Therefore, the aim of this retrospective study was to investigate the effects of the TNF-α blockers adalimumab, etanercept, and infliximab; the IL-17A antagonists ustekinumab, secukinumab, and ixekizumab; and acitretin and methotrexate, which are used in the treatment of psoriasis, on the PLR, NLR, NMR, and SII in psoriasis patients, and to seek answers to the question of whether these parameters can be biomarkers of treatment efficacy for these drugs. This evidence concerns the gene IL17A and psoriasis.