This article discusses the scientific rationale for the use of cytokine 
inhibitors, including ustekinumab, an inhibitor of the interleukin (IL)-12 and 
IL-23 pathways in psoriasis. Also addressed are the efficacy and safety data for 
this agent, as well as for several emerging therapies that target other cytokine 
pathways in psoriasis: the IL-17 inhibitors secukinumab, ixekizumab, and 
brodalumab, the IL-23 blocker tildrakizumab, and the small-molecule kinase 
inhibitors apremilast (a phosphodiesterase-4 blocker) and tofacitinib (a Janus 
kinase inhibitor).