Tumor penetration and epidermal growth factor receptor saturation by panitumumab correlate with antitumor activity in a preclinical model of human cancer

Mol Cancer. 2012 Jul 25;11:47. doi: 10.1186/1476-4598-11-47.


Background: Successful treatment of solid tumors relies on the ability of drugs to penetrate into the tumor tissue.

Methods: We examined the correlation of panitumumab (an anti-epidermal growth factor [EGFR] antibody) tumor penetration and EGFR saturation, a potential obstacle in large molecule drug delivery, using pharmacokinetics, pharmacodynamics, and tumor growth rate in an A431 epidermoid carcinoma xenograft model of human cancer. To determine receptor saturation, receptor occupancy, and levels of proliferation markers, immunohistochemical and flow cytometric methods were used. Pharmacokinetic data and modeling were used to calculate growth characteristics of panitumumab-treated tumors.

Results: Treatment with panitumumab in vivo inhibited pEGFR, Ki67 and pMAPK levels vs control. Tumor penetration and receptor saturation were dose- and time-dependent, reaching 100% and 78%, respectively. Significant tumor inhibition and eradication (p < 0.05) were observed; plasma concentration associated with tumor eradication was estimated to be 0.2 μg/ml. The tumor inhibition model was able to describe the mean tumor growth and death rates.

Conclusions: These data demonstrate that the antitumor activity of panitumumab correlates with its ability to penetrate into tumor tissue, occupy and inhibit activation of EGFR, and inhibit markers of proliferation and MAPK signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / administration & dosage
  • Antibodies, Monoclonal / pharmacokinetics
  • Antibodies, Monoclonal / pharmacology*
  • Antineoplastic Agents / administration & dosage
  • Antineoplastic Agents / pharmacokinetics
  • Antineoplastic Agents / pharmacology*
  • Carcinoma, Squamous Cell / drug therapy
  • Carcinoma, Squamous Cell / metabolism
  • Carcinoma, Squamous Cell / pathology
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • ErbB Receptors / antagonists & inhibitors*
  • ErbB Receptors / metabolism*
  • Female
  • Humans
  • Ligands
  • Mice
  • Mice, Nude
  • Neoplasms / drug therapy
  • Neoplasms / metabolism*
  • Neoplasms / pathology
  • Panitumumab
  • Phosphorylation / drug effects
  • Tumor Burden / drug effects
  • Xenograft Model Antitumor Assays


  • Antibodies, Monoclonal
  • Antineoplastic Agents
  • Ligands
  • Panitumumab
  • ErbB Receptors