Synta Announces Ganetespib Clinical Data Presentations at the 2011 American Society for Clinical Oncology (ASCO) Annual Meeting

Synta Pharmaceuticals Corp. (NASDAQ: SNTA) today announced that results from three clinical studies of ganetespib, a potent, second-generation Hsp90 inhibitor, will be presented at the 2011 American Society for Clinical Oncology (ASCO) Annual Meeting June 3-7 at the McCormick Place in Chicago. A fourth abstract will be published.

Phase 2 Results – Once weekly in NSCLC

"An open-label phase II study of the Hsp90 inhibitor ganetespib (STA-9090) as monotherapy in patients with advanced non-small cell lung cancer (NSCLC)." (Abstract #7500) – June 4, 8:00 a.m. – 9:30 a.m. CT; Emerging Novel Targets for Lung Cancer; Lung Cancer Track; Clinical Science Symposium session.

An oral presentation will be given by Dr. Kwok-Kin Wong, Dana-Farber Cancer Institute, Boston, MA, on Saturday, June 4, 8:00 -8:15 a.m. in Hall D1 at the McCormick Place.

Phase 2 Results – Once weekly in GIST

"An open-label phase II study of the Hsp90 inhibitor ganetespib (STA-9090) in patients with metastatic and/or unresectable GIST." (Abstract #10011) – June 4, 8:00 a.m. - 12:00 p.m. CT; Sarcoma; Discussion Session, Board #3, First author: Dr. George D. Demetri, Dana-Farber Cancer Institute, Boston, MA.

This poster will be presented on Saturday, June 4, 8:00 a.m.-12:00 p.m. in room E450a and will be discussed on Saturday, June 4, 12:00 p.m. in room E354b at the McCormick Place.

Phase 1 Results - Twice weekly Solid Tumors

"A phase I dose-escalation study of the Hsp90 inhibitor ganetespib (STA-9090) administered twice weekly in patients with solid tumors: Updated report." (Abstract #3051) – June 6, 8:00 a.m. - 12:00 p.m. CT; Developmental Therapeutics; General Poster Session, Board #12H, First author: Daniel C. Cho, M.D., Dana-Farber Cancer Institute, Boston, MA. Hall A at the McCormick Place.

Phase 1 Results - Combination with Docetaxel in Solid Tumors

The abstract for a Phase 1 study of ganetespib in combination with docetaxel in solid tumors was accepted for the ASCO publication. "A Phase 1 and Pharmacokinetic Study of Ganetespib (STA-9090), a Heat Shock Protein 90 Inhibitor, in Combination with Docetaxel in Subjects with Advanced Solid Tumor Malignancies.” (Abstract# e13591), First author: R. Donald Harvey, PharmD, BCPS, BCOP, FCCP, Winship Cancer Institute of Emory University.

About Ganetespib

Ganetespib (formerly STA-9090) is a potent, synthetic, small-molecule inhibitor of heat shock protein 90 (Hsp90). Hsp90 is a molecular chaperone required for the proper folding and activation of many cancer-promoting proteins, and is recognized as a key facilitator of cancer cell growth and survival. In preclinical experiments, ganetespib has shown activity in multiple tumor models both as a single agent and in combination with certain widely used cancer agents. Ganetespib is currently being evaluated in a broad range of cancer clinical trials. In these trials, ganetespib has shown clinical activity in heavily pretreated patients and has been well tolerated to date with no evidence of severe liver or common ocular toxicities seen with other Hsp90 inhibitors. The most common adverse event seen to date has been diarrhea, which has been manageable with standard supportive care. Information on clinical trials with ganetespib can be found at www.clinicaltrials.gov.

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 invented by Synta scientists using our compound library and discovery capabilities. For more information, please visit www.syntapharma.com.