Management Team

Jay Luly

Dr. Jay Luly has been leading Enanta since July 2003, having successfully navigated and grown Enanta through its venture-financed years, its successful IPO in 2013, and three major collaborations delivering over $1 billion in non-dilutive financing to date. Under Dr. Luly’s leadership, Enanta collaborated with AbbVie in the discovery and development of two novel hepatitis C virus protease inhibitors: glecaprevir and paritaprevir, which are part of the combination regimens commercialized as MAVYRET® (U.S.)/MAVIRET® (ex-U.S.) and VIEKIRA PAK®, respectively. MAVYRET (glecaprevir/pibrentasvir) which was approved by the FDA in 2017, requires only eight weeks of treatment, the shortest duration of any hepatitis C regimen.

Prior to joining Enanta, Dr. Luly was an Entrepreneur in Residence at Oxford Bioscience Partners. Previously, Dr. Luly held the positions of Senior Vice President, Research and Development Operations and Senior Vice President, Discovery Strategy and Operations at Millennium Pharmaceuticals following Millennium’s acquisition of LeukoSite, Inc. in 1999. Dr. Luly had served as Senior Vice President, Drug Discovery and Preclinical Development at Leukosite, prior to which he held several senior drug discovery positions at Abbott Laboratories from 1983 to 1997.

Dr. Luly received a B.S. in Chemistry from the University of Illinois, Urbana/Champaign and a Ph.D. in Synthetic Organic Chemistry from the University of California, Berkeley.


Tara L. Kieffer, Ph.D. joined Enanta in December 2020. Prior to Enanta, Dr. Kieffer was at Vertex Pharmaceuticals where she held roles of increasing responsibility. Most recently, she was Vice President, External Innovation, Business Development where she was responsible for assessing the external innovation landscape and leading projects aimed at identifying in-licensing and acquisition opportunities. Prior to that, she was Vice President, Integrated Program Management, after being Senior Director, Chief of Staff to the Chief Medical Officer. Dr. Kieffer also held the positions of Director, Clinical Biomarkers and Head of Clinical Virology where she built and led a team responsible for laboratory and clinical research studies to understand the development of antiviral drug resistance to Hepatitis C and influenza viruses. Before joining Vertex, Dr. Kieffer was at Johns Hopkins University School of Medicine in the Department of Molecular Biology and Genetics, where her research studies focused on ongoing replication in patients with well-suppressed Human Immunodeficiency Virus infection.

Dr. Kieffer graduated summa cum laude from Colgate University with a B.A. in Molecular Biology. She holds a Ph.D. in Immunology from Johns Hopkins University School of Medicine. She is co-author on more than 50 publications and an inventor on multiple patents involving treatments for Hepatitis.

Matt Kowalsky

Mr. Kowalsky joined Enanta in April 2024. He brings more than 20 years of experience handling legal matters across a range of disciplines in the life sciences industry. Prior to joining Enanta, Mr. Kowalsky held legal and operational roles of increasing responsibility at Sigilon Therapeutics, Inc., until its acquisition by Eli Lilly in 2023. Most recently, he served as the Chief of Staff and Chief Legal and Administrative Officer of Sigilon, which he joined in 2019 as its General Counsel and Corporate Secretary. Prior to Sigilon, Mr. Kowalsky was Vice President of Legal and Corporate Secretary at Proteon Therapeutics, Inc. from 2016 to 2019. Previously, he served as Senior Corporate Counsel at Sanofi Genzyme, supporting business development activities, marketed products and alliances for the rare disease business. Earlier, Mr. Kowalsky held similar roles at Cubist Pharmaceuticals, Inc., ARIAD Pharmaceuticals, Inc. and Lantheus Medical Imaging, Inc., formerly Bristol-Myers Squibb Medical Imaging, Inc. Mr. Kowalsky began his legal career in the corporate and intellectual property groups of Choate, Hall & Stewart LLP. He holds a B.A. from the University of Notre Dame and a J.D. from the Notre Dame Law School. Before attending law school, he served as a surface warfare officer in the U.S. Navy.

Brendan Luu

Mr. Luu joined Enanta in January 2021. Prior to Enanta, he was at Merck KGaA, where he held roles of increasing responsibility. Most recently, he was Vice President and Global Head of Oncology Business Development, responsible for setting the franchise business development strategy and was accountable for its execution, including the completion of several major transactions across all stages of drug development in line with the company’s R&D goals. Previously, Mr. Luu was Senior Director and Global Head of Business Development, Strategic Initiatives, where he led the strategy and partnering efforts to secure external financing for Merck KGaA’s late-stage pipeline. Before that, he was Director, Global Licensing and Business Development, Neurology and Immunology, where he led in/out licensing transactions for preclinical and clinical-stage assets to support R&D in neurodegenerative diseases. Previously, he was an Associate Director of Regional Business Development, General Medicines responsible for growing the product portfolio in the Asia-Pacific region. Earlier in his career, he held various roles in the chemicals industry with BASF Corporation and in telecommunications with Tyco International, working in engineering, sales and marketing.

Mr. Luu graduated magna cum laude from Drexel University with a B.S. in Chemical Engineering and Biology. He holds an M.B.A from the New York University Stern School of Business.


Mr. Mellett joined Enanta in September 2003. Prior to joining Enanta, he held the position of Senior Vice President and Chief Financial Officer of Essential Therapeutics. Previously, Mr. Mellett was the Chief Financial Officer and Vice President of Administration at GelTex Pharmaceuticals, Inc., a publicly held biotechnology company that was acquired by Genzyme Corporation in December 2000. Mr. Mellett also served as Chief Financial Officer of Marshall Contractors, a construction management firm specializing in the pharmaceutical, biotechnology and semiconductor industries, which was acquired by Fluor Corporation. Earlier in his career, Mr. Mellett was employed with Deloitte & Touche LLP, a public accounting firm, where he served as Audit Partner. Mr. Mellett received a B.S. in Business Administration from Boston College.


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.


Dr. Rottinghaus joined Enanta in August 2022. He brings more than 20 years of clinical experience in drug development, with expertise in a variety of therapeutic areas including rare disease, hematology, nephrology, neurology, dermatology, rheumatology, and infectious diseases. Prior to joining Enanta, Dr. Rottinghaus was Vice President and Head of Clinical Development for Hematology and Nephrology at Alexion, AstraZeneca Rare Disease, where he led development for several clinical assets, including ravulizumab, a complement C5 inhibitor for rare diseases. Before his time at Alexion, Dr. Rottinghaus was a senior director at Pfizer, driving the advancement of several drug programs such as tofacitinib in rheumatology and dermatology, as well as tigecycline, voriconazole, and anidulafungin in the infectious disease field. Earlier in his Pfizer career, he worked as a clinician on early-stage clinical trials for influenza vaccine development. Dr. Rottinghaus’ experience includes multiple NDA and MAA submissions and FDA Advisory Committee participation.

During his industry career, Dr. Rottinghaus continued to practice as an attending physician and assistant clinical professor in infectious diseases at Yale School of Medicine. He has co-authored more than 30 scientific publications. Dr. Rottinghaus trained in infectious diseases at the University of Alabama at Birmingham and in internal medicine at the Mayo Clinic. He holds an M.D. from Mayo Medical School, an M.Sc. in Biology from the University of Cambridge where he studied as a Marshall Scholar, and a B.S. in Biology as well as a B.A. in Latin and Greek from Kansas State University.