Disease activity guided stepwise tapering or discontinuation of rhTNFR:Fc, an etanercept biosimilar, in patients with ankylosing spondylitis: a prospective, randomized, open-label, multicentric study

BACKGROUND: The aim of this study was to evaluate disease-activity-guided stepwise tapering or discontinuation of rhTNFR:Fc, an etanercept biosimilar, in patients with ankylosing spondylitis (AS) in a prospective, randomized, open-label, multicentric study. METHODS: Active AS patients with AS disease activity score (ASDAS) ⩾2.1 recruited from 10 hospitals were treated with rhTNFR:Fc 50 mg weekly for 12 weeks, and further randomized into different tapering or discontinuation groups according to ASDAS at week 12. Patients who achieved clinical remission (ASDAS < 1.3) were assigned randomly to stepwise tapering group or discontinuation group. Patients who achieved low disease activity (LDA, 1.3⩽ASDAS < 2.1) were assigned randomly to stepwise tapering, delayed tapering, or discontinuation group. All patients were evaluated every 12 weeks until week 48. The primary endpoint was cumulative flare rates in different groups at week 48. RESULTS: A total of 311 patients were enrolled with an average ASDAS of 3.6 ± 1.0, and 259 completed 12 weeks of rhTNFR:Fc induction therapy, with 148 patients (57.1%) achieved clinical remission, 100 (38.6%) achieved LDA, and 11 (4.3%) remained as high disease activity (ASDAS⩾2.1). In patients who achieved clinical remission at week 12, stepwise tapering of rhTNFR:Fc demonstrated significantly lower flare rates at each evaluation compared with discontinuation. In patients who achieved LDA, there was no significant difference of flare rates between stepwise tapering, delayed tapering, and discontinuation. With stepwise tapering of rhTNFR:Fc, flare rates were comparable in AS patients, irrespective of initial ASDAS before tapering. CONCLUSION: Stepwise tapering of rhTNFR:Fc when patients achieved clinical remission was able to maintain favorable low flare rates in 48 weeks. LDA was an alternative therapeutic target, as well as an viable timing for initiation of rhTNFR:Fc tapering. rhTNFR:Fc 25 mg monthly maintained flare-free status in a considerable number of patients. However, abrupt discontinuation of rhTNFR:Fc even if patients achieved clinical remission should be avoided. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03880968, URL: https://clinicaltrials.gov/ct2/show/NCT03880968