Drug Retention Rate and Factors Associated with Discontinuation of Interleukin-17 Inhibitors in Patients with Axial Spondyloarthritis

PURPOSE: To assess the drug retention rate of interleukin-17 inhibitors (IL-17is) over long-term observation in patients with axial spondyloarthritis (axSpA) in whom treatment with tumor necrosis factor inhibitors (TNFis) failed and to determine baseline factors associated with discontinuation of IL-17is. MATERIALS AND METHODS: This retrospective cohort study included 68 patients with axSpA started on IL-17is after an inadequate response or intolerance to ≥1 TNFis. Drug retention rates at 1, 2, and 3 years were assessed. Baseline (i.e., at initiation of IL-17is) factors associated with discontinuation of IL-17is were evaluated using multivariable Cox proportional hazard regression analysis. RESULTS: Over 1933.9 person-months of observation in 68 patients, discontinuation of IL-17is occurred in 27 (39.7%) patients. Twenty (29.4%) patients discontinued IL-17is because of ineffectiveness, and 7 (10.3%) patients discontinued IL-17is because of adverse events. The 1-year, 2-year, and 3-year drug retention rates for IL-17is were 71.9%, 66.5%, and 62.0%, respectively. Current smoking was associated with a higher risk of IL-17is discontinuation [adjusted hazard ratio (HR)=2.256, 95% confidence interval (CI)=1.053–4.831, p=0.036], while previous use of ≥3 TNFis (vs. 1) was significantly associated with a lower risk of IL-17is discontinuation (adjusted HR=0.223, 95% CI=0.051–0.969, p=0.045). CONCLUSION: In patients with axSpA in whom TNFis failed, the long-term drug retention rate of IL-17is appears to be acceptable, with a 3-year drug retention rate of approximately 60%. Current smoking was associated with a higher risk of discontinuing IL-17is, whereas previous use of ≥3 TNFis was associated with a lower risk of discontinuing IL-17is.