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Development of a 68Gallium-Labeled D-Peptide PET Tracer for Imaging Programmed Death-Ligand 1 Expression
Published on: February 3, 2023
Positron Emission Tomography Imaging of Programmed Death 1 Expression in Cancer Patients Using 124I-Labeled
Shujing Wang1, Hua Zhu1, Jin Ding1
1From the Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute, Beijing.
Purpose:
Although anti-programmed cell death molecule-1 (PD-1)/PD-1 ligand therapy has achieved remarkable success in oncology field, the low response rate and lack of accurate prognostic biomarker identifying benefiting patients remain unresolved challenges. This study developed a PD-1 targeting radiotracer 124I-labeled toripalimab (124I-JS001) for clinical PET imaging and evaluated its biodistribution, safety, and dosimetry in human.
Methods:
Patients with melanoma or urologic cancer confirmed by pathology were enrolled. 124I-JS001 PET/CT and PET/MR were performed with or without coinjection of 5 mg unlabeled JS001, and 18F-FDG PET was undertaken within 1 week.
Results:
Eight melanoma and 3 urologic cancer patients were enrolled. No adverse events were noticed during the whole examination after the injection of 124I-JS001 and an acceptable dosimetry of 0.236 mSv/MBq was found. 124I-JS001 PET/CT showed high uptake in spleen and liver and slight uptake in bone marrow and lung. All primary and metastatic tumor lesions in 11 patients demonstrated different levels of uptake of 124I-JS001 with SUVmax ranging from 0.2 to 4.7. With coinjection of unlabeled JS001, the uptake in spleen was reduced significantly (P < 0.05), whereas tumor uptake and tumor background ratio increased significantly (P < 0.05). Four patients undertook regional 124I-JS001 PET/MR. All tumor lesions were detected effectively with abnormal MR signal on PET/MR, whereas PET/MR detected liver lesions more sensitively than PET/CT.
Conclusions:
The first-in-human study demonstrated 124I-JS001 was a safe tracer for PET with acceptable dosimetry, and the PET/CT results showed a favorable biodistribution. PET/MR could detect liver lesions more sensitively than PET/CT.
Insights
This study developed a novel radiotracer, 124I-labeled toripalimab (124I-JS001), for Positron Emission Tomography (PET) imaging. The tracer demonstrated safety and favorable biodistribution, showing potential for improved cancer patient selection.
Area of Science:
- Nuclear Medicine
- Oncology
- Radiopharmaceutical Development
Background:
- Anti-programmed cell death molecule-1 (PD-1)/PD-1 ligand therapy shows promise in oncology but suffers from low response rates.
- Accurate biomarkers are needed to identify patients who will benefit from PD-1/PD-1 ligand therapy.
- Positron Emission Tomography (PET) imaging offers a non-invasive method for evaluating drug distribution and target engagement.
Purpose of the Study:
- To develop and clinically evaluate a novel PD-1 targeting radiotracer, 124I-labeled toripalimab (124I-JS001), for PET imaging.
- To assess the biodistribution, safety, and dosimetry of 124I-JS001 in human subjects.
- To explore the utility of 124I-JS001 PET/CT and PET/MR in visualizing tumor lesions.
Main Methods:
- Eleven patients with melanoma or urologic cancer were enrolled.
- 124I-JS001 PET/CT and PET/MR imaging were performed, with and without unlabeled JS001 co-injection.
- 18F-FDG PET was conducted for comparison.
Main Results:
- 124I-JS001 exhibited a favorable safety profile with acceptable dosimetry (0.236 mSv/MBq).
- PET/CT showed high uptake in the spleen and liver, with varying uptake in tumor lesions (SUVmax 0.2–4.7).
- Co-injection of unlabeled JS001 significantly reduced spleen uptake while increasing tumor uptake and tumor-to-background ratio.
- PET/MR effectively detected tumor lesions and showed higher sensitivity for liver lesions compared to PET/CT.
Conclusions:
- 124I-JS001 is a safe and well-tolerated radiotracer for clinical PET imaging.
- The biodistribution of 124I-JS001 is favorable, with potential for improved tumor visualization when co-administered with unlabeled JS001.
- PET/MR offers enhanced sensitivity for detecting liver metastases compared to PET/CT.
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