Developing native peptide-based radiotracers for PD-L1 PET imaging and improving imaging contrast by pegylation

Herein, a PD-L1 targeted native peptide was developed for PET imaging. 18 F and 64 Cu were utilized to label the peptide. To improve the pharmacokinetics and biodistribution of the tracers, the peptide was further pegylated to form star-like tetramers. Consequently, four tracers were synthesized with acceptable radiochemical characteristics and their in vivo pharmacokinetics and PD-L1 imaging capability were systematically evaluated. This proof-of-principle study may provide new possibilities for PD-L1 PET imaging in cancers. Native peptide-based PET tracers were developed for PD-L1 imaging. The pegylation of the peptide improves the pharmacokinetics and biodistribution of the tracers.