CIMZIA (certolizumab pegol) is a TNF blocker. CIMZIA (certolizumab pegol) is a recombinant, humanized antibody Fab' fragment, with specificity for human tumor necrosis factor alpha (TNF?), conjugated to an approximately 40kDa polyethylene glycol (PEG2MAL40K). The Fab' fragment is manufactured in E. coli and is subsequently subjected to purification and conjugation to PEG2MAL40K, to generate certolizumab pegol. The Fab' fragment is composed of a light chain with 214 amino acids and a heavy chain with 229 amino acids. The molecular weight of certolizumab pegol is approximately 91 kiloDaltons.