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Updated: Jun 11, 2026
Development of a 68Gallium-Labeled D-Peptide PET Tracer for Imaging Programmed Death-Ligand 1 Expression
Published on: February 3, 2023
Development and Preclinical Evaluation of 68Ga-Labeled B7-H3-Specific Bicyclic Peptides as Immuno-PET Tracers for
Fengsheng Zhang1,2,3,4,5,6, Jindian Li1,7,3,4,5,6,8,9,10, Dongliang Wang1,3,4,5,6
1Department of Nuclear Medicine, Fudan University Shanghai Cancer Center, Shanghai 200032, China.
Abstract:
B7-H3 (CD276) is an emerging target for cancer theranostics, highlighting the need for imaging probes capable of noninvasively quantifying B7-H3 expression in tumors. Here, we developed three 68Ga-labeled B7-H3-targeting bicyclic peptide tracers with different PEG linker lengths. All tracers showed high radiochemical purity (>96%), favorable in vitro stability, and rapid blood clearance. Among them, [68Ga]Ga-B7H3-FZ1 exhibited the highest affinity (KD = 83.22 nM). Micro-PET/CT imaging demonstrated that tumor uptake of [68Ga]Ga-B7H3-FZ1 correlated positively with B7-H3 expression across multiple tumor models. In H1299 tumors. B7-H3 overexpression increased uptake from 1.09 ± 0.18 to 3.50 ± 0.97%ID/g at 30 min postinjection, confirming target specificity. Biosafety studies indicated no obvious toxicity. These results support [68Ga]Ga-B7H3-FZ1 as a promising PET tracer for noninvasive B7-H3 imaging.
Insights
Researchers developed novel Gallium-68 labeled bicyclic peptide tracers to image B7-H3 (CD276) expression in tumors. The tracer [68Ga]Ga-B7H3-FZ1 shows promise for noninvasive cancer theranostics.
Area of Science:
- Oncology
- Radiochemistry
- Molecular Imaging
Background:
- B7-H3 (CD276) is a promising target for cancer theranostics.
- Noninvasive methods are needed to quantify B7-H3 expression in tumors.
Purpose of the Study:
- To develop and evaluate Gallium-68 labeled bicyclic peptide tracers for B7-H3 imaging.
- To assess the affinity, stability, and tumor targeting of novel tracers.
Main Methods:
- Synthesis and radiolabeling of three 68Ga-labeled B7-H3-targeting bicyclic peptide tracers with varying PEG linker lengths.
- In vitro stability and affinity assays.
- In vivo micro-PET/CT imaging in tumor-bearing mouse models to evaluate tumor uptake and target specificity.
Main Results:
- All tracers demonstrated high radiochemical purity (>96%), good in vitro stability, and rapid blood clearance.
- [68Ga]Ga-B7H3-FZ1 showed the highest binding affinity (KD = 83.22 nM).
- Micro-PET/CT imaging confirmed that tumor uptake of [68Ga]Ga-B7H3-FZ1 positively correlated with B7-H3 expression and demonstrated target specificity in H1299 tumors.
Conclusions:
- [68Ga]Ga-B7H3-FZ1 is a highly promising PET tracer for noninvasive imaging of B7-H3 expression.
- This tracer has potential applications in cancer theranostics.
- The developed tracers offer a valuable tool for evaluating B7-H3 expression in various tumor models.
![Automated Preparation of [68Ga]Ga-3BP-3940 on a Synthesis Module for PET Imaging of the Tumor Microenvironment](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F68356.jpg&w=3840&q=50)
