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Updated: Apr 20, 2026
Computed Tomography-guided Time-domain Diffuse Fluorescence Tomography in Small Animals for Localization of Cancer Biomarkers
Published on: July 17, 2012
Synthesis and biological evaluation of panitumumab-IRDye800 conjugate as a fluorescence imaging probe for
Sibaprasad Bhattacharyya1, Nimit Patel2, Ling Wei1
1ADRD, Frederick National Laboratory for Cancer Research (FNLCR), Leidos Biomedical Research, Frederick, MD 21702.
Abstract:
To investigate panitumumab-IRDye800 as an intraoperative optical imaging agent for epidermal growth factor receptor (EGFR)-expressing cancers, we developed clinical-quality panitumumab-IRDye800 and evaluated its specificity and sensitivity to visualize tumors by fluorescence imaging in a variety of mouse xenograft models with different levels of EGFR-expression. Panitumumab was chemically conjugated to NIR-dye (Li-COR 800CW) at well-defined and limited substitution ratio (1:1-2) for the characterization of fluorescence signals. Yield and purity of the conjugate was 80±5% and 95±2% respectively (n= 6). Quality control (QC) tests showed that product was suitable for clinical development. Female athymic nude xenograft tumor bearing mice (n=5 per tumor model) with very low (BT-474), moderate (MDA-MB-231), and high (MDA-MB-468) EGFR-expression levels were administered panitumumab-IRDye800 formulations (100 microg of mAb in 100 microL of 0.9% saline) via tail-vein injection. Animal imaging and biodistribution experiments were conducted on the FMT 2500 (Perkin Elmer) fluorescence scanner at 24, 48, 72, 96, and 144 hours post injection. Immuno-fluorescence images of panitumumab-IRDye conjugate recorded in mouse xenograft models showed a good correlation (R2 = 0.91) between EGFR-expression level and tumor uptake. Uptake of panitumumab labeled with IR-Dye or [89Zr] in different tumor xenografts with high, medium, and low EGFR expression, as measured by fluorescence or radioactive counts are highly correlated (r2= 0.99). This preclinical in-vivo study proved that panitumumab-IRDye800 is specific and optical imaging in conjunction with this probe is sensitive enough to detect EGFR-expressing tumors.
Insights
Panitumumab-IRDye800 effectively visualizes epidermal growth factor receptor (EGFR)-expressing tumors using fluorescence imaging. This novel agent demonstrates high specificity and sensitivity for intraoperative cancer detection in preclinical models.
Area of Science:
- Oncology
- Medical Imaging
- Bioconjugation Chemistry
Background:
- Epidermal growth factor receptor (EGFR) is a target in various cancers.
- Intraoperative imaging agents can improve tumor detection and resection.
- Panitumumab is an antibody targeting EGFR, but its use in imaging requires modification.
Purpose of the Study:
- To develop and evaluate panitumumab-IRDye800 as an optical imaging agent for EGFR-expressing tumors.
- To assess the specificity and sensitivity of panitumumab-IRDye800 for intraoperative fluorescence imaging.
- To correlate imaging results with EGFR expression levels in preclinical cancer models.
Main Methods:
- Clinical-quality panitumumab was conjugated to IRDye800CW at a 1:1-2 substitution ratio.
- The conjugate's yield, purity, and suitability for clinical development were confirmed via quality control tests.
- Fluorescence imaging and biodistribution studies were performed in mouse xenograft models with varying EGFR expression levels (low, moderate, high) at multiple time points post-injection.
Main Results:
- The panitumumab-IRDye800 conjugate exhibited 80% yield and 95% purity, meeting quality standards.
- A strong correlation (R² = 0.91) was observed between EGFR expression levels and tumor uptake of the conjugate.
- Imaging results using panitumumab-IRDye800 highly correlated with those obtained using radioactive tracers ([89Zr]), with r² = 0.99.
Conclusions:
- Panitumumab-IRDye800 is a specific and sensitive agent for optical imaging of EGFR-expressing tumors.
- This preclinical study validates the potential of panitumumab-IRDye800 for intraoperative tumor visualization.
- The developed imaging probe shows promise for enhancing surgical precision in EGFR-driven cancers.
