Oxime Coupling of Active Site Inhibited Factor Seven with a Nonvolatile, Water-Soluble Fluorine-18 Labeled Aldehyde

Bioconjug Chem. 2019 Mar 20;30(3):775-784. doi: 10.1021/acs.bioconjchem.8b00900. Epub 2019 Feb 6.

Abstract

A nonvolatile fluorine-18 aldehyde prosthetic group was developed from [18F]SFB, and used for site-specific labeling of active site inhibited factor VII (FVIIai). FVIIai has a high affinity for tissue factor (TF), a transmembrane protein involved in angiogenesis, proliferation, cell migration, and survival of cancer cells. A hydroxylamine N-glycan modified FVIIai (FVIIai-ONH2) was used for oxime coupling with the aldehyde [18F]2 under mild and optimized conditions in an isolated RCY of 4.7 ± 0.9%, and a synthesis time of 267 ± 5 min (from EOB). Retained binding and specificity of the resulting [18F]FVIIai to TF was shown in vitro. TF-expression imaging capability was evaluated by in vivo PET/CT imaging in a pancreatic human xenograft cancer mouse model. The conjugate showed exceptional stability in plasma (>95% at 4 h) and a binding fraction of 90%. In vivo PET/CT imaging showed a mean tumor uptake of 3.8 ± 0.2% ID/g at 4 h post-injection, a comparable uptake in liver and kidneys, and low uptake in normal tissues. In conclusion, FVIIai was labeled with fluorine-18 at the N-glycan chain without affecting TF binding. In vitro specificity and a good in vivo imaging contrast at 4 h postinjection was demonstrated.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldehydes / chemistry*
  • Animals
  • Binding Sites
  • Catalytic Domain
  • Cyclization
  • Factor VII / antagonists & inhibitors*
  • Fluorine Radioisotopes / chemistry*
  • Mice
  • Oximes / chemistry*
  • Positron Emission Tomography Computed Tomography
  • Thromboplastin / metabolism
  • Tissue Distribution
  • Water

Substances

  • Aldehydes
  • Fluorine Radioisotopes
  • Oximes
  • Water
  • Factor VII
  • Thromboplastin