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

## TL;DR

This paper introduces a new multicyclic peptide targeting PD-L1 for better imaging and treatment of cancer.

## Contribution

The study presents a novel disulfide-directed multicyclic peptide platform for PD-L1 imaging and therapy.

## Key findings

- A disulfide-directed multicyclic peptide platform was developed for PD-L1 targeting.
- The platform enables high-affinity ligands for PD-L1 imaging and potential therapeutic use.
- This approach addresses limitations in tumor accumulation and pharmacokinetics of current radiotracers.

## Abstract

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 in vivo. 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.