Synthesis and Preclinical Evaluation of Dual-Targeted Molecular Tracer for Positron Emission Tomography Imaging of Programmed Cell Death Ligand-1 and Integrin αvβ3

Abstract

Dual-targeting strategies have shown considerable potential in improving the imaging contrast and specificity toward tumor tissues. In this study, we synthesized a dual-targeted tracer, [⁶⁸Ga]Ga-NOTA-IMB-RGD, which synergistically targeted programmed cell death ligand-1 (PD-L1) and integrin α_vβ₃. The tracer was produced with high radiochemical purity (>95%) and radiochemical yield (>95%). In vitro cellular uptake studies revealed that [⁶⁸Ga]Ga-NOTA-IMB-RGD exhibited high binding affinity for both PD-L1 and α_vβ₃, resulting in significantly higher uptake in PD-L1- and α_vβ₃-positive cells (U87, A375-hPD-L1, B16–F10, and MC38) compared to α_vβ₃-positive (A375) or PD-L1- and α_vβ₃-negative (LLC) cells. In vivo imaging of [⁶⁸Ga]Ga-NOTA-IMB-RGD in tumor-bearing mice revealed high and specific tumor uptake in double-positive tumors, modest tumor uptake in single-positive tumors, and low uptake in double-negative tumors, indicating strong binding to both PD-L1 and α_vβ₃ in vivo. Ex vivo tissue analysis further validated the high specificity and sensitivity of [⁶⁸Ga]Ga-NOTA-IMB-RGD in detecting tumors coexpressing PD-L1 and α_vβ₃. Importantly, [⁶⁸Ga]Ga-NOTA-IMB-RGD exhibited enhanced tumor uptake and retention compared to both PD-L1-targeted and α_vβ₃-targeted tracers in the same tumor models. In conclusion, the dual-targeted tracer [⁶⁸Ga]Ga-NOTA-IMB-RGD was successfully prepared and showed significantly specific targeting of both PD-L1 and α_vβ₃ in vivo, offering promising potential for clinical translation.