Sirtris Pharmaceuticals' Oral Drug Candidate SRT501 Shown To Be Neuroprotective: Implications for SIRT1 Activation in Neurodegenerative Eye Disorders.

Data Presented at Annual American Neurological Association Meeting in Washington D.C.

CAMBRIDGE, Mass. -- Sirtris Pharmaceuticals, Inc. (NASDAQ: SIRT), a biopharmaceutical company focused on discovering and developing small molecule drugs to treat diseases of aging, announced today that activation of SIRT1, a member of the sirtuin family of enzymes, was shown to be neuroprotective in an animal model of optic neuritis (inflammation of the optic nerve that can cause a complete or partial loss of vision). These findings appear in a poster presented at the 132nd Annual Meeting of the American Neurological Association, titled "Neuroprotection in CNS Demyelinating Disease by SIRT1 Activators: A Potential Oral Therapy."

The progressive loss of neurons with age may underlie a variety of debilitating neurological disorders including optic neuritis, one of the first signs of multiple sclerosis, a disease which has been associated with reduced mitochondrial function. Sirtuins are a recently discovered class of enzymes that appear to affect the aging process in mammals and increase the number and function of mitochondria.

According to the findings in this poster, oral dosing of SRT501, Sirtris' proprietary formulation of resveratrol, reduced the loss of retinal ganglion cells and preserved axonal function in a pre-clinical model of optic neuritis. Previous data published Invest Ophthalmol Vis Sci. 2007 Aug;48(8):3602-9 showed that intravitreal injection of SRT501 confers neuroprotection.

The authors of the poster include Sirtris Senior Vice President of Development, Peter Elliott, Ph.D., and Sirtris collaborator, Kenneth Shindler, M.D., Ph.D., F.M. Kirby Center for Molecular Ophthalmology, Department of Ophthalmology, University of Pennsylvania Scheie Eye Institute in Philadelphia, Pennsylvania.

"This striking neuroprotective data shows promise for sirtuin activators as potential therapeutics for diseases such as optic neuritis," said Kenneth Shindler, M.D., Ph.D.

"This is the first time that an orally administered SIRT1 activator has demonstrated neuroprotection; these are encouraging data and further support the potential for SRT501 as a therapeutic for a range of neurodegenerative diseases of aging," said Peter Elliott, Ph.D.

Christoph Westphal, M.D., Ph.D., Chief Executive Officer of Sirtris Pharmaceuticals, Inc., added: "These new findings add to a growing body of data that demonstrate that SIRT1 is an important therapeutic target for a broad range of diseases of aging, including metabolic, mitochondrial and neurological disorders."

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 for neurodegenerative diseases of aging including metabolic, mitochondrial, and neurological disorders, the progress and results of pre-clinical studies of SIRT1 activators, 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.