Etanercept in the treatment of psoriatic arthritis and psoriasis

Context

The level of tumor necrosis factor (TNF) expression in psoriatic arthritis (PsA) is similar to that seen in the rheumatoid synovium. Increased expression of TNF can also be found in the skin of psoriatic lesions. TNF inhibition with etanercept has previously been shown to diminish the activity of rheumatoid arthritis (RA). This study assessed the efficacy and safety of etanercept in patients with PsA and psoriasis.

Significant findings

In the etanercept group (n = 30), 26 patients (87%) met the Psoriatic Arthritis Response Criteria, compared with 7 patients (23%) in the placebo group (n = 30; P <0.0001). American College of Rheumatology 20% response criteria for RA (ACR 20) were acheived in 22 etanercept-taking patients compared with 4 taking placebo (P<0.0001).

ACR 50 was achieved in 50% and ACR 70 in 13% of the etanercept arm compared to 3% and 0% of the placebo group. Psoriasis could be assessed in 19 patients in both treatment groups. In the etanercept group, five out of 19 (26%) patients achieved 75% improvement in the psoriasis area and severity index compared with none in placebo group (P= 0.0154). Individual measures of arthritis also showed a significantly better response in the etanercept arm. No serious adverse event occurred in patients receiving etanercept. In conclusion, blocking TNF may offer a new therapeutic option in both PsA and psoriasis.

Comments

This study demonstrated that etanercept is effective in the short-term treatment of both PsA and psoriasis. These results are encouraging but longer follow-up is necessary to evaluate the full impact of TNF inhibition in this setting. The high response rate in arthritis is not surprising since most patients had polyarticular disease, a subset of PsA with striking similarities to RA. Despite the clinical and histologic similarities between PsA and RA there is a significant difference in their radiographic characteristics. Erosions are present in both diseases but new bone formation is seen only in PsA. Radiographic studies are therefore needed to evaluate the effect of TNF-blockade on bone erosions, as well as on new bone formation.

Methods

Randomized, double-blind, placebo-controlled trial; adults; stable doses of methotrexate or oral corticosteroid allowed