Merck Serono Receives Refuse to File Letter From FDA on Cladribine Tablets New Drug Application

GENEVA, November 30 - Merck Serono, a division of Merck KGaA, Darmstadt, Germany,
announced today that its US affiliate received a refuse to file letter from
the US Food and Drug Administration (FDA) on the New Drug Application (NDA)
for Cladribine Tablets, Merck Serono's proprietary investigational oral
formulation of cladribine, as a therapy for relapsing forms of multiple
sclerosis (MS).

"The company will work closely with the FDA to fully
understand FDA's concerns and define a path forward for a successful
resubmission of this application at the earliest point in time," said Elmar
Schnee, President of Merck Serono. "We remain focused on delivering on our
promise to transform the way people living with multiple sclerosis approach
their therapy options."

Based on current regulations, once a NDA is submitted to the
FDA, the Agency has 60 days to preliminarily review the NDA submission and
assess whether the NDA is sufficiently complete to permit a substantive
review. If it determines that the NDA is not sufficiently complete, the FDA
issues a refuse to file letter to the applicant. Merck Serono plans to
request a meeting with the FDA as soon as possible to discuss its comments on
the NDA submission and to reach an understanding on what would be required
for the Cladribine Tablets NDA to be accepted for review.

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.

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 its two-year
      extension 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.

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 more
than 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 alpha), 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 around EUR 1bn, 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 7.6 billion in 2008, a history that began in 1668, and a
future shaped by approximately 33,000 employees in 60 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, 9 Chemin des Mines, 1202 Geneva, Switzerland, Media Relations, Tel.: +41-22-414-36-00