Effect of interleukin-1 antagonist on growth of children with colchicine resistant or intolerant FMF

Abstract Introduction Familial Mediterranean Fever (FMF) is the most common monogentic autoinflammatory disease. FMF results from mutations in MEFV, which lead to a pro-inflammatory state and increased production of Interleukin 1 beta subunit (IL-1b) by myeloid cells. Despite the overall positive results obtained with anti-IL-1 agents in FMF patients, little is known about the long-term growth impact of these drugs in the pediatric population. Objectives To assess the long-term body weight and height trajectories in children with FMF treated with anti-IL-1 agents. Methods We conducted a retrospective analysis of 646 pediatric FMF patients followed in our center, of whom 22 were treated with either anakinra (36.3%) and/or canakinumab (90.9%). Patients were assessed for demographic, clinical and genetic characteristics and were followed for a mean of 3.05 ± 1.75 years. Data of height and weight percentiles were recorded before and after treatment. Results The most common indication for IL-1 blockers treatment was colchicine resistance (66.6%). Ninety percent of those patients had a moderate or severe disease according to the Pras score and had higher proportion of M694V homozygosity compared with patients who did not require anti IL-1 agents (95.2% vs. 30.5%, p < 0.001). Overall, anakinra and canakinumab resulted in a complete response in 80% of patients and exhibited low rates of adverse effects. We found a significant increase in height and body weight percentiles following treatment (19.6 ± 16% vs. 30.8 ± 23%, p = 0.007, and 29.5 ± 30% vs. 39.1 ± 36%, p = 0.043, respectively). Conclusion Treatment with anti-IL-1 agents in children with FMF is effective and safe and may potentiate long-term growth