An "On Demand" canakinumab regimen for treating children with Colchicine-Resistant familial Mediterranean fever - A multicentre study.

Objectives: Canakinumab, a human monoclonal antibody targeted at interleukin-1 beta, has demonstrated safety and efficacy in preventing familial Mediterranean fever (FMF) attacks among individuals with colchicine-resistant (crFMF). The manufacturer orders prescribe monthly subcutaneous injections. However, a subset of our patients is treated with an "canakinumab on demand " (COD) strategy, with wider intervals between drug administrations. Therefore, we aimed to compare disease activity and drug safety between COD and "canakinumab fixed frequency" (CFF) policies.

Methods: This retrospective study collected data from three Israeli paediatric rheumatology centres, of children with crFMF who were treated with canakinumab. Epidemiological and clinical parameters, cumulative drug dosages, and adverse events were compared between children treated by both policies.

Results: Twenty-five (49 %) children were treated according to COD policy and 26 according to CFF policy. Demographic parameters and most of the disease features did not differ significantly between the groups. Both groups showed significant reduction in attacks after canakinumab introduction. The median number (interquartile range) of attacks per month did not differ significantly between the COD and CFF groups (0.33 (0.08, 0.58) and 0.13 (0, 0.5), respectively, p = 0.485 (even though, per definition, COD patients presumably had an attack before receiving the second canakinumab dose). The mean monthly dose was lower for the COD than the CFF group (1.13 ± 1.13 vs. 3.16 ± 1.46 mg/kg, p < 0.001). Adverse events were similar between the groups.

Conclusion: For individuals with crFMF, COD compared to CFF policy can achieve similar efficacy and safety, with a lower accumulated canakinumab dose, rendering it less immunosuppressive and less expensive.