Predictors of disease flare after discontinuation of concomitant methotrexate in Japanese patients with rheumatoid arthritis treated with tocilizumab.

OBJECTIVE: To investigate predictors of disease flare after methotrexate discontinuation in Japanese rheumatoid arthritis (RA) patients with sustained low disease activity undergoing tocilizumab plus methotrexate combination therapy. METHODS: Participants of this multicenter, open-label, uncontrolled, prospective study were RA patients maintaining low disease activity (Clinical Disease Activity Index [CDAI]≤10) for≥12weeks with tocilizumab plus methotrexate. Methotrexate was discontinued after 12weeks of biweekly administration while continuing tocilizumab therapy. Disease flare was defined as either a CDAI score>10 or intervention with rescue treatments for any reason even if the CDAI score was≤10. The impact of baseline characteristics on disease flare at week 64 (52weeks after methotrexate discontinuation) was assessed with logistic regression models. RESULTS: Efficacy analyses were performed in 49 patients, of whom 15 had a disease flare by week 64. The proportion (95% confidence interval [CI]) of patients who maintained low disease activity without a flare at week 64 was 69.4% (54.6-81.8%). The dosing interval of tocilizumab was longer than that described on the drug label in Japan (i.e., intravenously every 4weeks, or subcutaneously every 2weeks) in 27% and 6% of patients with and without a flare, respectively. Multivariate analysis revealed that male sex (odds ratio [OR]: 18.00, 95% CI: 2.80-115.56) and extended dosing interval of tocilizumab (OR: 12.00, 95% CI: 1.72-83.80) were independent predictors of disease flare. CONCLUSION: Male patients and those receiving tocilizumab at an extended dosing interval are at high risk of disease flare after discontinuation of concomitant methotrexate. TRIAL REGISTRATION NUMBER: jRCTs041180071, UMIN000021247.