Long‐Term Follow‐Up of Anti‐Infliximab Antibodies in Patients With Radiographic Axial Spondyloarthritis: A Marker of Drug Survival and Tapering.

Objective: The aim of this study was to evaluate the influence of anti‐infliximab (IFX) antibodies on three different points of care: response/tolerance to IFX, tapering strategy, and in a subsequent treatment with a second tumor necrosis factor inhibitor (TNFi). Methods: A prospective cohort of 60 patients with radiographic axial spondyloarthritis who received IFX were evaluated retrospectively regarding clinical/laboratorial data, IFX levels, and anti‐IFX antibodies at baseline, after 6, 12 to 14, 22 to 24, 48 to 54, 96 to 102 weeks, and before tapering or switching. Results: Anti‐IFX antibodies were detected in 27 patients (45%), of whom 23 (85.1%) became positive in the first year of IFX treatment. In comparison to the group that was negative for anti‐IFX antibodies, patients who were positive for anti‐IFX antibodies demonstrated the following: less use of methotrexate as a concomitant treatment to IFX (5 [18.5%] vs 14 [42.4%]; P = 0.048), more infusion reactions at 22 to 24 weeks (P = 0.020) and 48 to 54 weeks (P = 0.034), more treatment failures (P = 0.028) at 48 to 54 weeks, reduced overall IFX survival (P < 0.001), and lower sustained responses (P = 0.044). Of note, patients who were positive for anti‐IFX antibodies exhibited a shorter tapering survival (9.9 months [95% confidence interval (CI) 4.0–15.8] vs 63.4 months [95% CI 27.9–98.8]; P = 0.004) in comparison with patients who were negative for anti‐IFX antibodies. Conversely, for patients who failed IFX, patients who were positive for anti‐IFX antibodies had better clinical response to the second TNFi at three months (15 [83.3%] vs 3 [27.3%]; P = 0.005) and six months (15 [83.3%] vs 4 [36.4%]; P = 0.017) than the patients who were negative for anti‐IFX antibodies after switching. Conclusion: This study provided novel data that anti‐IFX antibodies is a parameter for reduced tapering survival, reinforcing its detection to guide clinical decision. Additionally, we confirmed in a long‐term cohort the anti‐IFX antibody association with worse IFX performance and as predictor of the second TNFi good clinical response. [ABSTRACT FROM AUTHOR]