A Dual Reporter Iodinated Labeling Reagent for Cancer Positron Emission Tomography Imaging and Fluorescence-Guided Surgery

The combination of
early diagnosis and complete surgical resection
offers the greatest prospect of curative cancer treatment. An iodine-124/fluorescein-based
dual-modality labeling reagent, 124I-Green, constitutes
a generic tool for one-step installation of a positron emission tomography
(PET) and a fluorescent reporter to any cancer-specific antibody.
The resulting antibody conjugate would allow both cancer PET imaging
and intraoperative fluorescence-guided surgery. 124I-Green
was synthesized in excellent radiochemical yields of 92 ± 5%
(n = 4) determined by HPLC with an improved one-pot
three-component radioiodination reaction. The A5B7 carcinoembryonic
antigen (CEA)-specific antibody was conjugated to 124I-Green.
High tumor uptake of the dual-labeled A5B7 of 20.21 ± 2.70, 13.31
± 0.73, and 10.64 ± 1.86%ID/g was observed in CEA-expressing
SW1222 xenograft mouse model (n = 3) at 24, 48, and
72 h post intravenous injection, respectively. The xenografts were
clearly visualized by both PET/CT and ex vivo fluorescence imaging.
These encouraging results warrant the further translational development
of 124I-Green for cancer PET imaging and fluorescence-guided
surgery.