Objective: To determine whether a functional single-nucleotide polymorphism in the B-cell activating factor (BAFF) gene correlates with the response to treatment with rituximab (RTX) in RA.
Methods: SMART is a randomized open trial (NCT01126541) assessing two strategies of re-treatment in patients responding to 1-g infusion of RTX with MTX on days 1 and 15 after failure, intolerance or contraindication to TNF blockers. Among the 224 patients included, 115 provided informed consent, could be genotyped and were included in an ancillary study of SMART assessing European League Against Rheumatism (EULAR) response rate after the first course of RTX according to BAFF-871C>T polymorphism. Baseline clinical factors (patients and disease characteristics) and biologic factors (ESR, CRP, RF, anti-citrullinated peptide antibodies, serum immunoglobulins) were collected. Univariate analyses were performed to assess whether BAFF-871C>T polymorphism was associated with EULAR response at week 24. Results with P < 0.15 obtained in univariate analyses were then included in multivariate analysis adjusted on DAS28 level.
Results: Ninety-three patients (81%) were responders, of whom 31 (27%) were good responders. CC genotype was significantly associated with a higher response rate [92% of responders vs 64% for TT genotype, odds ratio (OR) = 6.9; 95% CI 1.6, 29.6; P = 0.03]. These results were also confirmed in RF-positive patients (96% vs 58%, P = 0.006). In multivariate analysis, C allele carriage was independently associated with response to RTX (OR = 4.1; 95% CI 1.3, 12.7; P = 0.017).
Conclusion: The BAFF-871C>T polymorphism seems to influence the response to RTX in RA patients after failure or intolerance to TNF blockers.