Sanofi Pasteur Initiates Phase III Study of Investigational Clostridium difficile Vaccine in the United States

   Sanofi Pasteur Initiates Phase III Study of Investigational Clostridium
                    difficile Vaccine in the United States

Cdiffense trial to evaluate vaccine against a leading cause of
life-threatening, healthcare-associated infections worldwide

PR Newswire

SWIFTWATER, Pa., Aug. 5, 2013

SWIFTWATER, Pa., Aug. 5, 2013 /PRNewswire/ -- Sanofi Pasteur, the vaccines
division of Sanofi (EURONEXT: SAN and NYSE: SNY), announced today the
initiation of its Phase III clinical program called Cdiffense to evaluate the
safety, immunogenicity and efficacy of an investigational vaccine for the
prevention of primary symptomatic Clostridium difficile infection (CDI).
Clostridium difficile (C. diff) is a potentially life-threatening,
spore-forming bacterium that causes intestinal disease. The risk of C. diff
increases with age, antibiotic treatment and time spent in hospitals or
nursing homes, where multiple cases can lead to outbreaks. The investigational
vaccine is designed to help protect at-risk individuals from C. diff, which is
emerging as a leading cause of life-threatening, healthcare-associated
infections (HAIs) worldwide.^[1]

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C. diff toxins cause gastrointestinal disease that can lead to death in
approximately eight to 15 percent of infected people,^[2] contributing to the
approximately 14,000 C. diff-related fatalities in the United States (U.S.)
each year.^[3] Since 20 to 30 percent of patients experience recurrences of
CDI, re-hospitalizations and longer hospital stays remain common.^[4] In
addition, CDI acute care costs U.S. healthcare systems approximately $4.8
billion annually.^[5] The investigational C. diff vaccine is designed to
produce an immune response that targets the toxins generated by C. diff
bacteria, which can cause inflammation of the gut and lead to diarrhea. It
ultimately may help prevent a future infection from occurring.

"With the emergence of difficult-to-manage strains of C. diff, CDI has become
more frequent, more severe and more difficult to treat in recent years,
raising concerns about how to control it and prevent transmission," explained
John Shiver PhD, Senior Vice President for Research & Development at Sanofi
Pasteur. "Vaccination could be an efficacious, cost-effective and important
public-health measure to protect individuals from C. diff."

The Cdiffense Phase III clinical program has just started recruiting
volunteers at approximately 100 sites in the U.S. for a randomized,
observer-blind, placebo-controlled, multi-center, multi-national trial that
will include up to 15,000 adults across 17 countries. Volunteers for the study
should be age 50 or older and planning an upcoming hospitalization or who have
had at least two hospital stays and have received systemic antibiotics in the
past year are also eligible. For more information on the Cdiffense trial,
please visit www.Cdiffense.org.

The U.S. Food and Drug Administration (FDA) granted fast-track designation to
Sanofi Pasteur's investigational C. diff vaccine candidate in 2010. The FDA's
fast-track program is designed to facilitate the development and expedite the
review of new investigational drugs and vaccines that are intended to treat or
prevent serious or life-threatening conditions and demonstrate the potential
to address unmet medical needs.

About C. diff
Clostridium difficile (C. diff) is a potentially life-threatening,
spore-forming bacterium that causes intestinal disease. According to the
Centers for Disease Control and Prevention (CDC), approximately 500,000
Americans are infected with C. diff,^[6] and at least 14,000 fatalities are
attributed to C. diff each year.^[3] The risk of contracting CDI increases
with age, antibiotic treatment and time spent in hospitals or nursing homes,
where multiple cases can lead to outbreaks.^[1] A main source of C. diff is
infected patients who release spores into the environment that can then infect
other people. When antibiotics disrupt the gut's normal flora and a person has
ingested C. diff spores, the C. diff bacteria multiply and release potent
toxins that can damage a person's intestinal lining and cause C. diff
disease.^[7]

About Sanofi
Sanofi, an integrated global healthcare leader, discovers, develops and
distributes therapeutic solutions focused on patients' needs. Sanofi has core
strengths in the field of healthcare with seven growth platforms: diabetes
solutions, human vaccines, innovative drugs, consumer healthcare, emerging
markets, animal health and the new Genzyme. Sanofi is listed in Paris
(EURONEXT: SAN) and in New York (NYSE: SNY).

