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Concert Pharmaceuticals Presents Preclinical Results Supporting Co-Administration of CTP-347 and Tamoxifen

ORLANDO, Fla.--(BUSINESS WIRE)--Sept. 25, 2008 - Concert Pharmaceuticals, Inc. announced today the presentation of data from a preclinical study demonstrating the potential of CTP-347, its novel deuterium-containing serotonin modulator, to avoid the risk of adverse drug-drug interactions when co-administered with tamoxifen, a widely-used breast cancer drug. These data were the subject of a poster presentation at the North American Menopause Society's 2008 Annual Meeting. Concert is developing CTP-347 as a non-hormonal treatment for vasomotor symptoms (VMS or hot flashes) in patients with increased risk of adverse effects due to, or contraindicated to using, hormone therapy, as well as in the larger menopausal population. CTP-347 is currently in Phase I clinical testing.

"Vasomotor symptoms, or VMS, are the most commonly reported adverse effect associated with tamoxifen use and can negatively affect a patient's quality of life. The ability to safely treat tamoxifen-induced VMS without reducing tamoxifen's effectiveness would be an important advance," said Roger Tung, Ph.D., President and Chief Executive Officer of Concert Pharmaceuticals. "We believe CTP-347 has the potential to be a best-in-class, non-hormonal treatment for VMS in women for whom hormone replacement therapy is undesirable or contraindicated."

CTP-347 is a new chemical entity developed by replacing key hydrogen atoms of paroxetine with deuterium. Studies have shown paroxetine is effective in the treatment of VMS. However, recent reports suggest that co-administration of paroxetine with tamoxifen may interfere with the body's ability to metabolize tamoxifen into its activated form, endoxifen. Endoxifen formation is critical to the effectiveness of tamoxifen as an anti-cancer agent. CTP-347 was designed to overcome this limitation.

Using human liver microsomes in vitro, Concert compared CTP-347 and paroxetine with respect to inactivation of CYP2D6, the liver enzyme responsible for the formation of endoxifen. In contrast to paroxetine, which time-dependently and irreversibly inactivates CYP2D6, time dependent inactivation of CYP2D6 was not observed with CTP-347. These results suggest that CTP-347 could potentially avoid the risk of adverse drug-drug interactions with many commonly prescribed drugs metabolized by CYP2D6, including tamoxifen and certain antiarrhythmics, beta-blockers, analgesics, and antipsychotics. Concert is seeking to further confirm that CTP-347 lacks clinically-relevant CYP2D6 inhibition in its ongoing CTP-347 Phase I clinical trial.

About Deuterium

Concert Pharmaceuticals has created a broad pipeline by replacing specific hydrogen atoms in existing, clinically-validated drugs with deuterium atoms, resulting in highly differentiated new chemical entities with potential as best-in-class and first-in-class therapeutic agents. Deuterium is a safe, non-radioactive relative of hydrogen that can be isolated from sea water and has been used extensively in human metabolic and clinical studies. Since deuterium resembles hydrogen, deuterium-modified compounds are expected to fully preserve the pharmacological activity of their hydrogen analogs. An important difference is that deuterium has greater mass than hydrogen and therefore forms stronger chemical bonds. The stronger chemical bond obtained by selective deuterium modification may improve the drug's metabolic properties, resulting in better safety, tolerability, and efficacy.

About Concert

Concert Pharmaceuticals, Inc. is a clinical stage biotechnology company dedicated to creating new medicines through a novel scientific approach utilizing the naturally-occurring element deuterium. Concert applies its innovative platform to create highly differentiated compounds starting from validated drug molecules, yielding a rich pipeline of new chemical entities (NCEs). Concert leverages decades of pharmaceutical experience to create drug candidates with potential for best-in-class efficacy and safety, while reducing R&D risk, time, and expense. The Company has over 100 patent applications for new drug candidates addressing a broad range of therapeutic areas, including vasomotor symptoms, HIV/AIDS and fibrotic diseases, among others. Since its inception in 2006, Concert has raised more than $96 million and has been financed by leading venture capitalists and institutional investors. A complete listing of Concert's shareholders and additional corporate information is available online at CoNCERT and CoNCERT Pharmaceuticals are trademarks of Concert Pharmaceuticals, Inc.


Concert Pharmaceuticals
Justine Koenigsberg, 781-674-5284
Pure Communications
Sondra Newman, 617-877-5687


Posted: September 2008