Recent Advances in Optical Cancer Imaging of EGF Receptors

G.      Kramer-Marek; M.      R. Longmire; P.      L. Choyke; H.      Kobayashi

Abstract

Epidermal growth factor (EGF) receptors are commonly expressed on the cell membrane of cancer cells and activity of these receptors results in accelerated cell growth and carcinogenesis. A variety of targeted molecules have been developed to block ligand binding and/or inhibit the function of these receptor tyrosine kinases, and several have proven therapeutic benefits. Along with the advent of new therapeutic agents comes a need for non-invasive tools to diagnose, characterize, and monitor tumor responsiveness to therapy. Imaging EGF receptors with radionuclides has been performed for decades. However, recently this area has advanced considerably with the development of EGF receptor-targeted optical imaging probes. Herein, we review recent advances in molecular imaging of the EGF receptor family, focusing specifically on optical imaging. Such agents provide the opportunity for earlier diagnosis, improved tumor characterization, and the ability to measure and monitor tumor responsiveness to anti-EGF receptor treatment strategies.

Keywords: Optical imaging, cancer, epidermal growth factor receptor, HER2, positron emission tomography, fluorescence, multiple color imaging, monoclonal antibody, affibody, activatable imaging probe, near infrared, molecular imaging, radionuclide imaging