Impact of pharmacogenomics upon the therapeutic response to etanercept in psoriasis and psoriatic arthritis.

INTRODUCTION: TNF-α inhibitors have demonstrated efficacy both as monotherapy and in combination with disease-modifying anti-rheumatic drugs (DMARDs) in the treatment of chronic inflammatory immune-mediated diseases. Etanercept is a decoy receptor" for TNF-α and it is composed of two p75 TNF-α receptors fused to human IgG1. Areas covered: We discuss the potential role of pharmacogenetics in predicting the response to etanercept in patients with Ps and PsA. Expert opinion: Pharmacogenetics represents the new frontier for the discovery of potential genetic markers of biological response to TNF-α inhibitors. Clinical studies showed that TNF-α -308 G/G, +489 GG and the +489 GA, TNF-α -857C (rs1799724), TNFRSF1B 676T (rs1061622), TNFAIP3 G SNP (rs610604), FcγRIIIA-V158F, HLA-C*06, IL-17 A (rs2275913 and rs10484879), IL-17F (rs763780) and IL17RA (rs4819554) SNPs favor the response to etanercept. However, most of these studies are often small and not sufficiently powered to detect an effect and markers tend to be more prognostic than predictive of therapeutic response. Furthermore, studies often examines only the effects of a single SNP, while it would be more useful to analyze more haplotypes in contemporary in the same patients. Appropriately designed clinical trials are needed before a pharmacogenetic approach may be applicable in daily clinical therapeutic practice.