REDWOOD CITY, Calif., April 14, 2008 (PRIME NEWSWIRE) -- Threshold Pharmaceuticals, Inc. (Nasdaq:THLD) today announced three presentations regarding its hypoxia-activated prodrug (HAP) platform, which includes the lead HAP candidate, TH-302. The presentations took place on Sunday, April 13 at the 2008 American Association for Cancer Research (AACR) annual meeting in San Diego, CA.
Poster 1441 (In vitro activity profile of the novel hypoxia-activated cytotoxic prodrug TH-302) demonstrated that TH-302 exhibits a favorable in vitro cytotoxicity profile for a hypoxia-activated prodrug. Additionally, preliminary results were presented from an ongoing Phase 1 clinical trial evaluating the safety and preliminary efficacy of TH-302 in patients with advanced solid tumors. Specific goals are to determine the maximum tolerated dose, dose limiting toxicities, safety, pharmacokinetics, and preliminary efficacy of TH-302 in patients with advanced solid tumors. The clinical trial was designed with an initial accelerated titration design followed by a standard dose escalation schema. The trial has currently enrolled the sixth dosing cohort (240mg/m2) and none of the 14 patients enrolled to date have experienced any grade 2 or greater drug related toxicities.
Poster 1447 (Plasma pharmacokinetics, oral bioavailability, and interspecies scaling of the hypoxically activated prodrug, TH-302, in mice, rats, dogs and monkeys) demonstrated that TH-302 exhibits linear pharmacokinetics, excellent oral bioavailability and high clearance.
"We are extremely encouraged by the preclinical results we have seen with TH-302," said Charles Hart, Ph.D., Senior Director of Biology at Threshold. "In more than twenty ectopic xenograft studies using five different tumor types, TH-302 is active as monotherapy and the combination of TH-302 with either chemotherapy or radiation consistently added efficacy above that seen with the single agent alone."
Threshold and its clinical investigators commenced a Phase 1 clinical trail of TH-302 in July 2007 and the Company plans to commence Phase 1 and 2 clinical trials of TH-302 in combination with docetaxel, gemcitabine, and pemetrexed in the third quarter of 2008.
Threshold has discovered and is characterizing several additional HAP candidates. One such candidate is TH-1011 which was discussed in Poster 1442 (Anti-cancer activity of TH-1011, a novel hypoxia-activated prodrug, is related to tumor blood vessel disruption). In summary, TH-1011 alone is effective in a colorectal xenograft model, and anti-tumor activity is greatly enhanced when combined with irinotecan, a chemotherapeutic agent mainly used in the treatment of colon cancer.
Copies of the posters presented at AACR may be obtained 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, clinical trial results and plans, 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, the possibility that results from these trials will not be confirmed in subsequent trials, potential adverse side effects, 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 Annual Report on Form 10-K, which was filed with the Securities Exchange Commission on March 12, 2008 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.