Teriflunomide in Adjunct to Interferon Beta Significantly Improved Outcomes of Multiple Sclerosis Patients

One-Year Phase II Data Presented at the 2010 ACTRIMS Meeting

PARIS, June 7, 2010 - Sanofi-aventis (EURONEXT: SAN and NYSE: SNY) reported today
new one-year data from a Phase II study with teriflunomide, a novel oral
disease modifier being investigated for the treatment of relapsing multiple
sclerosis (RMS). Study results demonstrated an improvement in outcomes, with
a consistent safety profile with the data from a previous Phase II
monotherapy study, in patients treated with interferon beta (IFN-[BETA]) - a
standard therapy in RMS - and receiving teriflunomide 7mg or 14mg, compared
with patients treated with IFN-[BETA] and receiving oral placebo.

The findings were the subject of the leading oral presentation
at the American Committee for Treatment and Research in Multiple Sclerosis
meeting (ACTRIMS) in San Antonio, TX, USA. This study is part of a
comprehensive clinical development program for teriflunomide both in
monotherapy and in adjunct therapy in MS patients.

Although this Phase II study (n=116) was not powered to test
for efficacy, patients taking 7mg or 14mg teriflunomide in adjunct to stable
dose IFN-[BETA] experienced a significant relative risk reduction (86%;
p=0.0005 and 82.8%; p<0.0001 respectively) in the number of gadolinium
enhancing T1 (T1-Gd) lesions on brain magnetic resonance imaging compared
with patients taking stable dose IFN-[BETA] with placebo. No unexpected
safety findings have been showed with teriflunomide during the one-year
period of the study as compared to the initial six-month period.
Discontinuations due to treatment-emergent adverse events (TEAEs) were low
and numerically similar in the three groups (placebo: 2; 7mg: 3; 14mg: 3).

"These full-year exploratory study results are encouraging as
they demonstrate significant improvement in disease activity based on MRI and
an acceptable safety profile associated with teriflunomide when added on top
of stable therapy with IFN-[BETA]," said Mark S. Freedman, HBSc, MSc, M.D.,
Professor of Neurology, Department of Medicine, University of Ottawa,
Ontario, Canada. "Adjunct therapy could fill an unmet medical need for those
patients who are on interferon therapy but have some disease activity as
measured by MRI or relapse rate. We hope to replicate the results in a Phase
III study program."

A dose-dependent trend toward a relative risk reduction in the
volume of brain lesions was observed with teriflunomide 7mg or 14 mg groups
when used as adjunct therapy compared with placebo (72.1%; p=0.11 and 70.6%;
p=0.01 respectively). There was also a dose-dependent trend to a reduction in
annualized relapse rate of 32.6% (p=0.43) and 57.9% (p=0.11) in 7mg or 14mg
teriflunomide adjunct groups respectively compared to IFN-[BETA] with
placebo.

The most frequently reported treatment emergent adverse events
were upper respiratory tract infections as a whole (placebo: 17.1%; 7mg:
16.2%; 14mg: 23.7%), mainly nasopharyngitis and sinusitis, all types of
headaches (placebo: 7.3%; 7mg: 5.4%; 14mg: 18.4%), all gastrointestinal
disorders (placebo: 24.4%; 7mg: 18.9%; 14mg: 31.6%). White blood cell counts
decreases were numerically comparable in both teriflunomide and placebo
treatment groups (placebo: 3; 7mg: 3; 14mg: 4) and no patients discontinued
treatment due to neutropenia or infection. Hepatic TEAEs were mainly
asymptomatic liver enzyme elevation; mostly alanine aminotransferase (ALT)
increased, not exceeding three times the upper limit of the norm and no cases
of concurrent increase of ALT and total bilirubine were reported.

About teriflunomide

Teriflunomide is a new oral disease modifier that blocks de
novo pyrimidine synthesis thus reducing T- and B-cells proliferation with no
cytotoxicity. A comprehensive clinical development program for teriflunomide
has been launched in monotherapy (Phase III studies are ongoing) and in
adjunct therapy (Phase II studies are closed). This Phase II study with once
daily oral teriflunomide on top of IFN-[BETA] was a multicenter,
placebo-controlled, double-blinded, randomized study, conducted in relapsing
multiple sclerosis patients. The primary objective of the study was to
evaluate the tolerability and safety of teriflunomide 7mg and 14mg in adjunct
therapy with IFN-[BETA]. The one-year results of this study presented this
year during the ACTRIMS congress complement the 24-weeks study results
presented last year at the European Committee for Treatment and Research in
Multiple Sclerosis congress (ECTRIMS). Results from a second Phase II study
with teriflunomide in adjunct therapy with glatiramer acetate (GA) compared
with matching placebo added to GA, were also presented this year during the
American Academy of Neurology (AAN) meeting.

About Multiple Sclerosis

Multiple sclerosis (MS) is one of the most disabling diseases
in young patients beside accidents. Today, over two million people around the
world suffer from MS. MS is the result of damage to myelin - a protective
sheath surrounding nerve fibres of the central nervous system. When myelin is
damaged, this interferes with messages between the brain and other parts of
the body. Multiple sclerosis is a very variable condition and the symptoms
depend on which areas of the central nervous system have been affected. There
is no set pattern to MS and everyone with MS has a different set of symptoms,
which vary from time to time and can change in severity and duration, even in
the same person. Management of MS is complex; early intervention in the
pathological process is essential in order to delay disease progression or at
least, slow it down. It involves several layers of health and social
services, as well as various healthcare professionals. Although there is no
known cure for multiple sclerosis, several therapies are proven to be helpful
but effective new oral therapies are eagerly awaited.

About sanofi-aventis

Sanofi-aventis, a leading global pharmaceutical company,
discovers, develops and distributes therapeutic solutions to improve the
lives of everyone. Sanofi-aventis is listed in Paris (EURONEXT: SAN) and in
New York (NYSE: SNY). For more information, please visit:
www.sanofi-aventis.com.

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Media contact : Philippe BARQUET, Tél. : +33(0)6-70-48-61-28, E-mail : philippe.barquet at sanofi-aventis.com