OP0200 Global DNA Methylation Patterns Differ Between Responders and Non-Responders in Psoriatic Arthritis Patients Treated with Tumor Necrosis Factor-α Inhibitors

BackgroundAlthough tumor necrosis factor-α inhibitors TNFi are well established treatment for psoriatic arthritis (PsA), the efficacy can vary greatly between patients. In this study, we examined the genome-wide epigenetic changes among TNFi responders and TNFi secondary failures in PsA patientsMethodsTwenty-one PsA patients (15 males; 6 females) were considered TNFi responders of which 13 were treated with etanercept and 8 with adalumimab. The median follow up duration was 18 months. Twenty patients (5 males; 15 females) were secondary TNFi failures of which 15 were treated with etanercept and 5 with adalumimab. The median follow up duration was 36 months. Genome-wide DNA methylation profiling was performed using the Illumina HumanMethylation450k Beadchip, which measures ∼480,000 different CpG sites per sample and covers 96% of RefSeq genes. The methylation level at each CpG site was measured by β values varying from 0 (no methylation) to 1 (100% methylation). Analysis was performed using a t-test after a Bonferroni-Holm correction was applied. Regions of interest were selected based on β value (β diff>5%) and p-value (p