Response to IL-17A inhibitors secukinumab and ixekizumab cannot be explained by genetic variation in the protein-coding and untranslated regions of the IL-17A gene: results from a multicentre study of four European psoriasis cohorts

Background Genetic predictors for treatment response could optimize allocation of biological treatment in patients with psoriasis. There is minimal knowledge about pharmacogenetics of anti-IL-17 agents. Objectives To assess whether genetic variants in the protein-coding region or untranslated regions of the IL-17A gene are associated with response to IL-17A inhibitors in patients with psoriasis. Methods This was a multicenter European cohort study investigating pharmacogenetics of IL-17A inhibitors in patients with psoriasis. Patients with plaque psoriasis treated with secukinumab or ixekizumab in daily practice were included. For all participants, the protein-coding region and untranslated regions of the IL-17A gene were analysed using Sanger sequencing. Identified genetic variants were tested for association with response to secukinumab/ixekizumab, measured as increment PASI, after 12 weeks (primary outcome) and after 24 weeks (secondary outcome). Association was tested using a linear regression model with correction for baseline PASI as a fixed covariate and for biological naivety and body mass index as additional covariates. Results In total, 134 patients treated with secukinumab or ixekizumab were included. Genotyping of the cohort identified genetic variants present in untranslated regions and intronic DNA, but not in the protein-coding region of the IL-17A gene. Five genetic variants in non-coding DNA with a known or suspected functional effect on IL-17A expression were selected for association analyses: rs2275913, rs8193037, rs3819025, rs7747909 and rs3748067. After 12 weeks, 62% of patients achieved PASI75 and 39% achieved PASI90. At week 24, PASI75 and PASI90 response rates were 72% and 62%, respectively. No associations were found between the five genetic variants and increment PASI, PASI75 or PASI90 after 12 and 24 weeks of anti-IL-17A treatment. Conclusions Response to IL-17A inhibitors secukinumab and ixekizumab cannot be explained by genetic variation in the protein-coding and untranslated regions of the IL-17A gene. Pharmacogenetics of IL-17A inhibitors in the treatment of psoriasis requires further exploration.