Development and Validation of a Multicyclic Peptide Targeting PD-L1 for Radiotheranostics

The advent of immune checkpoint blockade therapy, exemplified by inhibitors targeting programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) axis, has revolutionized the landscape of clinical oncology. Despite its remarkable success, therapeutic benefits remain limited to a subset of patients, highlighting the urgent need for more accurate methods of patient stratification. Conventional techniques for assessing PD-L1 expression, such as immunohistochemistry, provide static and localized information but lack the ability to capture whole-body distribution or temporal dynamics. In contrast, positron emission tomography (PET) offers a noninvasive approach for visualizing PD-L1 expression and disease burden <i>in vivo</i>. However, clinical translation of PD-L1-specific radiotracers has been hampered by suboptimal tumor accumulation and unfavorable pharmacokinetics. To address this limitation, a recent study established a disulfide-directed multicyclic peptide (DDMP) platform capable of generating high-affinity peptide ligands specifically designed for PD-L1 imaging and potential therapeutic applications.