Research Progress on Radiolabeled Small-Molecular Imaging Probes Targeting Programmed Cell Death Ligand 1

In recent years, the field of oncology therapy has evolved and research on immune checkpoint inhibitor therapy targeting programmed cell death 1 (PD-1) and its ligand (PD-L1) continues to grow. Tumor cells inhibit T-cell-mediated immune responses through the interaction of PD-1 and PD-L1, allowing them to escape the body's immune surveillance. This immune escape mechanism has become a major challenge in tumor therapy. Immune checkpoint inhibitor strategies induce apoptosis in tumor cells by blocking the PD-1/PD-L1 pathway. However, how to accurately screen the patient population suitable for this immunotherapy has become a critical issue to be addressed in clinical practice. Studies have shown that the expression level of PD-L1 on the tumor surface is closely related to the efficacy of this immunotherapy. Radionuclide-labeled imaging probes targeting PD-L1 can visualize the expression of PD-L1 in tumor cells and thus guide immunotherapy. This study adopts the literature review method to explore in depth the application of radiolabeled small-molecule imaging probes targeting PD-L1 in tumor imaging, providing guidance and reference for the further development of PD-L1-targeted small-molecule imaging probes.