Three-year follow up of canakinumab dose extension in children with colchicine resistant fasmilial Mediterranean fever: PeRA-RG Experience

Objectives Anti-interleukin-1 therapies are effective for colchicine-resistant familial Mediterranean fever (FMF), yet data on optimal duration in pediatric patients remain limited. A previous multicentre study showed favorable outcomes with a standardized canakinumab dose extension protocol, though follow-up was short. This study aimed to assess the long-term outcomes of this protocol. Methods The protocol, developed via a multicentre Delphi consensus in Turkey, recommends doubling the canakinumab dosing interval after six attack-free months and tripling it after one year of continued remission. This retrospective study included colchicine-resistant FMF patients treated according to the protocol, with data extracted from medical records. Results Forty-five patients initiated monthly canakinumab. The median follow-up after starting canakinumab was 47 months (range 35–78). After six months, intervals were extended to every two months. During bimonthly dosing, 7 patients (15.6%) experienced attacks and reverted to monthly dosing. Of the 38 patients (84.4%) whose interval was further extended to every three months, 11 returned to bimonthly dosing due to attacks. Among 10 patients who achieved remission with three-month intervals, treatment was discontinued; 5 remained attack-free, while 5 had attacks. Seventeen patients continued three-monthly dosing, one was lost to follow-up, and 16 (35.6%) remained attack-free at a median follow-up of 33 months (IQR: 6.5). Clinical and laboratory findings were similar between patients with and without attacks, except splenomegaly, which was absent in the attack-free group (p= 0.006). Conclusion The dose extension protocol shows promising long-term outcomes in colchicine-resistant FMF. Larger, prospective studies are warranted to optimize treatment strategies.