Background:The efficacy of tocilizumab, an interleukin (IL)-6 receptor inhibitor, has been proved in patients with adult Still’s disease on suppressing systemic inflammation and decreasing glucocorticoid dose. However, whether tocilizumab can be discontinued after remission achievement is unclear.Objectives:To clarify the possibility of tocilizumab discontinuation in patients with adult Still’s disease who achieved remission with tocilizumab.Methods:Consecutive patients with adult Still’s disease diagnosed according to the Yamaguchi’s criteria in our hospital from April 2012 until September 2019 were retrospectively reviewed. Patients who were in good control with tocilizumab were included in the analysis, and their clinical courses were collected from their medical charts. Patients were divided according to the presence of recurrence after tocilizumab discontinuation and compared.Results:Among 42 patients with adult Still’s disease who had a history of intravenous tocilizumab of 8mg/kg use, 13 patients discontinued tocilizumab following a good disease control. During the mean observation period of 26.4 months, six patients (46%) remained in remission while seven patients (54%) developed recurrence after tocilizumab discontinuation. The sex and the mean observation period were not different between the patients with recurrence and those without (71% vs 50%, p=0.43; 27.3 months vs 25.4 months, p=0.93, respectively), but the age at tocilizumab discontinuation tended to be higher in the recurrence group than the non-recurrence group (64.0 years vs 46.5 years, p=0.08). The disease activity including swollen joint counts and laboratory data at tocilizumab discontinuation were comparable between the two groups (serum ferritin levels, 88 ng/mL vs 122 ng/mL, p=0.67). While the duration of tocilizumab use was not different between the two groups (29.4 months vs 39.5 months, p=0.40), the mean interval of tocilizumab infusion at tocilizumab discontinuation in the recurrence group was 3.6 weeks, shorter than the 6.7 weeks in the non-recurrence group (p=0.03). The median dose of prednisolone at tocilizumab discontinuation was 5.0 mg/day in the recurrence group and 0.0 mg/day in the non-recurrence group (p=0.06). In the recurrence group, the duration from the last tocilizumab administration to recurrence was 7.8 months, and the median dose of prednisolone at recurrence was 5.0 mg/day.Conclusion:Patients with adult Still’s disease remaining in remission with a longer interval of tocilizumab administration and a lower dose of prednisolone was likely to succeed in withdrawal of tocilizumab.Disclosure of Interests:Hiroya Tamai: None declared, Yuko Kaneko Speakers bureau: Dr. Kaneko reports personal fees from AbbVie, personal fees from Astellas, personal fees from Ayumi, personal fees from Bristol-Myers Squibb, personal fees from Chugai, personal fees from Eisai, personal fees from Eli Lilly, personal fees from Hisamitsu, personal fees from Jansen, personal fees from Kissei, personal fees from Pfizer, personal fees from Sanofi, personal fees from Takeda, personal fees from Tanabe-Mitsubishi, personal fees from UCB, Tsutomu Takeuchi Grant/research support from: Eisai Co., Ltd, Astellas Pharma Inc., AbbVie GK, Asahi Kasei Pharma Corporation, Nippon Kayaku Co., Ltd, Takeda Pharmaceutical Company Ltd, UCB Pharma, Shionogi & Co., Ltd., Mitsubishi-Tanabe Pharma Corp., Daiichi Sankyo Co., Ltd., Chugai Pharmaceutical Co. Ltd., Consultant of: Chugai Pharmaceutical Co Ltd, Astellas Pharma Inc., Eli Lilly Japan KK, Speakers bureau: AbbVie GK, Eisai Co., Ltd, Mitsubishi-Tanabe Pharma Corporation, Chugai Pharmaceutical Co Ltd, Bristol-Myers Squibb Company, AYUMI Pharmaceutical Corp., Eisai Co., Ltd, Daiichi Sankyo Co., Ltd., Gilead Sciences, Inc., Novartis Pharma K.K., Pfizer Japan Inc., Sanofi K.K., Dainippon Sumitomo Co., Ltd.