Fc-engineered EGF-R antibodies mediate improved antibody-dependent cellular cytotoxicity (ADCC) against KRAS-mutated tumor cells

Cancer Sci. 2010 May;101(5):1080-8. doi: 10.1111/j.1349-7006.2010.01505.x. Epub 2010 Jan 20.


Oncogenic mutations of the KRAS gene have emerged as a common mechanism of resistance against epidermal growth factor receptor (EGF-R)-directed tumor therapy. Mutated KRAS leads to ligand-independent activation of signaling pathways downstream of EGF-R. Thereby, direct effector mechanisms of EGF-R antibodies, such as blockade of ligand binding and inhibition of signaling, are bypassed. Thus, a humanized variant of the approved EGF-R antibody Cetuximab inhibited growth of wild-type KRAS-expressing A431 cells, but did not inhibit KRAS-mutated A549 tumor cells. We then investigated whether killing of tumor cells harboring mutated KRAS can be improved by enhancing antibody-dependent cellular cytotoxicity (ADCC). Protein- and glyco-engineering of antibodies' Fc region are established technologies to enhance ADCC by increasing antibodies' affinity to activating Fcgamma receptors. Thus, EGF-R antibody variants with increased affinity for the natural killer (NK) cell-expressed FcgammaRIIIa (CD16) were generated and analyzed. These variants triggered significantly enhanced mononuclear cell (MNC)-mediated killing of KRAS-mutated tumor cells compared to wild-type antibodies. Additionally, cells transfected with mutated KRAS were killed as effectively by ADCC as vector-transfected control cells. Together, these data demonstrate that KRAS mutations are not sufficient to render tumor cells resistant to ADCC. Consequently Fc-engineered EGF-R antibodies may prove effective against KRAS-mutated tumors, which are not susceptible to signaling inhibition by EGF-R antibodies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibody-Dependent Cell Cytotoxicity*
  • Cell Line, Tumor
  • Cell Proliferation
  • ErbB Receptors / immunology*
  • Humans
  • Immunoglobulin Fc Fragments / immunology*
  • Leukocytes, Mononuclear / immunology
  • Mutation*
  • Neoplasms / genetics*
  • Neoplasms / immunology
  • Protein Engineering*
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins p21(ras)
  • Receptors, IgG / immunology
  • ras Proteins / genetics*


  • FCGR3A protein, human
  • Immunoglobulin Fc Fragments
  • KRAS protein, human
  • Proto-Oncogene Proteins
  • Receptors, IgG
  • ErbB Receptors
  • Proto-Oncogene Proteins p21(ras)
  • ras Proteins