Etanercept has demonstrated excellent safety and efficacy in the treatment of patients with
psoriatic arthritis (PsA), which is a chronic inflammatory
arthritis. Composed of 2 soluble
TNF receptor (p75) domains fused to human
immunoglobulin,
etanercept neutralizes the inflammatory
cytokines TNF and
lymphotoxin-alpha. In a phase 2, randomized, placebo-controlled trial of 60 patients with PsA,
etanercept 25 mg subcutaneously twice weekly resulted in significantly more improvement in
arthritis and skin symptoms than placebo. At 12 weeks, 87% of
etanercept-treated patients achieved a clinical response by the
Psoriatic Arthritis Response Criteria compared with 23% of the placebo group. The percent of those patients achieving an American College of Rheumatology 20% (ACR20), ACR 50, and ACR70 response were 73%, 50% and 13%, respectively, compared to 13%, 3%, and 0% in the placebo group. The median improvement in
skin disease activity (assessed by the
Psoriasis Area and Severity Index) in the
etanercept group was 46% versus 9% in the placebo group. In a 6-month open-label extension of this study, patients who originally had received placebo rapidly achieved responses to
etanercept that were comparable to responses in the group originally randomized to the active
drug; in the group originally on
etanercept, efficacy was maintained, and a large proportion of patients decreased or discontinued concomitant
prednisone or
methotrexate.
Etanercept was generally well tolerated throughout this trial. A phase 3 trial confirmed the efficacy and safety of
etanercept in PsA, with 59% of
etanercept-treated patients meeting the ACR20 improvement criteria at 12 weeks compared with 15% of placebo-treated patients. Significant improvements in skin lesions relative to placebo were also observed No adverse events were significantly more common with
etanercept than with placebo. Several case studies add to our body of knowledge of
etanercept in PsA.
Etanercept is well suited to long-term
therapy and provides a valuable treatment option for PsA.