Certolizumab is reduced in Crohn's disease relative to the efficacy observed with adalimumab [24, 25], which suggests that Fc-mediated effector functions may be important. Binding of mAbs to FcRn affects clearance, so a similarity assessment of biosimilars should also include sensitive methods to assess binding to FcRn. ABP 501 was shown to have similar binding to FcRn as compared with adalimumab.