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Updated: Jun 29, 2025
Development of a 68Gallium-Labeled D-Peptide PET Tracer for Imaging Programmed Death-Ligand 1 Expression
Published on: February 3, 2023
Preclinical development of novel PD-L1 tracers and first-in-human study of [68Ga]Ga-NOTA-RW102 in patients with lung
You Zhang1, Min Cao2, Yanfei Wu3
1Department of Nuclear Medicine, Institute of Clinical Nuclear Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Background:
The programmed cell death protein-1 (PD-1)/programmed death receptor ligand 1 (PD-L1) axis critically facilitates cancer cells' immune evasion. Antibody therapeutics targeting the PD-1/PD-L1 axis have shown remarkable efficacy in various tumors. Immuno-positron emission tomography (ImmunoPET) imaging of PD-L1 expression may help reshape solid tumors' immunotherapy landscape.
Methods:
By immunizing an alpaca with recombinant human PD-L1, three clones of the variable domain of the heavy chain of heavy-chain only antibody (VHH) were screened, and RW102 with high binding affinity was selected for further studies. ABDRW102, a VHH derivative, was further engineered by fusing RW102 with the albumin binder ABD035. Based on the two targeting vectors, four PD-L1-specific tracers ([68Ga]Ga-NOTA-RW102, [68Ga]Ga-NOTA-ABDRW102, [64Cu]Cu-NOTA-ABDRW102, and [89Zr]Zr-DFO-ABDRW102) with different circulation times were developed. The diagnostic efficacies were thoroughly evaluated in preclinical solid tumor models, followed by a first-in-human translational investigation of [68Ga]Ga-NOTA-RW102 in patients with non-small cell lung cancer (NSCLC).
Results:
While RW102 has a high binding affinity to PD-L1 with an excellent KD value of 15.29 pM, ABDRW102 simultaneously binds to human PD-L1 and human serum albumin with an excellent KD value of 3.71 pM and 3.38 pM, respectively. Radiotracers derived from RW102 and ABDRW102 have different in vivo circulation times. In preclinical studies, [68Ga]Ga-NOTA-RW102 immunoPET imaging allowed same-day annotation of differential PD-L1 expression with specificity, while [64Cu]Cu-NOTA-ABDRW102 and [89Zr]Zr-DFO-ABDRW102 enabled longitudinal visualization of PD-L1. More importantly, a pilot clinical trial shows the safety and diagnostic value of [68Ga]Ga-NOTA-RW102 immunoPET imaging in patients with NSCLCs and its potential to predict immune-related adverse effects following PD-L1-targeted immunotherapies.
Conclusions:
We developed and validated a series of PD-L1-targeted tracers. Initial preclinical and clinical evidence indicates that immunoPET imaging with [68Ga]Ga-NOTA-RW102 holds promise in visualizing differential PD-L1 expression, selecting patients for PD-L1-targeted immunotherapies, and monitoring immune-related adverse effects in patients receiving PD-L1-targeted treatments.
Trial Registration Number:
NCT06165874.
Insights
Researchers developed novel tracers for imaging programmed death-ligand 1 (PD-L1) expression in tumors. ImmunoPET imaging with [68Ga]Ga-NOTA-RW102 shows promise for patient selection and monitoring side effects of PD-L1 therapies.
Area of Science:
- Oncology
- Immunology
- Radiochemistry
- Molecular Imaging
Background:
- The programmed cell death protein-1 (PD-1)/programmed death receptor ligand 1 (PD-L1) pathway is crucial for cancer immune evasion.
- Antibody therapies targeting PD-1/PD-L1 have shown significant efficacy in various cancers.
- Immuno-positron emission tomography (ImmunoPET) offers a potential method for visualizing PD-L1 expression in solid tumors.
Purpose of the Study:
- To develop and validate novel PD-L1-targeted tracers for ImmunoPET imaging.
- To assess the diagnostic efficacy of these tracers in preclinical models and a first-in-human study.
- To explore the potential of ImmunoPET in patient selection and monitoring of immunotherapy-related adverse effects.
Main Methods:
- Generation and selection of high-affinity variable domain of the heavy chain of heavy-chain only antibody (VHH) clones (RW102) targeting human PD-L1.
- Engineering of an albumin-binding VHH derivative (ABDRW102).
- Development of four PD-L1-specific radiotracers ([68Ga]Ga-NOTA-RW102, [68Ga]Ga-NOTA-ABDRW102, [64Cu]Cu-NOTA-ABDRW102, and [89Zr]Zr-DFO-ABDRW102) with varying circulation times.
- Preclinical evaluation in solid tumor models and a first-in-human clinical trial in non-small cell lung cancer (NSCLC) patients.
Main Results:
- RW102 demonstrated high binding affinity (KD = 15.29 pM) to PD-L1; ABDRW102 showed high affinity for both PD-L1 (KD = 3.71 pM) and human serum albumin (KD = 3.38 pM).
- [68Ga]Ga-NOTA-RW102 enabled same-day visualization of differential PD-L1 expression in preclinical models.
- [64Cu]Cu-NOTA-ABDRW102 and [89Zr]Zr-DFO-ABDRW102 allowed longitudinal PD-L1 imaging.
- The first-in-human study confirmed the safety and diagnostic value of [68Ga]Ga-NOTA-RW102 ImmunoPET in NSCLC patients, suggesting potential for predicting immune-related adverse effects.
Conclusions:
- A series of PD-L1-targeted tracers were successfully developed and validated.
- [68Ga]Ga-NOTA-RW102 ImmunoPET imaging shows significant potential for visualizing PD-L1 expression.
- This imaging approach may aid in patient selection for PD-L1-targeted immunotherapies and in monitoring treatment-related adverse effects.
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