Interpreting modern randomized controlled trials of medical therapy in inflammatory bowel disease

Treatment options for the medical management of inflammatory bowel disease (IBD) have expanded substantially over the past decade. Multiple classes of advanced therapies, including both monoclonal antibodies and novel oral small molecules, are now available for the treatment of moderately-to-severely active Crohn's disease and ulcerative colitis, highlighted by the approvals of the first IL23p19 antagonists, selective Janus kinase inhibitors and sphingosine-1-phosphate receptor modulators. These advances have been accompanied by the identification of novel targets and the rapid growth in both the number and size of IBD clinical trials. Over a dozen landmark randomized controlled trials (RCTs) have been completed in the past 5 years, including the first head-to-head biologic trials, the first combination biologic studies, and multiple phase III registrational trials of novel compounds with new co-primary and composite end points that will change the treatment landscape for years to come. Importantly, the methodology of RCTs in IBD has evolved substantially, with new trial designs, evaluation of unique patient populations, and different types of efficacy and safety end points being key innovations. In this Review, we provide a comprehensive evaluation of how modern RCTs of IBD medical therapies have evolved and the implications for their appraisal that will help guide the application of these data to clinical practice.