PRESS RELEASE; Exelixis to Receive Milestone Payment From Bristol-Myers Squibb

Exelixis to Receive Milestone Payment From Bristol-Myers Squibb for Achievement of Liver X Receptor Agonist Development Milestone

SOUTH SAN FRANCISCO, Calif., Nov. 29 /PRNewswire-FirstCall/ -- Exelixis, Inc. today announced that its right to receive from Bristol-Myers Squibb a milestone payment of $5 million was triggered as a result of the acceptance of an Investigational New Drug application, or foreign equivalent, for a compound discovered and developed under the two companies' Liver X Receptor (LXR) collaboration.

This is the first clinical trial of a compound in this collaboration to discover novel therapies targeted against LXR, a nuclear hormone receptor implicated in a variety of cardiovascular and metabolic disorders. "The quality of our lead candidate and the speed at which it progressed into the clinic are testaments to the efficiency of our LXR collaboration with Bristol-Myers Squibb," said Michael Morrissey, Ph.D., Exelixis' president of research and development. "Our combined preclinical studies suggest that LXR agonists may have significant potential in treating a number of cardiovascular and metabolic disorders including atherosclerosis, and we look forward to Bristol-Myers Squibb's further investigating that potential in this trial."

Exelixis and Bristol-Myers Squibb established their joint LXR collaboration in January 2006 for an initial period of two years. The collaboration calls for Exelixis and Bristol-Myers Squibb to jointly identify drug candidates that are ready for IND-enabling studies, with Bristol-Myers Squibb then undertaking further preclinical development. Bristol-Myers Squibb also has responsibility for clinical development, regulatory, manufacturing and sales/marketing activities for such compounds. At time of signing, Exelixis received a $17.5 million upfront payment and a commitment from Bristol-Myers Squibb to provide R&D funding of approximately $10 million per year for the initial two year period. Exelixis may also receive pre-specified development and regulatory milestones totaling approximately $140 million per product for up to two products from the collaboration, as well as sales milestones and royalties on sales of products commercialized under the collaboration.

In September 2007, Exelixis announced that the collaboration had been extended through January 12, 2009. Terms of the extension include additional research funding paid to Exelixis in the amount of $7.5 million. Bristol-Myers Squibb also has an option to further extend the collaboration by an additional year.

About the Liver X Receptor

LXR activation by endogenous ligands, oxysterols (oxidized cholesterol) or by synthetic agonists, initiates a cascade of cellular events that both increase "reverse cholesterol transport," thereby removing excess cholesterol from the body, and suppress inflammation. Elevated cholesterol concentrations have been implicated in the progression of heart disease and plaque formation in the artery wall. LXR activation therefore directly targets two well-known risk factors of heart disease and provides a novel approach for decreasing the deposition of fat and lipids in the artery wall and suppressing the inflammatory damage associated with atherosclerosis. In animal models of heart disease, small molecule synthetic LXR ligands have been shown to cause regression of pre-existing atherosclerotic lesions. Thus, LXR may be a first-in-class target for therapies that directly target the pathology of atherosclerosis and coronary artery disease via a dual mechanism of stimulating reverse cholesterol transport and repression of inflammation.

About Exelixis

Exelixis, Inc. is a development-stage biotechnology company dedicated to the discovery and development of novel small molecule therapeutics for the treatment of cancer and other serious diseases. The company is leveraging its fully integrated drug discovery platform to fuel the growth of its development pipeline, which is primarily focused on cancer. Currently, Exelixis' broad product pipeline includes investigational compounds in phase 2 and phase 1 clinical development for cancer and renal disease. Exelixis has established strategic corporate alliances with major pharmaceutical and biotechnology companies, including GlaxoSmithKline, Bristol-Myers Squibb Company, Genentech, Wyeth Pharmaceuticals and Daiichi-Sankyo. For more information, please visit the company's web site at http://www.exelixis.com.

Exelixis' Forward Looking Language Statements

This press release contains forward-looking statements, including, without limitation, all statements related to the potential efficacy of the compound targeted against LXR, the discovery, development and commercialization of additional drug candidates targeting LXR under Exelixis' collaboration with Bristol-Myers Squibb and related costs and payments under the collaboration. Words such as "suggest," "may," "look forward" and similar expressions are intended to identify forward-looking statements. These forward-looking statements are based upon Exelixis' current expectations. Forward-looking statements involve risks and uncertainties and past performance is not indicative of future results. Exelixis' actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, the risk that products candidates that appeared promising in early research do not demonstrate safety or efficacy in clinical trials; the ability of Exelixis to advance preclinical compounds into clinical development; the uncertainty of the U.S. Food and Drug Administration approval process; and the therapeutic and commercial value of Exelixis' compounds and risks related to its need for additional financing. These and other risk factors are discussed under "Risk Factors" and elsewhere in Exelixis' quarterly report on Form 10-Q for the quarter ended September 30, 2007 and other filings with the Securities and Exchange Commission. Exelixis expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in Exelixis' expectations with regard thereto or any change in events, conditions or circumstances on which any such statements are based.