Clinical Translation of a 68Ga-Labeled Integrin αvβ6-Targeting Cyclic Radiotracer for PET Imaging of Pancreatic Cancer.

Abstract

The overexpression of integrin αvβ6 in pancreatic cancer makes it a promising target for noninvasive PET imaging. However, currently, most integrin αvβ6-targeting radiotracers are based on linear peptides, which are quickly degraded in the serum by proteinases. Herein, we aimed to develop and assess a 68Ga-labeled integrin αvβ6-targeting cyclic peptide (68Ga-cycratide) for PET imaging of pancreatic cancer. Methods:68Ga-cycratide was prepared, and its PET imaging profile was compared with that of the linear peptide (68Ga-linear-pep) in an integrin αvβ6-positive BxPC-3 human pancreatic cancer mouse model. Five healthy volunteers (2 women and 3 men) underwent whole-body PET/CT imaging after injection of 68Ga-cycratide, and biodistribution and dosimetry were calculated. PET/CT imaging of 2 patients was performed to investigate the potential role of 68Ga-cycratide in pancreatic cancer diagnosis and treatment monitoring. Results:68Ga-cycratide exhibited significantly higher tumor uptake than did 68Ga-linear-pep in BxPC-3 tumor-bearing mice, owing-at least in part-to markedly improved in vivo stability. 68Ga-cycratide could sensitively detect the pancreatic cancer lesions in an orthotopic mouse model and was well tolerated in all healthy volunteers. Preliminary PET/CT imaging in patients with pancreatic cancer demonstrated that 68Ga-cycratide was comparable to 18F-FDG for diagnostic imaging and postsurgery tumor relapse monitoring. Conclusion:68Ga-cycratide is an integrin αvβ6-specific PET radiotracer with favorable pharmacokinetics and a favorable dosimetry profile. 68Ga-cycratide is expected to provide an effective noninvasive PET strategy for pancreatic cancer lesion detection and therapy response monitoring.