JAK Inhibitors Safety in Ulcerative Colitis: Practical Implications

Janus kinase inhibitors JAKi are a new class of small molecule drugs that modulate inflammatory pathways by blocking one or more JAK receptors, and are increasingly being used in the treatment of immune-mediated diseases. Tofacitinib, a non-selective JAKi, is now approved for moderate-to-severe ulcerative colitis UC that is refractory or intolerant to tumour necrosis factor inhibitors TNFi. Whereas tofacitinib is associated with the advantages of oral administration, rapid onset of action, and lack of immunogenicity over TNFi, there are many safety considerations to take into account such as the risk of thromboembolism, infections, and hyperlipidaemia: each with specific nuances pertaining to prevention and monitoring strategies. Considerations such as pregnancy, breastfeeding, and history of malignancy also are to be navigated with utmost caution, given that very few data are available for guidance. With the use of JAKi in the real world progressively over time, safety implications will become more lucid, including caveats pertaining to JAK selectivity and gut-selective JAKi, as well as mechanistic data pertaining to adverse effects. This Viewpoint serves as a practical guide for clinicians managing inflammatory bowel disease IBD patients to navigate safety concerns around JAKi, including preventive and monitoring strategies.