Background Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease diagnosed usually during childhood period. It is managed appropriately with colchicine. Hovewer, even though very rare, there are cases that can not be controlled by colchicine treatment. Ultimate goal of treatment is to control attacks and subside inflammation both during and in between attacks. There are some drugs offered for resistant cases. The anti IL-1 therapy is the most promising one.
Objectives This study that is performed in two pediatric rheumatology centers in Turkey is aiming to collect and evaluate the data of children resistant to colcicine treatment and receving anti IL-1 treatment by means of eficacy and safety.
Methods Two pediatric rheumatology centers had been involved to the study. The medical data were collected retrospectively. The children had been diagnosed as FMF according to the Tel-Hashomer criteria. Colchicine resistance was defined as having 3 or more attacks despite maximum dose of colchicine treatment regarding to age. The severity of the disease before and after biological treatment was performed by Pras and FMF 50 scores.
Results From two pediatric rheumatology centers 26 children were enrolled to the study. The median age at onset of disease was 4 years [(IQR)2–5]. The consanguinity rate was 46.2%. Thirteen of the children had a family member with diagnosed FMF. Only 3 patients had a family history of amyloidosis. Abdominal pain (88.5%) was the most common symptom. The median number of attacks per year was 12 before colchicine treatment, the median attack number dropped to 11 per year after colchicine. The median dose of colchicine before biologic therapy was 1.5 g/day (range 1–1.5). The median duration of colchicine treatment before biologic therapy was 54 months (IQR 23.7–99 months). The median biologic treatment starting age was 11.5 years (range 8.7–16). As biological agent, nineteen patients were started with anakinra, 2 were with etanercept, 5 with canakinumab. The two patients who were under etanercept treatment were switched to anakinra due to lack of effectiveness. Of 19 patients who were commenced anakinra, 12 (63.1%) were switched to canakinumab due to painful injections, lack of effectiveness, allergy and patient's choice. There were no switches among canakinumab users. Pras scores had been changed from 10.17 to 6 in anakinra users, from 10 to 6 in canakinumab users. There was no difference of effectiveness between two drugs. The FMF 50 score showed improvement in 14 of 15 anakinra users, 15 of 15 canakinumab users. The difference of scores was not significant between both groups.
Conclusions Although colchicine is the main treatment option in FMF, resistant children need additional medications. IL-1 is the major cytokine modulating inflammation in FMF. There are reports pointing out these agents as promising for resistant cases. Our study is the largest cohort of children with resistant FMF under biological treatment. Both anakinra and canakinumab had shown good and similar efficiacy in resistant cases. Long term efficacy and safety evaluations should be done with controlled trials.
Disclosure of Interest None declared