Etanercept, a tumour-necrosis-factor inhibitor, has shown efficacy in the treatment of rheumatoid arthritis. Psoriatic arthritis and psoriasis are disease states in which tumour necrosis factor, a proinflammatory cytokine, is present in increased concentrations in joints and in the skin. Therefore, psoriatic arthritis and psoriasis may be appropriate therapeutic targets for etanercept.

This randomised, double-blind, placebo-controlled, 12 week study assessed the efficacy and safety of etanercept (25 mg twice-weekly subcutaneous injections) or placebo in 60 patients with psoriatic arthritis and psoriasis. Psoriatic arthritis endpoints included the proportion of patients who met the Psoriatic Arthritis Response Criteria (PsARC) and who met the American College of Rheumatology preliminary criteria for improvement (ACR20). Psoriasis endpoints included improvement in the psoriasis area and severity index (PASI) and improvement in prospectively-identified individual target lesions.

In this 12 week study, 26 (87%) of etanercept-treated patients met the PsARC, compared with seven (23%) of placebo-controlled patients. The ARC20 was achieved by 22 (73%) of etanercept-treated patients compared with four (13%) of placebo-treated patients. Of the 19 patients in each treatment group who could be assessed for psoriasis (≥3% body surface area), five (26%) of etanercept-treated patients achieved a 75% improvement in the PASI, compared with none of the placebo-treated patients (p=0·015). The median PASI improvement was 46% in etanercept-treated patients versus 9% in placebo-treated patients; similarly, median target lesion improvements were 50% and O, respectively. Etanercept was well tolerated.

Etanercept offers patients with psoriatic arthritis and psoriasis a new therapeutic option for control of their disease.