Sanofi Pasteur, the vaccines division of Sanofi, provides more than 1 billion
doses of vaccine each year, making it possible to immunize more than 500
million people across the globe. A world leader in the vaccine industry,
Sanofi Pasteur offers the broadest range of vaccines protecting against 20
infectious diseases. The company's heritage, to create vaccines that protect
life, dates back more than a century. Sanofi Pasteur is the largest company
entirely dedicated to vaccines. Every day, the company invests more than EUR 1
million in research and development. For more information, please visit:
www.sanofipasteur.comor www.sanofipasteur.us

Forward Looking Statements
This press release contains forward-looking statements as defined in the
Private Securities Litigation Reform Act of 1995, as amended. Forward-looking
statements are statements that are not historical facts. These statements
include projections and estimates and their underlying assumptions, statements
regarding plans, objectives, intentions and expectations with respect to
future financial results, events, operations, services, product development
and potential, and statements regarding future performance. Forward-looking
statements are generally identified by the words "expects", "anticipates",
"believes", "intends", "estimates", "plans" and similar expressions. Although
Sanofi's management believes that the expectations reflected in such
forward-looking statements are reasonable, investors are cautioned that
forward-looking information and statements are subject to various risks and
uncertainties, many of which are difficult to predict and generally beyond the
control of Sanofi, that could cause actual results and developments to differ
materially from those expressed in, or implied or projected by, the
forward-looking information and statements. These risks and uncertainties
include among other things, the uncertainties inherent in research and
development, future clinical data and analysis, including post marketing,
decisions by regulatory authorities, such as the FDA or the EMA, regarding
whether and when to approve any drug, device or biological application that
may be filed for any such product candidates as well as their decisions
regarding labelling and other matters that could affect the availability or
commercial potential of such product candidates, the absence of guarantee that
the product candidates if approved will be commercially successful, the future
approval and commercial success of therapeutic alternatives, the Group's
ability to benefit from external growth opportunities, trends in exchange
rates and prevailing interest rates, the impact of cost containment policies
and subsequent changes thereto, the average number of shares outstanding as
well as those discussed or identified in the public filings with the SEC and
the AMF made by Sanofi, including those listed under "Risk Factors" and
"Cautionary Statement Regarding Forward-Looking Statements" in Sanofi's annual
report on Form 20-F for the year ended December 31, 2012. Other than as
required by applicable law, Sanofi does not undertake any obligation to update
or revise any forward-looking information or statements.

[1] Centers for Disease Control and Prevention. Frequently Asked Questions
about Clostridium difficile for Healthcare Providers. Centers for Disease
Control and Prevention.
http://www.cdc.gov/HAI/organisms/cdiff/Cdiff_faqs_HCP.html. Last Updated March
6, 2013. Accessed May 30, 2013.
[2] Mitchell BG and Gardner A. (2012) Mortality and Clostridium difficile
infection: a review. Aric journal.
[3] Centers for Disease Control and Prevention. Clostridium difficile
Infection. Centers for Disease Control and Prevention.
http://www.cdc.gov/hai/organisms/cdiff/cdiff_infect.html. Last Updated March
1, 2013. Accessed May 30, 2013.
[4] Garey KW, et al. (2008). Meta-analysis to assess risk factors for
recurrent Clostridium difficile infection. Journal Hospital Infection, 70, p.
298-304.
[5] Dubberke ER and Olsen MA. Burden of Clostridium Difficile on the
Healthcare System. Clinical Infectious Diseases 55, no. suppl 2 (2012):
S88–S92. doi:10.1093/cid/cis335.
[6] Rohlke F and Stollman N. Fecal microbiota transplantation in relapsing
Clostridium difficile infection. Therap Adv Gastroenterol.2012
November;5(6): 403–420.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3491681/#bibr37-1756283X12453637.
Accessed May 30, 2013.
[7] Delmee M and Warny M. (1995). Clostridium difficile colitis: recent
therapeutical and immunological considerations. Acta Gastroenterol Belg, 58
(3-4), p. 313-317.



SOURCE Sanofi Pasteur

Website: http://www.sanofipasteur.us
Contact: U.S. Media Relations, Susan Watkins, T. +1 570-957-2563,
susan.watkins@sanofipasteur.com, www.sanofipasteur.us; Global Media Relations,
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www.sanofipasteur.com