SAN ANTONIO, Texas – Recently released data from an international multicenter trial suggest that independent of the arthritis response, clinicians should continue to use the anti-tumor necrosis factor-α (TNF-α) agent infliximab for patients with active psoriatic arthritis because the drug markedly reduces skin symptoms.

Although 58% of psoriatic arthritis patients in the study achieved an ACR20 – a relatively modest score – at week 14 of the trial, 63.9% with that articular score had a robust Psoriasis Area Severity Index (PASI) 75 improvement (P <0.001 vs placebo) in the subset of patients with a baseline body surface area of at least 3%. "The impact of this drug on skin is quite dramatic," Philip Mease, MD, of Seattle Rheumatology Associates/Swedish Medical Center, Seattle, Washington, said Wednesday at the 2004 annual scientific meeting of the American College of Rheumatology.

The IMPACT 2 trial recruited 200 patients with active psoriatic arthritis who were randomly assigned to receive either placebo or infliximab 5 mg/kg at the start of the trial and then at Week 2, Week 6, Week 14 and Week 22. The patients were evaluated at Week 24.

Among ACR20 responders overall at week 14, 75% of patients taking infliximab achieved a PASI 75 score, compared with 18% in the placebo group (P <0.001), the study found.

"These drugs are worthwhile in treating patients with stubborn cases of psoriasis," said John Reveille, MD, Chief of Rheumatology at the University of Texas Health Science Center at Houston, who commented on the study. "Many people with psoriasis will never need to have treatment with the anti-TNF agents. In my practice, I reserve treatment with these agents for those people who are most severely affected by the disease."

Infliximab demonstrated improved psoriasis irrespective of the arthritis response, Dr. Mease said, noting that the best responses to quality of life evaluations occurred with those who achieved both an ACR20 and a PASI 75.

"There is a lot more going on in the joint with B-cells and macrophages aside from T-cells [which are deactivated by anti-TNF drugs]," said Dr. Mease, lead IMPACT 2 investigator. "But in the skin it is mainly T-cells."

He speculated that these factors may explain why infliximab worked better on the skin symptoms of the psoriatic arthritis patients.

Reference:

Mease P, Kavanaugh A, Krueger GG, et al. Infliximab improves psoriasis regardless of arthritis response in patients with active psoriatic arthritis: results from the IMPACT 2 trial. Presented at: Annual Meeting of the American College of Rheumatology; October 20, 2004; San Antonio, Texas. Abstract 1635