Update: Daiichi Sankyo Completes Enrollment of the Edoxaban Global Phase III ENGAGE AF-TIMI 48 Study in Patients With Atrial Fibrillation

More Than 21,000 Patients Enrolled in the Largest Clinical Study with a Factor Xa Inhibitor

TOKYO, December 1, 2010 - Daiichi Sankyo Company, Limited (TSE: 4568), announced today
that it has successfully completed patient enrollment for its phase III
ENGAGE AF-TIMI 48 clinical study of edoxaban, a direct, specific, oral Factor
Xa inhibitor that is being investigated in two different dosing regimens
given once-daily, to prevent the occurrence of strokes and systemic embolic
events (SEE) in patients with atrial fibrillation (AF).

An estimated 4.5 million people in Europe, 2.2 million
Americans, and more than 800,000 people in Japan suffer from AF.[1],[2],[3]
Due to the aging population, the number of patients with AF worldwide is
likely to increase 2.5-fold by the year 2050.[4]

The ENGAGE AF-TIMI 48 study began enrollment in November 2008.
It is an event-driven, randomised, double-blind, double-dummy, parallel
group, multi-centre, multi-national study designed to assess the efficacy and
safety of edoxaban compared to the current standard of care, warfarin.
Patients in the study are randomised to one of three treatment groups: 30 mg
edoxaban once-daily, 60 mg edoxaban once-daily, or warfarin, a vitamin K
antagonist. In addition, edoxaban doses are further adjusted to treat
patients with renal impairment and/or low body weight, or those taking strong
P-glycoprotein inhibitors. Those randomised to warfarin are dosed once-daily
to achieve an International Normalised Ratio (INR) between 2.0 and 3.0.

"The completion of enrollment for the largest AF outcomes
study ever undertaken — ENGAGE AF-TIMI 48 — marks a key milestone in the
development of edoxaban and for Daiichi Sankyo," said Glenn Gormley, MD, PhD,
Chief Science Officer & President, Daiichi Sankyo Pharma Development.

This phase III global AF study, Effective aNticoaGulation with
factor xA next GEneration in Atrial Fibrillation (ENGAGE AF-TIMI 48),
enrolled 21,107 subjects at nearly 1,400 clinical trial sites located
throughout North America, South America, Africa, Asia, Europe and
Australia/New Zealand. The primary endpoint of this study is to compare the
efficacy of edoxaban to warfarin in the prevention of stroke and SEE. The
primary safety assessment is the incidence of major bleeding events.

"As new options to prevent stroke in AF patients become
available, it will be important that these treatments eliminate the need for
extensive monitoring and dietary modifications," said Elliott Antman, MD,
Professor of Medicine, Harvard Medical School, Senior Investigator with the
Brigham and Women's Hospital-based TIMI Study Group. "Based on phase II study
results, edoxaban has shown promise of potentially addressing the needs of
patients with AF and the physicians caring for them."

About Atrial Fibrillation

Atrial fibrillation (AF) is an irregular heartbeat that is
caused when the upper chambers of the heart (the atria) do not beat regularly
and instead quiver erratically. When this happens, blood may stagnate in the
atria leading to blood clots. These blood clots can break off and travel
through the blood stream to the brain where they can plug the blood vessels,
causing a stroke. AF is the most common type of clinically significant
arrhythmia.[5]

Patients with AF have five times higher risk of having a
stroke than individuals without AF.[6] These patients also tend to have more
serious first strokes than patients without AF, resulting in higher mortality
rates and longer hospital stays.[7]

About Edoxaban

Edoxaban is a once-daily oral anticoagulant that directly
inhibits Factor Xa, an important factor in the coagulation process. Edoxaban
may offer physicians a wide therapeutic window to help address patients'
unique needs. Daiichi Sankyo is developing edoxaban as a potential new
treatment for the prevention of both arterial and venous thromboembolism.
Notably, Daiichi Sankyo has more than 25 years experience conducting research
in the area of Factor Xa inhibition and was the first company to study these
compounds in humans. Edoxaban is being developed solely by Daiichi Sankyo.

