Threshold Pharmaceuticals Announces a Presentation At the 2009 American Society of...

Threshold Pharmaceuticals Announces a Presentation At the 2009 American Society
of Clinical Oncology (ASCO) Annual Meeting

REDWOOD CITY, Calif., May 27, 2009 (GLOBE NEWSWIRE) -- Threshold
Pharmaceuticals, Inc. (Nasdaq:THLD) today announced a presentation of clinical
trial results on its hypoxia-activated prodrug, TH-302. The presentation will
take place at the 2009 American Society of Clinical Oncology (ASCO) Annual
Meeting being held May 29 to June 2, 2009, at the Orange County Convention
Center in Orlando, FL.

The following poster presentation will take place:

Final results of a phase 1 study of TH-302, a hypoxia-activated cytotoxic
prodrug (HAP) Bendell et al., Saturday, May 30 from 8:00am - 12:00pm (abstract
2573)

Copies of the poster may be obtained after the poster session by calling the
Company.

About Threshold Pharmaceuticals

Threshold is a biotechnology company focused on the discovery and development of
drugs targeting Tumor Hypoxia, the low oxygen condition found in
microenvironments of most solid tumors. This approach offers broad potential to
treat most solid tumors. By selectively targeting tumor cells, we are building a
pipeline of drugs that hold promise to be more effective and less toxic to
healthy tissues than conventional anticancer drugs. For additional information,
please visit our website (www.thresholdpharm.com).

Forward-Looking Statements

Except for statements of historical fact, the statements in this press release
are forward-looking statements, including statements regarding Threshold's
product candidates, and potential therapeutic uses and benefits of our product
candidates. These statements involve risks and uncertainties that can cause
actual results to differ materially from those in such forward-looking
statements. Potential risks and uncertainties include, but are not limited to,
Threshold's ability to commence its anticipated clinical trials, the time and
expense required to conduct such clinical trials and analyze data, issues
arising in the regulatory or manufacturing process and the results of such
clinical trials (including product safety issues and efficacy results). Further
information regarding these and other risks is included under the heading "Risk
Factors" in Threshold's Quarterly Report on Form 10-Q, which was filed with the
Securities Exchange Commission on May 7, 2009 and is available from the SEC's
website (www.sec.gov) and on our website (www.thresholdpharm.com) under the
heading "Investors." We do not intend to update any forward-looking statement
made in this news release.

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CONTACT: Threshold Pharmaceuticals, Inc.
Denise T. Powell, Sr. Director, Corporate Communications
650-474-8206
dpowell@thresholdpharm.com