Drug retention rate and predictive factors of drug survival for interleukin-1 inhibitors in systemic juvenile idiopathic arthritis

Introduction: The advent of biologic agents has revolutionized therapeutic approaches in systemic juvenile idiopatic arthritis (sJIA) as their introduction has been shown to modify disease course and improve overall outcomes, particularly when initiated early. Few studies have reported the drug retention rate (DRR) of biologic drugs in JIA, and none of them has specifically investigated the DRR of interleukin (IL)-1 inhibitors on sJIA. Objectives: The primary aim of the study was to examine the overall DRR of IL-1 blockers in sJIA patients. Secondary aims of our study were to: (i) explore the influence of biologic line of treatment, adverse events (AEs), type of anti-IL-1 agent and the concomitant use of conventional disease modifying anti-rheumatic drugs (cDMARDs) on DRR; (ii) find eventual predictive factors associated with events leading to drug discontinuation. The corticosteroid sparing effect and the impact of disease duration and treatment delay on survival constituted ancillary aims. Methods: sJIA patients – diagnosed according to the revised International League of Association for Rheumatology (ILAR) criteria – treated with anakinra (ANA) and canakinumab (CAN) were enrolled in 15 Italian tertiary referral centers. Demographic, clinical and therapeutic data collected from medical records were retrospectively collected and statistically analyzed. Results: Seventy seven patients were enrolled for a total of 86 treatment courses. The cumulative retention rate of the IL-1 inhibitors at 12-, 24-, 48-, and 60-months of follow-up was 79.9, 59.5, 53.5, and 53.5%, respectively, without any statistically significant differences between ANA and CAN (p = 0.056), and between patients treated in monotherapy compared to the subgroup co-administered with conventional immunosuppressors (p = 0.058). On the contrary, significant differences were found between biologic-naive patients and those previously treated with biologic drugs (p = 0.038) and when distinguishing according to AEs occurrence (p = 0.04). In regression analysis, patients pre-treated with other biologics (HR = 3.357 [CI: 1.341–8.406], p = 0.01) and those experiencing AEs (HR = 2.970 [CI: 1.186–7.435], p = 0.020) were associated with a higher hazard ratio of IL-1 inhibitors withdrawal. The mean treatment delay was significantly higher among patients discontinuing IL-1 inhibitors (p = 0.0002). Conclusion: Our findings suggest an excellent overall DRR for both ANA and CAN that might be further augmented by paying attention to AEs and employing these agents as first-line biologics in an early disease phase.