Baseline Renal Functions Predict the Effect of Canakinumab on Regression of Proteinuria in Patients with Familial Mediterranean Fever

Introduction And Objectives: Canakinumab, an IL-1 blocking drug, decreases the frequency and severity of the attacks and decreases the proteinuria level in colchicine resistant/intolerant familial Mediterranean fever (FMF) patients. However, it is not known whether patients with impaired or preserved renal functions respond differently to IL-1 blocking therapies in terms of proteinuria reduction and progression of kidney dysfunction which was the aim of this study.

Materials And Methods: Adult FMF subjects with biopsy proven amyloidosis who had 24-h urine protein excretion>150mg/day before initiation of canakinumab were divided into two groups as patients with preserved renal function (GFR≥60mL/min) and patients with impaired renal function (GFR<60mL/min). The response in proteinuria and renal functions are compared between two groups in this cross-sectional study.

Results: A total of 18 patients (11 with preserved and 7 with impaired renal function) were included in this study. Although proteinuria levels of both groups were similar at the baseline and at six months after initiation of canakinumab, proteinuria at 12 months was significantly lower for patients with preserved renal function compared to patients with impaired renal function (2462±1760mg/day vs. 7065±3035mg/day respectively, p=0.02). All of the patients with preserved renal function had more than 50% decrease in proteinuria at 12 months compared to baseline values, while none of the patients with impaired renal function had more than 50% decrease in proteinuria.

Conclusions: Canakinumab, an IL-1 blocking agent, is not effective in decreasing proteinuria in FMF patients with already impaired renal functions and should be started early in the course of disease to prevent renal impairment.