Correlating EGFR expression with receptor-binding properties and internalization of 64Cu-DOTA-cetuximab in 5 cervical cancer cell lines

J Nucl Med. 2008 Sep;49(9):1472-9. doi: 10.2967/jnumed.108.052316. Epub 2008 Aug 14.

Abstract

The anti-epidermal growth factor receptor (anti-EGFR) antibody cetuximab is clinically approved for the treatment of EGFR-expressing metastatic colorectal cancer and advanced head and neck cancer. Overexpression of EGFR has also been found in more than 70% of carcinomas of the cervix. The overall goal of this study was to determine whether (64)Cu-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-cetuximab has potential as an agent for measuring EGFR concentration by PET imaging in cervical cancer tumors.

Methods: Cetuximab was conjugated to the bifunctional chelator DOTA and labeled with (64)Cu. EGFR messenger RNA (mRNA) expression was correlated with EGFR densities on the cell surface of 5 different cervical cancer cell lines and with receptor function, measured by internalization of (64)Cu-DOTA-cetuximab. Imaging in tumor-bearing mice with small-animal PET was performed using the highest-expressing cervical cancer cell line.

Results: The affinity of (64)Cu-DOTA-cetuximab binding for the EGFR was similar in 4 EGFR-positive lines, varying from 0.1 to 0.7 nM. The mRNA expression corresponded well with EGFR densities and levels of internalization, with responses decreasing in the order of CaSki>ME-180>DoTc2 4510>HeLa>C-33A. Biodistribution and small-animal PET studies with (64)Cu-DOTA-cetuximab in CaSki tumor-bearing nude mice showed relatively high tumor uptake at 24 h after injection (13.2+/-1.2 percentage of injected activity per gram), although there was also significant retention of activity in the blood and liver accumulation.

Conclusion: (64)Cu-DOTA-cetuximab was successfully used to detect and quantify EGFR expression in cervical cancer tumors, and small-animal PET/CT of EGFR-expressing CaSki tumors suggests potential for PET/CT of EGFR-positive tumors.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antibodies, Monoclonal / pharmacokinetics*
  • Antibodies, Monoclonal / therapeutic use
  • Antibodies, Monoclonal, Humanized
  • Cell Line, Tumor
  • Cetuximab
  • Drug Delivery Systems / methods
  • ErbB Receptors / metabolism*
  • Female
  • HeLa Cells
  • Humans
  • Metabolic Clearance Rate
  • Mice
  • Mice, SCID
  • Organ Specificity
  • Organometallic Compounds / pharmacokinetics*
  • Organometallic Compounds / therapeutic use
  • Radionuclide Imaging
  • Statistics as Topic
  • Tissue Distribution
  • Uterine Cervical Neoplasms / diagnostic imaging*
  • Uterine Cervical Neoplasms / metabolism*

Substances

  • 64Cu-DOTA-cetuximab
  • Antibodies, Monoclonal
  • Antibodies, Monoclonal, Humanized
  • Organometallic Compounds
  • ErbB Receptors
  • Cetuximab