Management Team


Yat Sun Or, Ph.D.

Chief Scientific Officer

Dr. Or joined Enanta in November 1999 and led its preclinical and early clinical development efforts, including the team responsible for achieving all milestones in the collaboration with AbbVie to develop hepatitis C treatments. Dr. Or and his team discovered glecaprevir, the protease inhibitor in AbbVie’s successful combination treatment for hepatitis C virus currently marketed as MAVYRET®. He is leading Enanta’s ongoing research on antivirals for hepatitis B virus, respiratory syncytial virus, human metapneumovirus and SARS-CoV-2, as well as the non-viral liver disease nonalcoholic steatohepatitis. Dr. Or’s team also worked on the earlier protease inhibitor in AbbVie’s VIEKIRA PAK® treatment for hepatitis C virus, and previously developed antibacterials for methicillin-resistant staphylococcus aureus (MRSA). Further, Dr. Or has managed Enanta’s research and development collaborations with Shionogi, Abbvie and Novartis.

Prior to Enanta, Dr. Or was a senior project leader and research fellow of antibacterial research at Abbott Laboratories from 1985 to 1999. Prior to Abbott, he was a member of the cardiovascular drug discovery team at Schering-Plough.

Dr. Or received his Ph.D. in Organic Chemistry from the University of Chicago and completed Postdoctoral Fellowships at Ohio State University and Indiana University. He has co-authored more than 100 publications and is listed as a co-inventor on over 260 filed U.S. patent applications.