The OSI Pharma has to face the hostile takeover bid launched from the Astellas Pharma valued at about $3.5 billion, which they further aim to expand into the U. S. oncology market.

According to the planning of Astellas said it has decide to commence an all-cash tender offered at a price of $52 a share for all of Melville, which shall be representing by a 40% premium over the shares. Commenting ahead the Astellas group expressed that the deal of acquiring OSI would bring a boost to its oncology business, in the U. S. market.

The OSI's best-selling product is Tarceva, a therapy which has been co-marketed by Swiss conglomerate Roche Holdings. Tarceva's is a therapy used in treating cancers of the lung and pancreas. The OSI group has been conducting tests of Tarceva for the treatment of ovarian and colorectal cancers if possible to craft.

Tokyo based Astellas, accounts for more than 14,000 headcounts. The company has a wide variety of products, mostly for the urology, dermatology and immunology domain.