TNF and rheumatoid arthritis: Cimzia® (certolizumab pegol) is a PEGylated anti tumor necrosis factor (TNF) recombinant antibody Fab fragment approved for the treatment of rheumatoid arthritis, Crohn’s disease, and axial spondyloarthritis (Blick and Curran, 2007; Nesbitt et al., 2009).