Indeed, several studies have reported that MRP8/14, measured before treatment initiation, predicts response to both bDMARDs and conventional synthetic DMARDs (csDMARDs) in patients with RA and JIA.11 12 16–22 Specifically in RA, MRP8/14 has been reported to correlate well with response to tumour necrosis factor (TNF) inhibitors (TNFis) and rituximab—with good responders presenting with higher pre-treatment MRP8/14.16 Several studies have also shown that MRP8/14 levels decrease following successful treatment.11 12 16 19 21 23 24. Here, S100A8 is linked to juvenile idiopathic arthritis.