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Immuno-PET and activatable near-infrared fluorescence dual-modality imaging of L1-CAM expression in cholangiocarcinoma model.

2016; Society of Nuclear Medicine and Molecular Imaging; Volume: 57; Linguagem: Inglês

1535-5667

Hye Ri Kim, In Ho Song, Tae Sup Lee, Hyo Jung Hong, Gwang Il An, Kwang Il Kim, Yong Jin Lee, Joo Hyun Kang, Sang Moo Lim,

Cancer, Hypoxia, and Metabolism

1213 Objectives L1 cell adhesion molecule (L1-CAM) is implicated in the control of proliferation, migration, and invasion of several tumors including cholangiocarcinoma. We prepared a chimeric anti-L1-CAM antibody (cA10-A3) tagged with both 64Cu and indocyanine green (ICG) and evaluated for the feasibility of dual-modal PET/NIRF imaging of L1-CAM expression and image-guided surgery using dual labeled antibody in cholangiocarcinoma xenograft model. Methods We labeled cA10-A3 with both 64Cu via p-SCN-Bn-NOTA and a NIRF dye, ICG as an activatable fluorescent probe. Immunoconjugates were treated with detergent and reducing agent to re-activate the fluorescence of bound ICG. Serum stability, immunoreactivity test and flow cytometry analysis were performed. Cell binding assay of 64Cu-NOTA-cA10-A3-ICG was performed in ACHN, SK-OV-3-Luc and SCK-L1-Luc cells. Biodistribution and PET/NIRF imaging of 64Cu-NOTA-cA10-A3-ICG were obtained at 24, 48 and 72 h in SCK-L1-Luc xenografted mice. Blocking experiment with cold cA10-A3 was also performed. Results The conjugates had minimal fluorescence signal in PBS, but became fluorescent by re-activation. 64Cu-labeled antibody showed high radiolabeling yield, high stability (> 99%) and favorable immunoreactivity (0.98). Cell bound radioactivity and fluorescence intensity of 64Cu-NOTA-cA10-A3-ICG in cell lines were well correlated with the levels of L1-CAM expression by flow cytometry analysis. In biodistribution study, tumor uptakes of 64Cu-NOTA-cA10-A3-ICG were 39.3 ± 7.5, 41.2 ± 5.9 and 45.0 ± 6.2 %ID/g at 24, 48 and 72 h, respectively. In ex vivo NIRF imaging, the fluorescent activity of SCK-L1-luc tumor was higher than those of most major organs, except for liver. Considering the absolute tumor uptake, tumor-to-background ratio and half-life of 64Cu, the optimal time point for PET imaging was 48 h. Excellent contrast for NIRF imaging was achieved at 72 h when tumor-to-backgrounds ratio peaked. In blocking study, tumor uptakes were markedly reduced (P Conclusions We showed the feasibility for immune-PET and intraoperative optical imaging of L1-CAM expressing cholangiocarcinoma using dual-labeled cA10-A3. Dual-labeled L1-CAM targeting agent may provide useful information to improve delineation of tumors and image-guided surgery for cholangiocarcinoma.