However, blocking of C5aR in small cohort of RA patients (n = 21) did not reduce synovial inflammation [39] and the orally administered C5aR-antagonist AcF- (OpdChaWR) (PMX53) in that study binds to C5aR but not C5L2 [40]. This evidence concerns the gene C5AR1 and rheumatoid arthritis.