Treatment of colchicine-resistant Familial Mediterranean fever in children and adolescents

Familial Mediterranean fever (FMF) is the most common autoinflammatory disease worldwide. Approximately 5-10 % of patients are unresponsive to colchicine. Aim of this study was to determine the short- and long-term efficacy and safety of anti-interleukin 1 (anti-IL1) and anti-tumor necrosis factor agents in colchicine-resistant FMF cases in Turkish children and adolescents. This is a single-center retrospective case series of colchicine-resistant FMF patients. The included patients were treated with biologics for either colchicine resistance or because of one of the following: (1) amyloidosis, (2) recurrent prolonged febrile myalgia and frequent need of steroid and (3) persistent arthritis. Colchicine resistance was defined as at least one attack per month for three consecutive months and elevated erythrocyte sedimentation rate or C-reactive protein or serum amyloid A in-between attacks despite taking adequate dose of colchicine. Response to biologicals was evaluated by the Autoinflammatory Diseases Activity Index (AIDAI) score sheet, patients/parents'/physicians' global assessment of disease severity and laboratory parameters every 3-6 months. Fourteen patients were included in the study. Three patients were treated with etanercept for median 7 months (range 3-11 months), and all patients had to be switched to anti-IL1 treatment because of adverse effects and/or partial response. Eleven patients were treated with anakinra with a median duration of 8 months (4-60 months). Nine patients responded to treatment at the third month, but four of them switched to canakinumab because of noncompliance, local side effects and active arthritis. Nine patients were treated with canakinumab, all responded. At follow-up, in two patients the dose had to be increased, and on the other hand, in three patients the interval was increased to every 12-16 weeks. In three patients, anti-IL1 treatment could be stopped and they are fine with colchicine. This case series describes the largest cohort of colchicine-resistant FMF patients in childhood and adolescence. Anti-IL1 treatment is a safe and effective therapy to control inflammation. The treatment should be modified and decided for each patient on an individual basis.