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

• Published in: Bioconjugate chemistry 2019-03, Vol.30 (3), p.775-784
• Main Authors: Jeppesen, Troels E, Kristensen, Lotte K, Nielsen, Carsten H, Petersen, Lars C, Kristensen, Jesper B, Behrens, Carsten, Madsen, Jacob, Kjaer, Andreas
• Format: Article
• Language: English
• Subjects: Aldehydes; Aldehydes - chemistry; Angiogenesis; Animals; Binding; Binding Sites; Cancer; Catalytic Domain; Cell adhesion & migration; Cell migration; Cell proliferation; Cell survival; Coagulation factors; Computed tomography; Coupling; Cyclization; Factor VII - antagonists & inhibitors; Fluorine; Fluorine isotopes; Fluorine Radioisotopes - chemistry; Glycan; Hydroxylamine; Kidneys; Medical imaging; Mice; Oximes - chemistry; Pancreas; Pancreatic cancer; Positron emission; Positron Emission Tomography Computed Tomography; Prostheses; Thromboplastin - metabolism; Tissue Distribution; Tissue factor; Tomography; Water; Xenografts; Xenotransplantation
• ISSN: 1043-1802; 1520-4812
• DOI: 10.1021/acs.bioconjchem.8b00900

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.