Small Molecules, Big Results: How JAK Inhibitors Have Transformed the Treatment of Patients with IBD.

Small molecule Janus kinase (JAK) inhibitors have revolutionized the management of ulcerative colitis (UC) and Crohn's disease (CD) through their low immunogenicity, safety, and consistent pharmacologic response that are superior to existing therapeutic options. In this perspective, we highlight existing evidence supporting the use of currently approved JAK inhibitors (upadacitinib, tofacitinib, and filgotinib) for UC or CD, additionally emphasizing the evidence for their use in related autoimmune conditions such as rheumatoid arthritis and spondyloarthropathies. Our perspective concludes with a review of the existing comparative effectiveness literature, which positions JAK inhibitors, particularly upadacitinib, favorably compared with other biologic therapies. This perspective is paired with a companion publication highlighting the origins and development of JAK inhibitors and a more in-depth review of their pathophysiologic mechanisms.