Investor and Media Inquiries: Maeve Conneighton Argot Partners 212-600-1902 Willie Quinn Sunesis Pharmaceuticals Inc. 650-266-3716 Sunesis Pharmaceuticals Reports Third Quarter 2018 Financial Results and Recent Highlight

Sunesis Pharmaceuticals Reports Third Quarter 2018 Financial Results and Recent Highlights

Sunesis to Host Conference Call Today at 4:30 PM Eastern Time

SOUTH SAN FRANCISCO, Calif., November 5, 2018 -- Sunesis Pharmaceuticals, Inc. (Nasdaq: SNSS) today reported financial results for the quarter ended September 30, 2018. Loss from operations for the three and nine months ended September 30, 2018 was $6.3 million and $20.0 million. As of September 30, 2018, cash and cash equivalents totaled $20.2 million. This capital is expected to fund the company into the second quarter of 2019.

"We remain focused on advancing our non-covalent BTK inhibitor vecabrutinib to help patients who have developed resistance to covalent BTK inhibitors such as ibrutinib," said Dayton Misfeldt, Interim Chief Executive Officer of Sunesis. "We continue to learn more about this unique asset and its market opportunity and will share an update at the ASH Annual Meeting in December. As announced last week, one of our accepted abstracts for presentation at ASH includes an update on the Phase 1b/2 trial of vecabrutinib, and as presented in the published abstract, the pharmacokinetic profile is consistent with the results from our Phase 1a study. We continue to believe that 100mg to 300mg will be the potentially active dose levels. Thus far, vecabrutinib appears well tolerated in the context of advanced disease. We continue with the dose escalation part of the trial and look forward to sharing a complete clinical update at the meeting next month and at a company-sponsored webcast event concurrent with the meeting."

Financial Highlights

Conference Call Information

Sunesis will host a conference today at 4:30 p.m. Eastern Time. The call can be accessed by dialing (844) 296-7720 (U.S. and Canada) or (574) 990-1148 (international) and entering passcode 5971729. To access the live audio webcast, or the subsequent archived recording, visit the "Investors and Media - Calendar of Events" section of the Sunesis website at www.sunesis.com. The webcast will be recorded and available for replay on the company's website for two weeks.

About Sunesis Pharmaceuticals

Sunesis is a biopharmaceutical company developing new therapeutics for the treatment of hematologic and solid cancers. Sunesis has built an experienced drug development organization committed to improving the lives of people with cancer. The Company is focused on advancing its novel kinase inhibitor pipeline, with an emphasis on its oral non-covalent BTK inhibitor vecabrutinib. Vecabrutinib is currently being evaluated in a Phase 1b/2 study in adults with chronic lymphocytic leukemia and other B-cell malignancies that have progressed after prior therapies. The Company's proprietary PDK1 inhibitor SNS-510 is in preclinical development. PDK1 is a master kinase that activates other kinases important to cell growth and survival including members of the AKT, PKC, RSK, and SGK families. Sunesis plans to submit an IND for SNS-510 in 2019. Sunesis is exploring strategic alternatives for vosaroxin, a late-stage

investigational product for relapsed or refractory AML. Sunesis also has an interest in the pan-RAF inhibitor TAK-580 which is licensed to Takeda. TAK-580 is in a clinical trial for pediatric low-grade glioma.

For additional information on Sunesis, please visit www.sunesis.com.

SUNESIS and the logos are trademarks of Sunesis Pharmaceuticals, Inc.

This press release contains forward-looking statements, including statements related to Sunesis' cash sufficiency forecast, the continued development of vecabrutinib (SNS-062), including the timing of Phase 1b/2 trial of vecabrutinib and the therapeutic potential of vecabrutinib, further development and potential of its kinase inhibitor pipeline, and planned development of SNS-510 and TAK-580. Words such as "expect," "look forward," "will" and similar expressions are intended to identify forward-looking statements. These forward-looking statements are based upon Sunesis' current expectations. Forward-looking statements involve risks and uncertainties. Sunesis' 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 related to the timing or conduct of Sunesis' clinical trials, including the vecabrutinib Phase 1b/2 trial, the risk that Sunesis' clinical or preclinical studies for vecabrutinib, SNS-510 or other product candidate may not demonstrate safety or efficacy or lead to regulatory approval, the risk that data to date and trends may not be predictive of future data or results, risks related to the timing or conduct of Sunesis' clinical trials, that Sunesis' development activities for vecabrutinib or SNS-510 could be otherwise halted or significantly delayed for various reasons, that Sunesis may not be able to receive regulatory approval of vecabrutinib, or SNS-510 in the U.S. or Europe, and risks related to Sunesis' ability to raise the capital that it believes to be accessible and is required to fully finance the development and commercialization of vecabrutinib, SNS-510 and other product candidates. These and other risk factors are discussed under "Risk Factors" and elsewhere in Sunesis' Quarterly Report on Form 10-Q for the quarter ended September 30, 2018 and Sunesis' other filings with the Securities and Exchange Commission. Sunesis expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein reflect any change in Sunesis' expectations with regard thereto or any change in events, conditions or circumstances on which any such statements are based.