Faculty Biographies

Waseem Ahmed, MD

Waseem Ahmed, MD

Debbie Cheng, MD

Debbie Cheng, MD

Benjamin Click, MD


Waseem Ahmed, MD
, received his undergraduate degree from the University of Michigan and attended medical school at Indiana University. He then completed an internal medicine residency at New York University Langone Medical Center followed by a fellowship in gastroenterology and hepatology at Indiana University Medical Center.  After his fellowship training, he completed an advanced fellowship in inflammatory bowel disease at the Jill Roberts Center for Inflammatory Bowel Disease at New York Presbyterian Hospital – Weill Cornell Medicine prior to joining the University of Colorado Crohn’s and Colitis Center in September 2021 as an Assistant Professor of Medicine in the Division of Gastroenterology and Hepatology. Dr. Ahmed is passionate about providing innovative, comprehensive, and compassionate care for all patients with IBD. He has multiple research interests including IBD medical education for both patients and providers, post-operative management of Crohn's disease, clinical trials, and use of dual-biologic or small molecule therapy in refractory IBD.

Debbie Cheng, MD
received her undergraduate degree from University of Pennsylvania and attended medical school at University of Michigan. She then completed her internal medicine residency and gastroenterology & Hepatology fellowship at University of Pittsburgh Medical Center before joining the University of Colorado Crohn's and Colitis Center in August 2021. Dr. Cheng strives to provide comprehensive, evidence-based care for patients with inflammatory bowel disease. She also has a clinical interest in patients who develop gastrointestinal immune-related adverse events from checkpoint inhibitor therapies, such as immune-mediated enterocolitis. Outside of work, Dr. Cheng's hobbies include spending time with her family and friends, hiking, running, and watching college football.

Benjamin Click, MD earned his undergraduate and medical degrees from the University of Virginia and completed his internal medicine and gastroenterology training at UPMC in Pittsburgh, PA where he received an NIH T32 training award and served as chief fellow. He simultaneously earned a Masters’ in Clinical Research from the University of Pittsburgh. Dr. Click then served as Staff Gastroenterologist at Cleveland Clinic from 2018 to 2022 before joining the faculty at the University of Colorado in 2022 as Assistant Professor of Medicine. He is board-certified in Internal Medicine and Gastroenterology. Dr. Click’s clinical research interests include the collection, organization, and utilization of large-scale observational data for natural history studies, comparative effectiveness analyses, and construction of personalized predictive models in IBD with a focus in postoperative Crohn’s disease. He has served as principal investigator on multiple clinical trials in IBD. Dr. Click’s personal interests include hiking with his family, skiing, reading, playing guitar, and exploring Colorado activities.

​Blair Fennimore, MD



Blair Fennimore, MD, received his bachelor’s degree from the University of North Carolina at Chapel Hill.  He studied medicine at the Wake Forest University School of Medicine and completed his internal medicine residency and gastroenterology fellowship at the University of Colorado.  As part of the University of Colorado’s Crohn’s and Colitis Center, Dr Fennimore’s clinical interests are focused on the diagnosis and multi-disciplinary management of inflammatory diseases of the GI tract including Crohn’s and Ulcerative colitis.  He is particularly interested in the management of IBD during pregnancy and lactation and primary-sclerosing cholangitis associated inflammatory bowel disease including post liver transplant IBD management. Dr Fennimore’s research interests focus on inter-organ cross-talk mechanisms; specifically in understanding inflammatory cross-talk between the liver and intestine in primary sclerosing cholangitis associated inflammatory bowel disease. In true Colorado spirit, his hobbies include snow-boarding, fly fishing, and triatholon.

​Sarah Funk, RD, CNSC



Sarah Funk, RD, CNSC, received her Bachelor of Science Degree in Human Nutrition and Food Science at New Mexico State University. She completed her dietetic internship at Oregon Health and Science University in Portland, Oregon and has been a practicing clinical dietitian since 2003. She has a broad experience in the field of clinical nutrition but has always had a special interest in surgical and GI nutrition. Working at UCH has allowed her to gain more experience with IBD patients and recognizing the need for one on one counseling to ensure a nutrition plan meets their specific needs. In her spare time, Sarah enjoys snowboarding, running, and learning to play the guitar.

​Mark Gerich, MD, MBA



Mark Gerich, MD, MBA, received his undergraduate degree from Cornell University and a dual MD/MBA degree from McGill University in Montreal, Quebec, Canada. He received his internal medicine training at the University of California Davis Medical Center and completed his fellowship in gastroenterology and hepatology at the University of Colorado in 2011. After completing an advanced IBD fellowship at Cedars-Sinai Medical Center in Los Angeles, Dr. Gerich joined the faculty in the Division of Gastroenterology and Hepatology at the University of Colorado, where he now serves as the Clinical Director of the University of Colorado Crohn's & Colitis Center and conducts clinical and translational research focused on the pathogenesis and treatment of IBD. Dr. Gerich is a native of Minnesota who spent formative years in Pittsburgh, upstate New York, and Quebec. In addition to his family and the Pittsburgh Steelers, Dr. Gerich’s personal interests include alpine and backcountry skiing, hiking, and fly-fishing.

