Development of a Novel HER2-Targeted Peptide Probe for Dual-Modal Imaging of Tumors

Human epidermal growth factor receptor 2 (HER2) may serve as a valid target for diagnosis of cancer. The probes with capability for near-infrared window one region II (NIR-II) and positron emission tomography (PET) dual-modal imaging are highly desired for HER2-positive tumor detection. Herein, three HER2-targeted peptides were designed and further modified with indocyanine green (ICG) and 2,2',2″,2″-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (DOTA), which were used for NIR-II imaging and complexation with ⁶⁸Ga for PET. Among the resulted probes (DOTA-ZC01-ICG, DOTA-KSP-ICG, and DOTA-ZC02-ICG), NIR-II imaging revealed that DOTA-ZC02-ICG had the best tumor imaging performance in SKOV3 tumor-bearing mice. The highest T/N ratio (5.4) was achieved at 4 h post-injection. Furthermore, DOTA-ZC02-ICG was radiolabeled with ⁶⁸Ga to generate [⁶⁸Ga]-DOTA-ZC02-ICG for PET, and it clearly delineated at 0.5, 1, and 2 h post-injection. The tumor uptake reached 1.9 %ID/g at 0.5 h, and the tumor uptakes were significantly inhibited in the blocking study (p < 0.05). Overall, it provides a promising technique for tumor dual-modal imaging and a new molecular scaffold for developing HER2-targeted theranostic agents.