About DAIICHI SANKYO

The DAIICHI SANKYO GROUP is dedicated to the creation and
supply of innovative pharmaceutical products to address the diversified,
unmet medical needs of patients in both mature and emerging markets. The
company was created in 2005 through the merger of two traditional Japanese
enterprises, Daiichi and Sankyo. With net sales of nearly EUR 7.3 billion,
DAIICHI SANKYO is one of the world's 20 leading pharmaceutical companies.
While maintaining its portfolio of marketed pharmaceuticals for hypertension,
hyperlipidemia, and bacterial infections, the Group is engaged in the
development of treatments for thrombotic disorders and focused on the
discovery of novel oncology and cardiovascular-metabolic therapies.
Furthermore, the DAIICHI SANKYO GROUP has created a "Hybrid Business Model,"
which will respond to market and customer diversity and optimize growth
opportunities across the value chain.

The company's world headquarters are in Tokyo. Its European
base is located in Munich. DAIICHI SANKYO EUROPE has affiliates in 12
European countries in addition to a global manufacturing site located in
Pfaffenhofen, Germany.

For more information, please visit www.daiichisankyo.com or
www.daiichisankyo.eu

Forward-Looking Statements

This news release may contain forward-looking statements based
on current assumptions and forecasts made by Daiichi Sankyo group. Various
known and unknown risks, uncertainties and other factors could lead to
material differences between the actual future results, financial situation,
development or performance of the company and the estimates given here. These
factors include those discussed in our public reports, which are available on
the website at www.daiichisankyo-us.com. The company assumes no liability
whatsoever to update these forward-looking statements or to conform them to
future events or developments.

References

———————————

[1] Fuster V et al. "ACC/AHA/ESC 2006 Guidelines for the Management of
Patients with Atrial Fibrillation - Executive Summary," Circulation. 2006;
114:700-752.

[2] American Heart Association. "Atrial Fibrillation,"
www.americanheart.org/presenter.jhtml?identifier=4451. Last accessed
November 24, 2010.

[3] Inoue H et al. "Prevalence of Atrial Fibrillation in the General
Population of Japan: An Analysis Based on Periodic Health Examination
International," International Journal of Cardiology. 2009; 137:102-107.

[4] Santini M, Ricci RP. "The Worldwide Social Burden of Atrial
Fibrillation: What Should Be Done and Where Do We Go," Journal of
Interventional Cardiac Electrophysiology. 2006; 17:183-188.

[5] National Heart Lung and Blood Institute. "What is Atrial
Fibrillation,"
www.nhlbi.nih.gov/health/dci/Diseases/af/af_what.html. Last accessed
November 24, 2010.

[6] Hylek HM et al. "Effect of Intensity of Oral Anticoagulation on
Stroke Severity and Mortality in Atrial Fibrillation,"
The New England Journal of Medicine. 2003; 349:1019-1026.

[7] Jorgensen HS et al. "Acute Stroke with Atrial Fibrillation," Stroke.
1996; 27:1765-1769.

    For more information, please contact:
    Toshiaki Sai
    Daiichi Sankyo Co., Ltd (Tokyo)
    Phone: +81-3-6225-1126

    Dr Michaela Paudler-Debus
    Daiichi Sankyo Europe
    Phone: +49-(0)89-7808-685
    Mobile: +49-(0)172-845-8974 

    Kimberley Wix
    Daiichi Sankyo, Inc. (US)
    Phone: +1-973-944-2338
    Mobile: +1-908-656-5447

For more information, please contact: Toshiaki Sai , Daiichi Sankyo Co., Ltd (Tokyo) , Phone: +81-3-6225-1126 ; Dr Michaela Paudler-Debus, Daiichi Sankyo Europe, Phone: +49-(0)89-7808-685, Mobile: +49-(0)172-845-8974 ; Kimberley Wix , Daiichi Sankyo, Inc. (US) , Phone: +1-973-944-2338 , Mobile: +1-908-656-5447