, the No. 2 drugmaker in Japan, reached an agreement to acquire
for $4 billion.
Astellas increased its offer for OSI to $57.50 a share, up from
in March. The offer is a premium of 55% to the $37.02 closing price of OSI on Feb. 26, the last trading day Astellas announced its bid.
OSI shares closed Friday at $59.80.
OSI's drug line-up includes the blockbuster cancer drug Tarceva, which had $1.2 billion in sales in 2009.
"The merger with OSI provides Astellas with a top-tier oncology platform in the U.S. and an expanded product portfolio and pipelines," said Masafumi Nogimori, president and CEO of Astellas in a statement Monday.
-- Reported by Joseph Woelfel in New York.
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