Threshold Pharmaceuticals Completes $18 Million Private Equity Financing

REDWOOD CITY, Calif., Sept. 2, 2008 (GLOBE NEWSWIRE) -- Threshold
Pharmaceuticals, Inc. (Nasdaq:THLDD), today announced that its previously
announced private placement of Threshold common stock and warrants received
shareholder approval and has been completed. Threshold sold 8,970,574 shares of
its common stock at $2.04 per share, and warrants to purchase up to 3,588,221
shares of its common stock for gross proceeds of $18.3 million and net offering
proceeds of approximately $17.0 million. The warrants have an exercise price of
$2.34 per share, subject to adjustment, and an expiration date of August 29,
2013. The number of shares of common stock issued and exercisable under the
warrants, the purchase price of the common stock and the exercise price of the
warrants described in this paragraph give effect to the reverse stock split
effected by the Company as of August 20, 2008.

"We are extremely pleased that several high-quality, new investors joined our
existing major shareholders, including both investors and members of the
company's management team, in this financing," said Barry Selick, Ph.D.,
Threshold's chief executive officer. "This financing will enable us to evaluate
the activity of TH-302 against several cancer types in multiple clinical
trials."

The Company intends to use the proceeds of this financing to complete its
ongoing clinical trials evaluating TH-302, its Hypoxia-Activated Prodrug (HAP)
for the treatment of various solid tumors and, pending promising results from
those trials, to initiate at least one controlled Phase 2 clinical trial of
TH-302 alone or in combination with chemotherapy, on preclinical activities
related to another HAP clinical candidate, and for general corporate purposes,
including working capital.

The shares and warrants sold in the private placement and the shares issuable
upon the exercise of the related warrants have not been registered under the
Securities Act of 1933, as amended (the "Securities Act"), or state securities
laws, and may not be offered or sold in the United States without being
registered with the Securities and Exchange Commission ("SEC") or through an
applicable exemption from SEC registration requirements. The shares and warrants
were offered and sold only to accredited investors. Threshold has agreed to file
a registration statement with the SEC covering the resale of the shares issued
in the private placement and the shares issuable upon the exercise of the
warrants.

This news release shall not constitute an offer to sell or the solicitation of
an offer to buy, nor shall there be any sale of any of the securities referred
to in this news release in any state in which such offer, solicitation or sale
would be unlawful prior to the registration or qualification under the
securities laws of any such state. Any offering of the Company's common stock
under the resale registration statement referred to in this news release will be
made only by means of a prospectus.

About Threshold Pharmaceuticals

Threshold is a biotechnology company focused on the discovery and development of
therapeutics for the potential treatment of cancer. By selectively targeting
abnormally-proliferating tumor cells, the Company's drug candidates are designed
to be potentially more effective and less toxic to healthy tissues than
conventional treatments. 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 approach to developing new product candidates, clinical
trials and anticipated results, potential therapeutic uses and benefits of our
product candidates and financial results, estimates, projections and
requirements. 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 attract and retain employees, commence, enroll or
complete 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 and Exchange
Commission on August 7, 2008 and is available from the SEC's website
(www.sec.gov) and on our website (www.thresholdpharm.com) under the heading
"Investors." We undertake no duty to update any forward-looking statement made
in this news release.

-0-
CONTACT: Threshold Pharmaceuticals, Inc.
Denise T. Powell, Sr. Director, Corporate Communications
650-474-8206
dpowell@thresholdpharm.com