Merck Serono Announces Extension of FDA Priority Review Period for Cladribine Tablets for the Treatment of Relapsing Forms of Multiple Sclerosis

FDA Extends Priority Review period of Cladribine Tablets by Three Months

GENEVA, Switzerland, November 26, 2010 - Merck Serono, a division of Merck KGaA, Darmstadt, Germany,
announced today that the U.S. Food and Drug Administration (FDA) has extended
its review period for Cladribine Tablets as a therapy for relapsing forms of
multiple sclerosis (MS) by three months to February 28, 2011.

The FDA granted Priority Review status for Cladribine Tablets
in July of 2010, reducing the standard 10-month review period to six months,
which was set to end on November 28, 2010. The FDA extended the review period
to provide additional time for a full review of additional information
provided under the new drug application (NDA).

"Merck Serono continues to work closely with the FDA during
the review process of the Cladribine Tablets new drug application," said
Bernhard Kirschbaum, Merck Serono's Head of Global Research and Development.
"We will continue working towards our goal of providing an oral
disease-modifying drug for the treatment of relapsing multiple sclerosis."

About Cladribine Tablets

Merck Serono's oral formulation of cladribine (Cladribine
Tablets) is an investigational treatment for patients with relapsing forms of
multiple sclerosis (MS). Cladribine is a small molecule that may interfere
with the behavior and the proliferation of certain white blood cells,
particularly lymphocytes, which are thought to be involved in the
pathological process of MS. Cladribine Tablets were approved in Russia in
July 2010 and in Australia in September 2010 as a treatment of
relapsing-remitting MS and are under regulatory review in other countries.

    The clinical development program for Cladribine Tablets includes:

    - The CLARITY (CLAdRIbine Tablets treating MS orallY) study and its
      extension: a two-year Phase III placebo-controlled trial designed to
      evaluate the efficacy and safety of Cladribine Tablets as a monotherapy
      in patients with relapsing-remitting MS and the CLARITY EXTENSION two-
      year Phase III study designed to provide data on the long-term safety
      and efficacy of extended administration of Cladribine Tablets for up to
      four years.
    - The ORACLE MS (ORAl CLadribine in Early MS) study: a two-year Phase III
      placebo-controlled trial designed to evaluate the efficacy and safety
      of Cladribine Tablets as a monotherapy in patients at risk of
      developing MS (patients who have experienced a first clinical event
      suggestive of MS). This trial was announced in September 2008.
    - The ONWARD (Oral Cladribine added oN to interferon beta-1a
      in patients With Active Relapsing Disease) study: a Phase II
      placebo-controlled trial designed primarily to evaluate the safety and
      tolerability of adding Cladribine Tablets treatment to patients with
      relapsing forms of MS, who have experienced breakthrough disease while
      on established interferon-beta therapy. This trial was announced in
      January 2007.
    - The PREMIERE (PRospective observational long-term safEty
      registry of Multiple sclerosis patIEnts who have participated in
      CladRibinE clinical trials) registry: an eight-year observational
      safety registry of patients who have participated in Cladribine Tablets
      clinical trials, designed to support the evaluation of the long-term
      safety of Cladribine Tablets in MS.

About multiple sclerosis

Multiple sclerosis (MS) is a chronic, inflammatory condition
of the central nervous system and is the most common, non-traumatic,
disabling neurological disease in young adults. It is estimated that
approximately two million people have MS worldwide. While symptoms can vary,
the most common symptoms of MS include blurred vision, numbness or tingling
in the limbs and problems with strength and coordination. The relapsing forms
of MS are the most common.

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 Geneve, Suisse, Media relations, Tel: +41-22-414-36-00