This is in agreement with several previous biomarker studies of the PDE4 inhibitor apremilast in psoriasis patients, showing a significant modulation of TH1 and TH17 cytokines involved in the pathogenesis of psoriasis (e.g., IL‐17A/F, IL‐22 and TNFα) [16, 17, 18]. This evidence concerns the gene TNF and psoriasis.