IL17A and psoriasis vulgaris: Based on this evidence, monoclonal antibodies targeting the IL-17 program have made their way into clinical practice: Treatment of psoriasis vulgaris with secukinumab (targeting IL-17A) or ustekinumab (targeting IL-12/IL-23) led to a rapid reduction of psoriasis symptoms in clinical studies, corroborating the detrimental role of the IL-23/IL-17-axis in the pathogenesis of psoriasis [221, 222].