A prospective, randomized, placebo-controlled study to identify biomarkers associated with active treatment in psoriatic arthritis: effects of adalimumab treatment on lesional and nonlesional skin.

BACKGROUND: There is a need for biomarkers to screen the effectiveness of (novel) therapeutic agents for psoriasis at an early stage. OBJECTIVE: We aimed to determine which of the changes in psoriatic skin correlates best with clinical improvement 4 weeks after effective adalimumab therapy. METHODS: Twenty-two psoriatic arthritis patients were randomized to receive adalimumab or placebo. T cell numbers and markers of innate immunity were estimated in lesional and nonlesional skin biopsies at baseline and after 4 weeks of treatment. RESULTS: CD161+ and elastase+ dermal cells in lesional skin were significantly reduced upon 4 weeks of successful adalimumab treatment compared with placebo. CONCLUSION: Early improvement of psoriasis lesions during adalimumab therapy is associated with a marked reduction of infiltrated dermal CD161+ T cells and elastase+ neutrophils, suggesting that these parameters could be used as biomarkers to monitor early changes after active treatment in small proof-of-concept studies of short duration.