In vivo detection of head and neck cancer orthotopic xenografts by immunofluorescence.
OBJECTIVE
To determine whether Cy5.5-labeled antiepidermal growth factor (EGFR) antibody could be used to detect head and neck squamous cell carcinoma (HNSCC) xenografts in vivo.


METHODS
AntiEGFR antibody (cetuximab) was labeled with Cy5.5, a fluorophore with emission in the near infrared range. The cetuximab-Cy5.5 conjugate was systemically administered in subtherapeutic doses (50 microg) to mice bearing orthotopically xenografted HNSCC cell lines (SCC1, CAL27, and FaDu). As a control, isotype-matched human immunoglobulin (Ig)G1k antibody labeled with Cy5.5 was systemically injected in parallel experiments. All tumor regions (n = 6) were imaged by fluorescent stereomicroscopy at 0, 6, 24, 48, or 72 hours. Tumor size was measured by high-frequency ultrasonography at 72 hours. Transcervical partial and near-total resections were then performed with stereomicroscopic imaging after each resection. The mandible and associated structures were then resected, paraffin embedded, and then serial sectioned for analysis.


RESULTS
Tumors could be clearly visualized by near infrared fluorescent stereomicroscopy at 48 and 72 hours after systemic administration of cetuximab-Cy5.5 but not after administration with the labeled isotype control antibody, IgG1k-Cy5.5. Ultrasound measurement of tumors (n = 5) correlated with fluorescent measurements of tumor (Spearman's coefficient, 0.92, P </= .01). When fluorescent stereomicroscopic findings were correlated with histologic findings in near-total resections, this technique could accurately identify residual tumor less than 1 mm in size.


CONCLUSIONS
Fluorescent immunoguided neoplasm detection may be used as a diagnostic tool and to guide surgical therapy by providing real-time imaging information about the extent of disease or the presence of residual disease.
Rosenthal
Eben L
EL
Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Kulbersh
Brian D
BD
Duncan
Ryan D
RD
Zhang
Wenyue
W
Magnuson
J Scott
JS
Carroll
William R
WR
Zinn
Kurt
K
D000818:Animals; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D002232:Carbocyanines; D045744:Cell Line, Tumor; D000068818:Cetuximab; D004815:Epidermal Growth Factor / Q000031:analogs & derivatives; D006258:Head and Neck Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006801:Humans; D007074:Immunoglobulin G; D051379:Mice; D016513:Mice, SCID; D008856:Microscopy, Fluorescence / Q000379:methods*; D014183:Transplantation, Heterologous; D014463:Ultrasonography
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; C098793:CY5.5 cyanine dye; D002232:Carbocyanines; D007074:Immunoglobulin G; D004815:Epidermal Growth Factor; D000068818:Cetuximab