The Emerging Safety Profile of JAK Inhibitors in Rheumatic Disease

Nature Reviews Rheumatology 2017;13:234–43

This review discusses the current understanding of the safety of JAK inhibitors, including providing an overview of the changes in laboratory parameters, infection and malignancy risks associated with each JAK inhibitor compound.The review discusses the adverse event profiles and cellular changes characteristically seen with each JAK inhibitor, as well as the overlap or differences between the various compounds. The relative specificities for different JAKs between each compound do not always predict or explain the differences or similarities in this regard observed between compounds.The author highlights that, apart from tofacitinib, safety data on JAK inhibitors are limited but, despite any differences in selectivity, herpes zoster (HZ) risk seems to be increased by most if not all compounds. Other than this viral signal, the safety data so far reported is similar to that of most biologics. It is recognised that although no malignancy signals have been found to date, long-term data are needed. As for biologic agents, many of the adverse effects seen for JAK inhibitors, including HZ and opportunistic infections, are preventable through screening, vaccination or laboratory monitoring; thus JAK inhibitors remain a promising class of oral therapeutics.