Efficacy and safety of interleukin-1 inhibitors in familial Mediterranean fever patients complicated with amyloidosis

Background: Colchicine is the mainstay of the treatment of familial Mediterranean fever (FMF). However, 10% of FMF patients do not respond well to colchicine. Efficacy of interleukin (IL)-1 inhibitors in reducing attacks have been demonstrated in colchicine-resistant FMF (crFMF) patients recently. Colchicine is still the only approved drug for the prevention of amyloidosis in FMF and utility of IL-1 inhibitors in crFMF cases who already has amyloidosis remain to be elucidated. Herein, we evaluated efficacy and safety of IL-1 inhibitors in patients with crFMF-associated AA amyloidosis in a relatively large single center study. Methods: Medical records of FMF patients complicated with AA amyloidosis in our dedicated FMF center were retrospectively reviewed and those patients who ever treated with IL-1 inhibitors were enrolled into the study. Patient global, physician global assessments (on 0-10 cm visual analog scale), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), serum creatinine and 24-h urinary protein excretion values for each visit were recruited from computer-based hospital records. Treatment response of patients were assessed with clinical symptoms, serum albumin, CRP and ESR values. Renal outcome parameters were analyzed on those not receiving renal replacement therapy. Results: Seventeen patients were identified with crFMF-amyloidosis that ever treated with IL-1 inhibitors. Background colchicine therapy was continued in all patients in maximal-tolerated dose along with IL-1 inhibitors. All patients benefit from IL-1 antagonists assessed by patient and physician global assessments. Inflammatory markers, CRP and ESR, were significantly reduced in all and normalized in 12 out of 17 patients. More importantly, the amount of proteinuria was remarkably improved following IL-1 inhibitor therapy (1606 mg/day to 519 mg/day, p = .008). Both anakinra and canakinumab were well-tolerated without severe side effects. All patients were initially treated with anakinra but switched to canakinumab in seven patients (one leukopenia, four injection site reaction, two inefficacy). Conclusion: We evaluated the clinical and laboratory responses to IL-1 inhibitors in crFMF-associated amyloidosis patients. We found significant decreases in CRP, ESR and proteinuria after IL-1 inhibitor therapy. This study confirmed that IL-1 inhibitors are effective for controlling attacks and inflammatory activity in FMF patients complicated with AA amyloidosis. Moreover, they reduce or stabilize amount of proteinuria and preserve renal function in short-term follow-up. Prolonged prospective clinical trials are warranted to assess their long-term efficacy in this particular patient group.