Singapore, Mar 02, 2010: Japan's Astellas Pharma has launched a hostile bid to acquire OSI Pharmaceuticals, a Nasdaq listed developer of molecular targeted therapies for oncology, diabetes and obesity.

Astellas has offered to buy OSI for $52 per share, a significant premium of over 40% on the closing price of OSI's common stock of $37.02 per share on February 26, 2010, a 53% premium to its three-month average of $34.01 per share, and a 31% premium to its 52-week high of $39.66 per share. Astellas' offer is not subject to any financing conditions.

The acquisition of OSI, a biotechnology company would support Astellas' growth strategy of becoming a Global Category Leader in oncology. OSI manufactures and sells Tarceva (erlotinib), a leading cancer medication and has several prospective new oncology medications in its R&D pipeline. The transaction would provide Astellas with a top-tier oncology business in the US and an expanded product portfolio and pipeline. OSI would also augment Astellas' strong existing franchises in urology and immunology.

Astellas said its scale and financial strength will help OSI realize the value of its current product pipeline, as well as continue the necessary funding of its discovery engine.

Masafumi Nogimori, President and Chief Executive Officer of Astellas said, "This offer follows our attempts over the past 13 months to engage OSI in meaningful discussions. We firmly believe in the compelling strategic rationale behind the combination and the opportunity it provides to the OSI stockholders to realize full and fair value, in cash, immediately. As recently as February 12, 2010, Astellas presented this proposal to acquire OSI, which reflected a 50% premium on that date. However, we received a response stating that our offer 'very significantly undervalues' OSI. That response was the latest indication to us that OSI is not interested in engaging in substantive discussions. We are therefore taking our offer directly to OSI's stockholders. Our proposal and its significant premium recognize both the value created by OSI to date and its future prospects. Of course, we are open to, and we hope that OSI's Board and management will commence, discussions with us to effect a negotiated transaction."

Astellas has made numerous attempts to engage in substantive discussions to acquire OSI.