Eisai to Submit Marketing Authorization Applications in the U.S. and EU for Perampanel as Adjunctive Therapy for Partial Seizures in Patients with Epilepsy

Submissions Planned for First Quarter of Fiscal 2011

HATFIELD, England, January 25, 2011 - Eisai announced today that it will submit Marketing Authorization
Applications in the United States and the European Union for the
investigational compound perampanel (E2007) based on the results of three
Phase III pivotal studies. Perampanel is a first-in-class, highly selective
non-competitive AMPA-type glutamate receptor antagonist, discovered and being
developed by Eisai for adjunctive treatment of partial seizures in patients
with epilepsy. Partial seizures involve epileptic activity in just a part of
the brain and the symptoms experienced depend on which area of the brain is
affected.

The clinical development plan for perampanel consisted of three global
Phase III studies: Studies 306, 305 and 304 in which a total of 1,490
patients participated. The key goal of Study 306 was to identify the minimal
effective dose and included four treatment arms (placebo, 2mg, 4mg, and 8mg).
Studies 304 and 305 included three arms (placebo, 8mg, and 12mg) and were to
evaluate a more extended dose range.

The studies were similar in design: global, randomized, double-blind,
placebo-controlled, dose-escalation, parallel-group studies. The primary and
secondary endpoints were the same in all the studies: standard median percent
seizure reduction, 50% responder rate, percentage reduction of complex
partial plus secondarily generalized seizures, and evaluation for dose
response.

Each of the studies showed consistent results in the efficacy and
tolerability of perampanel given as an adjunctive therapy in patients with
partial seizures.

Based upon these study results, Eisai intends to submit regulatory
applications simultaneously in the U.S. and EU during the first quarter of
our Fiscal Year 2011.

The development of perampanel is an example of Eisai's human health care
corporate mission. Eisai is committed to the therapeutic area of epilepsy and
addressing the unmet medical needs of patients with epilepsy and their
families.

About Perampanel

Eisai is currently developing perampanel for the potential treatment of
partial seizures in patients with epilepsy. Perampanel is a highly selective,
non-competitive AMPA (a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic
acid)-type glutamate receptor antagonist that has demonstrated broad-spectrum
anti-seizure effects in Phase II and III studies. AMPA receptors, widely
present in almost all excitatory neurons, transmit signals stimulated by the
excitatory neurotransmitter glutamate within the brain and are believed to
play a role in central nervous system diseases characterized by excess
neuroexcitatory signalling including epilepsy, neurodegenerative disorders,
movement disorders, pain and psychiatric disorders.

If approved, perampanel will be the first product in this class.

About Epilepsy

Epilepsy is one of the most common neurological conditions in the world,
affecting approximately 8 in 1,000 people in Europe(i). There is an estimated
2.4 million people living with epilepsy in Europe(ii) and estimated 50
million people worldwide.(iii)

Epilepsy is a chronic disorder of the brain that affects people of all
ages. It is characterized by abnormal discharges of neuronal activity causing
seizures. Seizures can vary in severity, from brief lapses of attention or
jerking of muscles, to severe and prolonged convulsions. Depending on the
seizure type, seizures may be limited to one part of the body, or may involve
the whole body. Seizures can also vary in frequency from less than one per
year, to several per day. Epilepsy has many possible causes but often the
cause is unknown.

About Eisai Europe in Epilepsy

Eisai is committed to developing and delivering highly beneficial new
treatments to help improve the lives of people with epilepsy. The development
of anti-epileptic drugs (AEDs) is a major strategic area for Eisai in the
European market.

In Europe, Eisai currently has three marketed treatments including:

    - Zonegran(R) (zonisamide) as adjunctive therapy in adult
      patients with partial-onset seizures, with or without secondary
      generalisation
    - Zebinix(R) (eslicarbazepine acetate) as adjunctive therapy in
      adult patients with partial-onset seizures, with or without secondary
      generalization
    - Inovelon(R) (rufinamide) for the treatment of seizures associated
      with Lennox-Gastaut Syndrome

About Eisai

Eisai is one of the world's leading research-based pharmaceutical
companies that has defined its corporate mission as "giving first thought to
patients and their families and to increasing the benefits health care
provides," which we call human health care (hhc). Eisai concentrates its
research activities in three key areas

    - Integrative Neuroscience including: Epilepsy, Alzheimer's
      disease, multiple sclerosis, neuropathic pain and depression
    - Integrative Oncology including: anticancer therapies; tumour
      regression, tumour suppression, antibodies, etc and supportive cancer
      therapies; pain relief and nausea
    - Vascular/Immunological Reaction including: acute coronary
      syndrome, atherothrombotic disease, sepsis, rheumatoid arthritis,
      psoriasis and Crohn's disease

With operations in the U.S., Asia, Europe and its domestic home market of
Japan, Eisai employ more than 11,000 people worldwide.

In Europe, Eisai undertakes sales and marketing operations in over 20
markets, including the United Kingdom, France, Germany, Italy, Spain,
Switzerland, Sweden, Ireland, Austria, Denmark, Finland, Norway, Portugal,
Iceland, Czech Republic, Hungary, and Slovakia.

For further information please visit our web site www.eisai.co.jp

References

(i) Pugliatti M et al. Estimating the cost of epilepsy in Europe: A
review with economic modeling. Epilepsia 2007: 48(12) 2224 - 2233

(ii) Forsgren L, Beghi E, Oun A, Sillanpaa M. The epidemiology of
epilepsy in Europe - a systematic review. Eur J Neurol. 2005 Apr;12(4):245-53

(iii) Epilepsy Society UK:
www.epilepsysociety.org.uk/AboutEpilepsy/Whatisepilepsy/Epilepsy-didyouknow
Last accessed Dec 2010

Benjamyn Tan, Tonic Life Communications, +44-(0)-20-7798-9262, benjamyn.tan at toniclc.com, or Helen Swift, Tonic Life Communications, +44-(0)-20-7798-9900, helen.swift at toniclc.com, or Cressida Robson, Eisai Europe Limited, +44-(0)-7908-314-155, +44-(0)-845-676-5318, cressida_robson at eisai.net