To determine whether soluble urokinase plasminogen activator receptor is a useful biomarker to predict the response to adalimumab (ADA) in Japanese patients with rheumatoid arthritis.
Rheumatoid arthritis (RA) patients administrated ADA (n=51) were classified as good responders (n=18) or nonresponders (n=9) according to the EULAR response criteria after 8 weeks of bi-weekly ADA administration. We examined the expression of cytokines and chemokines in these groups by antibody array methods. Positive results obtained by antibody array methods were further confirmed by ELISA.
Antibody array has identified that the macrophage migration inhibitory factor (MIF), vascular endothelial growth factor (VEGF) and soluble urokinase plasminogen activator receptor (uPAR) decreased in the good responders to ADA whereas these changes were not observed in the non-responders. The decrement of serum uPAR was confirmed by ELISA in the good responders to ADA. Furthermore, serum uPAR at baseline was significantly high in non-responders compared with good responders.
An antibody array is convenient for screening the expression of proteins of interest. Examination of serum uPAR at baseline and thereafter may be useful as a predictive biomarker for primary failure toward ADA in patients with RA.