Use of biologic agents in combination with other therapies for the treatment of psoriasis.

Psoriasis is a chronic inflammatory skin disorder, which is associated with a significant negative impact on a patient's quality of life. Traditional therapies for psoriasis are often not able to meet desired treatment goals, and high-dose and/or long-term use is associated with toxicities that can result in end-organ damage. An improved understanding of the involvement of cytokines in the etiology of psoriasis has led to the development of biologic agents targeting tumor necrosis factor (TNF)-α and interleukins (ILs)-12/23. While biologic agents have improved treatment outcomes, they are not effective in all individuals with psoriasis. The combination of biologic agents with traditional therapies may provide improved therapeutic options for patients who inadequately respond to a single drug or when efficacy may be increased with supplementation of another treatment. In addition, combination therapy may reduce safety concerns and cumulative toxicity, as lower doses of individual agents may be efficacious when used together. This article reviews the current evidence available on the efficacy and safety of combining biologic agents with systemic therapies (methotrexate, cyclosporine, or retinoids) or with phototherapy, and the combination of biologic agents themselves. Guidance is provided to help physicians identify situations and the characteristics of patients who would benefit from combination therapy with a biologic agent. Finally, the potential clinical impact of biologic therapies in development (e.g., those targeting IL-17A, IL-17RA, or IL-23 alone) is analyzed.