CD274 and cancer: Although their binding affinity is lower than that of antibodies, they are small, easy to synthesize, and capable of flexible chemical modification.179 With these distinctive advantages over antibodies, peptides have been increasingly used as probes for tumor receptor imaging, such as peptides for PD-L1 imaging,180–183 integrin αvβ3 imaging,184–186 and somatostatin receptor imaging.187 To date, many peptide-based probes have been developed and clinically used for cancer diagnosis and treatment.187–189