Association between canakinumab dose and long-term remission in Still’s disease: insights from the AIDA network registry

Objective The primary aim of this study was to assess, in Still’s disease, whether the employment of canakinumab at a strictly on-label dose may increase the likelihood of treatment discontinuation due to study-defined long-term remission (LTR), compared with patients receiving lower doses. Methods Patients were drawn from the international Autoinflammatory Disease Alliance (AIDA) Network registry dedicated to Still’s disease and stratified based on the starting canakinumab dose: the on-label group received either 300 mg every 4 weeks or 150 mg every 4 weeks (corresponding to 4 mg/kg), while the underdosed group received 150 mg every 4 weeks (corresponding to a dose not exceeding 3.5 mg/kg). Bayesian regression models were implemented to estimate the probability of achieving long-term remission with subsequent canakinumab withdrawal in the two groups, as well as the mean differences in probabilities and posterior probabilities indicating whether the on-label group was superior in achieving the endpoint. Results In total, 131 patients (16.7%) were enrolled, 81 (61.8%) receiving the on-label posology and 50 (38.2%) the underdosed posology. The estimated marginal posterior probability of canakinumab discontinuation due to LTR was 19% (CrI 7.5%–34.6%) in the on-label group and 3.9% (CrI 0.7%–15.2%) in the underdosed group, yielding a mean difference of 15.1% (CrI 1.4%–31.4%) and a posterior probability of 98.4%. This difference remained credible, with posterior probabilities ranging from 97.9% to 99.6%, irrespective of disease course or age at disease onset. Conclusion On-label canakinumab dosing appears to increase the likelihood of study-defined LTR with subsequent treatment discontinuation, compared with underdosed treatment strategies.