Cubist Pharmaceuticals Completes Acquisition of Trius Therapeutics

Cubist Pharmaceuticals, Inc. (NASDAQ: CBST) today announced that it has completed the previously announced acquisition of Trius Therapeutics, Inc. (NASDAQ: TSRX) for an aggregate upfront cash consideration of approximately $704 million. Effective today, Trius common stock will cease to be traded on the NASDAQ.

“We are very pleased to complete this acquisition and welcome the Trius team to Cubist,” said Cubist Chief Executive Officer Michael Bonney. “Trius is an excellent strategic fit, and its lead product candidate, tedizolid phosphate, has the potential to be an important new treatment in the fight against resistant infections. The need for new treatments to combat drug resistant bacteria is growing, and we will work diligently to bring this antibiotic product candidate to market in order to help hospitals and their patients combat these infections. This transaction is also an important step towards achieving Cubist’s Building Blocks of Growth and continuing our track record of driving shareholder value over the long term.”

About Cubist

Cubist Pharmaceuticals, Inc. is a biopharmaceutical company focused on the research, development, and commercialization of pharmaceutical products that address significant unmet medical needs in the acute care environment. Cubist is headquartered in Lexington, Mass. Additional information can be found at Cubist’s web site at www.cubist.com.

Forward Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and other federal securities laws. Any statements contained herein which do not describe historical facts, including but not limited to, statements regarding: Cubist’s acquisition of Trius, including the anticipated strategic benefits of the acquisition; the therapeutic and commercial potential of tedizolid phosphate; and our progress against our Building Blocks of Growth long-term goals, are forward-looking statements which involve risks and uncertainties that could cause actual results to differ materially from those discussed in such forward-looking statements. Such risks and uncertainties include: the ability of Cubist to successfully integrate Trius’ operations and employees; the anticipated benefits of the transaction may not be realized; risks related to drug development and commercialization; the ability of Cubist to achieve its Building Blocks of Growth long-range goals, including as a result of Cubist’s ability to continue to grow revenues from the sale of CUBICIN® and ENTEREG®, generic and other competition, manufacturing issues, Cubist’s ability to successfully develop, gain marketing approval for and commercially launch its product candidates for their planned indications and on their expected timelines, and Cubist’s ability to discover, in-license or acquire new products and product candidates; and those additional factors discussed in Cubist’s and Trius’ most recent Quarterly and Annual Reports on Forms 10-Q and 10-K filed with the Securities and Exchange Commission. Cubist and Trius caution investors not to place considerable reliance on the forward-looking statements contained in this press release. These forward-looking statements speak only as of the date of this document, and Cubist and Trius undertake no obligation to update or revise any of these statements.