SEPTEMBER 15, 2008
Enanta Initiates Phase 1 Study on EDP-322, an Oral Antibiotic with Activity Against Hospital- and Community-Acquired MRSA

-EDP-322 is a First-in-class MRSA-active Bicyclolide, a novel macrolide-related drug class-

WATERTOWN, Mass., September 15, 2008 – Enanta Pharmaceuticals, a leader in the development of small molecule anti-infective drugs, announced today the initiation of a Phase 1 study on investigational oral antibiotic EDP-322, a first-in-class, MRSA-active Bicyclolide, which is a novel macrolide-related drug class with a distinct resistance profile. The clinical development program for EDP-322 will include the treatment of hospital- and community-acquired gram-positive infections, including methicillin-resistant Staphylococcus aureus (MRSA). Preclinically, EDP-322 has demonstrated strong in vitro activity against hospital-acquired MRSA strains resistant to vancomycin, Zyvox® (linezolid), and CUBICIN® (daptomycin).

“Macrolides have been commonly prescribed to treat community infections for decades due to their convenient oral dosing and favorable safety profile,” said Robert Moellering, M.D., a professor of medicine at Harvard Medical School and Beth Israel Deaconess Medical Center. “Now with the discovery of a new generation of macrolides having high potency against hospital-acquired pathogens and a distinct resistance profile relative to other hospital antibiotics, there is a tremendous new opportunity to explore their use within not only the community, but the hospital setting as well.”

“In our in vitro studies, EDP-322 demonstrated good potency against both hospital- and community-acquired MRSA, even against highly drug-resistant MRSA strains,” explained Yat Sun Or, Ph.D., Senior Vice President of Research and Development at Enanta. “The potency of EDP-322 against hospital-acquired MRSA, community-acquired MRSA, and other gram-positive pathogens, combined with the convenience of oral administration, has the potential to uniquely position EDP-322 among marketed MRSA drugs in both the hospital and community settings.”

Phase 1a Study Design
The Phase 1a, double-blind, placebo controlled study for EDP-322 announced today is a single ascending dose trial in healthy volunteers.

About Enanta’s Bicyclolide research program
Bicyclolides posses a reengineered back-bone structure of traditional macrolides, whose benefits include the potential for oral and intravenous administration and limited side-effects. The discovery of Bicyclolides’ effectiveness against MRSA and VRE infections is part of Enanta’s broad antibiotic research program. Enanta has applied several research strategies to develop these new classes of antibiotics, including innovative medicinal chemistry approaches to create novel and proprietary chemical structures. Enanta has applied its chemistry approach to create promising product pipelines and a vast intellectual property estate.

About MRSA
More than 130,000 people each year need hospital care for MRSA, according to the Centers for Disease Control and Prevention. Staphylococcus aureus is a bacterium that can live harmlessly on human skin and is found in the nose of 20 to 40 percent of healthy individuals, but can sometimes cause infections when exposed to broken skin. MRSA is a particular type of the bacteria that has developed resistance to many antibiotics, including methicillin, making it difficult to treat. Currently, the antibiotic drugs typically administered to MRSA patients are intravenous. This method is expensive and inconvenient, especially for those who acquired the infection in the community and must seek hospital treatment for lengthy intravenous treatment.