About Us

Stephen A Harrison, MD

Gastroenterologist Hepatologist
Specializing in Liver Disease

Led by our Medical Director, Dr. Stephen Harrison, Pinnacle has five board-certified investigators involved with the daily oversight of clinical trials. Our coordinating team consists of eight Clinical Research Coordinators and Research Assistants with extensive experience in conducting all phases of clinical trials. Our quality control, and regulatory team work with sponsors to ensure the highest quality of data collection and documentation, according the good clinical practices and the FDA regulations for every trial.


Dr. Harrison earned his medical degree from the University of Mississippi School of Medicine. He completed his internal medicine residency and gastroenterology fellowship at Brooke Army Medical Center and  a 4th year advanced liver disease fellowship at Saint Louis University. He is board certified in both internal Medicine and Gastroenterology. Dr. Harrison served as a Professor of Medicine at the Uniformed Services University of the Health Sciences and is currently a Visiting Professor of Hepatology at Radcliffe Department of Medicine, University of Oxford. He is a past Associate Editor for Hepatology and is currently an Associate Editor for Alimentary Pharmacology and Therapeutics. He is a peer-reviewer for over 20 medical journals and is internationally known for studies in hepatitis C and non- alcoholic fatty liver disease with over 150 peer reviewed publications in these fields. Dr. Harrison most recently served as a Colonel in the United States Army. Retiring in 2016, he concluded 20 years of dedicated service to his country. During his army tenure, he served as the Director of Graduate Medical Education at Brooke Army Medical Center, Associate Dean for the san Antonio Uniformed Services Health Education Consortium and Gastroenterology Consortium and Gastroenterology Consultant to the Army Surgeon General.

Nadege Gunn, MD

Gastroenterologist / Hepatologist
Specializing in Liver Disease

Dr. Nadege Gunn serves as the lead physician investigator for Pinnacle Clinical Research for the Austin, Texas site. She is a hepatology consultant to Austin Gastroenterology. Dr. Gunn focuses on cutting edge clinical trials in non- alcoholic fatty liver disease and gastrointestinal illnesses.


• Viral Hepatitis
• Nonalcoholic fatty liver disease (NAFLD)
• Nonalcoholic steatohepatitis (NASH)
• Cirrhosis
• Primary biliary cholangitis
• Primary sclerosing cholangitis


She is a fellowship trained gastroenterologist and board certified in both Internal Medicine and Gastroenterology. She has a broad clinical research and community practice background.


Dr. Gunn is a graduate of the University of Florida College of Medicine. She completed an Internal Medicine Residency at the Greenville Health System in Greenville, South Carolina.


Her Gastroenterology and Hepatology Fellowship were completed in Texas at the San Antonio Uniformed Services Health Education Consortium as an active duty member of the United States Air Force.
Prior to separating from her military practice in 2015, Dr. Gunn earned the rank of Major and acted as the Chief of Gastroenterology at Eglin Air Force Base in Florida.


She most recently served as the site lead physician for The Liver Institute of Virginia in Newport News, Virginia.
She is passionate about the management of chronic liver disease and is committed to providing world class care for her patients.

cutting-edge research