News Release

Enanta Nominates EDP-239 as Lead Development Candidate for NS5A HCV Inhibitor Program

March 2, 2010 at 3:13 PM EST

WATERTOWN, Mass., March 2, 2010 – Enanta Pharmaceuticals, Inc. announced today the nomination of lead development candidate, EDP-239, from its NS5A hepatitis C virus (HCV) inhibitor program. EDP-239 has demonstrated picomolar potency against multiple genotypes of the virus and a preclinical pharmacokinetic profile amenable to once-a-day dosing.

"Our NS5A inhibitor program is well positioned to generate a pipeline of clinical candidates, and we are excited about further characterization of our various leads with distinct structural diversity," said Yat Sun Or, Ph.D., Senior Vice President and Chief Scientific Officer of Enanta Pharmaceuticals. "The NS5A program represents an important asset in our portfolio of HCV inhibitors, which additionally includes protease, polymerase, and cyclophilin inhibitors. We look forward to exploring combinations and potential synergies of EDP-239 with our broader HCV portfolio."

Enanta's NS5A program and intellectual property estate in the HCV field were derived from its internal drug discovery efforts. Enanta anticipates progressing into IND-enabling preclinical studies for EDP-239 with the goal of initiating clinical trials in 2011.

About Hepatitis C Virus

Hepatitis C is a liver disease affecting over 170 million people worldwide. The virus is spread through direct contact with the blood of an infected person. Hepatitis C increases a person’s risk of developing chronic liver disease, cirrhosis, liver cancer and death. Liver disease associated with HCV infection is growing rapidly, and current therapies only provide sustained benefit in about half of patients with the genotype1 form of the virus. Specifically targeted antiviral therapies for HCV, such as NS3/4a protease and NS5A inhibitors, may have the potential to increase the proportion of patients in whom the virus can be eradicated.

About Enanta

Enanta Pharmaceuticals is a research and development-focused biotechnology company that uses its robust chemistry-driven approach and drug discovery capabilities to create best in class small molecule drugs in the infectious disease field. Enanta is discovering and developing novel inhibitors designed for use against the hepatitis C virus (HCV). These inhibitors include members of the direct acting antiviral (DAA) inhibitor classes – protease (partnered with Abbott), NS5A (partnered with Novartis) and nucleotide polymerase – as well as a host targeted antiviral (HTA) inhibitor class targeted against cyclophilin. Additionally, the company has created a new class of antibiotics, called Bicyclolides, for the treatment of multi-drug resistant bacteria, with a current focus on developing intravenous and oral treatments for hospital and community MRSA infections. Enanta is a privately-held company headquartered inWatertown, Massachusetts. Enanta's news releases and other information are available on the company's website at www.enanta.com.

For Enanta Investor Relations, please contact:
Paul Mellett
617-607-0761

For Enanta Public Relations, please contact MacDougall Biomedical Communications:
Kari Watson
508-647-0209 or kwatson@macbiocom.com