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

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.