New Data Supporting Cladribine Tablets as a Potential New Therapeutic Option Presented at the 62nd AAN Annual Meeting

TORONTO and GENEVA, April 16, 2010 - Merck Serono, a division of Merck KGaA, Darmstadt, Germany, today
announced that new data providing further understanding on Cladribine
Tablets as a potential new therapeutic option for relapsing forms of
multiple sclerosis (MS) were presented at the 62nd Annual Meeting of the
American Academy of Neurology (AAN). Cladribine Tablets, Merck Serono's
proprietary investigational oral formulation of cladribine, is currently
under regulatory review in a number of countries.

"The relevance of the CLARITY study is further substantiated by the
series of additional analyses presented at AAN", said Bernhard Kirschbaum,
Merck Serono's Head of Global Research and Development. "We are committed
to continuing to work with regulatory authorities to bring Cladribine
Tablets to patients at the earliest point in time."

The data presented at AAN are from pre-specified and post-hoc analyses
of the Phase III CLARITY a clinical trial and show that the administration
of Cladribine Tablets in study subjects resulted in:

    - Increase in the proportion of patients with disease activity-free
      status compared with the placebo group over the entire 96-week study
      (43% and 44% of patients treated with Cladribine Tablets total dose
      of 3.5 mg/kg and 5.25 mg/kg respectively compared with 16% of patients
      who received placebo - p<0.001 for both Cladribine Tablets groups) with
      statistically significant findings as early as 24 weeks (67% and 70%
      of patients treated with Cladribine Tablets total dose of 3.5 mg/kg and
      5.25 mg/kg respectively compared with 39% of patients who received
      placebo - p<0.001 for both Cladribine Tablets groups). Disease
      activity-free status was defined as having no clinical activity (no
      relapse and no sustained disability progression) and no radiological
      activity (no T1 Gd+ lesions and no active T2 lesions) over the
      96-week study(1)
.
    - Reductions in annualized relapse rate (ARR) compared to the placebo
      group over 96 weeks across the spectrum of baseline demographics and
      disease characteristics included in the CLARITY study (gender, age,
      treatment history, number of relapses in the 12 months preceding study
      entry, baseline disease disability, baseline MRI activity and burden
      of disease)(2)

    - Reduced consumption of healthcare resources, a decreased need for
      societal support, improvements in patient productivity, and reductions
      in total non-drug expenditure, relative to placebo, as measured by
      data collected in the CLARITY study with a 'resource utilization form'
      at baseline and at scheduled patient visits(3)
.
    - Decrease of proportions of circulating CD4+ T cells relative to the
      total number of lymphocytes at the end of treatment periods compared
      to baseline, while the proportions of other lymphocyte subtypes
      (CD8+ T, B and natural killer cells) were preserved or increased
      relative to total lymphocytes.(4)

Overall, the frequencies of adverse events by MedDRA System Organ Class
in both Cladribine Tablets treatment groups from the CLARITY study were
comparable to those observed in the placebo group. The most commonly
reported adverse events were headaches, upper respiratory tract infection,
nasopharyngitis and nausea. Lymphopenia, an expected event based on the
presumed mechanism of action of cladribine, occurred more frequently in
the Cladribine Tablets treatment groups (3,5 mg/kg total dose: 21.6%;
5.25 mg/kg total dose: 31.5%; placebo: 1.8%). The overall rate and incidence
of infections in patients treated with Cladribine Tablets and placebo were
similar. Herpes zoster infections were reported in 2.3% of patients treated
with Cladribine Tablets. These herpes infections were localized to the skin
and responded appropriately to treatment.

