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Threshold Pharmaceuticals Reports Second Quarter 2011 Financial and Operational Results

The net loss for the second quarter of 2011 was $7.9 million compared to $0.3 million for the second quarter of 2010. Included in the net loss, for second quarter of 2011 was non-cash expense of $1.2 million compared to non-cash income of $5.7 million in the second quarter of 2010. The non-cash income (expense) was related to the changes in fair value of the Company's outstanding warrants and was classified as other income (expense). Research and development expenses were $5.1 million for the second quarter of 2011 compared to $5.0 million for the second quarter of 2010. The increase in research and development expenses primarily reflects an increase in clinical trial expenses related to TH-302. General and administrative expenses were $1.7 million for the second quarter of 2011 versus $1.0 million for the second quarter of 2010. The increase in general and administrative expenses was primarily due to an increase in consulting, facilities and personnel related expenses. Non-cash stock compensation expense for the Company was $0.2 million for the second quarter of 2011 versus $0.2 million for the second quarter of 2010.

For the six months ended June 30, 2011, the net loss was $16.3 million, compared to $6.2 million for the six months ended June 30, 2010. Included in the net loss, for the six months ended June 30, 2011 was non-cash expense of $2.1 million compared to non-cash income of $5.5 million for the six months ended June 30, 2010. The non-cash income (expense) was related to the changes in fair value of the Company's outstanding warrants and was classified as other income (expense). Research and development expenses were $11.2 million in the first half of 2011 compared to $9.4 million in the first half of 2010, and increased primarily due to clinical trial expenses related to TH-302. General and administrative expenses increased to $3.0 million in the first half of 2011 from $2.3 million in the first half of 2010, primarily due to an increase in consulting, facilities and personnel related expenses. Total non-cash stock compensation expense for the Company was $0.5 million for the first half of 2011 versus $0.3 million for the first half of 2010. This increase was primarily due to the amortization of an increased number of options.

For the six months ended June 30, 2011, the Company's operating cash requirements were $12.9 million. The Company currently expects 2011 operating cash requirements to be in the range of $27.0 million to $29.0 million. The Company also expects existing cash, cash equivalents and marketable securities to be sufficient to fund the Company's projected operating requirements into the third quarter of 2012.

2011 Key Milestones

The Company currently anticipates the following key clinical milestones in 2011:

• Report top line results from the Phase 1 clinical trial in advanced leukemias in the second half of 2011,
• Report top line efficacy analysis results from the randomized Phase 2 trial in pancreatic cancer at the end of 2011, and
• Initiate a pivotal Phase 3 clinical trial of TH-302 plus doxorubicin compared to doxorubicin alone in patients with metastatic or locally advanced unresectable soft tissue sarcoma in the third quarter of 2011.

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 as well as the bone marrows of some hematologic malignancies. This approach offers broad potential to treat a variety of cancers. 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 approach to developing new product candidates, clinical trials and anticipated results and announcements, potential therapeutic uses and benefits of TH-302 and financial results, estimates, projections and requirements, including the need for additional cash. 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 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 has been filed with the Securities Exchange Commission on August 4, 2011 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.

Threshold Pharmaceuticals, Inc.
Joel A. Fernandes, 650-474-8273
ir@thresholdpharm.com