Daiichi Sankyo Initiates Largest Single, Double-Blind, Randomized, Phase III Trial for Treatment and Prevention of Recurrent Venous Thromboembolism

First Patient Randomized and Dosed in New Trial With Factor Xa Inhibitor, Edoxaban

TOKYO, Japan and EDISON, New Jersey, February 3 - Daiichi Sankyo Company, Limited (TSE: 4568), announced today that it has
initiated a new large-scale pivotal Phase III trial for edoxaban, its
investigational oral Factor Xa inhibitor. This new study, called HOKUSAI
(pronounced hoe-koo-sigh) VTE, is evaluating the safety and efficacy of
edoxaban in reducing recurrent venous thromboembolic (VTE) complications in
patients with deep-vein thrombosis (DVT) and/or pulmonary embolism (PE).

It is estimated that more than 900,000 fatal and non-fatal VTE events
occur in the U.S. annually, and approximately 300,000 deaths are related to
VTE per year.[i] In Europe, VTE affects more than 750,000 people in six major
European countries (France, Germany, Italy, Spain, Sweden, UK) annually, and
approximately 370,000 deaths are related to VTE per year in these
countries[ii].

"The incidence of VTE is predicted to double by 2050,[iii]" said Harry R.
Büller, M.D., Professor of Internal Medicine, chairman of the Department for
Vascular Medicine at the Academic Medical Center, Amsterdam and chairman of
the Steering Committee for HOKUSAI VTE. "Based on what we've seen in Phase II
and other trials, edoxaban shows promise as an agent to help fulfill the need
for treatment options that are safe, effective and more convenient than the
current standard of care, which requires extensive monitoring, careful dose
adjusting and may have the potential for various drug and food interactions."

The primary efficacy endpoint for HOKUSAI VTE is the recurrence of
symptomatic VTE (i.e., the composite of DVT, non-fatal PE and fatal PE). The
primary safety assessment of the trial is the incidence of major and
clinically relevant non-major bleeding.

"HOKUSAI VTE is the largest, single Phase III study ever undertaken in
the area of VTE, and is our second large-scale edoxaban trial," said Glenn
Gormley, president of Daiichi Sankyo Pharma Development. "Daiichi Sankyo is
proud to be advancing the research of Factor Xa inhibitors with edoxaban,
which may help prevent deadly clots in various patient populations."

HOKUSAI VTE Study Design

HOKUSAI VTE is a Phase III multi-center study that will include
approximately 7,500 patients in more than 450 clinical sites in approximately
40 countries worldwide. This is an event-driven, randomized, double-blind,
double-dummy, parallel-group, multi-center, multi-national study, which will
randomize patients to two different treatment groups. Both groups will
receive open label enoxaparin or unfractionated heparin for at least five
days and up to 12 days, followed by double-blind warfarin or edoxaban 60 mg
once-daily. Patients will be treated for up to 12 months in accordance to the
standard of care and international guidelines.

The HOKUSAI VTE study is named after the famous Japanese artist and
painter Katsushika Hokusai (1760-1849) of the former Edo period; Edo is the
city currently known as Tokyo, the location of the Daiichi Sankyo global
headquarters.

About Venous Thromboembolism

Venous thromboembolism (VTE) is the term for the generation of a blood
clot and the obstruction of a vein or a pulmonary artery by a blood clot.
Deep vein thrombosis (DVT) and pulmonary embolism (PE) are types of VTE. DVT
is a blood clot anywhere in the deep veins of the legs or pelvis. PE is
caused by a clot that travels to the lungs, lodging in the pulmonary
arteries.

About Edoxaban

Edoxaban, the free base of DU-176b, is an oral anticoagulant that
directly inhibits Factor Xa, an important factor in the coagulation process.
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.

Daiichi Sankyo is also actively enrolling 16,500 patients in its pivotal
Phase III trial for edoxaban in patients with atrial fibrillation. The Phase
III study, Effective Anticoagulation with Factor Xa Next Generation in Atrial
Fibrillation (ENGAGE AF-TIMI 48), began enrolling patients in late 2008 and
is comparing edoxaban with warfarin (target INR 2-3) for the prevention of
stroke and systemic embolic events (SEE) among patients with atrial
fibrillation.

In Japan, edoxaban is currently being developed for the prevention of VTE
in patients after total knee (TKR) and total hip replacement (THR) surgery:
results from one pivotal Phase III trial for TKR were announced in late 2009
and a second Phase III trial for THR is ongoing.

About Daiichi Sankyo

A global pharmaceutical innovator, Daiichi Sankyo Co., Ltd., was
established in 2005 through the merger of two leading Japanese pharmaceutical
companies. This integration created a more robust organization that allows
for continuous development of novel drugs that enrich the quality of life for
patients around the world. Areas of central focus of Daiichi Sankyo research
and development are thrombotic disorders, malignant neoplasm, diabetes
mellitus, and autoimmune disorders. Equally important to the company are
hypertension, hyperlipidemia or atherosclerosis and bacterial infections. For
more information, visit www.daiichisankyo.com.

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 or
www.daiichi-sankyo.eu. The company assumes no liability whatsoever to
update these forward-looking statements or to conform them to future events
or developments.

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[i] Heit JA, Cohen AT, Anderson FAJ, on behalf of the VTE Impact
Assessment Group. Estimated annual number of incident and recurrent,
non-fatal and fatal venous thromboembolism (VTE) events in the US. ASH Annual
Meeting Abstracts. 106:910. 2005.

[ii] Cohen AT et al. Venous Thromboembolism (VTE) in Europe. Thromb
Haemost 2007: 98:756-64

[iii] Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2:
abstract number OC-WE-018, Available at:
www.blackwellpublishing.com/isth2009/abstract.asp?id=76605. Accessed,
September 23, 2009

    For more information, please contact:

    Toshiaki Sai,
    Daiichi Sankyo Co., Ltd,
    (Tokyo),
    Phone: +81-3-6225-1126 ;

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

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

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