Woodcliff Lake, NJ, January 3, 2012 — Eisai Inc. announced today that the Centers for Medicare and Medicaid Services (CMS) has assigned a unique, permanent Healthcare Common Procedure Coding System (HCPCS) J-code for Halaven® (eribulin mesylate) Injection. Halaven was approved in November 2010 to treat metastatic breast cancer - breast cancer that has spread - in patients who have received at least two other types of anticancer medicines. Previous therapy should have included an anthracycline and a taxane for either early or advanced breast cancer. The new J-code, J9179, becomes effective on January 1, 2012.

"We are very pleased to have received the J-Code," said Dave Martin, Vice President, Managed Markets, Value and Access, Eisai Inc. "It will help facilitate reimbursement for providers who have patients who may be candidates for Halaven treatment, thus ensuring access to those patients who need it."

J-codes are part of the Healthcare Common Procedure Coding System (HCPCS), and used by providers to identify drugs to help facilitate reimbursement.

About HALAVEN^®
HALAVEN^® is a non-taxane, microtubule dynamics inhibitor that is a synthetic analog of halichondrin B, a natural product that was isolated from the marine sponge Halichondria okadai. HALAVEN^® targets microtubules, the major cytoskeletal component of cells which play a pivotal role in cell replication. It is believed to inhibit the growth phase of microtubule dynamics, which can cause a cell to stop dividing and self-destruct.

Important Safety Information about HALAVEN^®

Decreased White Blood Cells (Neutropenia)
Your doctor should do a blood test to monitor your blood cells before you receive each dose of HALAVEN, and should monitor you more often if you develop lower white blood cells. If you develop severe neutropenia lasting longer than 7 days or neutropenia with a fever, your next dose of HALAVEN should be delayed and reduced. Severe neutropenia occurred in 57% (287/503) of patients who received HALAVEN and lasted more than 1 week in 12% (62/503) of patients. Neutropenia with a fever occurred in 5% (23/503) of patients; 2 patients died from complications of neutropenia with a fever. Neutropenia with a fever can result in serious infections that could lead to hospitalization or death. Call your healthcare provider immediately if you have any of the following symptoms; fever (temperature above 100.5 ۫ F), chills, coughing, burning or pain when you urinate.

Nerve Disorders (Peripheral Neuropathy)
HALAVEN can cause numbness, tingling, or burning in your hands and feet (peripheral neuropathy). You should be monitored closely for signs of neuropathy. If you develop severe neuropathy, treatment with HALAVEN should be delayed until the neuropathy improves and the next dose of HALAVEN should be reduced. Severe peripheral neuropathy occurred in 8% (42/503) of patients who received HALAVEN. Neuropathy lasting more than one year occurred in 5% of patients. Twenty-two percent (109/503) of patients developed a new or worsening neuropathy that had not recovered after an average of 269 days. Peripheral neuropathy was the most common side effect that caused patients to stop receiving HALAVEN.

Pregnancy and Nursing
HALAVEN may harm your unborn baby. Avoid becoming pregnant while you are receiving HALAVEN. Tell your healthcare provider right away if you become pregnant or think you are pregnant while you are receiving HALAVEN. You and your healthcare provider should decide if you will receive HALAVEN or breastfeed. You should not do both.

Heartbeat Changes
HALAVEN can cause changes in your heartbeat (called QTc prolongation). This can cause irregular heartbeats that may lead to death. Your healthcare provider will decide if you need heart monitoring (electrocardiogram or ECG), or blood tests during your treatment with HALAVEN to watch for this problem.

Liver and Kidney Problems
In patients with mild or moderate liver problems, and/or moderate kidney problems, a lower starting dose of HALAVEN is recommended.

Most Common Side Effects
The most common side effects reported in >25% of patients receiving HALAVEN were low white blood cells (82%), low red blood cells (58%), weakness/tiredness (54%), hair loss (45%), numbness, tingling or burning in your hands and feet (35%), nausea (35%), and constipation (25%). The most common serious side effects reported in patients receiving HALAVEN were neutropenia with or without a fever (4% and 2%, respectively).

For full prescribing information for HALAVEN, please visit www.halaven.com.

About Eisai Inc.

Eisai Inc. was established in 1995 and began marketing its first product in the United States in 1997. Since that time, Eisai Inc. has rapidly grown to become a fully integrated pharmaceutical business. Eisai's areas of commercial focus include neurology, gastrointestinal disorders and oncology/critical care. The company serves as the U.S. pharmaceutical operation of Eisai Co., Ltd., a research-based human health care (hhc) company that discovers, develops and markets products throughout the world.

Eisai has a global product creation organization that includes U.S.-based R&D facilities in Massachusetts, New Jersey, North Carolina and Pennsylvania, as well as manufacturing facilities in Maryland and North Carolina. The company's areas of R&D focus include neuroscience; oncology; vascular, inflammatory and immunological reaction; and antibody-based programs. For more information about Eisai, please visit www.eisai.com/US.