[摘要]：Radiolabeled RGD and bombesin peptides have been extensively investigated for tumor integrin avb3 and GRPR imaging, resp. Due to the fact that many tumors are both integrin and GRPR pos., we designed and synthesized a heterodimeric peptide Glu-RGD-BBN, which is expected to be advantageous over the monomeric peptides for dual-receptor targeting. A PEG3 spacer was attached to the glutamate a-amino group of Glu-RGD-BBN to enhance the 18F labeling yield and to improve the in vivo kinetics. PEG3-Glu-RGD-BBN possesses the comparable GRPR and integrin avb3 receptor-binding affinities as the corresponding monomers, resp. The dual-receptor targeting properties of 18F-FB-PEG3-Glu-RGD-BBN were obsd. in PC-3 tumor model. 18F-FB-PEG3-Glu-RGD-BBN with high tumor contrast and favorable pharmacokinetics is a promising PET tracer for dual integrin and GRPR pos. tumor imaging. This heterodimer strategy may also be an applicable method to develop other mols. with improved in vitro and in vivo characterizations for tumor diagnosis and therapy.
