Johan Auwerx, MD, PhD, a member of Sirtris’ Scientific Advisory Board and Professor at the Medical Faculty of the University of Strasburg, France, will present the unpublished data at the Keystone Symposia on Diabetes Mellitus, Insulin Action and Resistance Conference on Saturday, January 26 from 8-11:30 am CST.

The new data will show that mice on a high-fat diet treated with one of Sirtris’ new chemical entities (NCEs) remained lean while consuming the same number of calories as the untreated mice. Mice on the highest dose of the NCE had no weight gain over 13 weeks, and in exercise testing, ran over 1,600 meters before tiring, while the untreated mice tired at roughly 800 meters.

The treated mice also showed lowered glucose, improved insulin sensitivity and increased energy expenditure due to an increase in the number and function of mitochondria, the powerhouses of the cell. These results are similar to a study previously published in the November 2006 issue of Cell by Dr. Auwerx when mice were treated with resveratrol.

“In this study we demonstrated that Sirtris’ new chemical entity stimulates the SIRT1 enzyme, and mimics the powerful effects we’ve seen in earlier studies but with lower dosage levels,” said Auwerx. “This activity provides evidence of a potential new, front-line therapy for Type 2 Diabetes.”

“We plan to have one of our new development compounds in a human clinical trial in the first half of this year,” said Sirtris Pharmaceuticals Chief Executive Officer and Vice Chair Christoph Westphal, MD, PhD. “In Dr.Auwerx’s study we see lowered glucose levels and improved insulin sensitivity, characteristics of other oral agents for Type 2 Diabetes.”

About Sirtris Pharmaceuticals

Sirtris Pharmaceuticals is a biopharmaceutical company focused on discovering and developing proprietary, orally available, small molecule drugs with the potential to treat diseases associated with aging, including metabolic diseases such as Type 2 Diabetes. Our drug candidates are designed to mimic certain beneficial health effects of calorie restriction, without requiring a change in eating habits, by activation of sirtuins, a recently discovered class of enzymes that control the aging process. The company's headquarters are in Cambridge, Massachusetts.

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Such statements include, but are not limited to, the potential therapeutic effects of SIRT1 activators including NCEs for diseases of aging, such as Type 2 Diabetes:, the progress and results of pre-clinical studies of SIRT1 activators including NCEs; the timing of clinical studies for NCEs; and the potential of sirtuin modulators to receive regulatory approval. These forward-looking statements about future expectations, plans and prospects of Sirtris Pharmaceuticals involve significant risks, uncertainties and assumptions, including risks related to the lack of results that would provide a basis for predicting whether any of the Company's product candidates will be safe or effective, or receive regulatory approval, the possibility that results of pre-clinical studies are not necessarily predictive of clinical trial results, the Company's potential inability to initiate and complete pre-clinical studies and clinical trials for its product candidates, the fact that none of the Company's product candidates has received regulatory approvals, the potential inability of the Company to gain market acceptance of the Company's product candidates, and those other risks factors that can be found in the Company's filings with the Securities and Exchange Commission. Actual results may differ materially from those Sirtris Pharmaceuticals contemplated by these forward-looking statements. Sirtris Pharmaceuticals does not undertake to update any of these forward-looking statements to reflect a change in its views or events or circumstances that occur after the date of this release