Lexington, MA- September 14, 2005- Synta Pharmaceuticals, a biopharmaceutical company focused on discovering, developing, and commercializing small-molecule drugs to treat serious conditions, announced today the initiation of a multi-national, multi-center, randomized, placebo-controlled Phase 2b trial examining the efficacy and safety of STA-5326 in patients with active Crohn's disease. STA-5326 is the first and only oral, small-molecule, selective inhibitor of the interleukin (IL)-12 cytokine family, including IL-12 and IL-23. These cytokines play a central role in inflammatory diseases such as Crohn's disease and other chronic inflammatory diseases. The study is designated as SCORE (Study in Crohn's disease of the Oral IL-12/IL-23 inhibitor, STA-5326, for the induction of REsponse and remission). A companion study will be conducted concurrently to evaluate biological markers of activity in Crohn's disease.

"The findings from our Phase 2a study suggest that STA-5326 is active and generally well-tolerated in Crohn's disease patients, and we believe that that our novel approach to this disease could help advance the treatment of the hundreds of thousands of patients whose disease is not optimally controlled today," said Matthew L. Sherman, MD, Senior Vice President and Chief Medical Officer at Synta. "Given that STA-5326 is formulated as a once-daily, oral therapy, this level of convenience could represent an important clinical advance for patients suffering from Crohn's disease."

At Digestive Disease Week in May, Synta reported that in a Phase 2a study, treatment with STA-5326 at daily doses of 35 mg and above demonstrated clinically meaningful response and disease remission rates in patients with active Crohn's disease. STA-5326 also showed an acceptable safety profile with the most common adverse events being dizziness, nausea, headache, and fatigue.

About STA-5326

STA-5326 is a novel, orally-administered, small-molecule drug candidate that selectively and potently inhibits the production of the IL-12 family of proteins, including IL-12 and IL-23. Overproduction of these proteins plays a central role in chronic inflammatory diseases, including Crohn's disease, psoriasis and rheumatoid arthritis, causing the body's immune system to infiltrate and damage tissues and organs. Development in rheumatoid arthritis is anticipated to commence in late 2005.

About Crohn's Disease

Crohn's disease is a chronic inflammatory bowel disease characterized by inflammation throughout the length of the gastrointestinal, or digestive, tract. Symptoms can be severe, and include abdominal pain, frequent diarrhea, and intestinal bleeding. Approximately 500,000 people in the U.S. and over a million people worldwide are affected by Crohn's disease.

About Synta

Synta Pharmaceuticals Corporation 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 chronic inflammatory disease and cancer. Synta currently has three drug candidates in human clinical trials, as well as a diverse pipeline of internally developed discovery programs. For more information, please see www.syntapharma.com.