Janus Kinase Inhibitors for the Management of Patients With Inflammatory Bowel Disease.

In recent years, knowledge about the pathophysiology of inflammatory bowel disease (IBD) has led to the development of novel therapies and biologics with differing mechanisms of action. A major innovation has been the development of small molecules. Tofacitinib was the first pan-Janus kinase (Jak) inhibitor approved for the treatment of IBD, targeting the 4 isoforms of cytokine-associated Jaks (Jak1, Jak2, Jak3, and tyrosine-protein kinase 2). Compared with biologic agents, novel small molecules have a short half-life, a rapid onset of action, and no immunogenicity, but they are associated with a potentially increased risk of off-target side effects. These differences in properties between biologic and oral small molecule therapies may be important when considering their relative treatment positioning and role in clinical practice. Although tofacitinib has been demonstrated to be highly effective as both first- and second-line therapy for ulcerative colitis, concerns about safety, including the risk of infection, venous thromboembolism, major adverse cardiovascular events, and malignancy, have dampened enthusiasm for its widespread use. Subsequently, several Jak inhibitors with more selective profiles, and potentially improved safety while maintaining treatment efficacy, are currently in late-stage clinical trials for use in patients with IBD. This article summarizes the current data regarding the use, safety, and efficacy of Jak inhibitors in patients with IBD.