TNF‐alpha gene polymorphisms can help to predict response to etanercept in psoriatic patients

BACKGROUND: Genetic factors might have a role for lack of therapeutic response to anti-TNF-alpha agents, as previously suggested in patients with rheumatoid arthritis and inflammatory bowel disease. OBJECTIVES: We evaluated the role of the main TNF-alpha polymorphisms (-238G>A, -308G>A, -857C>T) in predicting the response to etanercept, an anti-TNF-alpha fusion protein. MATERIAL AND METHODS: Genomic DNA was extracted from buccal epithelial cells in a series of 97 psoriatic patients who received etanercept for at least 3 months. Patients were classified as responders, if they achieved a PASI improvement ≥ 75% after 12 weeks of etanercept treatment, and non-responders, if PASI improvement was <75%. Single-nucleotide polymorphisms (SNPs) in TNF-alpha gene (-238G>A, -308G>A, -857C>T) were genotyped by PCR restriction fragment length polymorphism (RFLP) assays. RESULTS: We found that patients heterozygous (GA) for the -238G>A polymorphism were more likely not responsive to therapy compared to the GG genotype. In fact, the GA genotype was found in 5/59 (8.5%) responders and in 14/38 (36.8%) non-responders (P = 0.001). A significant relationship with therapy was also observed for the -308G>A polymorphisms. In fact, the GG, GA and AA genotypes were detected in 48 (81.4%), 9 (15.3%) and 2 (3.4%) of the 59 responders and in 22 (57.9%), 11 (28.9%) and 5 (13.2%) of the 38 non-responder patients (P = 0.03). No association with therapy was observed for the -857C>T polymorphisms. CONCLUSION: Our study supports the role of TNF-alpha polymorphisms in predicting the response to anti-TNF-alpha agents. In particular, we found that the presence of -238G>A and -308G>A polymorphisms is associated with poor response to a 3-month therapy with etanercept. However, our data have yet to be validated in larger cohorts.