Evaluation of Pan-SSTRs Targeted Radioligand [⁶⁴Cu]NOTA-PA1 Using Micro-PET Imaging in Xenografted Mice

⁶⁴Cu-labeled new pan-somatostatin receptors (pan-SSTRs) probe PA1 was synthesized, characterized, and evaluated by in vitro and in vivo experiments. [⁶⁴Cu]NOTA-PA1 was obtained with high specific activity, high radiochemical purity, and good stability. Cell uptake of [⁶⁴Cu]NOTA-PA1 was higher than that of [⁶⁴Cu]DOTA-TATE in MCF-7, A549, BGC823, and HT-29 cell lines. [⁶⁴Cu]NOTA-PA1 showed high binding affinity for SSTRs expressed in A549 cells. The in vivo biodistribution and micropositron emission tomography (micro-PET) imaging studies of [⁶⁴Cu]NOTA-PA1 revealed good detection ability in MCF-7 and A549 xenografted nude mice. The radiosynthesis, quality control, and preliminary biological evaluation of [⁶⁴Cu]NOTA-PA1 have broaden the application of radiolabeled octreotide for SSTRs imaging, which could act as a potential multisubtypes targeted radiotracer for imaging SSTRs-positive tumors.