Emerging therapies for the treatment of psoriasis.

Psoriasis is an immune-mediated disease that affects 1%-2% of the European and North American population. While topical agents such as corticosteroids and vitamin D derivatives are prescribed for mild disease, they are generally unable to adequately control patients with more severe disease. Over the past decade, research into the immunopathogenesis of psoriasis, including investigations into the role of tumor necrosis factor-alpha and more recently interleukins (IL) 12/23, has led to the advent of targeted biologic therapies based on the central role of a new subset of T cells, Th17. Because of their increased specificity, biologic agents have revolutionized short- to medium-term treatment outcomes and safety profiles for moderate to severe disease over previously gold standard systemic agents. The immunopathogenesis of the disease is still a focus for researchers and novel targets for future agents are being discovered and investigated in clinical trials. In particular, specifically targeting the IL-23/Th17 pathway has given rise to IL-23p19 and IL-17 antagonists, both of which have shown significant promise in clinical trials. IL-22 is involved in keratinocyte proliferation and is being studied as a treatment target for psoriasis. New small molecule oral agents, including Janus kinase and phosphodiesterase inhibitors are currently in phase 2 and 3 clinical trials.