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.