Leflunomide Improves Psoriasis in Patients with Psoriatic Arthritis: An In-Depth Analysis of Data from the TOPAS Study

BACKGROUND: Leflunomide has shown promise in the treatment of psoriasis. OBJECTIVE: To provide an in-depth analysis of the effect of leflunomide on psoriasis in patients with psoriatic arthritis (PsA). METHODS: 190 patients with plaque psoriasis (at least 3% skin involvement) and active PsA were randomized to double-blind treatment with leflunomide (100 mg/day loading dose for 3 days followed by 20 mg/day orally) or placebo for 24 weeks. RESULTS: As previously reported, leflunomide resulted in a significantly higher Psoriatic Arthritis Response Criteria response rate than placebo (58.9 vs. 29.7%; p < 0.0001). Significant differences in favor of leflunomide were also observed in the Psoriasis Area and Severity Index (PASI 50 in 30.4% of patients vs. 18.9% for placebo; p = 0.05), target lesion response (46.4 vs. 25.3%; p = 0.0048), combined skin and joint response (27.2 vs. 8.9%; p < 0.0001), Dermatology Life Quality Index (improvement of 1.9 points vs. 0.2; p = 0.0173) and certain SF-36 subdomains. Dermatological responses were observed at the earliest examination (4 weeks) and increased throughout the 24-week study. CONCLUSION: Once-daily oral leflunomide is an effective and convenient treatment for PsA and plaque psoriasis.