Background
Anti‐tumor necrosis factor‐α (TNF‐α) is used for the treatment of severe cases of IBD, including Crohn's disease (CD) and ulcerative colitis (UC). However, one‐third of the patients do not respond to the treatment. We have previously investigated whether single nucleotide polymorphisms (SNPs) in genes involved in inflammation were associated with response to anti‐TNF therapy among patients with CD or UC.

Aim
A new cohort of patients was established for replication of the previous findings and to identify new SNPs associated with anti‐TNF response.

Methods
Fifty‐three SNPs assessed previously in cohort 1 (482 CD and 256 UC patients) were genotyped in cohort 2 (587 CD and 458 UC patients). The results were analysed using logistic regression (adjusted for age and gender).

Results
Ten SNPs were associated with anti‐TNF response either among patients with CD (TNFRSF1A(rs4149570) (OR: 1.92, 95% CI: 1.02‐3.60, P = 0.04), IL18(rs187238) (OR: 1.35, 95% CI: 1.00‐1.82, P = 0.05), and JAK2(rs12343867) (OR: 1.35, 95% CI: 1.02‐1.78, P = 0.03)), UC (TLR2(rs11938228) (OR: 0.55, 95% CI: 0.33‐0.92, P = 0.02), TLR4(rs5030728) (OR: 2.23, 95% CI: 1.24‐4.01, P = 0.01) and (rs1554973) (OR: 0.49, 95% CI: 0.27‐0.90, P = 0.02), NFKBIA(rs696) (OR: 1.45, 95% CI: 1.06‐2.00, P = 0.02), and NLRP3(rs4612666) (OR: 0.63, 95% CI: 0.44‐0.91, P = 0.01)) or in the combined cohort of patient with CD and UC (IBD) (TLR4(rs5030728) (OR: 1.46, 95% CI: 1.01‐2.11, P = 0.04) and (rs1554973)(OR: 0.80, 95% CI: 0.65‐0.98, P = 0.03), NFKBIA(rs696) (OR: 1.25, 95% CI: 1.01‐1.54, P = 0.04), NLRP3(rs4612666) (OR: 0.73, 95% CI: 0.57‐0.95, P = 0.02), IL1RN(rs4251961) (OR: 0.81, 95% CI: 0.66‐1.00, P = 0.05), IL18(rs1946518) (OR: 1.24, 95% CI: 1.01‐1.53, P = 0.04), and JAK2(rs12343867) (OR: 1.24, 95% CI: 1.01‐1.53, P = 0.04)).

Conclusions
The results support that polymorphisms in genes involved in the regulation of the NFκB pathway (TLR2, TLR4, and NFKBIA), the TNF‐α signalling pathway (TNFRSF1A), and other cytokine pathways (NLRP3, IL1RN, IL18, and JAK2) were associated with response to anti‐TNF therapy. Our multi‐SNP model predicted response rate of more than 82% (in 9% of the CD patients) and 75% (in 15% of the UC patients), compared to 71% and 64% in all CD and UC patients, respectively. More studies are warranted to predict response for use in the clinic.