Etanercept, a TNF antagonist for treatment for psoriatic arthritis and psoriasis.

Etanercept (Enbrel, Amgen and Wyeth), a tumor necrosis factor (TNF) antagonist, was approved in January 2002, for the treatment of psoriatic arthritis (PsA). The anti-inflammatory effects of etanercept are due to its ability to bind to the pro-inflammatory cytokine TNF, preventing it from interacting with cell-surface receptors and rendering it biologically inactive. Etanercept was evaluated for the treatment of PsA and psoriasis in a preliminary study of 60 patients and in a confirmatory phase III study of 205 patients. In both studies, etanercept was shown to be significantly superior to placebo for the treatment of PsA, evaluated by Psoriatic Arthritis Response Criteria (PsARC) and American College of Rheumatology (ACR) criteria. It also was superior to placebo in improving psoriatic skin lesions, evaluated by the Psoriasis Area and Severity Index (PASI) and target lesion scores. Side-effects were minimal; mild injection site reactions, which resolved during continued therapy, were experienced by approximately one-quarter of the patients. Overall, etanercept is highly effective and well tolerated by patients with PsA, with a safety profile similar to that seen in rheumatoid arthritis.