Targeting the Plasticity of Psoriasis.

Psoriasis is a common inflammatory condition found in 1-2% of the population. The greatest advances in psoriasis treatment have occurred in patients with severe psoriasis, moving from systemic small molecules including methotrexate, cyclosporine, and retinoids to targeted agents against psoriasis-associated cytokines, such as TNF-α, IL-12, IL-23, and IL-17. Although the new biologics do not have the same adverse effects as the systemic drugs, they do predispose to systemic infections (and perhaps cancer), and they are extremely expensive. The focus on biologic therapies has been accompanied by a relative neglect of small molecules, which can be used either topically or systemically. No small molecule has been able to compete significantly with topical glucocorticoids, the mainstay of treatment for mild to moderate psoriasis for more than half a century.