SIRTRIS COMPLETES EXCLUSIVE LICENSE TO HARVARD’S SIRT3-BASED INTELLECTUAL PROPERTY

CAMBRIDGE, MA [September 16, 2008] – Sirtris, a GSK Company focused on discovering and developing small molecule drugs to treat diseases of aging such as Type 2 Diabetes, announced today that it has completed an agreement with Harvard University to exclusively license two patent applications covering SIRT3-based methods of treatments and assays.

Sirtuins are a family of enzymes which regulate the aging process and have been the subject of extensive research.  While SIRT1 — the founding member of this class of enzymes — is currently the most studied in the group, considerable research is underway on other members in this family, SIRTs 2-7.  A study by Sirtris Scientific Advisory Board members and Harvard University scientists, published in the journal Cell in September 2007, showed for the first time that activation of SIRT3 and SIRT4 protects against cell damage.  The findings further validated sirtuins as important targets for treating diseases of aging.  The two patent applications being exclusively licensed from Harvard include assays useful for identifying SIRT3 activators for diseases of aging.

 “This is an important addition to our broad sirtuin intellectual property portfolio,” said Christoph Westphal, M.D., Ph.D., Chief Executive Officer of Sirtris, a GSK company.  “This agreement will enable us to further advance our research in SIRT3 activators for various metabolic and neurodegenerative diseases.  We will continue to expand our work on SIRT3, which will broaden the potential of our drug discovery platform.”

ABOUT SIRTRIS
Sirtris, a GSK Company, is 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 the Company believes control the aging process. Sirtris is engaged in human clinical trials for Type 2 Diabetes, and is planning similar trials in cancer, another age-related disease. Sirtris is also engaged in a human clinical trial for MELAS, a mitochondrial disorder. The company’s headquarters are in Cambridge, Massachusetts. On June 5, 2008, GlaxoSmithKline plc successfully completed the planned acquisition of Sirtris Pharmaceuticals.  For more information, visit www.sirtrispharma.com

GSK cautionary statement regarding forward-looking statements:
Under the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995, the company cautions investors that any forward-looking statements or projections made by the company, including those made in this Announcement, are subject to risks and uncertainties that may cause actual results to differ materially from those projected. Factors that may affect the Group's operations are described under 'Risk Factors' in the 'Business Review' in the company's Annual Report on Form 20-F for 2007.

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