Sirtris Pharmaceuticals, Inc. Announces Exercise of Over-Allotment Option by Underwriters

  
    
  
  
    
      Sirtris Pharmaceuticals, Inc. (NASDAQ: SIRT), a biopharmaceutical 
      company focused on discovering and developing small molecule drugs to 
      treat diseases of aging such as Type 2 Diabetes, announced today that 
      the underwriters have exercised in full their over-allotment option to 
      purchase an additional 900,000 shares of the company's common stock at 
      the initial public offering price of $10.00 per share granted to them in 
      connection with the company's initial public offering that priced on May 
      22nd, 2007.
    
    
      J.P. Morgan Securities Inc. is acting as the sole book-running manager 
      and CIBC World Markets Corp., Piper Jaffray & Co., JMP Securities LLC, 
      and Rodman & Renshaw, LLC are acting as co-managers for the offering.
    
    
      A registration statement relating to these securities was declared 
      effective by the Securities and Exchange Commission on May 22nd, 
      2007. The public offering is being made by means of a written 
      prospectus. Copies of the final prospectus relating to the offering may 
      be obtained from: J.P. Morgan Securities Inc., Attention: Prospectus 
      Department, 4 Chase Metrotech Center, CS Level, Brooklyn, NY 11245. 
      Phone: [phone]. Email: [e-mail].
    
    
      This press release shall not constitute an offer to sell or the 
      solicitation of an offer to buy, nor shall there be any sale of these 
      securities in any state in which such offer, solicitation or sale would 
      be unlawful prior to their registration or qualification under the 
      securities laws of any such state.
    
    
      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. The 
      company's headquarters are in Cambridge, Massachusetts.