P1309 Is there any association between genetic polymorphisms and response to Anti-TNFs in patients with inflammatory bowel disease ? Experience of a Tunisian IBD center

Abstract Background Although highly effective, primary failure and loss of response to anti tumor necrosis factors (anti-TNF) alpha in inflammatory bowel disease (IBD) are common and associated with poor clinical outcomes. Multiple factors, including genetics, have been involved in the response to anti TNF alpha therapy. Thus, the purpose of our study was to evaluate the impact of the polymorphism of the SNPs rs1799724 (TNF alpha), rs767455 (TNFRSF1A), and rs1061622 (TNFRSF1B) in the response to anti-TNF alpha treatment in Tunisian IBD patients. Methods We conducted a prospective study including patients followed for IBD and treated with anti-TNF alpha. We classified these patients into two groups: responders and non-responders to anti-TNF alpha. Genomic DNA was purified from peripheral blood leucocytes using the salting-out method. Subjects were genotyped for polymorphisms TNF (rs 1799724), TNFRSF1A (rs767455) and TNFRSF1B (rs1061622) using a variant of allele-specific PCR, Mutagenically Separated PCR (MS-PCR). Genotypic and allelic frequencies were compared between the two groups of patients. Results We included 61 IBD patients with a mean age of 38,9 years [18-64 years]. Forty six patients (75.4%) had CD and 15 (24.6%) had UC. In the CD group, 35 (76.1%) patients were treated with infliximab and 11(23.9%) with Adalimumab. Nineteen were responders to treatment (41,3%) and 27 (58.7%) experienced treatment failure: primary failure in 4 and loss of response in 23. Genetic analysis did not show any association between the response to anti TNF alpha treatment and SNPs rs1799724 (TNF alpha) (P= 0,12 ; OR = 1,9) and rs1061622 (TNFRSF1B) (P= 0,9; OR= 1,06). Although, the CT genotype of rs767455 (TNFRSF1A) was associated with non-response (OR= 3.5 with a 95% CI [0.98-12.4], p=0.049). In the UC group, 14 patients were treated with Infliximab and only one patient treated with Adalimumab. Seven patients responded to anti-TNF therapy (46.7%) and 8 were non-responders (53.3%) with 5 cases of primary failure and 3 cases of loss of response. We didn’t find any association between the SNPs rs1799724 (TNF alpha), rs767455 (TNFRSF1A), and rs1061622 (TNFRSF1B) and response to anti TNF alpha in the UC patients. Conclusion Among the three SNPs studied, only the rs767455 (TNFRSF1A) was shown to be associated with non-response to anti-TNF in chrohn’s disease patients. However, our results need to be validated in a larger sample of patients.