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Cucurbituril-Ferrocene: Host-Guest Based Pretargeted Positron Emission Tomography in a Xenograft Model


Jallinoja VIJ , Carney BD , Zhu M , Bhatt K , Yazaki PJ , Houghton JL , . Bioconjugate chemistry. 2021 06 22; ().


Pretargeted positron emission tomography is a macromolecule-driven nuclear medicine technique that involves targeting a preadministered antigen target-bound macromolecule with a radioligand aiming to minimize the overall radiation dose. This study investigates the use of antibody based host-guest chemistry methodology for pretargeted positron emission tomography. We hypothesize that the novel pretargeting approach reported here overcomes the challenges the current pretargeting platforms have with the stability and modularity of the pretargeting components. A cucurbit[7]uril host molecule modified, anti-carcinoembryonic antigen antibody (M5A; CB7-M5A) and a Ga-radiolabeled ferrocene guest radioligand ([Ga]Ga-NOTA-PEG-NMe-Fc) were studied as potential host-guest chemistry pretargeting agents for positron emission tomography in BxPC3 xenografted nude mice. The viability of the platform was studied via biodistribution and positron emission tomography. Tumor uptake of [Ga]Ga-NOTA-PEG-NMe-Fc was significantly higher in mice which received CB7-M5A prior to the radioligand injection (pretargeted) (3.3 ± 0.7%ID/g) compared to mice which only received the radioligand (nonpretargeted) (0.2 ± 0.1%ID/g).