UPDATE 2-Japan's Eisai suffers big sepsis drug setback

* Eisai says to review trial data before deciding next step

* Eisai says will seek U.S., European approval for perampanel (Adds details)

TOKYO, Jan 25 (Reuters) - In a significant setback, Japan's Eisai Ltd 4523.T has put on hold plans to seek approval for its sepsis medication after a late-stage trial showed no reduction in mortality rates compared to a placebo.

The sepsis drug eritoran had been touted as a potential blockbuster drug, with annual peak sales of more than $1 billion worldwide, and a key driver of growth for Eisai which saw its top-selling Alzheimer’s drug Aricept lose U.S. patent protection in November.

Eisai, Japan’s No. 4 drugmaker, said last March that it expected annual U.S. sales of Aricept to fall 60 percent to $800 million between 2011 and 2013.

Eisai had planned to seek approval for eritoran from U.S., Japanese and European authorities by March. It said it would continue to analyse the data and determine its next step.

Caused by massive bodywide immune response to infection that damages organs and other tissues, sepsis kills around 210,000 people in the United States alone, nearly as many as lung, colorectal and breast cancers combined.

Eisai said, however, that it would seek approval by end-June in the United States and Europe for a first-in-class epilepsy drug, perampanel, after late-stage studies went well. (Reporting by Tim Kelly; Editing by Edwina Gibbs)