​Alexis Oonk, MSN, FNP​



Alexis Oonk, MSN, FNP, received her Bachelors of Science in Biology at Rhodes College in Memphis, Tennessee prior to attending a nursing program at University of Southern Maine. While at University of Southern Maine, she completed a Master’s of Science in Nursing to become a nurse practitioner. She worked as a registered nurse at Maine Medical Center throughout her graduate program.  After becoming credentialed as a Family Nurse Practitioner, Alexis moved to Colorado and spent three years working at a general GI community practice caring for patients with a variety of GI disorders. During this time, she discovered that working with patients with inflammatory bowel disease (IBD) is a passion of hers and was excited to join the IBD team here at University of Colorado Crohn’s and Colitis Center in 2013.  Alexis’ clinical interests include providing high quality, evidence based care to our patients within the Crohn’s and Colitis Center. She finds providing care for our complex inflammatory bowel disease patients with attention to their multidisciplinary needs to be very rewarding.  She supports research efforts of the IBD clinic as well by performing screening and follow-up visits within the context of our clini​cal trials. Outside of the work, Alexis’ hobbies include skiing, yoga and hiking with her husband and dog.

John Sabel, MD



Dr. John Sabel received his medical degree from the University of Virginia and his internal medicine and gastroenterology specialty training at Baylor Affiliated Hospitals at the Texas Medical Center in Houston, Texas. He then moved to Colorado where he was in private practice with South Denver Gastroenterology.   John is Board Certified in both internal medicine and gastroenterology and has received honorary fellowships from the American College of Gastroenterology (ACG), the American Gastroenterological Association (AGA) and the American College of Physicians (ACP). After 35 years in private practice, he joined the University of Colorado Crohn's and Colitis Center on a volunteer basis as an Associate Clinical Professor to help with the training of GI fellows in the management of IBD patients and also to participate in the review of evaluation and treatment options for complex IBD patients at our weekly multidisciplinary IBD Conference.  John has served on the Boards of the Colorado Health Foundation and the Rocky Mountain Chapter of the Crohn's and Colitis Foundation of America (CCFA), and he is the longtime Chairman of the Rocky Mountain CCFA Medical Advisory Committee (CMAC).  In 2013, he was honored with a Lifetime Achievement Award from the Rocky Mountain Chapter of the CCFA, who have also honored him as Physician of the Year.

Frank I. Scott, MD, MSCE

Frank Scott IMG

Calen Steiner, MD

Calen Steiner, MD


​Frank I. Scott, MD, MSCE, received his undergraduate degree from the University of Pennsylvania and then attended medical school at Temple University in Philadelphia.  After completing his internal medicine residency at Weill Cornell Medical Center at New York-Presbyterian Medical Center, Dr. Scott returned to Philadelphia for his gastroenterology fellowship at the University of Pennsylvania, where he then also completed an advanced fellowship in inflammatory bowel diseases.  During this time he also completed his Masters' in Clinical Epidemiology. He was on faculty at the Perelman School of Medicine at the University of Pennsylvania from 2012 to 2015 as an Instructor of Medicine and Assistant Professor of Medicine and Epidemiology before joining the Crohn's and Colitis Center at the University of Colorado in January 2016.


​Calen Steiner MDcompleted his undergraduate degree in physiological science from UCLA and then his master's of science in Physiology from the University of Cincinnati College of Medicine. He then completed medical school at the University of Cincinnati College of Medicine before completing his training in internal medicine followed by gastroenterology at the University of Michigan. He joined the University of Colorado in July 2021. In addition to being an IBD specialist he is a physician scientist and part of the GI and Liver Innate Immune Programs (GALIIP) and Mucosal Inflammation Program (MIP) at the University of Colorado School of Medicine. Dr. Steiner strives to provide the best care for patients and believes in a multidisciplinary and comprehensive approach to care for the person as a whole. He is committed to delivering cutting edge, evidence-based care for our patients. His many clinical interests include the medical and endoscopic management of patients with Inflammatory Bowel Disease (IBD) including Crohn's Disease and Ulcerative Colitis. His main research focus is on elucidating cellular and molecular mechanisms of intestinal fibrosis in IBD, with the goal of leading to new therapies for intestinal fibrosis. Outside of work he enjoys spending time with his family, hiking, and skiing.  

Division of Gastroenterology and Hepatology

CU Anschutz

Academic Office One

12631 East 17th Avenue


Aurora, CO 80045

CU Anschutz

Anschutz Outpatient Pavilion

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Aurora, CO 80045

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