Does Prior Exposure Affect Retention? A Real-World, Multicentre Assessment of IL-17 Inhibitor Cycling in Psoriatic Arthritis

Introduction: Interleukin-17 inhibitors (IL-17i) represent a key therapeutic option for psoriatic arthritis (PsA), but real-world evidence regarding the effectiveness of cycling strategies within this class is lacking. This study evaluated the real-world retention of IL-17i in PsA, focusing on whether prior IL-17i exposure affects subsequent IL-17i persistence. Methods: This multicentre, retrospective, observational study included consecutive patients with PsA treated with an IL-17i across 24 Italian rheumatology centres. The primary outcome was drug retention, analysed using Kaplan–Meier methods, with differences between IL-17i-naïve and IL-17i-experienced patients assessed with the log-rank test. Secondary outcomes included baseline clinical characteristics and predictors of discontinuation. Results: A total of 868 patients were included (59.3% female, 40.7% male; median age 56 [48–63] years; 89.3% IL-17i-naïve). The overall median IL-17i retention rate was 90.7% [95% CI 88.7–92.8] at 6 months, 77.5% [95% CI 74.6– 80.6] at 12 months, 60.9% [95% CI 57.3–64.8] at 24 months, and 52.1% [95% CI 48.1–56.4] at 36 months. Among IL-17i-naïve patients, retention rates were 90.5%, 77.6%, 61.7%, and 53.9% at 6, 12, 24, and 36 months, respectively. Among IL-17i-experienced patients, the corresponding retention rates were 92.2%, 77.0%, 54.0%, and 33.9%. In multivariable Cox regression, male sex and prior IL-17 inhibitor exposure were associated with a lower risk of discontinuation, whereas axial involvement, a higher number of previous biologic/targeted synthetic diseasemodifying anti-rheumatic drugs (b/tsDMARDs), and later calendar year of IL-17i initiation predicted poorer retention. Conclusions: IL-17i showed high long-term retention in real-world PsA, with no significant difference between naïve and previously exposed patients. These findings support the sustained effectiveness of IL-17i therapy and suggest that cycling within the class may remain a reasonable option for selected cases.