Tocilizumab discontinuation after remission achievement in patients with adult-onset Still’s disease

Abstract Objectives Tocilizumab, an IL-6 inhibitor, has been proven effective in patients with adult-onset Still's disease (AOSD). This study aimed to clarify whether tocilizumab can be discontinued after achieving remission and to identify factors relevant to its successful discontinuation. Methods Consecutive patients with AOSD diagnosed according to Yamaguchi's criteria from April 2012 to July 2022, who were treated with tocilizumab, were retrospectively reviewed. Results Forty-eight patients with AOSD treated with intravenous tocilizumab, with sufficient information, were included. Thirty-eight patients (79.2%) achieved remission after 6 months of tocilizumab treatment, 12 of whom discontinued tocilizumab during remission. Within 1 year after tocilizumab discontinuation, six patients (50.0%) recurred at a mean of 5.5 months, while the other six (50.0%) remained in remission. Between the non-recurrence and recurrence groups, no difference was found in disease activity at tocilizumab discontinuation (systemic feature score, P = 0.24; ferritin, P = 0.46). While the duration of tocilizumab use was not different (P = 0.32), the interval of tocilizumab administration at tocilizumab discontinuation in the recurrence group was 21 (14–35) days, which tended to be shorter than 35 (28–53) days in the non-recurrence group (P = 0.08). Patients with prednisolone dose 7 mg/day at last tocilizumab treatment had fewer recurrences than those without (P = 0.001). After recurrence, tocilizumab was resumed in half of the patients, resulting in successful disease control. Conclusions The recurrence rate after tocilizumab discontinuation was 50% in 1 year. Patients who remained in remission with a longer interval of tocilizumab administration and lower prednisolone dose were likely to succeed in the withdrawal of tocilizumab.