Radiolabeling and evaluation of (64)Cu-DOTA-F56 peptide targeting vascular endothelial growth factor receptor 1 in the molecular imaging of gastric cancer.

Noninvasive imaging of vascular endothelial growth factor receptor 1 (VEGFR1) remains a great challenge in early diagnosis of gastric cancer. Here we reported the synthesis, radiolabeling, and evaluation of a novel (64)Cu-radiolabeled peptide for noninvasive positron emission tomography (PET) imaging of VEGFR1 positive gastric cancer. The binding of modified peptide WHSDMEWWYLLG (termed as F56) to VEGER-1 expressed in gastric cancer cell BCG823 has been confirmed by immune-fluorescence overlap. DOTA-F56 was designed and prepared by solid-phase synthesis and folded in vitro. (64)Cu-DOTA-F56 was synthesized in high radiochemical yield and high specific activity (S.A. up to 255.6 GBq/mmol). It has excellent in vitro stability. Micro-PET imaging of (64)Cu-DOTA-F56 identifies tumor in BCG823 tumor-bearing mice, while that of (18)F-FDG does not. Immunohistochemical analysis of excised BCG823 xenograft showed colocalization between the PET images and the staining of VEGFR1. These results demonstrated that (64)Cu-DOTA-F56 peptide has potential as a noninvasive imaging agent in VEGFR1 positive tumors.