Efficacy and safety of tocilizumab in adult-onset Still's disease: Real-life experience from the international AIDA registry

Background/objectives: Long-term efficacy and safety of tocilizumab (TCZ) in adult-onset Still’s disease (AOSD) mostly derive from small case series. Herein we report a registry-based study investigating TCZ efficacy and safety in a cohort of patients with AOSD evaluated by clinical and serum inflammatory markers as well as drug retention rate analysis. Methods: This is an international multicentre study analyzing data from patients with AOSD regularly enrolled in the AIDA registry. TCZ efficacy was evaluated between baseline and last follow-up assessment in terms of changes in the Pouchot score and laboratory findings. Drug-retention rate was estimated by the Kaplan-Meier method, while Cox-regression analysis was employed to detect potential predictive factors of treatment withdrawal. Results: Data from 31 patients (15 men, 16 women) refractory to the conventional therapies and treated with TCZ were extracted from the AIDA registry. Mean ± SD time of treatment duration with TCZ was 24.32 ± 20.57 months. Pouchot score significantly decreased from baseline 2.00 (4.00) to the last follow-up assessment 00.00 (00.00), p=0.003). Similarly, laboratory parameters significantly decreased from baseline to the last follow-up visit. With regard to drug survival, cumulative TCZ retention rate at 12-, 24-, and 36-month follow-up visit were 83.1%, 71.7% and 63.7%, respectively, without significant differences between biologic naïve patients and those previously treated with other biologics (p=0.329). Likewise, no significant differences were observed between chronic articular course of AOSD and other types of disease course (p=0.938) or between patients co-administered with conventional immunosuppressants and patients receiving TCZ as monotherapy (p=0.778). Cox-regression analysis identified no variable associated with a higher hazard of treatment withdrawal. Treatment was discontinued in 9 patients due to long-term remission (n=4), adverse events (n=2), loss of efficacy (n=1)