Expiration Date Of OSI Offer Extended To May 17, 2010

TOKYO, April 23 /PRNewswire/ -- Astellas Pharma Inc. (TSE: 4503) announced today that it has extended its all-cash tender offer for $52 per share for all of the currently outstanding shares of common stock (including the associated stock purchase rights) of OSI Pharmaceuticals, Inc. (Nasdaq: OSIP) to 5:00 p.m. New York City time on Monday, May 17, 2010, unless further extended.  The tender offer was previously set to expire at 12:00 midnight New York City time on Friday, April 23, 2010.

As of 4:00 p.m. New York City time on Thursday, April 22 2010, 42,283 shares of OSI had been tendered in and not withdrawn from the tender offer.

Citigroup is acting as exclusive financial advisor to Astellas and Morrison & Foerster LLP is acting as legal counsel.

Additional Information

Further details related to this proposal can be found on www.oncologyleader.com

About Astellas

Astellas Pharma Inc., located in Tokyo, Japan, is a pharmaceutical company dedicated to improving the health of people around the world through the provision of innovative and reliable pharmaceuticals. Astellas has approximately 15,000 employees worldwide.  The organization is committed to becoming a global category leader in urology, immunology & infectious diseases, neuroscience, DM complications & metabolic diseases and oncology. For more information on Astellas Pharma Inc., please visit our website at http://www.astellas.com/en.

Important Additional Information

This communication is for informational purposes only and does not constitute an offer to purchase or a solicitation of an offer to sell OSI Pharmaceuticals ("OSI") common stock. The tender offer (the "Tender Offer") is being made pursuant to a tender offer statement on Schedule TO (including the Offer to Purchase, Letter of Transmittal and other related tender offer materials) filed by Astellas Pharma Inc., Astellas US Holding, Inc. and Ruby Acquisition, Inc. (collectively, "Astellas") with the Securities and Exchange Commission ("SEC"). These materials, as they may be amended from time to time, contain important information, including the terms and conditions of the Tender Offer, that should be read carefully before any decision is made with respect to the Tender Offer.  Investors and security holders may obtain a free copy of these materials and other documents filed by Astellas with the SEC at the website maintained by the SEC at www.sec.gov.  The Offer to Purchase, Letter of Transmittal and other related Tender Offer materials may also be obtained for free by contacting the information agent for the Tender Offer, Georgeson Inc., at [phone] for banks and brokers and at [phone] for persons other than banks and brokers.

In connection with Astellas' proposal to nominate directors at OSI's annual meeting of stockholders, Astellas expects to file a proxy statement with the SEC.  Investors and security holders of OSI are urged to read the proxy statement and other documents related to the solicitation of proxies filed with the SEC carefully in their entirety when they become available because they will contain important information.  Stockholders of OSI and other interested parties may obtain, free of charge, copies of the proxy statement (when available), and any other documents filed by Astellas with the SEC in connection with the proxy solicitation, at the SEC's website as described above.  The proxy statement (when available) and these other documents may also be obtained free of charge by contacting Georgeson Inc. at the numbers listed above.