing a portfolio of Nanobody-based
therapeutics in a number of major disease areas, including inflammation,
thrombosis, oncology and Alzheimer's disease. Ablynx now has over 25
programmes in its therapeutic pipeline including four Nanobodies in clinical
development. So far, Nanobodies have been successfully generated against more
than 220 different protein targets including several complex targets such as
chemokines, GPCRs, ion channels and viruses, which are typically very
difficult to address with conventional monoclonal antibodies. Efficacy data
have been obtained in 35 in vivo models for Nanobodies against a range of
different targets.

Ablynx has an extensive patent position in the field of
Nanobodies for healthcare applications. It has exclusive and worldwide rights
to more than 130 families of granted patents and pending patent applications,
including the Hamers patents covering the basic structure, composition,
preparation and uses of Nanobodies.

Ablynx has ongoing research collaborations and significant
partnerships with several major pharmaceutical companies, including
Boehringer Ingelheim, Merck Serono, Novartis and Pfizer (previously Wyeth
Pharmaceuticals). Ablynx is building a diverse and broad portfolio of
therapeutic Nanobodies through these collaborations as well as through its
own internal discovery programmes.

The Company's lead programme ALX-0081, an intravenously
administered novel anti-thrombotic, entered a Phase II study in patients
undergoing percutaneous coronary intervention (PCI) in September 2009. Ablynx
demonstrated proof-of-concept by biomarker for ALX-0081 in December 2009.
ALX-0681, a subcutaneous administration of the anti-von Willebrand factor
(vWF) Nanobody and ALX-0081 entered into a Phase II study in TTP patients in
September 2010.

In September 2009, Ablynx's partner Pfizer entered a Phase II
study in RA patients, with an anti-TNF-alpha Nanobody.

In December 2009, Ablynx initiated a double-blind, randomised,
placebo-controlled Phase I study with ALX-0141, a Nanobody targeting Receptor
Activator of Nuclear Factor kappa B Ligand (RANKL), in healthy postmenopausal
women. ALX-0061, an anti-IL6R Nanobody is in preclinical development for the
treatment of autoimmune and inflammatory diseases. In February 2010, Ablynx
announced that it had reached its criteria for initiating the preclinical
development of ALX-0651, a Nanobody against CXCR4, and will progress this
programme towards the clinic. CXCR4 plays an important role in cell mobility,
tumor growth and metastasis. In March 2010, Ablynx advanced an anti-RSV
Nanobody, ALX-0171, into preclinical development. ALX-0171 will be developed
for the treatment of respiratory syncytial virus (RSV) infections, delivered
through inhalation and has the potential to be effective both in the
prevention of infection as well as in treatment once infection has occurred.

Nanobody(R) is a registered trademark of Ablynx NV.

About Merck Serono

Merck Serono is the division for innovative prescription
pharmaceuticals of Merck KGaA, Darmstadt, Germany, a global pharmaceutical
and chemical company. Headquartered in Geneva, Switzerland, Merck Serono
discovers, develops, manufactures and markets innovative small molecules and
biopharmaceuticals to help patients with unmet medical needs. In the United
States and Canada, EMD Serono operates through separately incorporated
affiliates.

Merck Serono has leading brands serving patients with cancer (Erbitux(R),
cetuximab), multiple sclerosis (Rebif(R), interferon beta-1a), infertility
(Gonal-f(R), follitropin alfa), endocrine and metabolic disorders (Saizen(R)
and Serostim(R), somatropin), (Kuvan(R), sapropterin dihydrochloride) as well
as cardiometabolic diseases (Glucophage(R), metformin), (Concor(R),
bisoprolol), (Euthyrox(R), levothyroxine). Not all products are available in
all markets.

With an annual R&D expenditure of more than EUR 1 billion,
Merck Serono is committed to growing its business in specialist-focused
therapeutic areas including neurodegenerative diseases, oncology, fertility
and endocrinology, as well as new areas potentially arising out of research
and development in autoimmune and inflammatory diseases.

About Merck

Merck is a global pharmaceutical and chemical company with
total revenues of EUR 7.7 billion in 2009, a history that began in 1668, and
a future shaped by approximately 40,000 (including Merck Millipore) employees
in 64 countries. Its success is characterized by innovations from
entrepreneurial employees. Merck's operating activities come under the
umbrella of Merck KGaA, in which the Merck family holds an approximately 70%
interest and free shareholders own the remaining approximately 30%. In 1917
the U.S. subsidiary Merck & Co. was expropriated and has been an independent
company ever since.

For more information, please visit www.merckserono.com
or www.merck.de

Merck Serono S.A. - Geneva, 9 Chemin des Mines, 1202 Genève, Suisse, Media relations, Tel: +41-22-414-36-00