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Sunesis to Present Data on SNS-595 at American Association of Cancer Research Meeting

04/15/05

South San Francisco, California, April 15, 2005 – Sunesis Pharmaceuticals, Inc. today announced that three posters addressing in vitro and in vivo studies of the company’s lead anti-cancer therapy, SNS-595, will be presented at the 96th American Association of Cancer Research (AACR) annual meeting in Anaheim, California at a session named Cell Cycle Mechanisms of Anticancer Drug Action.

  • SNS-595 is a novel cytotoxic agent currently under clinical evaluation for safety and tolerability. Three posters providing further insights into SNS-595’s mechanism of action will be presented at the AACR meeting on Monday April 18, from 8:00 a.m. to 12 noon.
    SNS-595, a novel cell-cycle inhibitor in Phase I clinical trials, causes tumor regressions, cell cycle arrest, and apoptosis in murine models of colon cancer
    Abstract # 2277
  • The Phase I clinical compound SNS-595 acts during S-phase and causes sustained G2 arrest
    Abstract # 2293
  • The potent cytotoxic agent SNS-595 causes a rapid onset of apoptosis during the S-phase of the cell cycle
    Abstract # 2285

About SNS-595
Sunesis’ lead compound, SNS-595 is a novel cytotoxic cell cycle inhibitor currently in Phase I clinical studies with multiple Phase II studies planned for the second half of 2005. The Phase I clinical studies are primarily assessing safety, tolerability, pharmacokinetics and dosing. In pre-clinical studies, SNS-595, consistently demonstrated broad activity, including complete regressions and cures, in a variety of cancers, including drug resistant tumors.

About Sunesis Pharmaceuticals
Sunesis is a clinical-stage biopharmaceutical company focused on the discovery, development and commercialization of small molecule therapeutics for oncology, inflammatory diseases and other unmet medical needs. Sunesis has built a product candidate portfolio through internal discovery and acquisition of novel cancer therapeutics. Sunesis is advancing its product candidates through in-house research and development efforts and strategic collaborations with leading pharmaceutical and biopharmaceutical companies. For further information, visit
www.sunesis.com.

Forward-Looking Statements
This press release contains forward-looking statements that involve substantial risks and uncertainties. The company may not actually achieve the plans, intentions or expectations contained in such forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations contained in such forward-looking statements. The company does not assume any obligation to update any such forward-looking statements.

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CONTACTS:
Eric Bjerkholt,
CFO of Sunesis Pharmaceuticals, Inc.,
+1-650-266-3717

Media and Investors:
BCC Partners
Karen L. Bergman or Michelle Coral
650.575.1509 or 415.794.8662