title: Activatable fluorescent molecular imaging of peritoneal metastases following pretargeting with a biotinylated monoclonal antibody.
abstract: Optical probes that yield high target-to-background ratios are necessary to detect microfoci of cancer that would otherwise escape detection with white light imaging. Target-specific activation of the optical signal at tumor foci is one mechanism by which high target and low background signal can be achieved. Here, we describe a two-step activation process in which the tumors are first pretargeted with a nonfluorescent biotinylated monoclonal antibody [cetuximab (Erbitux) targeting human epidermal growth factor receptor type 1 (HER1)]. Following this, a second agent, neutravidin-BODIPY-FL fluorescent conjugate, is given and binds to the previously targeted antibody, resulting in an approximately 10-fold amplification of the optical fluorescence signal, leading to high tumor-to-background ratios. Spectral fluorescence imaging was done in a mouse model of peritoneal metastasis using a HER1-overexpressing cell line (A431) after pretargeting with biotinylated cetuximab and 3 h after administration of neutravidin-conjugated BODIPY-FL. Both aggregated tumors as well as small cancer implants were clearly visualized in vivo. For lesions approximately 0.8 mm or greater in diameter, the spectral fluorescence imaging had a sensitivity of 96% (178 of 185) and a specificity of 98% (188 of 191). This two-step activation paradigm (pretargeting followed by neutravidin-biotin binding with an attached activatable fluorophore) could be useful in tumor-specific molecular imaging of various targets to guide surgical resections.
authors: Molecular Imaging Program, Center for Cancer Research, National Cancer Institute/NIH, Bethesda, MD 20892, USA.
authors: Yukihiro
authors: Y
authors: Hama
authors: Yasuteru
authors: Y
authors: Urano
authors: Yoshinori
authors: Y
authors: Koyama
authors: Peter L
authors: PL
authors: Choyke
authors: Hisataka
authors: H
authors: Kobayashi
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000378:metabolism*; D061067:Antibodies, Monoclonal, Humanized; D001360:Avidin / Q000737:chemistry / Q000378:metabolism*; D019921:Biotinylation; D001896:Boron Compounds / Q000737:chemistry / Q000378:metabolism; D000068818:Cetuximab; D066246:ErbB Receptors / Q000276:immunology; D005434:Flow Cytometry; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D010534:Peritoneal Neoplasms / Q000276:immunology / Q000378:metabolism* / Q000473:pathology / Q000556:secondary*; D012680:Sensitivity and Specificity
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D001896:Boron Compounds; D005456:Fluorescent Dyes; D018796:Immunoconjugates; C093483:neutravidin; D001360:Avidin; C512478:EGFR protein, human; D066246:ErbB Receptors; D000068818:Cetuximab