Presence of antidrug antibodies correlates inversely with the plasma tumor necrosis factor (TNF)-α level and the efficacy of TNF-inhibitor therapy in psoriasis.

Antidrug antibodies have been shown to be associated with a loss of response during biologic therapy. Despite the potential association, there has been no report on the simultaneous monitoring of the following parameters in psoriasis: presence of neutralizing antibodies, plasma tumor necrosis factor (TNF)-α concentration, TNFi concentration and disease activity. Plasma concentrations of adalimumab, infliximab, etanercept and their respective antidrug antibodies, as well as plasma concentrations of TNF-α were measured in 77 psoriasis patients receiving biologic therapy, and the values were correlated with the clinical activity of the skin disease. Antidrug antibodies were identified in the plasma of 25% of infliximab-treated patients and 29.6% of adalimumab-treated patients, but not in the etanercept group. Clinical severity scores were significantly higher in the antibody-positive patients. In patients receiving infliximab or adalimumab therapy, the presence of antidrug antibodies was directly associated with reduced plasma TNF-inhibitor concentration and elevated plasma TNF-α level.