LEXINGTON, Mass.--(BUSINESS WIRE)--Nov. 8, 2007--Synta Pharmaceuticals Corp., (NASDAQ: SNTA) a biopharmaceutical company focused on discovering, developing, and commercializing small molecule drugs to treat severe medical conditions, today announced that the first patient has been treated in a Phase 1 clinical study of its novel heat shock protein 90 (Hsp90) inhibitor, STA-9090. STA-9090 is a synthetic, small molecule Hsp90 inhibitor with a novel chemical structure that is unrelated to the Hsp90 inhibitor geldanamycin or its family of related compounds, such as 17-AAG.

In preclinical studies, STA-9090 has shown the ability to inhibit multiple kinases with comparable potency to, and a broader activity profile than specific kinase inhibitors such as imatinib (Gleevec(R)), erlotinib (Tarceva(R)), and sunitinib (Sutent(R)). In addition, STA-9090 has shown potency 10 to 100 times greater than the geldanamycin family of Hsp90 inhibitors, as well as activity against a wider range of kinases. In in vivo models, STA-9090 has shown strong efficacy in a wide range of cancer types, including cancers resistant to Gleevec, Tarceva, and Sutent.

"Initiating our Phase 1 trial for STA-9090 represents a key clinical milestone for Synta and an important step in delivering on our strategy to build a pipeline of oncology compounds with first- or best-in-class mechanisms, strong scientific rationale, and broad therapeutic utility," said Safi Bahcall, Ph.D., President and Chief Executive Officer, Synta. "We are particularly excited about STA-9090 because of the strength of the preclinical data package, including activity against highly resistant cancers and superior potency to first-generation Hsp90 inhibitors."

The open-label Phase 1 study in patients with solid tumors is designed to identify the maximum tolerated dose of STA-9090 based on a twice-a-week intravenous dosing schedule. In addition to an evaluation of safety and tolerability, patients will be assessed for response rate based on the RECIST criteria. A second Phase 1 study with an alternative, once-a-week dosing schedule is planned.

"Hsp90 inhibition has the potential to provide a new strategy for treating cancer," said Geoffrey Shapiro, M.D., Ph.D., Dana-Farber Cancer Institute and lead investigator of the Phase 1 trial. "Based on the strength of the preclinical data we have seen to date, we believe STA-9090 is differentiated in important ways from other Hsp90 inhibitors, and this Phase 1 trial can advance our knowledge of this new therapeutic category."

About Hsp90

Hsp90 is an emerging therapeutic target of interest for the treatment of cancer. It is responsible for modulating cellular response to stress by maintaining the function of numerous signaling proteins - known as 'client proteins' - that are associated with cancer cell survival and proliferation. Many cancers result from specific mutations in, or aberrant expression of, these client proteins. Examples of cancer-associated client proteins of Hsp90 include c-KIT in gastrointestinal stromal tumors, epidermal growth factor receptor (EGFR) in lung cancer, and BCR-ABL in chronic myelogenous leukemia. In preclinical studies, inhibiting Hsp90 causes the degradation of these proteins and cancer cell death. Inhibiting Hsp90 has also proven effective in killing cancer cells that have developed resistance to targeted therapies such as kinase inhibitors.

About Synta Pharmaceuticals

Synta Pharmaceuticals Corp. is a biopharmaceutical company focused on discovering, developing, and commercializing small molecule drugs to extend and enhance the lives of patients with severe medical conditions, including cancer and chronic inflammatory diseases. Synta has a unique chemical compound library, an integrated discovery engine, and a diverse pipeline of clinical- and preclinical-stage drug candidates with distinct mechanisms of action and novel chemical structures. All Synta drug candidates were discovered and developed internally. Synta has a partnership with GlaxoSmithKline (GSK) for the joint development and commercialization of its lead investigational drug candidate, elesclomol. For more information, please visit www.syntapharma.com.

Safe Harbor Statement

This media release may contain forward-looking statements about Synta Pharmaceuticals Corp. Such forward-looking statements can be identified by the use of forward-looking terminology such as "will", "would", "should", "expects", "anticipates", "intends", "plans", "believes", "may", "estimates", "predicts", "projects", or similar expressions intended to identify forward-looking statements. Such statements, including statements relating to the timing and progress of our clinical and preclinical programs, reflect our current views with respect to future events and are based on assumptions and subject to risks and uncertainties that could cause actual results to differ materially from those expressed or implied by such forward-looking statements, including those described in "Risk Factors" of our Form 10-K for the year ended December 31, 2006 as filed with the Securities and Exchange Commission. Synta undertakes no obligation to publicly update forward-looking statements, whether because of new information, future events or otherwise, except as required by law.

    CONTACT: Synta Pharmaceuticals Corp.
             Rob Kloppenburg, 781-541-7125
             or
             MacDougall Biomedical Communications
             Doug MacDougall, 508-647-0209

    SOURCE: Synta Pharmaceuticals Corp.