This work is part of a broad collaboration established between Exelixis and Bristol-Myers Squibb in July 2001 to discover new generations of cancer therapeutics that selectively destroy cancers that harbor defects in tumor suppressor gene pathways. The initial target selection process took place at the end of 2001.

"Our cancer collaboration with Bristol-Myers Squibb continues to advance rapidly and to strengthen both companies' drug discovery programs," said George Scangos, Ph.D., Exelixis president and chief executive officer. "Because of the high level of validation of these targets, and the breadth and productivity of our discovery platform, we have already advanced several important new targets through high throughput screening and have identified promising compounds that are moving into preclinical development. We believe that this collaboration has high visibility within the Bristol-Myers Squibb research and development organization, and we will continue to work closely together to identify promising new targets that could lead to the next generation of safer, more effective cancer therapeutics."

Under the terms of the cancer collaboration with Bristol-Myers Squibb, Exelixis identifies and validates various molecular targets that trigger cell death in cancer cells while leaving normal cells unharmed. Each company has the option to obtain worldwide rights to equal numbers of validated targets arising from the collaboration. As part of the agreement, Exelixis has received an exclusive worldwide license to develop and commercialize a specific analogue of the Bristol-Myers Squibb anticancer compound, DEAE Rebeccamycin, which has completed Phase I safety trials and is currently in Phase II clinical trials with the National Cancer Institute. Bristol-Myers Squibb made an equity investment in Exelixis, paid an up-front licensing fee and continues to provide research support to Exelixis.

Exelixis, Inc. is a leading genomics-based drug discovery company focused on product development through its expertise in comparative genomics and model system genetics. These technologies provide a rapid, efficient and cost effective way to move from DNA sequence data to knowledge about the function of genes and the proteins they encode. The company's technology is broadly applicable to all life sciences industries including pharmaceutical, diagnostic, agricultural biotechnology and animal health. Exelixis has partnerships with Bayer CropScience, Bristol-Myers Squibb, Cytokinetics, Dow Agrosciences, Elan Pharmaceuticals, Merck, Protein Design Labs, Schering- Plough Research Institute and Scios and is building its internal development program in the area of oncology. For more information, please visit the company's web site at www.exelixis.com.

The forward looking statements contained in this press release involve risks and uncertainties that may affect our research and development efforts, as more fully discussed in the "Risk Factors" section of our filing with the U.S. Securities and Exchange Commission. These risks and uncertainties include, but are not limited to, Exelixis' ability to successfully develop compounds against targets it selected under the collaboration, and Exelixis' ability to successfully identify the novel targets of Bristol-Myers Squibb compound researched through this collaboration, and for Bristol-Myers Squibb to develop novel products, if any, based on our identification of these targets.

    NOTE:  Exelixis and the Exelixis logo are registered U.S. trademarks.

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CONTACT:          Jane M. Green, Ph.D., VP, Corporate Communications of Exelixis,
                  Inc., +1-650-837-7579, or jmgreen@exelixis.com

URL:              http://www.exelixis.com
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