title: Synthesis and biological evaluation of panitumumab-IRDye800 conjugate as a fluorescence imaging probe for EGFR-expressing cancers.
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 μg of mAb in 100 μL 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.
authors.affiliation: ADRD, Frederick National Laboratory for Cancer Research (FNLCR), Leidos Biomedical Research, Frederick, MD 21702.
authors.forename: Sibaprasad
authors.initials: S
authors.lastname: Bhattacharyya
authors.affiliation: SAIP, FNLCR, Leidos Biomedical Research, Frederick, MD 21702.
authors.forename: Nimit
authors.initials: N
authors.lastname: Patel
authors.affiliation: ADRD, Frederick National Laboratory for Cancer Research (FNLCR), Leidos Biomedical Research, Frederick, MD 21702.
authors.forename: Ling
authors.initials: L
authors.lastname: Wei
authors.affiliation: SAIP, FNLCR, Leidos Biomedical Research, Frederick, MD 21702.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Riffle
authors.affiliation: SAIP, FNLCR, Leidos Biomedical Research, Frederick, MD 21702.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Kalen
authors.affiliation: Clinical Research Directorate/Clinical Monitoring Research Program, FNLCR, Leidos Biomedical Research, Frederick, MD 21702.
authors.forename: G Craig
authors.initials: GC
authors.lastname: Hill
authors.affiliation: DCTD/CIP, NCI, Bethesda, MD.
authors.forename: Paula M
authors.initials: PM
authors.lastname: Jacobs
authors.affiliation: School of Medicine, University of Alabama at Birmingham.
authors.forename: Kurt R
authors.initials: KR
authors.lastname: Zinn
authors.affiliation: School of Medicine, University of Alabama at Birmingham.
authors.forename: Eben
authors.initials: E
authors.lastname: Rosenthal