Japan's Astellas to Buy U.S. Drugmaker OSI for $4 Bil.
By wchung | 03 Apr, 2026

Astellas Pharma Inc., Japan’s No. 2 drug maker, said Monday it will buy U.S. cancer drug company OSI Pharmaceuticals Inc. for $4 billion in cash in a bid to expand its cancer drug business worldwide.

Astellas said it will pay $57.50 per OSI share, up from $52 the Japanese company had offered earlier. The transaction will be completed within a month.

The acquisition is part of Astellas’ drive to expand its cancer drug business worldwide. OSI’s drugs include Tarceva, for lung cancer, which generated $1.2 billion in global sales last year.

The Japanese maker said it hopes to jointly develop cancer drugs with OSI.

Apart from cancer, OSI focuses on oncology, diabetes and obesity treatments.

TOKYO (AP)