Profiling Response to Tumor Necrosis Factor Inhibitor Treatment in Axial Spondyloarthritis

Objective Lack of response to tumor necrosis factor inhibitor (TNFi) agents is not uncommon, encountered during the treatment of axial spondyloarthritis (SpA) patients, and it can be classified as primary lack of response (PLR) or secondary lack of response (SLR). The primary aim of this study was to evaluate factors associated with TNFi failure types and their characteristics in axial SpA. Methods Adult axial SpA patients who were TNFi naive at the time of baseline evaluation and started receiving their first biologics for active axial disease were identified. Based on the clinical response to the first TNFi, patients were then stratified into 3 groups: PLR, SLR, and responders. Clinical, demographic, and laboratory data were collected and analyzed. Results There was a total of 249 axial SpA patients in the study (70.7% male, mean ± SD age 37.3 ± 12.4 years), which included PLR (n = 62), SLR (n = 93), and responders (n = 94). PLR patients tended to be older, with a lower HLA–B27 rate, a higher percentage of nonresponder axial SpA patients, and a higher baseline Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score compared to SLR patients or responders. In multiple regression analysis, increasing age, negative HLA–B27, higher baseline BASDAI, and treatment with the soluble TNF receptor protein were the independent predictors of PLR. Conclusion PLR accounted for nearly 40% of the TNFi failures in axial SpA patients. Older age, negative HLA–B27, higher baseline disease activity, and treatment with soluble TNF receptors were the independent predictors of the primary nonresponse to TNFi.