Synthesis of [ ¹⁸F]anginex with high specific activity [ ¹⁸F]fluorobenzaldehyde for targeting angiogenic activity in solid tumors

Anginex is a 33-residue peptide that has been previously demonstrated to possess antiangiogenic properties. To provide a tool to evaluate the regional biodistribution and pharmacokinetics of anginex, and possibly to provide a useful angiogenesis-targeted radiotracer, we have radiolabeled anginex with fluorine-18. High specific activity [ ¹⁸F]fluorobenzaldehyde (1.5-4.8 TBq (40-130 Ci)/μmol) was used to label anginex via reductive amination in 76% yield. The effective specific activity of the product was lower because unlabeled anginex was not separated. However, the high specific activity labeling reagent increased the labeling yield and reduced the amount of anginex required for labeling. Regional pharmacokinetics were measured by PET scanning in mice, demonstrating tumor uptake and low background, with up to 30% of total injected dose localized in some tumors.