Synta Oncology Candidate STA-4783 Clinical Trial Results to Be Presented at the ASCO Annual Meeting

Survival and Sub-population Analyses from Phase 2b Trial in Stage

               IV Metastatic Melanoma to be Highlighted

LEXINGTON, Mass.--(BUSINESS WIRE)--May 23, 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 survival and sub-population data from the Phase 2b clinical trial in metastatic melanoma of the Company's lead oncology drug candidate, STA-4783, will be presented at the annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago, Illinois on Tuesday, June 5, 2007. In this double-blind, randomized, multi-center trial, patients treated with STA-4783 in combination with paclitaxel were compared with patients treated with paclitaxel alone. All patients had stage IV metastatic melanoma.

STA-4783 is a novel, injectable, small molecule investigational drug candidate that induces a potent oxidative stress response in cancer cells, driving programmed cell death and enhancing the activity of anti-cancer agents that act through the mitochondrial apoptosis pathway, including paclitaxel. In September 2006, Synta reported positive Phase 2b results for STA-4783 in combination with paclitaxel in a double-blind, randomized, controlled, multi-center clinical trial in patients with stage IV metastatic melanoma. In November 2006, Synta received Fast Track designation from the FDA for the development of STA-4783 in metastatic melanoma. Synta plans to initiate a pivotal Phase 3 clinical trial for STA-4783 in mid-2007 and one or more Phase 2 studies in other cancer indications later in the year.

The schedule and meeting places for the presentation, together with the abstract numbers, are listed below:

Poster Presentations

Tuesday, June 5, 2007 at 8:00 a.m. to 12:00 p.m. - Poster Presentation: 17

Abstract No. 8528

"Subgroup analysis of efficacy and safety analysis of a randomized, double-blinded controlled phase 2 study of STA-4783 in combination with paclitaxel in patients with metastatic melanoma"

    Presenter: Steven O'Day, M.D.

    Location: Display - S103a (Board 6), Discussion - S504

    About Metastatic Melanoma

Melanoma, the most deadly form of skin cancer, arises from melanocytes, the pigment-producing cells of the skin. According to the American Cancer Society, melanoma accounts for approximately five percent of all skin cancers but causes about 75% of all skin cancer-related deaths. An estimated 60,000 people will be diagnosed and nearly 8,000 people will die from melanoma this year in the U.S. alone. If diagnosed and surgically removed while localized in the outermost skin layer, melanoma is potentially curable; however, for patients with deeper lesions or metastatic disease, the prognosis is poor, with limited available treatments and an expected survival of only six to nine months. The incidence of melanoma has increased more rapidly than any other cancer during the past ten years. The FDA has not approved a novel, small molecule drug for the treatment of metastatic melanoma in over 30 years.

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. For more information, please see 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.