SAN DIEGO, December 20, 2007 — Conatus Pharmaceuticals Inc. today announced the initiation of a clinical trial with a novel drug candidate for the treatment of liver disease associated with Hepatitis C Virus (HCV) infection in patients who have failed the approved standard of care treatments.

The oral, small molecule drug candidate, CTS-1027, is being studied as a treatment for the inflammatory damage to the liver resulting from infection by HCV. CTS-1027 inhibits the activity of key members of a class of protease enzymes, the matrix metalloproteinases or MMPs. In the liver and in other solid organs, MMPs play an important role in regulating inflammation as well as in maintaining the integrity of the extracellular matrix. CTS-1027 has been shown to be effective in multiple preclinical models of liver disease.

The clinical trial is a double-blind, placebo-controlled, multiple-dose trial lasting for four weeks followed by a voluntary open label period of up to eight additional weeks. The Company expects approximately 100 patients to be enrolled. The clinical trial will be conducted at up to ten medical centers in the U.S. Additional information about the trial can be found at www.clinicaltrials.gov (Identifier NCT00570336) or http://clinicaltrials.gov/ct2/show/NCT00570336?term=CTS-1027&rank=1.

“We are excited to initiate this proof of concept trial in HCV patients with CTS-1027,” said Steven J. Mento, President and CEO of Conatus. “We believe that CTS-1027 represents a novel approach to treating liver inflammation and look forward to developing this drug candidate to fill an important medical need in HCV-infected patients.”

Conatus Pharmaceuticals Inc. is a privately-held specialty pharmaceutical company engaged in the development of innovative human therapeutics to treat liver disease. Chronic liver disease affects millions of people worldwide and can be caused by many different conditions or “insults” to the liver including Hepatitis C and other viral infections, obesity, chronic alcohol abuse or autoimmune diseases. Conatus was founded by the executive management team of Idun Pharmaceuticals in July 2005 following the successful sale of Idun to Pfizer.

www.conatuspharma.com