The Emerging Safety Profile of JAK Inhibitors in Rheumatic Diseases.

Janus kinase inhibitor (JAKi) medications are small-molecule drugs that affect intracellular signal transduction. They are highly effective oral medications that have been approved for the treatment of various rheumatic diseases, with rheumatoid arthritis being a key example of an autoimmune rheumatic disease. JAKi are oral-route medications that are alternatives to injectable biologic therapies, launched in the late 1990s. While most safety concerns with JAKi are similar to the biologics, there are many differences. New data on comparative safety of JAKi versus tumor necrosis factor inhibitors (TNFi) were recently published that led to new black box warnings by the US Food and Drug Administration (FDA) about cardiovascular and cancer risks and a label change for JAKi. This review summarizes the current published data with regards to the safety of JAKi, focused on rheumatic diseases. Specifically, any risk differences between agents or across different indications are discussed, as well as the risk factors for these adverse outcomes.