(a) CLARITY: CLAdRIbine Tablets Treating MS OrallY

References:

(1) Analysis of Clinical and Radiological Disease Activity-Free Status
in Patients with Relapsing-Remitting Multiple Sclerosis (RRMS) Treated with
Cladribine Tablets, in the Double-Blind, 96-Week CLARITY Study (presentation
S21.008, Wednesday, April 14, 2010, 3:45 pm EDT)

(2) Consistent Efficacy of Cladribine Tablets across Multiple Sclerosis
and Patient Characteristics, in the Double-Blind, 96-Week CLARITY Study
(poster P02.186, Tuesday, April 13, 2010, 3:00 pm-7:30 pm EDT)

Reductions in the annualized relapse rate (ARR) across the various
patient strata:

    - Gender (man or woman): Relative reductions in ARR were 61% and 55%,
      respectively, for 3.5 mg/kg and 68% and 48%, respectively, for
      5.25 mg/kg (all p<0.001 versus placebo)

    - Age (=40 or >40): Relative reductions in ARR were 58% and 57%,
      respectively, for 3.5 mg/kg and 63% and 46%, respectively, for
      5.25 mg/kg (all p<0.001 versus placebo) 

    - Treatment history (previously treated with disease-modifying therapy
      or drug-naïve patients): Relative reductions in ARR were 45% and 61%,
      respectively, for 3.5 mg/kg and 58% and 58%, respectively for
      5.25 mg/kg (all p=0.0013 versus placebo)

    - Number of relapses in the 12 months preceding study entry (=1, 2 or
      =3 relapses): Relative reductions in ARR ranged from 48% (relative
      risk: 0.50; 95% confidence interval: 0.37, 0.66) to 76% (relative
      risk: 0.24; 95% confidence interval: 0.09, 0.64) depending on dose
      group (all p=0.006 versus placebo) 

    - Level of disability at baseline (EDSS 0-2.5 or EDSS =3): Relative
      reductions in ARR ranged from 49% (relative risk: 0.51; 95%
      confidence interval: 0.38, 0.68) to 65% (relative risk: 0.35; 95%
      confidence interval: 0.25, 0.50) depending on dose group (all p<0.001
      versus placebo)

    - T1 Gd+ lesions (no lesions or =1 lesion): Relative reductions in ARR
      ranged from 45% (relative risk: 0.55; 95% confidence interval: 0.42,
      0.72) to 75% (relative risk: 0.26; 95% confidence interval: 0.17, 0.40)
      depending on dose group (all p<0.001 versus placebo)

    - T2 lesion volume (>or = median T2 lesion volume status): Relative
      reductions in ARR ranged from 48% (relative risk: 0.53; 95% confidence
      interval: 0.39, 0.71) to 67% (relative risk: 0.33; 95% confidence
      interval: 0.24, 0.47) depending on dose group (all p<0.001
      versus placebo)

(3) Health Resource Utilization in the CLARITY Study (poster P01.205,
Tuesday, April 13, 2010, 7:30 am-12:00 pm EDT)

(4) Effects of Cladribine Tablets on Circulating Lymphocyte Subsets in
the 96-Week CLARITY Study in Relapsing-Remitting Multiple Sclerosis (RRMS)
(poster P04.219, Wednesday, April 14, 2010, 3:00 pm-7:30 pm EDT)

CLARITY study design

The CLARITY study was a two-year (96-week), randomized, double-blind,
placebo-controlled, international trial. It randomized 1,326 patients with
relapsing-remitting MS according to the revised McDonald criteria. Study
participants were randomized to one of three different treatment groups
consisting of two different dose regimens of Cladribine Tablets or matching
placebo tablets (1:1:1 ratio). Cladribine Tablets were given in two
(3.5 mg/kg total dose) or four (5.25 mg/kg total dose) treatment courses in
the first year, with each course consisting of once daily administration for
four to five consecutive days (depending on patient weight), which means
study patients took Cladribine Tablets for 8 to 20 days during the year.
In the second year, two treatment courses were administered to all patient
groups, meaning that patients took Cladribine Tablets for 8 to 10 days
during the year.

The primary endpoint of the CLARITY study was the relapse rate over
96 weeks. Secondary endpoints included MRI endpoints, proportion of subjects
relapse-free and disability progression at 96 weeks.

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 more than 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 7.7 billion in 2009, a history that began in 1668, and a future
shaped by approximately 33,000 employees in 61 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.

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