Measurement of pre‐treatment inflammatory cytokine levels is valuable for prediction of treatment efficacy to tumor necrosis factor inhibitor in axial spondyloarthritis patients

AIM: To evaluate the correlation of inflammatory cytokines with the treatment response to tumor necrosis factor inhibitor (TNFi) in axial spondyloarthritis (axSpA) patients. METHODS: This study enrolled 86 axSpA patients and 20 healthy controls (HCs). Inflammatory cytokines including tumor necrosis factor‐α (TNF‐α), interleukin (IL)‐1β, IL‐6, IL‐12, IL‐17A, IL‐21, IL‐23, and IL‐32 were determined in serum samples of axSpA patients before treatment and in HCs after enrollment. All patients received 40 mg adalimumab every 2 weeks for 12 weeks; meanwhile, ASAS40 (40 criteria of the Assessment by the SpondyloArthritis International Society) response rates were evaluated at weeks 2, 4, 8, and 12. RESULTS: Most inflammatory cytokines were elevated in axSpA patients compared with HCs (all P < 0.05) except for IL‐32 (P = 0.101). In axSpA patients, ASAS40 response rates were 0%, 19.5%, 34.5%, 47.1%, and 56.3% at weeks 0, 2, 4, 8, and 12, respectively. Baseline [interquartile range] IL‐6 (47.3 [32.5‐53.4] pg/mL vs 31.7 [23.0‐50.9] pg/mL, P = 0.005) and IL‐17A (127.9 [90.7‐149.5] pg/mL vs 96.6 [56.1‐112.6] pg/mL, P < 0.001) were higher in axSpA patients with ASAS40 response compared with those without ASAS40 response, while baseline TNF‐α, IL‐1β, IL‐12, IL‐21, IL‐23, and IL‐32 were not different between them (all P > 0.050). Multivariate logistic regression analysis disclosed that baseline IL‐17A (P = 0.037), C‐reactive protein (P = 0.012), and history of TNF inhibitor (P = 0.029) were independently associated with ASAS40 response. Furthermore, baseline IL‐17A, C‐reactive protein, history of TNFi, and their combination had an acceptable to good ability for predicting ASAS40 response. CONCLUSION: Measurement of pre‐treatment inflammatory cytokine levels is valuable for predicting treatment efficacy of TNFi in axSpA patients.