Interleukin (IL)-12/23 and IL-23 Inhibitors

Biologic therapies have transformed the treatment of moderate-to-severe psoriasis. This is a rapidly evolving field, with several new monoclonal antibody medications reaching the market over the last few years. A number of classes of biologic agents now exist, corresponding to the underlying cytokine target of the antibody therapy. The interleukin (IL)-12/23 and IL-23 inhibitors make up two closely related and commonly prescribed classes. Interleukins are cytokines that allow communication between different immune cells. In the skin, dendritic cells are the major source of these cytokines. IL-12 signalling leads to the activation of Th1 T-lymphocytes. IL-23 signalling leads to activation of the Th17 arm of the immune system. During the development of ustekinumab, a biologic agent designed to target IL-12, it was fortuitously discovered that ustekinumab inhibited both IL-12 and IL-23 due to a common structural subunit, p40. Females of childbearing potential with psoriasis who are starting biologic therapy should be advised to use effective contraception.