We evaluated the influence of clinical, biochemical, and genetic factors on response in 142 patients diagnosed with rheumatoid arthritis, of whom 87 patients were treated with tocilizumab (61.26%) and 55 patients were treated with rituximab (38.7%;) according to the variables European League Against Rheumatism (EULAR) response, remission, low disease activity, and improvement in Disease Activity Score, 28 joints (DAS28) at 6, 12, and 18 months. A retrospective prospective cohort study was conducted. Patients carrying the FCGR3A rs396991‐TT genotype treated with tocilizumab showed higher EULAR response (OR, 5.075; 95%CI, 1.20–21.33; P = .027) at 12 months, those who were naive for biological disease‐modifying antirheumatic drugs (bDMARDs) at the beginning of treatment showed satisfactory EULAR response, higher remission, and greater improvement in DAS28 at 6 months. Younger age at start of tocilizumab treatment was associated with satisfactory EULAR response at 18 months and greater remission at 6 and 18 months. Subcutaneous tocilizumab administration was associated with higher remission at 6 months and improved low disease activity rate at 12 months. In patients treated with rituximab, carriers of the FCGR2A rs1801274‐TT genotype had higher EULAR response at 6 months (OR, 4.861; 95%CI, 1.11–21.12; P = .035), 12 months (OR, 4.667; p = 0.066, 95%CI, 0.90–24.12; P = .066), and 18 months (OR, 2.487; 95%CI, 0.35–17.31; P = .357), higher remission (OR: 10.625; p = 0.044, CI95%: 1.07, 105.47) at 6 months, and greater improvement in DAS28 at 12 months (B = 0.782; 95%CI, −0.15 to 1.71; P = .098) and 18 months (B = 1.414; 95%CI, 0.19–2.63; P = .025). The FCGR3A rs396991‐G allele was associated with improved low disease activity rate (OR, 4.904; 95%CI, 0.84–28.48; P = .077) and greater improvement in DAS28 (B = −1.083; 95%CI, −1.98 to −0.18; P = .021) at 18 months. Patients with a lower number of previous biological therapies had higher remission at 12 months. We suggest that the FCGR3A rs396991‐TT genotype, higher baseline value of DAS28, subcutaneous tocilizumab administration, younger age at the beginning of treatment, and being bDMARD naive are associated with better response to tocilizumab. In patients treated with rituximab, we found better response in those patients with the FCGR2A rs1801274‐TT genotype, the FCGR3A rs396991‐G allele, and lower number of previous biological therapies.

In the present study, we aimed to investigate the influence of clinical parameters and single-nucleotide polymorphisms of interleukin-6 receptor (rs12083537, rs2228145, rs4329505 and rs11265618) on response to tocilizumab, TCZ (European League Against Rheumatism (EULAR) response, remission, low disease activity (LDA) and improvement of DAS28). We performed a retrospective cohort study in patients with Rheumatoid Arthritis (RA) treated with TCZ for 12 months. Multivariable analysis showed that the only variable independently associated to satisfactory EULAR response (odds ratio (OR): 0.61; 95% of confidence interval (CI): 0.42, 0.88; P=0.008), remission (OR: 0.51; CI: 0.35, 0.75; P=0.001), LDA (OR: 0.41; CI: 0.24, 0.72; P=0.002) and improvement in DAS28 (B=-0.32; CI: -0.47, -0.17; P=7.5 × 10) at 12 months was lower number of previous biological therapy (BT). High baseline DAS28 was also associated with a greater decrease in DAS28 at 12 months of treatment (B=0.99; CI: 0.79, 1.20; P=1.5 × 10). Those patients who were carriers of AA genotypes for rs12083537 (OR: 13.0; CI: 2.31, 72.91; P=0.004) and CC for rs11265618 (OR: 12.15; CI: 2.18, 67.81; P=0.004) had better LDA response at 12 months of treatment with TCZ. In conclusion, RA patients treated with TCZ showed better EULAR response, remission, LDA and DAS28 improvement rates when a lower number of BT were previously administered. The AA genotype for rs12083537 and CC for rs11265618 polymorphisms for may act as predictors of good response LDA.

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