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

Bioconjug Chem. 2021 Aug 18;32(8):1554-1558. doi: 10.1021/acs.bioconjchem.1c00280. Epub 2021 Jun 22.

Abstract

Pretargeted positron emission tomography is a macromolecule-driven nuclear medicine technique that involves targeting a preadministered antigen target-bound macromolecule with a radioligand in vivo, 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 in vivo stability and modularity of the pretargeting components. A cucurbit[7]uril host molecule modified, anti-carcinoembryonic antigen antibody (M5A; CB7-M5A) and a 68Ga-radiolabeled ferrocene guest radioligand ([68Ga]Ga-NOTA-PEG3-NMe2-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 in vivo biodistribution and positron emission tomography. Tumor uptake of [68Ga]Ga-NOTA-PEG3-NMe2-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).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carcinoembryonic Antigen / analysis
  • Ferrous Compounds / chemistry*
  • Humans
  • Immunoconjugates / chemistry
  • Macrocyclic Compounds / chemistry*
  • Male
  • Metallocenes / chemistry*
  • Mice
  • Mice, Nude
  • PC-3 Cells
  • Positron-Emission Tomography
  • Prostatic Neoplasms / diagnostic imaging*
  • Radiopharmaceuticals / chemistry

Substances

  • Carcinoembryonic Antigen
  • Ferrous Compounds
  • Immunoconjugates
  • Macrocyclic Compounds
  • Metallocenes
  • Radiopharmaceuticals
  • cucurbit(n)uril
  • ferrocene